APRIL 1977 VOLUME. 2, Nu `'

www.americanradiohistory.com Old Fashion W a

in the Tradition

Our 6800 computer system repre- you who have purchased extra con - That's another thing. Mikbug is a sents the best value available today, nectorsfor your S -100 machines know standard Motorola part. It is used in with no sacrifice in performance. what kind of money this can run many systems and supported by the into. The 6800 is supplied with all Motorola software library in addition I would like to explain why this is mother board connectors. No extras, to our own extensive collection of true. The most basic reason is that or options like memory, or con- programs. It is not an orphan like the 6800 is a simpler, more elegant nectors for the mother board are many monitor systems that are uni- machine. The 6800 architecture is in our que to the manufacturer using them memory oriented rather than bus needed 6800 system. and which can only run software pro- oriented as are the older 8008, 8080 The 6800 is not beautiful, but "Oh vided by that manufacturer. Check and Z -80 type processors. This is an Boy" is it functional. That plain the program articles in Byte, Interface important difference. It results in a black box is strong and it has an and Kilobaud. You will find that al- computer that is far easier to program annodized finish. This is the hardest, most all 6800 programs are written on the more basic machine language toughest finish you can put on alu- for systems using a Mikbug monitor. and assembly language levels. It also minum. Most others use paint, or Guess how useful these are if you results in a far simpler bus structure. other less expensive finishes. The have some off -brand monitor in your The 6800 uses the SS -50 bus which 6800 does not have a pretty front computer. has only half the connections needed panel with lights and multicolor swit- in the old S -100 (IMSAI /MITS) bus ches. This is because the lights and The 6800 will never win any beauty system. If you don't think this makes switches are not only expensive, and prizes. It is like the Model "T" and a difference, take a look at the mother unnecessary, but also a great big pain the DC -3 not pretty, but beautiful boards used in both systems -com- to use. We don't crank up the 6800; in function. It is simple, easy to use pare them. The SS -50 system has we use an electric starter -a monitor and maintain and does its job in wide, low impedance 0.1 lines with ROM called Mikbug. He automatical- the most reliable and economical way good heavy, easily replaced Molex ly does all the loading for you with- possible. What more could you want? connectors. The S -100 bus, on the out any time wasting switch flopping. Mikbug 0 is a registered trademark other hand, has a very fine hair -like So in the 6800 system you don't buy of Motorola Inc. lines that must be small enough to something expensive (the console) pass between pins on a 100 contact that you will probably want to stop using as soon as you can get your EOM edge connector. I'll give you one Computer System guess which is the most reliable and hands on a PROM board and a good with serial interface and 4,096 words noise free. As for cost -well any of monitor. of memory $395.00

Enclosed is $395 for my SwTPC Computer Kit r Send Data

or BAC

or MC Ex Date

NAME

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www.americanradiohistory.com Meet the most powerful µC system available for dedicated work. Yet it's only $595:

Here's the muscle you've been telling us you Standard rack -mount style construction that's wanted: a powerful Cromemco microcomputer in a usable with a variety of cabinets and is upward style and price range ideal for your dedicated com- compatible with larger systems. Bench cabinet puter jobs - ideal for industrial, business, instru- optional. mentation and similar applications. Card retainer to secure cards in sockets under all It's the new Cromemco Z -2 Computer System. conditions. In the Z -2 you get all of the following for only $595: 110- or 220 -volt operation.

The industry's fastest 1 P board (4 MHz or 250 - DEDICATED APPLICATIONS nanosecond cycle time). The new Z -2 is specifically designed as a powerful The power and convenience of the well -known but economical dedicated computer for systems Z -80 ,.P. work. Notice that the front panel is entirely free of A power supply you won't believe ( +8V @ 30A, controls or switches of any kind. That makes the +18V and -18V @ 15A. That's not only ample Z -2 virtually tamper -proof. No accidental program power for a full set of cards but ample additional changes or surprise memory erasures. power for other peripherals such as floppy disk (For your custom work, Cromemco will supply drives). blank panels.) A full -length shielded motherboard with 21 card 4 MHz SPEED slots to let you plug in almost any conceivable Cromemco's microcomputers are the fastest and combination of memory, I/O or your own cus- most powerful available. The 4 MHz speed of the tom circuits. Z -2 means you get about twice the speed of nearly Power -on -jump circuitry to begin automatic pro- any other microcomputer. gram execution when power is (continued on next page) turned on. The S -100 bus that's widely supported by a host of peripherals manufacturers. All -metal chassis and dust case. Z-2 Shown with optional bench Conltur,rri¡ri,IL cabinet

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www.americanradiohistory.com That 4 MHz speed cuts running time in half - cuts your waiting time in half. Lets you do more sophisticated work that might not otherwise be practical with a microcomputer. Z -80 GIVES MORE COMPUTER POWER The Z -2 uses the powerful Z -80 microprocessor with its 158 -instruction set, 19 internal registers, 10 addressing modes, and 16 bit arithmetic operations. The Z -80 is widely regarded as the standard microprocessor of the future. So you're in the technical fore with the Z-2. But you can also plug in other microprocessor boards if you wish. BROAD SOFTWARE SUPPORT Since the Z -2 uses the Z -80, your present 8080 soft- Full -width motherboard ware can be used with the Z -2. In addition, Cromemco has slots for 21 cards. also offers software support including a monitor, assembler, and a BASIC interpreter.

STANDARD S -100 BUS The Z -2 uses the S -100 bus that has become standard in the microcomputer field. Dozens of manufacturers support it with compatible peripherals. Of course, all Cromemco peripherals such as our 7- channel A/D and D/A converter, our well -known IÌ ii Ìf BYTESAVER with its built -in PROM programmer, our color graphics interface, etc., will also plug into the bus. LOW NOISE Cromemco engineers have been careful to design the Z -2 for reliable operation at its fast 4 MHz speed. Noise on the motherboard, for example, has been carefully minimized by a unique ground -plane design (we call it our 'Blitz Bus'"'). With this bus you won't get erratic operation due to ground current noise. RACK OR CABINET MOUNTING The basic Z -2 is supplied in a black- anodized metal case for mounting in a standard 19 -inch relay rack. A high -quality stylized bench cabinet in an attractive blue color is also available.

Z -2 is supplied for rack mounting. KIT OR ASSEMBLED Attractive bench cabinet shown is You can get the Z -2 either kit or assembled. The kit also available. includes the Z -2 for rack mounting, the Cromemco 4 MHz microprocessor card, full -length 21- card -slot motherboard, power supply, one card socket and card - guide set, and front panel. The assembled Z -2 includes the above as well as all 21 sockets and card guides and a cooling fan. LOW, LOW PRICE All who've seen the Z-2 have been surprised and impressed with its low price. You'll be impressed, too, with its technical excellence and quality. So see it right away at your computer store - or order now directly from the factory. The sooner you put this advanced computer to work for you, the sooner you'll be solving problems and saving time /money. Z -2 Computer System kit (Model Z -2K) $595. Heavy -duty retainer bar insures that Z -2 Computer System assembled cards won't jostle out of sockets. (Model Z -2W) $995. Cromemeo in c o r p o r a t e d Specialists in computers and peripherals 2432 CHARLESTON RD., MOUNTAIN VIEW, CA 94043 (415) 964 -7400

www.americanradiohistory.com nin APRIL 1977 Volume 2 In the Queue Number 4

PUBLISHERS Foreground Virginia Peschke Manfred Peschke 8 KIM GOES TO THE MOON EDITOR Software -Butterfield Carl T Helmers Jr PRODUCTION MANAGER 40 A SOFTWARE CONTROLLED 1200 BPS AUDIO TAPE INTERFACE Judith Havey Peripherals- Helmers CIRCULATION MANAGER 60 DESIGNING THE "TINY ASSEMBLER " -Defining the Problem Manfred Peschke ASSISTANT PUBLISHER Emmerichs Software- Debra Boudrieau 100 NAVIGATION WITH MINI -O, Part 3 CO.OP EDITOR Software -Salter Scott Morrow PRODUCTION EDITOR Karen Gregory Background CIRCULATION Kimberly Barbour

12 A GUIDE TO BAUDOT MACHINES: Part 1 Ginnie F Boudrieau Hardware -McN att Cheryl Hurd Deborah R Luhrs 18 HAVING A "PRIVATE AFFAIR" WITH YOUR COMPUTER Carol Nyland Humor -Ciarcia ADVERTISING Elizabeth Alpaugh 34 A REVIEW OF TOM PITTMAN'S TINY BASIC Virginia Peschke Software- Rosner ART 50 ARTIFICIAL INTELLIGENCE: WHAT IS IT? Noreen Bardsley Software -Rosenbaum Mary Jane Frohlich Ellen Shamonsky 70 ESTABLISHING THE CHU DYNASTY DRAFTING Fanaticisms -Gray Lynn Malo Bill Morello 78 EARLY INDICATIONS OF TECHNOLOGY IN ROMAN MILITARY Stephen Kruse ARTS or PLEXITUS SPECIAL PRODUCTS History-Barnes Susan Pearne Floyd Rehling 94 WHY AREN'T THERE ANY ALTAI RS ON ARCTURUS II? TYPOGRAPHY Commentary -Melton Custom Marketing Resources Inc 110 MICROPROCESSOR UPDATE: 8008 Goodway Graphics PHOTOGRAPHY History -Baker Ed Crabtree 124 MICROCOMPUTER GLOSSARY PRINTING Terminology -Price The George Banta Company Custom Marketing Resources Inc EDITORIAL CONSULTANT Nucleus Daniel Fylstra ASSOCIATES 4 In This BYTE Bob Baker 6 Born 300 Years Ahead of My Time BYTE magazine is published Walter Banks monthly by BYTE Publica- Steve Ciarcia 10 A Nybble on the Apple tions, Inc, 70 Main St, Peter- borough, New Hampshire David Fylstra 32 Letters 03458. Subscription rates are Portia Isaacson 59 Ask BYTE $12 for one year, $22 for two Harold A Mauch years, $30 for three years in CLUBS, CLASSIFIED 77 Review North America. Second class postage paid at Peterborough Peter Travisano 82, 141 What's New? New Hampshire 03458 and at TRAFFIC MANAGER additional mailing offices. Gregory Spitzfaden 90 Book Reviews Phone 603 -924 -7217. Entire 123 Classified Ads contents copyright © 1977 AFFILIATE PUBLISHER BYTE Publications, Inc, Peter- Southeast Asian Editions 128 Technical Forum borough NH 03458. All rights John Bannister reserved. Address editorial cor- 140 BYTE's Bits respondence to Editor, BYTE, 145 Computer Stores in Canada 70 Main St, Peterborough NH 03458. Opinions expressed by 146 Clubs, Newsletters authors are not necessarily those of BYTE magazine. 158 Kil O'Byte Address all subscription cor- 161 An 8080 Bug in the Stack respondence to: BYTE Subscriptions 162 PAPERBYTES Forum PO Box 361 Arlington MA 02174 176 BOMB 617- 646 -4329 176 Reader Service

www.americanradiohistory.com In This STE About the Cover ... E April Fool! This cover depicts a working (believe it or not) computer called "Spider," which was first seen Many people who play with com- Waiting for a slow audio tape inter- in a black and white shot in our puters have seen a version of that well face is one of the annoying aspects of August 1976 issue. The computer was known game, "lunar lander." Much stand alone computer systems without built by Roger Amidon, and this color has been written about different ver- much in the way of mass storage print was taken by Marj Kirk. For sions of the game in books and other peripherals. In this issue, find out how those who missed the August issue, the publications. In his article, KIM Goes you can run a Southwest Technical method of construction for this 12 bit to the Moon, Jim Butterfield adds one Products Corporation AC -30 tape mini was to wire point to point be- more chapter as he describes not only interface at four times its usual rate in tween small circuit cards. The Niagara a version of the game, but also the the article on A Software Controlled Falls effect of spilling off the table logic behind his particular develop- 1200 bps Audio Tape Interface. This was due to a wayward cat. ment of a lunar lander program to fit same interface can incidentally be run the limited resources of a single board at 300 bps to read Kansas City computer. (BYTE) standard tapes for which the AC -30 was intended. Who is Plexitus? He's the main Are you thinking of adding a hard - character in E E Barnes' hysterical copy device to your microprocessor For some time there has been a account of a jinxed Roman named but can't afford the price that is mystique associated with the phrase Plexitus who is credited with the required? Well, there are a lot of old "artificial intelligence." The mystery invention of flight, creation of the Baudot type teleprinters out there often lies in defining what it is. If we word idiot, and last (but hardly least) which have plenty of use left in them. take the definition offered by Turing the invention of the computer. Early Michael McNatt describes some of as "able to mimic the behaviour and Indications of Technology in Roman these devices that are available on the decision making of a human," then we Military Arts or Plexitus is a most surplus market today in his article, A are using artificial intelligence every interesting fictional history. Guide to Baudot Machines: Part 1, time we play a simple computer game Description of Available Devices. such as nim. In his article Artificial Science fiction has long been the Intelligence, What Is It ?, Richard L mainstay of people who are interested Watch out for complicated inter- Rosenbaum dispels some of the in the frontiers of the future, the personal situations. Your computer, if mystique that surrounds artificial in- possibilities of tomorrow's technology it is found out, could lead to events telligence, by means of some intro- today. But living in the world of today reminiscent of a jai alai fronton at ductory background information. has made much of yesterday's science mid game, as you'll find out by read- fiction ordinary occurrence. And some ing Steve Ciarcia's humorous account No system is truly complete with- of today's technology hasn't even been of Having a Private Affair With Your out some systems software to help you touched upon by science fiction Computer. create personalized software applica- writers! Henry Melton's essay, Why tions. But if memory is limited, how Aren't There Any Altairs on Arcturus Tom Pittman's Tiny BASIC lan- can you accomplish minimal functions II ?, concerns the curious absence of guage provides both the novice and such as assembly of programs? One personal computers in the works of experienced programmer with a way for 6800 users with 4 K bytes or science fiction, a small discrepancy in vehicle for conveying thoughts from more is described in Jack Emmerichs' the vision of our prophets ... the flowchart stage to working pro- article on Designing the "Tiny Assem- grams quickly and efficiently. Tiny bler." In this first part, he describes In this issue, we conclude the three BASIC is a language that can be the necessary prelude to such a design: part series about Omega Navigation

quickly mastered by the novice, yet Defining the Problem. (In our next with Mini -O with Richard J Salter's ar- has enough variations to satisfy the issue, the article continues with de- ticle on the software used to drive the experienced programmer. In the article tailed information, object code and hardware described in Ralph Burhans' A Review of Tom Pittman's Tiny some comments on customization to articles. In Richard's article you'll find BASIC, Richard Rosner details what individual circumstances.) out how to use a 6502 processor to abilities the language provides. He also measure Omega phase differences, and gives a fine example of the type of Learn about Establishing the CHU as an extra bonus, how to calibrate a programming which can be accom- Dynasty in your local computer club local clock in your lab with the Ce- plished in one short evening using such by reading Steven B Gray's somewhat sium atomic clocks used by the Omega a high level language. tongue -in -cheek article ... system.

www.americanradiohistory.com Undoubtedly ANON was talking sembled and tested, $745) includes all of of your new computer kit, you want about some of today's PC computers. the following as standard features: everything you need to be there. Exciting as they may be, most of them Video display interface. And with Sol, it is. give you a few surprises you really don't Keyboard interface. To order or to get more informa- need. Audio cassette interface. tion write Processor Technology, 6200 For example you have the board all 8080 microprocessor. Hollis St., Box B, Emeryville, CA 94608. wired, and suddenly it occurs to you, 512 eight bit bytes of PROM on (415) 652 -8080. "Where's the TV interface ?" a plug -in personality module. Surprise! (The TV interface is extra 2048 eight -bit words of RAM. and costs $200 plus.) A 1024 character video display TEMX6 "And the keyboard interface - generator. where's that ?" Serial and parallel interfaces for Surprise! (Add another $185 extra.) connection to external devices and "How about an audio cassette inter- an edge connector for memory face so you can store and enter low cost expansion. programs and large amounts of data ?" Optional extras include a power Surprise! (Add $175 more.) supply, video monitor, ASCII keyboard, And what about software ?" walnut case, floppy disk system, high Surprise! (Each program will cost speed paper tape reader, PROM pro- you $20 plus.) grammer, and color graphics interface. See what we mean? We also have a library of low cost soft- The new Sol PC Terminal Com- ware that's the best and most extensive puter. Ws a complete kit, hardware, in the industry. software and no surprises for $475. In short, you get a complete, It's the first small computer con- powerful, small computer and smart The ceived as part of a total system. terminal that's fully expandable to a larger Not only do you get everything you Sol system, as your requirements grow. Sol PC Terminal need, but our systems approach is more Surprises are great at Christmas- economical, too. The $475 kit (fully as- time. But when you're opening the box Computer

www.americanradiohistory.com it be a persistent gossip columnist or a more pleasing manifestation of reality. It seems Editorial that according to Arthur C Clarke, I really lived in the 23rd century of our current calender: That noted historian of the future wrote a historical novel about my adventures as the mildly tragic hero of his latest book on life in the 23rd century, Imperial Earth. The book is available at any local book store in paperback form, on the science fiction shelves. It's Clarke's contribution to the American Bicentennial. Like most historical novels (according to my mental stereotype), it is a mildly boring book which takes a lot of pages and features a slowly developing plot, giving ample opportunity to tour the wonders of the age in question. I find on reading the book that one of the three major characters in the story is named (at various places - the editors were inconsistent) Karl Helmer or Karl Helmers. I What a shock. While I would have liked How Was Born 300 Years to imagine myself the principal by namesake

of an Ayn Rand novel, I guess I'll just have by Carl Helmers Ahead of My Time to put up with Arthur C Clarke as a distant second best. (I really have no choice in the It started late last summer, the first of matter, and I'm certainly not about to be so as name John the rumors and innuendos. Someone walked superficial to change my to However, is an interesting coinci- Articles Policy up to me and said words to the effect of Galt.) it BYTE is continually seek- dence since there are numerous parallels ing quality manuscripts writ- "you know, Carl, Arthur C Clarke writes ten by individuals who are well about you...." How would you feel if with the character in the story (as well as applying personal systems, or vast differences). Here I am, fancying myself who have knowledge which someone walked up to you and made such a in an age will prove useful to our profound statement? To an old science an imaginative technologist of readers. Manuscripts should technology, revelling in the fun I'm having, have double spaced type- fiction addict turned science fictionish re- and all a sudden I find that the hero of written texts with wide mar- ality purveyor, it is a rather astonishing of gins. Numbering sequences one my own hero's novels is an imagina- should be maintained sepa- statement. Arthur C Clarke is sitting up of rately for figures, tables, the gods tive technologist in another era, with a very photos and listings. Figures there in my private pantheon of of and tables should be provided great literature along with Robert Heinlein, close approximation to my own name. Aside on separate sheets of paper. from the unfortunate end of the hero's life Photos of technical subjects Poul Anderson, Isaac Asimov, and Larry should be taken with uniform Niven (as well as editor John Campbell, now in the story, the net effect of reading the focus and lighting, sharp novel was an ego boost I could not in all should be supplied in the form deceased, who cultivated the talents of many of clear glossy black and white science fiction writers over the years). I've modesty ignore. or color prints (if you do not have access to quality photog- never spoken to the man, communicated raphy, items to be photo- Personal Computing in 2276 graphed can be shipped to us with him, let alone imagined that I would. in many cases). Computer He's the person who suggested the idea of Science fiction occasionally catches up listings should be supplied using the darkest ribbons pos- the synchronous satellite before today's with reality. (See Henry Melton's article sible on new (not recycled) technology ever existed, and is author of "Why Aren't There Any Altairs on Arcturus blank white computer forms or bond paper. Where possible, numerous widely read science fiction stories. IV ?" in this issue.) Arthur C Clarke's Imperial to we would like authors sup- So when someone suggested to me that one Earth presents a concept of the personal ply a short statement about their background and experi- of those remote names on book jackets had computer which is in effect an evolutionary ence. Articles which are accepted somehow taken notice of yours truly, my outgrowth of what we see now, but takes are typically acknowledged immediate reaction was to file it as amusing the pocket calculator (programmable) as his with a binder check 4 to 8 weeks after receipt. Honorar- and forget it, as if someone had walked up point of departure. The name of the beast is iums for articles are based to me and said "I understand Herman the "Minisec," a sort of advanced pocket upon the technical quality and suitability for BYTE's reader- Melville had a whale of a good time with you calculator, which is introduced in chapter 18 ship and are typically $25 to when you guys went to school together." when the principal character of the story 650 per typeset magazine page. We recommend that However, this vicious rumor kept dogging (Duncan Makenzie) reaches Earth on his authors record their name and address information redun- me. More than one person mentioned it in pilgrimage to the 2276 celebration of the dantly on materials submitted, passing. Eventually I found out, another Quincentennial. The specifications of the and that a return envelope with postage be supplied in example of the truism that if there is a Minisec? Read the following excerpt from the event the article is not persistently rumored or mentioned fact, accepted. there is often a source to that story, whether Continued on page 133

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www.americanradiohistory.com KIM Goes to the Moon

CSTART J

Figure 1: A general block Jim Butterfield INITIALIZE ALTI- diagram of a simple lunar 14 Brooklyn Av TUDE, RATE OF DESCENT, FUEL lander program. It can be Toronto Ontario M4M 2X5 CANADA AND THRUST seen that a lunar lander program basically breaks down into a number of There are quite a few lunar landing pro- updating routines. These grams available nowadays: some for pocket UPDATE updating routines are con- RATE OF calculators, others using graphic displays. DESCENT tinuously repeated until The one I wrote for my KIM -1, based on the the lunar lander has MOS Technology 6502 microprocessor, illus- reached the surface. trates many of the techniques needed to

UPDATE develop the program. ALTITUDE The KIM -1 comes with a six digit LED

display, which can be accessed by the user. I used the first four digits to represent the craft's altitude, and optionally, the fuel ALTITUDE = 0 remaining. The last two digits, which are MOTOR OFF slightly separated from the rest of the display, are used for rate of descent. Both values change continually as the craft moves. The KIM -1 keyboard is used as the pilot's UPDATE OCCUR panel. is set by pressing 'EVERY OIS UPDATE control Thrust FUEL controls 1 to 9. A value of 1 is minimum thrust, and the craft's rate of descent will increase due to gravity. Nine is maximum thrust, which slows the rate of descent YES FUEL =0 THRUST = 0 sharply. In addition to power control, the MOTOR OFF pilot can elect to view either current altitude, by pressing A, or remaining fuel, by pressing F.

ILLUMINATE DISPLAY, DETECT The Equations of Motion AND DECODE INPUT The craft, of course, moves in accordance with the forces acting upon it: thrust and gravity. A physics textbook shows some

YES NO rather formidable equations. However, they can be boiled down to the following simple procedure:

www.americanradiohistory.com Listing 1: An example lunar /cinder program written for the KIM -7

microprocessor that uses the flowchart of figure 1 as a base. The input and Every 0.01 second, output of this program is handled by routines that are inherent to the KIM -1 add 0.01 of the acceleration to the system. The data display is seen on the keypad and LED display of the KIM -1 velocity; assembly. This display continuously shows the rate of descent, and on will display either the amount fuel left, or the altitude the add 0.01 of the velocity to the alti - command of of tude; craft. Keys I through 9 are used to input thrust commands, while key A subtract 0.01 of the thrust from the chooses the altitude display mode and the F key chooses the fuel display fuel. mode. All the numbers in this listing are in hexadecimal unless otherwise stated. The acceleration is set equal to thrust minus gravity, and gravity is set at the constant Address Op Operand Label Mnemonic Commentary value 5. 0000 A2 OC GO LDX #OC The time period of 0.01 s is arbitrary. 0002 B5 B8 LP1 LDA INIT,X initialize values; Since KIM can operate in decimal mode, 0004 95 E2 STA ALT,X dividing by 100 becomes an elementary 0006 CA DEX 0007 10 F9 BPL LP1 operation. Everything would work just as 0009 A2 05 CA LC LDX =05 X:=05; well if it were done in any other small time 000B AO 01 RECAL LDY x01 Y: =01; increment. 000D F8 SED set decimal mode; 000E 18 CLC clear carry; Figure 1 shows an elementary block 000F B5 E2 DIGIT LDA ALT,X diagram of the program. After setting the 0011 75 E4 ADC ALT +2,X } add each digit; initial flight values, we settle into three main 0013 95 E2 STA ALT,X 0015 CA DEX jobs: updating the flight, lighting the dis- 0016 88 DEY set up next digit; play, and detecting input from the pilot. 0017 10 F6 BPL DIGIT f 0019 B5 E5 LDA ALT +3,X 001B 10 02 BPL INCR Setting Initial Values 001D A9 99 LDA #99 001F 75 E2 INCR ADC ALT,X An interesting flight can be obtained by 0021 95 E2 STA ALT,X starting the lunar module at a height of 0023 CA DEX counter:=counter - 1; 0024 10 E5 BPL RECAL if counter positive go to 4,500 feet with 800 pounds of fuel. That's RECAL; more than sufficient fuel for a safe landing, 0026 AS E2 LDA ALT else check if altitude is but not enough to allow for prolonged positive; 0028 10 OB BPL UP if altitude positive go to UP; hovering. 002A A9 00 LDA ñ00 else altitude: =00; It's not difficult to set all the initial 002C A2 02 LDX #02 X:=02 002E 95 E2 DD STA ALT,X values by programming them individually. 0030 95 E8 STA TH2,X else engine; However, a faster method is to set them all 0032 CA DEX turn off together in memory and use a loop to 0033 10 F9 BPL DD 0035 38 UP SEC set carry; initialize all of them. This is what I did as 0036 A5 ED LDA FUEL +2 shown in listing 1 on hexadecimal lines 0000 0038 E5 EA SBC THRUST fuel; 003A 85 ED STA FUEL +2 update to 0007. 003C A2 01 LDX #01 003E B5 EB LP2 LDA FUEL,X Updating the Flight 0040 E9 00 SBC #00 0042 95 EB STA FUEL,X check if fuel left; Every 0.01 s we must update our rate of 0044 CA DEX 0045 10 F7 BPL LP2 descent, altitude and fuel. As previously 0047 BO OC BCS TANK if fuel left go to TANK; indicated, we have to add 0.01 of various 0049 A9 00 LDA #00 A2 03 LDX #03 values into the totals. We can accomplish 004B 004D 95 EA LP3 STA THRUST,X else turn off engine; this quite easily by using a gimmick. Instead 004F CA DEX of holding the altitude, for example, in feet, 0050 10 FB BPL LP3 0052 20 AA 00 JSR THRSET go to THRSET; use two digits and store it as let's more 0055 AS EE TANK LDA MODE A:= display mode; multiples of 0.01 feet. Now we can add the 0057 DO OA BNE SHOFL if mode not 00 go to rate of ascent directly into the six digit SHOFL; 0059 A5 E2 LDA ALT } AX:= location of altitude; number; and the division by 100 happens 005B A6 E3 LDX ALT +1 005D FO 08 BEQ ST automatically. For display purposes, of go to ST; 005F DO 06 BNE ST course, we drop the last two digits, so that 0061 FO A6 LINK BEQ CALC we're back to height in feet. Using the same 0063 AS EB SHOFL LDA FUEL A: =FUEL; technique on the other parameters, we find 0065 A6 EC LDX FUEL +1 X:= FUEL +1; 0067 85 FB ST STA POINTH that the updating job becomes relatively 0069 86 FA STX POINTL display values; easy. 006B AS E5 LDA VEL A:= velocity sign; During the updating task, we must also 006D 30 06 BMI DOWN if sign negative go to DOWN; 006F AS E6 LDA VEL +1 A:= /velocity /; detect two special conditions: touchdown 0071 FO 07 BEQ FLY go to FLY; and out of fuel. This seems fairly simple 0073 DO 05 BNE FLY } 0075 38 DOWN SEC 0076 A9 00 LDA #00 1 velocity: = /velocity /; Text, listing continued on page 132 0078 E5 E6 SBC VEL +1

www.americanradiohistory.com A Nybble on the Apple

capabilities, I suggested that we sit down and implement a "Color Eater" algorithm with Apple -II's integer BASIC interpreter with

color graphics extensions. I had first seen the Color Eater program demonstrated in an advanced graphics research laboratory late in 1975 (the idea of the program is not original

with me, and I will provide the source upon request). The Color Eater always lives in the matrix in the color TV display at some point. The Color Eater is a very simple animal. It looks at its nearest neighbors in the color matrix, searching in a clockwise direction for its current "digestible" color. If it finds this color, it moves its location to the matrix position of that color, digests it into a new color, and reiterates its search. Occasionally, the Color Eater becomes a very frustrated little animal. It eats itself into a corner and no longer is able to find any digestible colors. When this catastrophe happens, it throws a fit and turns itself into another variety of Color Eater which can eat itself out of the frustration point. The result is a constantly changing random color pattern on the screen, illustrated in one state in this photo made with the Apple -II computer's output to a standard color television. That evening last November, Steve Jobs,

Steve Wozniak and I sat down and Notes by Carl Hel mers proceeded to use the Apple -II BASIC (which is a 5 K interpreter with 16 bit integer arithmetic) to program the Color Eater Next month, we'll have an article by Steve game. After perhaps 30 to 45 minutes, we Wozniac, designer of the Apple -Il computer, had a working BASIC language version describing this beautiful new conception of which used the Apple -II's graphics facilities. the small computer. As a taste of the Since it was done interpretively, the program Apple -II, here is one frame of the "Color ran a bit slow in this version, but it certainly Eater," an interesting program which illus- illustrated the concept. Later, Steve Wozniak trates the facilities of the Apple -II. recoded the program using the 6502 The Apple-II, which is to be introduced in processor's assembly language facility as April at the first West Coast Computer Faire implemented in the Apple -II, and reports in San Francisco, may be the first product to that the Color Eater now runs like lightning, fully qualify as the "appliance computer." which is its normal mode of operation these An "appliance computer" is by definition a days as a demonstration program for the completed system which is purchased off the Apple -I I. retail shelf, taken home, plugged in and If you attend the first West Coast used. I first saw the Apple -II on November Computer Faire, stop by the Apple Com- 20 1976 when Stephen Wozniak and puter booth and take a look at this Stephen Jobs stopped by a motel room in interesting processor; if you don't see it in

Palo Alto where I was staying at the time. person, then you'll have to wait until next They brought along the prototype Apple -II month's BYTE for a more complete to give a demonstration. description of the design concepts of the To serve as an interesting challenge to its machine as explained by Steve Wozniak.

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www.americanradiohistory.com Photo 1: A Teletype Model 15 RO printer. This "receive only" model is shown with cover removed (above) and with the cover in place. A Guide

Michael S McNatt 4658 E 57 St Tulsa OK 74135

Are you wondering why you should consider yet another peripheral for your system when you may already have a nice, quiet video display and even a panel of Das Blinkenlights? Consider the following excellent quote by Robert H Cushman, one of the editors of EDN magazine, who has written several articles on designing with microprocessors:

Never Underestimate the Value of Hard Copy

Working at the Teletype is a superior way to learn ... software and, later, to put the microprocessor

to use .. .

www.americanradiohistory.com Upper (Figures) Case Lower Bit Numbers (Letters) Communications Bell System (TWX) Weather 5 4 3 2 1 Case (Standard) Stock Market Code

0 0 0 0 0 0 Blank Blank Blank - 1 00001 E 3 3 3 2 0 0 0 1 0 Line Feed Line Feed Line Feed Line Feed 3 00011 A - - I

4 0 0 1 0 0 Space Space Space Space

5 0 0 1 0 1 S ' (Apos) ' (Apos) Bell

6 00110 I 8 8 8 7 00111 U 7 7 7

8 0 1 0 0 0 Car Ret Car Ret Car Ret Car Ret 9 01001 D SWRU $ 10 01010 R 4 4 4 11 01 01 1 J Bell Bell

12 0 1 1 0 0 N 7/8

13 01 1 01 F l 1/4 14 01 1 1 0 C 1/8 15 01 1 1 1 K ( 1/2 -

16 1 0000 T 5 5 5 17 1 0001 Z + +

18 1 001 0 L 1 3/4 Table 1: A listing of the 19 10011 W 2 2 2 various Baudot key code 20 1 0 1 0 0 H _ - I assignments. The weather 21 10101 Y 6 6 6 22 10110 P 0 0 0 code column, taken from 23 10111 Q 1 1 1 the Reference Data for Ra-

24 1 1000 0 9 9 9 dio Engineers, fifth . edi- 25 1 1 0 0 1 B ? 5/8 tion, pages 35 to 38, table 26 11010 G & & 22, includes wind direc- 27 1 1 0 1 1 Figures Figures Figures Figures tion and cloud cover 28 1 1 1 00 M 29 11101 X / / / symbols. In the communi- 30 11110 V 3/8 cations column, the letters 31 1 1 1 1 1 Letters Letters Letters Letters "WRU" stand for "Who are you ?" to Baudot Machines:

Part 1, Description of Available Devices

The hardcopy record provided by explain earlier mysteries. Psychologi- the Teletype printer proved unex- cally this is most comforting, because pectedly useful. Sample programs and it wipes away the frustations that their execution results ... could be invariably build up when neither you reviewed many days later, often nor the computer appear to under- clearing up today's cause of confu- stand each other. sion... EDN tears off the 6 foot or so strip Hardcopy records are especially of Teletype paper that results from the helpful during this learning process typical bout with the computer, folds because when one attacks some new it accordionstyle, and files it. To make feature of programming a particular our reference complete we start each machine, he or she invariably begins session by entering the day's date and by probing and experimenting, making the session's objective, and end it with many false tries. At that instant, all a summary of what was, or wasn't, inconclusive attempts seem like a accomplished. complete waste time. But later, as The compact hardcopy printout of Photos 1 -5 courtesy Donald you advance, copies of your first that you get is a much more useful Clum. Photo 6 courtesy Rob- attempts enable you to go back and debugging tool than the transient ert W Cook.

13 www.americanradiohistory.com displays of console lamps, or the Speed Up the µP Design Process," temporary frames of similar video EDN, April 20 1976, pages 63-72.] readouts. You can study this hardcopy at leisure, make notes on it, and What Kinds of Baudot Machines are then file away future reference. it for Available? All these practical virtues of performing program development through Perhaps the best way to answer the typewriter -like terminals have been question of what's around is to catalogue known to computer types for two each machine briefly, starting with the Tele- decades. These old timers are amazed type Corp models and following with units to learn that it is taking the newcom- by other manufacturers such as Klein - ers to the computer world so long to schmidt, Creed, etc. In these descriptions, catch up. I've included photographs of many, but hardly all, of the typical machines. Most of [ "How Development Systems Can these units will be found with nameplates and number plates identifying the model and manufacturer (if you purchase a whole machine).

Beware: Model 15s May be Model 11 Hazardous to Your Health! The first machine introduced with the If you are considering a Teletype Model name Teletype, in 1921. Used a type wheel 75 or similar surplus page printer, be fore- and printed on paper tape at 40 words per warned: Not only is the Model 15 obsolete minute. (Teletype Corp no longer manufactures parts), but: Teletype Model 12 Introduced in 1922, about 12,000 of It's a rude, ugly mechanical mon- these units were sold. Practically all Model strosity next to LED readouts, shiny 12s had been removed from service by the microprocessor cabinetry, and solid - 1940's, which makes it a real antique. The state keyboards. unit consisted of a Baudot page printer and a It's a veritable assault of clanking, keyboard, and sounded like a cement mixer. grinding, and roaring among the silent The electrical noise or hash generated by flash of panel lights, video displays, would require and the barely audible hum of power these machines extensive shielding and use a supply transformers. cables for with microprocessor. Give it to a museum you find Foul smelling oil and burning grease if pour out of its bowels to drown the one... clean, woodsy smell of new programming books and operating manuals. Teletype Model 14 It crawls along at a yawning, hair This series of Baudot paper tape readers pulling, nail biting 60 to 100 words and punches were manufactured beginning per minute, while a blazing processor in 1925, with about 57,000 Model 14s of all hurries along wasting thousands of types being sold. The Model 14 series con- cycles between character outputs. sists of: But a Model 15 hardcopy page printer will Model 14TD, or "transmitter distrib- cost between $35 and $100 depending on utor" reads the paper tape and trans- your resourcefulness, and luck. mits serial data on a current loop. Speeds of 60, 66, 75 or 100 words per minute can be selected by installing the appropriate set of gears. Easily modified for parallel output. Price range from $20 to $150. Table 2: Physical characteristics of the four common teleprinter speeds for Model 14 RO "Reperforator" or re- Baudot machines. In many cases, the same machine can be run at several ceiver, punches paper tape from serial different speeds simply by changing gears. data received from a current loop. In 1940 a typing reperforator was intro- Words Per Data Characters Bit Stop Operations duced which also prints on the tape, Minute Rate Per Second Pulse Width Pulse Width Per Minute but the printing is several characters 60 45 bps 6 22 ms 31 ms 368 behind the punches. Speeds are 60, 66, 66 50 bps 6.6 20 ms 30 ms 400 75 57 bps 7.5 18 ms 25 ms 460 and 75 words per minute. Price range 100 75 bps 10 13.5 ms 19 ms 600 from $10 to $50.

www.americanradiohistory.com Photo 2: The author's Model 28 KSR Teletype machine. Note the much more compact mechanism (above) of this model compared to a similar view of the previous generation's Model 15 in photo 1. The Model 28 KSR with cover in place is shown below,

Model 14 KSR: A Model 14 RO with a keyboard. Enables punching of paper tape off line. I've seen prices range from $15 to $75. 1 Teletype Model 15 W111110'4'4 t This machine comes in two versions: a 41 `1" "-4`Yg 0 / x10 d 40A A s Model 15 KSR with page printer and key- W . t y ' board and a Model 15 RO with page printer only (see photo 1). About 237,000 Model 15s were produced from 1930 to 1957, with Bell Systems receiving about 100,000 of these, the US government about 60,000, and Western Union, the wire services, newspapers, railroads, airlines and RCA Corp making up the balance. The page printer is usually set up for 60 words per minute, but occasionally 66 and 75 words per minute machines are encountered. The typical used price ranges from $30 to $200.

Teletype Model 19 A set of Baudot machines which includes a Model 15 page printer and keyboard, a paper tape perforator, a Model 14 TD reader, and a heavy duty loop supply. On some Model 19s, the punch is mechanically linked to the keyboard. Thus, tape must be punched locally and cannot be punched via computer control. The punch magnet requires a 100 VDC source capable of sup- plying one amp. The tape reader is usually connected in series with the keyboard so that serial Baudot signals can be generated from either unit. The surplus price ranges from $125 to $250.

Teletype Model 20 This model was used by the wire services and was similar to the Model 15 except it used a six level code for an expanded character set. This is a rare machine and nave not seen it advertised.

Teletype Model 26 Another rare, light duty machine used by the wire services.

www.americanradiohistory.com Photo 3: The "standard" Teletype so often seen in computer centers and personal computing contexts is the Model 33 ASR shown here with a modem option installed. This light duty machine is the war horse of the minicomputer world.

T T41 461,00`navili,rityrit.*via .410Ar,rl, telVolp irted* . ?` :. ='w .

www.americanradiohistory.com Teletype Model 28 is from 6 to 12 months. None are in stock Photo 4: A view of a and each machine is built to order. Used Kleinschmidt Model 150 A general number for a series of Baudot prices range from $200 to $1500. This variant the machines, which includes ROs, KSRs, ASRs, KSR. of design TDs and reperforators. These are heavy duty basic Teletype Model its to the machines like the Model 15, but generally Teletype 29 (note similarity Model 15) contains a cur- operate at 100 words per minute. This is the Another rare machine, essentially a spe- rent loop power supply. most prevalent Teletype model used by the cial Model 28 built for IBM. MARS people. Since production began in 1952, almost 300,000 Model 28s have been Teletype Model 31 is being produced so sold. This machine still A rare teleprinter and keyboard combina- new replacement parts are plentiful. Photo tion, designed to print on 0.25 inch (0.64 2 shows a Model 28 KSR. cm) paper tape. This was a small piece of There is an actual advantage of owning a military aircraft equipment (nomenclature used Model 28 as opposed to the popular TT- 30 /AGA -1) which was designed shortly Model 33 ASCII machines. This is because after World War II. It measured 9 by 14 by the Model 28 is a heavy duty machine made 12 inches (23 cm by 36 cm by 31 cm) and for 24 hours per day operation, year after weighed 23 pounds (10.4 kg). Although year. However, the Model 33 is a light duty assigned the Teletype number 31, there is machine, which means it was designed for little indication that there was ever any limited use: 3 to 4 hours per day, average. It civilian production. will work for reasonably long periods of time but will require maintenance and Teletype Model 32 adjustment more often than the Model 28 or any of the other heavy duty machines such Looks just like the ASCII Model 33 as the Models 14, 15 and 19. except it has a three row Baudot keyboard. New prices from the Teletype Corp at last This is a light duty, 100 words per minute report were: Model 28 RO, $1750 to $2000; Baudot machine still in commercial use. 28 KSR, $2000 to $2250; 28 ASR, $3300 Available as RO, KSR and ASR. Used price to $3900; prices vary with options; delivery Continued on page 154

www.americanradiohistory.com Having a "Private Affair"

with Your Computer

What you are about to read is a true workers I knew a lot about microprocessors. story. The names haven't been changed to This was not unusual - the conversation protect the innocent because, frankly, there often gravitated to such topics because we aren't any innocent parties. all worked for a large computer manu- Steve Ciarcia It was the beginning of a cool autumn in facturer. Working with computers and own- POB 582 Connecticut. The leaves were falling with ing one is a completely different situation Glastonbury CT 06033 increasing rapidity and the children who had though. It's just ho -hum when cranking out played noisily in front of my house all the answer to a 40 by 40 matrix in 10 ms summer had been removed conveniently to during working hours, but this same person schools well out of earshot. There was just a goes bananas when getting the correct slight rustle in the leaves and now was the answer to 2 times 2 in BASIC on a home time to contemplate the future without the computer. It's absolutely crazy - but then disturbances of the present. again, I'm an engineer, not a psychiatrist. Many technical individuals are probably One member of the group, Ralph, con- like me - the quiet and solitude stimulate tinued to quiz me about what I had said. He the mind. Through your consciousness race knew from past experience that when it

thoughts of all kinds of inventions which came to hardware, I wasn't an idle conver- haven't even been thought of yet. But you sationalist. Since he asked and I was in an resign yourself to living quietly with a few exceptionally happy and unguarded mood

modest pleasures which complement this after a good lunch with pleasant company, I

attitude. told him that I knew about microprocessors Then I made a mistake! I consider a home computer system to be because I had one. Well, the cat was out of told someone that I had a within my definition of modest. It is just a the bag. computer! small 8080 system with 10 K and supported "Waiter! Bring my friend here another BASIC. I didn't intend it for any particular martini!" he shouted as his interest began to purpose, just relaxation. I assembled it and heighten. placed it in my shop with my other modest I'm sure everyone knows or has worked pleasures and plinked away on the keyboard with a character like Ralph. He's a mild occasionally. It was more the challenge of mannered suburban family man whose goal getting the computer up and running than is to own the world. It's not an idle fantasy, writing exotic programs to keep an inven- but rather a calculated approach to life - all tory of the kitchen cupboards, or calculate of it dollar signs. The day to day moods of the surface area of the family car. I put people like this are in direct proportion to together a CRT and cassette mass storage the Dow Jones daily average. When the system and was content just generating Dow is down, don't mention anything con-

peripherals. Then I made a mistake! I told troversial, lest it be interpreted as a personal

someone that I had a computer! affront challenging his integrity. On a good While at lunch one day and after a few market day, Ralph is the wise philosopher

martinis, I let it slip to a group of fellow who has a kind expression of optimism for

www.americanradiohistory.com everyone with whom he comes in contact. It is during these latter periods that everyone must be wary. His generosity is overwhelming even though the drinks he orders end up on someone else's check, and his money- making schemes get more and more prolific. It's only the little bald spot on the top of his head which really seems to change. I guess it's a simple case of not getting older - just getting better. If there is a way of turning a profit on that, Ralph will find it. Ralph held back the torrent of questions until the third martini was half consumed. And, preferring not to be too obvious, he just asked leading questions calculated to make me talk. I was brilliantly coy, even though a bit giddy and was quite able to fend off the barrage of questions until he said, "I'm sure that even though you may have a microprocessor - and I'm sure you only mean the microprocessor chip - that it Just as I had finished loading the game, would be virtually impossible for even an Ralph came downstairs into my shop carry- experienced engineer like yourself to put ing a briefcase stuffed beyond normal together some sort of computer that could capacity, an armload of papers, pamphlets conceivably be worth anything." and other notebooks. I didn't bother to ask

"What do you mean, couldn't build it!" I what all the junk was for, I just greeted him said, defending myself without realizing and welcomed him to the inner sanctum. what I was about to say. "I have already Ralph was very familiar with computer built it, brother! I have a running 10 K rooms and industrial facilities, but he could system with a CRT, keyboard, and cassette not cease to be amazed at the quantity of storage system. I'm running BASIC now and equipment that I had amassed in my have a few games like blackjack and ... and basement. "Well, with all this junk, you must really

Oh, Oh! I did it, and I knew it ... have a computer," he pronounced as a Ralph's ear twitched just like someone subdued compliment. "Do you have it work- pulled the handle on a one -armed bandit and ing? Can I see the instruction set for the his eyes began to spin. When they stopped, it BASIC? How many lines of BASIC can be was like looking into two dollar signs and put in 10 K ?" Ralph had hit the jackpot. "And ... if you "Hold it, Ralph! One thing at a time. don't believe me, come over tonight and see Here's a copy of the instruction set. Why I couldn't help but notice it!" don't you sit down here at the keyboard and that Ralph's little bald Why I ever said that I'll never know. I play blackjack while I go upstairs and make could have kicked myself and had even us some coffee." Going and getting a cock- spot was a brighter pink considered ordering a half dozen martinis tail would probably have been a more hostly than normal - a rare hoping to be rushed to the hospital with gesture, but after the luncheon, the thought occurrence, usually only acute alcohol poisoning just to find a good of another martini was painful, so I resigned after a big killing in the excuse not to keep our engagement. I was a myself to coffee. market. blabbermouth and should face the music, so I'm basically a perfectionist and as with I shook off the suicidal tendencies and went the computer, so goes the coffee - or is it back to the office. All afternoon while I was the other way? Well, I mixed scoops of consumed with a dull headache, I couldn't Jamaican Blue Mountain with Mocha and a help but notice that Ralph's little bald spot touch of Deep Java and ground the coffee. was a brighter pink than normal - a rare All the while, I could hear the keyboard occurrence, usually only after a big killing keys being pounded madly and a little verbal in the market. noise, somewhat like a kid talking to himself By that evening, I had regained my while doing a difficult math homework composure and decided to make the best of problem. It took about a half hour to it. Maybe if I just load a silly game written in prepare this exquisitely brewed concoction BASIC and entertain Ralph for a while, I as well as bake a special tea biscuit (from an could convince him that this computer is a old family recipe, of course) which I always toy. You know, a toy like Odyssey or Pong. like to serve guests.

www.americanradiohistory.com When I reached the area of my work fact, he had written a lot of it already and

bench with the tray of biscuits and coffee, I opened one of his notebooks to show me glanced at the CRT. My blackjack program five solid pages of BASIC programming. was no longer on the screen, but rather a "And that's just to enter the player simple little program which took daily stock statistics and post positions," he exclaimed, quotes and computed weekly and monthly delighted that he had accomplished so much averages. in so little time and indicating as subtly as

"I was only gone a half hour," I possible that this was just the beginning.

exclaimed. "Statistics? Post position? For what ?" I Out go games, relaxation, "Oh? Yeah, I learned BASIC when I was asked. pleasure - in come the in Australia building an oil refinery one "For jai -alai, of course!" he exclaimed stock market, aggression, time. It was the same time that I got into the and I immediately knew that the odd look ulcers. foreign stock markets. There's not much else and pink bald spot had nothing to do with to do down there, you know." He had a the cool night air. "We enter the players' broad smile on his face which was an statistics, their post positions, and all their obvious result of having mastered the com- previous performance records, the computer puter so easily, and he took the coffee and does a little mathematical hocus -pocus and biscuits. He pounded the keyboard, plays the game and predicts the winners." chomped biscuits down in one gulp, slurped He could hardly hold still as he was describ- noisily, and shuffled papers madly while his ing this mind -boggling scheme to me. "And head continually bobbed up and down look- when we add the betting section to the ing at the CRT. program, it will tell exactly how much to bet "I think I can really do something with on the trifectas, perfectas, and quinellas. this system. I want a little time to study the And ..." instructions some more, then I'd like to "Hold it! You mean you are going to come over and discuss some businesss appli- write a game program like my blackjack

cations with you." This seemed to be a program ?" I asked. A game program was

reasonable request and I agreed, but before only natural as far as I was concerned. I was he could leave, we had to make a copy of his a true nongambler and never bet on anything program on cassette tape. but a sure thing. Even then, it wasn't really a

"Gee, I only have this one cassette which bet because the things I would place a wager

has the blackjack on it, but I suppose we can on entailed no risk and I'd be an idiot not

use it. I can always load it by hand. It only taking a chance. Such things were betting

took a half an hour." I sighed and inserted that my salary this week was the same as last my cassette and hit the record button. Out week, or with the gas station attendant that go games, relaxation, pleasure - in come the car needed a quart of oil (I checked it the stock market, aggression, ulcers. Oh well, before going to the gas station), or that it it's only a cassette tape and a lousy corn - would snow in Connecticut this winter. puter game. have never been to a horse track, dog track, I have never been to a "Wow, Ralph, it's almost 12:30. It's been betting parlor, pool parlor, Las Vegas, horse track, dog track, a long night. Glad you could come over. church bingo game, or even bought a raffle betting parlor, pool parlor, Study up and maybe we'll get to do it again ticket. Sometimes I think I lead a protected Las Vegas, church bingo soon." I nearly choked on the last comment. life. Actually, I'm really not that bitter and "Hell no! I mean a program to play and game, or even bought a raffle ticket. warped. I really like Ralph, and he means bet real money at the jai -alai fronton here in well. But to be on the safe side, I'll buy a Hartford!" he exclaimed almost jumping off

half -dozen cassettes tomorrow. his seat. There was a point at which I

The saga continues ... wondered whether I should fear for my life Two nights later, Ralph came over again and considered calling my dog, but affec- with the same enthusiasm and more notes tionate Scottish Terriers don't seem to and papers. Ralph had a funny look in his demand the same respect as Doberman eyes and his bald spot was unusually pink, Pincers. but I didn't pursue it. It was probably "This is only a 10 K system. We don't coming in from the cool night air to the have enough memory to do a program like

warm house. The greetings and salutations that," I rebutted, hoping to clip this crazy were hardly over when Ralph had sat down proposal in the bud. in front of the computer and announced "Oh, don't worry about that. We'll add

that he was ready to go. I asked if he wanted some more memory. I figure it will take me to load his stock program which we had about 24 K and of course, we'll eventually put on the cassette from the previous ses- need some sort of hard copy device ..." sion, but he protested that was child's play "OK..OK.. go program something while I

and he was really ready to program now. In think about it," I said in a resigned sigh. I

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www.americanradiohistory.com took note of the fact that Ralph used the bad about the bugs. I guess you won't be term "we" when he mentioned system able to do it after all."

expansion, but I seriously doubted it. The "I'll take care of the program bugs, but thought of using my computer for betting you had better check some of the hardware. was crazy. Obviously, if it were a good idea, I've been dumping the program to cassette

someone would have already done it. That's about every 30 minutes so that I could keep the American Way. It sure seemed like a an accurate revision record or in case of a

risky idea. I had visions of putting down my power failure and I noticed that your cas- life savings at the betting window just as the sette interface drops a bit once in a while. computer takes a power hit and goes down When you've got a lot of money on the line, complete with my money and my sanity. we can't afford dropping bits," he inter- I had visions of putting Ralph is a good programmer, but he can't jected with an authoritative resolve. "I've down my life savings at possibly do the entire job himself. Besides, used up all but 300 bytes of the 10 K and the betting window just as my system is much too small to accomplish we'll need some more space if you want to the computer takes a what he's attempting. Maybe I should let do this right. Didn't you say that you him plink away at the keyboard until he wanted to expand the system to put larger power hit and goes down realizes that he can't do it and then I can game programs in it ?" complete with my money have my system back and relax while I play He was correct. I did eventually want to and my sanity. Kingdom or something. expand the system with more memory, but "Fantastic," yelled Ralph. "I've got the would have been happy just playing black-

player entry and post position sections jack by myself right then. I couldn't even do

already working! I can't believe how easy it that. The six cassettes I had just bought were is to program this computer." conveniently written with various versions of The little man was amazing. All day he jai -alai. Ralph was correct - my $39 El sits in his office, shuffling papers and Cheapo cassette recorder probably did drop occasionally discussing business with cus- a bit or two, but when you're playing

tomers, but I had never experienced this blackjack, who cares? Still, I couldn't have

completely "off- the -wall" emotionalism. someone criticize my hardware. I was a good

"This is terrific! I can see that we'll have hardware designer and didn't want anyone

this program really going as soon as I get rid to think otherwise; especially someone I of a few bugs," he continued. worked with. Bugs? Was that bugs he said? Salvation is Ralph gathered up his paper work and as what those bugs were. With a program bug, he left, he tossed me a jai -alai program to

it might never work. I might yet get to use study so I could understand the betting my system again. "Gee, Ralph. That's too terms and be able to use the program

www.americanradiohistory.com It's a two touch affair

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www.americanradiohistory.com eventually. I didn't say anything except myself while thinking what kind of line goodnight and come again sometime. Some- Ralph must have laid on him to get him to

time would be soon he assured me and I felt work on this crazy scheme. a sudden pain in the center of my forehead. "So, did you get a chance to fix the bit

I never used to get headaches. Maybe I problem ?" Ralph asked.

needed a vacation .... "Yes," I answered. "It was nothing that a

I didn't want any more The next four evenings I diligently better tape recorder wouldn't cure," I cassette storage criticism, worked at improving the system and increas- replied, still wondering whether replacing but telling Ralph about my ing the memory. The leaves were piling up my low bid recorder was really necessary. depleting bank account around the front door and I knew I should The replacement was a $149 Sony tape be raking them or antifreeze in the I I would have fallen on deaf putting recorder - the best one could find. didn't cars, or something. I hadn't picked the ripe want any more cassette storage criticism, but ears. tomatoes from the garden before last night's telling Ralph about my depleting bank

freeze, but now I don't have to worry about account would have fallen on deaf ears. I

them anymore. I saw my wife this evening in also added another 8 K of memory and the hall on my way down to the workshop. beefed up the power supply. That was only She looked pleasant and gave me a half- about $300. hearted smile. It was her subtle way of "Great! We'll really be able to make

saying, "I remember you. Wasn't I married progress now," he chanted. "We'll give you a

to you some time ago ?" I just didn't have the cut of the winnings to help cover the time to explain because Ralph was on his hardware costs," he continued. "Hey Walt,

way over and I wanted to show him all the sit here at the desk under the light and see if

improvements, so I patted the dog and you can find the bug." descended the stairs into the workshop. Ralph loaded the last program version

I looked around at all the equipment and and spread his papers out all over my bench. some of the unfinished projects on my desk. Papers hung over the top of my oscilloscope,

For a couple of months, I had been develop- propped against my parts cabinets and ing an analog interface to be attached to the thoroughly covered my work area. Walt computer to allow joystick inputs to liven asked if it was OK to move the analog

up future game programs I was contem- interface board which was on the desk, so plating. It was all done, just awaiting check- that he could spread out some papers and

out and debugging, but I needed the corn - not have to worry about accidentally leaning puter to check it dynamically, and with all on something. "Sure Walt, let me move

the stuff with Ralph lately, I hadn't been everything for you," I said as I cleared off

able to even get close to it. I still had an the desk. "Can I get anyone a drink or older 8008 system with 4 K of memory something?"

which I could use, but it was located right "I'd like a beer if you have one," said next to the 8080 system and with Ralph Walt.

sitting there, I couldn't even get close to it. I "I'll have a gin and tonic and if you have

resolved that I would sit at my desk and any of those biscuits left, that would be recheck the wiring again. tremendous," said Ralph. is a Working with Walt "OK, are we ready to go ?" asked Ralph I slowly walked upstairs and stopped on little nerve -wracking as he came into view while descending the the landing to pat my dog. Scottish Terriers because in computer terms, stairs. "I hope you don't mind - I invited are like people. They can communicate with he is a LI FO, or "last in, Walt along to help me debug the software. their eyes and he was giving me that "You first out" interrupt He's a genius when it comes to don't play with me anymore" look, and dropped a tennis ball by my hand hoping processor. programming." Ralph was quite correct; Walt was indeed would have a favorable reaction to his

a software genius. Walt is one of those truly request. I used to work at my bench and helpful people who continually goes out of occasionally kick a ball around the cellar for his way to accommodate everyone. Working him. Now we both knew that we couldn't do with Walt is a little nerve -wracking because that any more and we sat watching the two in computer terms, he is a LIFO, or "last in, men intently discussing the program and

first out" interrupt processor. The poor guy inspecting the CRT display. I went upstairs will be diligently working on something to prepare refreshments and invited the dog important, and if someone asks for his help, to follow, hoping to placate him with a fresh he drops everything, solves the other per- baked biscuit. son's problem, then returns to his own task. My wife walked into the kitchen and Some interesting situations have evolved being the understanding soul that she is,

when he's interrupted by five different asked me if I could possibly light a fire in

people each asking for his help. I suppose the fireplace and use the den for whatever it

that's the price of genius. I just chuckled to was that I did downstairs.

www.americanradiohistory.com "That's it! That's how I can do it!" I a ranch instead of a colonial or at least I'd

yelled. If I was Polish, I would have danced a put the den on the first floor, but for right

polka, but instead I grabbed the tennis ball now, I just didn't look down and concen- and threw it down the hall and the dog made trated on the "do or die" situation at hand.

a mad dash after it. I started the electric drill, placed it

"I can't use the den, but they can! All I against the house and pushed! I drilled have to do is put a remote terminal in the through the storm window, the inside

den." It was an extravagant idea, but I was window and half the window sill. It wasn't

desperate. I would move my friends to necessary to tell my wife that someone was

another section of the house, out of my outside the window, because I heard her shop and out of my dog's playground.

I hadn't worked out the details yet, but

that's what I was going to do. I had contemplated moving the computer, but like any hobbyist's, it was spread out all over three shelves with patch cords and was impossible to move. The details of the design flashed

through my head and I hurriedly looked for a pad to record my thoughts. Twisted pair shielded wire, asynchronous interface, coaxial cable for the monitor, perf board, line drivers - Hold It! - one thing at a time. The design of the remote terminal was fairly simple, but would take a little time to build. I'd do that later. Right now, it was impor-

tant to see if I had enough wire to go from

the computer to the den and I made a mad dash down into the shop and started

rummaging through my storage bins until I found a 200 foot roll of coax and a big tangled mess of what appeared to be twisted pair shielded wire. Ralph and Walt didn't seem to be bothered by all the commotion

behind them until I pulled down half the bookcase while yanking on the tangled mass of wire.

I grabbed some tools and dragged the wire outside through the garage. Ralph and Walt had kicked the books out of the way

and returned to programming by the time I was out on the front lawn. It was cold outside, but that was the only place with enough room to spread out the mess. I'm sure the neighbors thought it a bit strange to see a grown man out on the front lawn at nine o'clock in the evening with a flashlight scream. Apparently, she was watching tele-

doing what appeared to be playing in the vision in the den and the window I had just leaves. My dog came out to investigate and drilled through was behind the TV. It hit me with all his jumping around and barking, it all of a sudden what her reaction would be - really must have looked pretty bad, but it was something I had suggested she do if was determined. she were ever home alone or needed protec-

It took quite a while, but finally I tion. She had probably rushed off for the untangled the mess and had two twisted pair bedroom closet to get the shotgun we kept and one coax line stretching down the street there. Well, if you think firemen come down

past the neighbors' home. I decided to put in ladders fast, you should have seen me.

an extra twisted pair line in case I had other It took a while to calm her down, but she

friends and had to go to time -sharing. I said that after having been married to me so placed a ladder up against the side of the long, she should have expected it. As a

house under the den window, and with the gesture of peace, I agreed to put off wiring wires between my teeth and an electric drill the house until daylight hours and decided in one hand, attempted to scale the ladder. instead to design the asynchronous interface.

swore that the next house I bought would be Ralph and Walt had finished for the evening

www.americanradiohistory.com and were apparently unaware of the preced- stairs consisted of the receiver section of ing "fiasco" when Ralph said, "I hope your a UART (universal asynchronous receiver/ evening was as productive as ours. Walt transmitter) while the box in the den configured out the bugs but it will take a few tained the transmitter and line driver. A more sessions to incorporate the revisions. keyboard is plugged in upstairs, and when a That's quite a system you've got there. You key is pressed, the ASCII keyboard data is must really enjoy it." serialized and sent to the receivers down-

I didn't get mad, I just looked tired. Even stairs where it is reconverted to parallel for

the dog decided he couldn't take anymore the computer. I chalked up the $40 it cost and went to lie down in front of the fire. to build this interface to experience for the I smiled from ear to ear "Well Ralph, it will be nice to see the sake of family harmony. The $175 for and thought of the coup I program work so you can spend all your another keyboard and another TV monitor was about to perpetrate. time at the jai -alai fronton." was a bit harder to take. "I'm looking forward to that too. But we Ralph, Walt and whoever else was coming

still have a lot of work. Day after tomorrow over would be there soon. I decided on a evening is a good night for me. My wife may lark to try to type in the blackjack program

not be home, so I might bring the kids. Do before they came and busily attached the

you like kids ?" he asked. keyboard. When I was through, I took the

"Kids are fine. It's their paren...," I tape containing their oldest revision of jai started as he interrupted. alai and recorded my blackjack back on it

"Great. Walt and I will see you then," ... just in case. When I was done, I loaded was his final pronouncement as he stepped their latest program version and ran up to out of the door; but on the way to the car, the den to check that all was working he turned long enough to yell, "Hey, some- correctly. The screen was brightly lit with one left this big mess on your front lawn, the BASIC operating system indicating that but if you pile enough leaves over it, nobody the video link worked properly. Data entry will know." on the keyboard also proved successful and

"Thanks, Ralph." I just closed the door, felt like a new man. I smiled from ear to ear

closed my eyes, and leaned against the wall. and thought of the coup I was about to

I judged that I didn't have much time before perpetrate. I made myself a Tangueray

they were coming again, so I had better get martini, sat by the fireplace and awaited the to work on the communication link to the arrival of my honored guests. den. It wasn't long before Ralph and his two

During the next two days, I worked at a kids were at the door with Walt closely

feverish pace, stringing wire and soldering behind. I hadn't even closed the door before

components. I stuffed the three wires the dog and the children were off chasing through the hole in the den window, ran the each other through the house. "Are all kids

wires down the side of the house to the first like this ?" I asked. floor level, and then drilled a hole through "Only happy ones," answered Ralph. "So

the outside wall into the garage. I had to go do you want to come downstairs and see through the back and out the front of a how this works ?" he inquired. garden tool cabinet in the garage, but my My opportunity was there, but with all During the next two days, wife wouldn't notice that she couldn't open the noise I couldn't think and just said, I worked at a feverish pace, the door any more until spring - I'd just use "Tonight we are going to put you in the den. stringing wire and soldering my skill saw and make a new opening for I put a monitor and a keyboard up there and components. her. you guys work upstairs while I work in the

Stringing the wire through the garage was shop!" The words were finally out. I had

easy. I just hung it across the ceiling and stated my declaration of independence and I looped it through the garage door springs for had demanded my workshop back.

support. It was only when I started chopping "Sure. That sounds OK with us," stated a hole through the concrete wall into the Ralph as he and Walt spread out their papers

basement that I got upset. Some idiot put a all over the den. "It sure is nice up here. layer of sheet metal in the center of the How do you keep a den looking so nice? concrete and the drill bits wouldn't even Anyone with kids can't have furniture like penetrate it; but this turned out to be no this," continued Ralph as he threw his match for a cold chisel and a five pound briefcase on the velour covered Louis XVI hammer. The hole did turn out to be a bit chair next to the fireplace.

larger than I intended, but I always wanted I looked at him and stated, "I don't have to install one of those little doors where a any children, remember ?" Just then, a tennis dog lets himself in and out. ball whizzed by with two kids and a dog in

I quickly attached the twisted pair to the hot pursuit. Usually the dog wasn't even line receiver in the shop. The unit down- allowed on the oriental rug, but who was

www.americanradiohistory.com The Small Computer

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www.americanradiohistory.com going to scold first? I just picked up the before game time, so we'll have to work fast. bottle of Tanqueray from the bar and left Do you think we could put it into a motel the room to go to the shop. room near the fronton ?" he asked very As I descended the stairs into the base- seriously.

ment, I listened to the three -ring circus and "Not without a great deal of difficulty," I

wondered if children came with volume said as calmly as I could, considering the controls or on /off switches. The sadistic question.

humor ceased when I sat down at my bench "Well, you know I wouldn't want to put

and contemplated my next action. I looked you out. So I guess what we'll have to do is Ralph was so enthusiastic at the 8008 system which didn't have BASIC get the player programs of Friday and he hardly even noticed the and couldn't play games and shivered a little Saturday evenings, run over here, pump in dog was chewing on one of from the chill of the cold cellar. It took only the data and determine who to bet on. Since his program sheets and the a few minutes to realize that there was no the program takes a while to crunch all the kids were making paper way I could work downstairs while the gang numbers and come up with an answer, we'll airplanes out of others. was upstairs. have to get some other people from the

I went upstairs and upon entering the office to help set up a shuttle between here den, Ralph said, "I thought you were going and the fronton to relay the bets and bring to enjoy yourself ?" back news of any player changes not covered "I thought so too, Ralph. How are you in the initial schedule. It actually won't be doing ?" I asked trying not to show any too long before we're at that point." Ralph frustration. was so enthusiastic he hardly even noticed "I'd say we're almost ready. We entered the dog was chewing on one of his program the player statistics of ten games played last sheets and the kids were making paper week and the program picked the winner in airplanes out of others.

40 percent of the cases. I still want to make "Wow, did you see that ?" I yelled and some other program revisions, but we can do pointed to the CRT screen. Author Ciarcia will not be that some other night," he said. "What? What happend ?" piped Ralph as able to answer any "When we get this program going full he squirmed around to check the CRT. inquiries about the pro- blast, we'll have to have better access, "The CRT momentarily blanked out. I grams described in this though. The program listing the evening's must have a computer problem or the power article. So don't write! players doesn't come out until one hour supply is ready to give out. Hold on, let me

www.americanradiohistory.com Put exceptional versatility and control

check," I yelled back and dashed out of the into your S-100 bus room, down the stairs and into the basement. I stood in front of the computer and system with the momentarily watched the twinkling lights. With a grin that only a Cheshire cat could 'blue boards' . . . anc1 appreciate, I leaned over to the computer and hit the reset button which would cause the monitor upstairs to blank for about a save second. I did this twice more for good measure and then pulled the fuse, causing the entire computer to come to a dead stop. rolled the fuse around in the palm of my in hand a few times and gazed at it as I would a gold nugget. When the momentary elation

had passed, I pocketed the fuse and went bargain! back to the den.

I couldn't have looked more depressed when I arrived upstairs. I just frowned in the direction of Ralph and said in a somber tone, "It died!" "What do you mean, 'it died ?'" was the XB1 Ex ender Boa d MT1 15 slot Mother Board Board On y 59.00 Board Only 545.00 frantic reply. With Connector $13 50 With Connectors $105.00 "Just that, Ralph. IT DIED! The power supply which I jerry- rigged to add extra memory for you blew up and I don't know what else it took with it. I'm afraid we're out of business for a long time," I added after a deep long audible sigh. "Considering that this is like a child to me, do you think I M04 4K Static RAM (low power) VB1A Video Board Kit $129.95 Kit $189.95 could be alone, Ralph ?" This additional Assembled $179.95 Assembled $264.95 remark was probably a little much, but I was really rolling now. "Sure. Let me know how things are and whether you need any help. I hate to leave you feeling like this, but it probably is a time you want to be alone." Ralph gathered r-- up his entourage and I waved as they exited, MB6A 8K Static RAM (low power) SB1 Synthesizer Kit Kit $265.00 Kit $250.00 still looking quite somber. Assembled $325.00 Assembled $325.00

I closed the front door, clapped my hands IIIIINIIIII INNIIIIIINIIJ nllilNl together and for the basement. I ...... took off NIIINIIIII NIIIIIIIIIIONIlNIIIIII

- NIIIIIINII had the fuse out of my pocket by the time I Ii" IIIIIIICININNINI ;IInlNllll 1 I reached the fuse box and inserted it IINWINNIININ NIIIII;__ : immediately. The computer flashed back to IIMNIWWI i:(,,.

life as I placed the blackjack tape I had made 111111110111 1111 III 111111 I I IIII 111111 into the cassette recorder and hit the play MB3 2K14K EPROM (1702A) 1/02 Interface Board button. After the program was loaded, Kit loss PROM's 565.00 Kit $55.00 2K-5105.00/4K-$145.00 Assembled $79.95 took off upstairs with the dog close to my Assembled- - -- board savailable - -N heels. I threw all my computer magazines r - MB7 16K Static RAM (low power) which I still wanted to read down on the Kit $525.00 Assembled 5599.95 floor around the keyboard and sat down i 16K next to it myself, still elated at my triumph. The dog, who had found a comfortable spot (Available April, 1977) INN ow J We're the blue boards! in the middle of all the papers, watched as I entered the keyboard. "RUN" on Compare the Cybercom blue boards with any others on the market The program did its thing and displayed a today. You'll find exceptional quality plus prompt delivery and message on the screen. Turning to the dog, significant cost savings. All Cybercom kits are guaranteed 90 days said, "Dog, you show a seven and a jack and for parts and labor. the dealer shows a six. Do you want to stand Contact your local computer hobbyist store or write for details. pat or do you want another card ?" "Woof! " cL.berc pT1 A division of Solid State Music 2102A Walsh Avenue, Santa Clara, CA 95050 Telephone (408) 246 -2707 www.americanradiohistory.com letters to obviate a carriage shift for each As part of a project (still in progress)

letter printout. I haven't found the to develop a cheap terminal for use on

format to be objectionable; the error our campus, I have considered a method rate has been acceptable for my hobby of displaying more characters per line use with main maintenance items being that are reasonable on a single monitor ribbon cartridge replacement and con- by using multiple monitors with a line tact cleaning on the keyboard. As you split between 2 or more monitors. In can see from the picture, the main effort this scheme, two side by side 6 MHz during construction was function not monitors could be used to present a 64 A SOLENOID appearance. by 16 format, 3 in a row could display TYPEWRITER HACK An avid reader of BYTE magazine. 96 by 16 characters, and a 2 by 2 cluster could go to 64 by 32. Harold L Baldwin In past issues of your excellent maga- The additional electronics and switch- zine I have noted items from your This avid reader is bashful, but with ing logic needed to support such an readers expressing interest in converting luck we'll find him sitting down at a increase seems to me almost certain to typewriters for use as printout devices. typewriter to write an article on his be far less expensive than going to higher The accompanying pictures show the typewriter hack. bandwidth monitors whose cost increases results of my efforts along these lines. very rapidly as large displays are required. The keyboard is a slightly modified PROCESSOR ID NEEDED (132 by 24 format is not unreasonable Teletype unit rescued from a salvage to ask for since many printing terminals store while the typewriter is a Smith - I recently bought several PC boards have such line widths, and once used Corona, Coronet, Super /12 electric with the intent of removing and reusing make a 32 character line extremely portable. The only modification to the the chips. One of these boards is labeled restrictive.) typewriter was removal of the carriage - ASSY 591700 Gen Purpose Proc- I am not aware of any efforts along shift -lock -key. The input /output is mod- essor -FBA and it appears to be a com- these lines; is anyone else? ified RS232C and operates at about 84 plete 16 bit processor. Before dis- Robert E Monroe format. The mantling this board, I'd like to find out bits per second in ASCII Associate Director keyboard actuators are sole- if it can be used as the basis of a 16 bit typewriter Computing and Data Processing Center noids, also rescued from the salvage mini. Wayne State University decoding The only clue to the manufacturer store, one per key with logic Detroit MI 48202 circuitry and aGl /AY -5 -1013 UART. seems to be the initials or name LEC and Lower case was selected as format for the letters M /L -J etched on the front of 64 by 16 line displays have been the board. I'm not familiar with this demonstrated in one product which has company, so any information at all on proven itself in the marketplace already, the board of the manufacturer would be demonstrating at least that resolution much appreciated. capability with a standard television Larry Ingram bandwidth. As far as I'm concerned, 20 Locust St however, a far better thing to do is to Cambridge MA 021 38 have a multi- window text editor with separate wide displays for different WIDE DISPLAYS IN CHUNKS? kinds of information in the text file. For instance, as a documentation I have just finished reading Dr Robert machine, consider two side by side dis- Suding's piece on television readout de- plays (64 characters wide or more) with vices in the August 76 issue, page 66, one containing indexing, outline, or and was interested in his discussion of the bandwidth requirements of monitors versus characters per screen. Continued on page 115

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www.americanradiohistory.com A Review of Tom Pittman's Tiny BASIC

While at the Personal Computing 76 To use Tiny BASIC you first load the paper Trade Show at Atlantic City I bought a copy tape of the interpreter into the program- of Tom Pittman's Tiny BASIC Interpreter mable memory. This takes about ten min- for my home computer, a 6502 with the utes on a Teletype. Then write the addresses MOS Technology TIM program in read only of the 10 routines into the proper locations memory. Tom Pittman has several different and jump to the start of the interpreter. In

versions of Tiny BASIC for different sys- less than an hour I had it up and running. I tems. I purchased the KIM version even wrote and debugged a plot routine one though my computer uses a Teletype and Friday night and made several revisions by the TIM instead of a keyboard. This allows the time the weekend was over. me to load the interpreter starting at 0200 The Tiny BASIC plot program shown in

hexadecimal instead of at 1000 hexadecimal, listing 1 accepts the X and Y origin and the leaving more memory space for my user X and Y increments as inputs. Then, using a programs. function placed in a subroutine, the program Richard Rosner Tiny BASIC is a subset of Dartmouth plots a 50 by 50 point graph. Pocono Rd BASIC. It can handle only 16 bit signed The first input, on line 10, determines the Brookfield CT 06804 integer numbers between -32768 and form of the output. A 1 input stops the +32767 and recognizes the following program after the LIST command at line 20 commands: causes lines 1000 to 1999 to be printed. These lines are the subroutine containing the CLEAR REM GOSUB function to be plotted. INPUT LET RETURN A 2 input causes a request for two more LIST IF ... THEN END inputs: the X origin and the X increment, T PRINT GOTO RUN and V in line 200. The printed outputs are the function to be plotted and a table of X The only operations understood by Tiny and Y values. This table is helpful in BASIC are addition, subtraction, multiplica- choosing the Y origin and Y increment to be tion, and division ( +, -, *, and /). There are used for the graph. two intrinsic functions. One generates a ran- A value of 3 as the first input causes a dom number and the other, USR, allows request for four more inputs: the X origin, subroutine jumps to machine language pro- the X increment, the Y origin, and the Y grams. More about USR later. increment; T, V, U and W in line 300. The Even with these limitations, Tiny BASIC outputs are the function to be plotted and is very powerful. It is easy to learn and use, the graph. and programs can be written very quickly. Lines 205 through 290 generate and print

www.americanradiohistory.com :L15í

14 INPUT% 21 LIS11 i44.1999 34 IFx.IGJ43144 44 IF%.2GOTU240 54 IF><.3GJT0341 141 ENO 244 INPUr T.V 245 6T 214 P.Y'I.'Y' 215 Pd'----..,..----.. 221 G05Jd1044 234 P46.4 24.1 44450V 254 IFU.T.55VG1rJ220 294 Ell 344 INPUT r.V.U.M 314 P4

324 P4' Y ..J. . .O25.4. .U54.ti

334 P4' ......

344 P.( ' R. 354 6.r 364 GJSJ81434 365 Y(7-0.4/2)/4 371 IFT411GOrU491 375 IFT.1G)T051) 3Pi P4.. ..,A...... , 391 IF1..5dG013434 441 44 Listing 1: Tiny BASIC listing a routine using a function. The 414 GJ40510 for plot 434 Y.T-I equation to be plotted is in the subroutine located at lines 1000 through 441 IFY.4G)rU471 454 P,1 ..1 1999. The routine has the ability to print three types of outputs. If a value of 461 GUr3434 471 44 1 is input only the function to be plotted is printed. If a value of 2 is input 414 GOr0510 494 PN' "I4."4" the program requests the X origin and increment to generate and print a table 495 6440510 544 4.. )6. of X and Y values for the equation on line 1010. The X increment is always S 511 .+c.v times the input increment value. a value 3 is input the program requests 524 IF6.r.S1V600364 If of 591 EN4 the X, Y origins and increments. The output consists of the equation to be 1041 tEM (ME E61J471J.4 fJ LIE PLANE.) IS 1314 744.4.1/4-3.6.712.6-1 plotted and the graph. 199V .(E f JiN

the table of X and Y values. Starting with X axis. The semicolon at this PRINT state- the first X, which has the value of T, and for ment causes the next PRINT statement to ten other X values spaced at five times the X write on the same line without any spacing. increment, eleven Y values are calculated by If the scaled value of Y is greater than 50 the calls to the subroutine at line 1000. In Tiny PRINT at line 400 closes this line and causes BASIC, PRINT statements are abbreviated the next PRINT statement to start printing "PR." The PRINT statements at lines 210 at the beginning of the next line. If the and 215 print the heading and the PRINT scaled value of Y is between 1 and 50 the statement at line 230 prints the X and Y statements on lines 430 through 470 cause a values. The IF statement at line 250 con- plus sign to be printed Y spaces above the X tinues the loop until the eleventh X and Y axis. The statements at lines 510 and 520 values are calculated and printed. increment X and continue the loop until the Lines 310 through 590 generate the last (51st) values of X and Y are computed graph. The PRINT statements at lines 310 to and plotted. 340 print the heading. Line 320 prints three The example of listings 2 and 3 are for values of Y. U is the value of Y at the origin, the cubic equation: U + 25 * W is the value of Y at the midpoint of the Y axis, and U + 50 * W is the greatest Y 3X2 + 2X 1 value of Y plotted. The subroutine call at =3 - - line 360 brings in a value for Y which is scaled and rounded up at line 365. Lines 370 Listing 2a is the table of values for X and through 500 print the X value, the X axis, Y starting at X equal to -50 with an X and a "<" or " +" to indicate the value of Y. increment of 2. The jump to negative values If the scaled value of Y is less than zero, the of Y (at X equal to 40) and the exceptional IF statement at line 370 causes a jump to values of Y at X equals -50 and -40 are due the PRINT statement at line 490 where a to computations exceeding the range of Tiny caret is printed on the X axis to indicate that BASIC. Listing 2b is the same table with the the value of Y is below the lower limit of the first term rearranged. This keeps the value of Y axis. If the scaled value of Y equals zero, Y within the range of precision for variables the IF statement at line 375 causes a jump for a larger range of X. Listing 3 is the plot to line 500 where a plus sign is printed on of the equation with the starting value of X tire. X axis. If the scaled value of Y is greater equal to -25, the X increment equal to 1, than zero, the PRINT at line 380 prints the and the starting value of Y and the Y value of X and an exclamation mark for the increment equal to -100 and 4, respectively.

www.americanradiohistory.com :RUN 2. -11. Listing 2a: The 2 command has been read telling the program to request a

1114 dE* rii EJJArIUV ro dE .'IUffEU IS value for the X origin and increment. A table of X and Y values for the 1111 1=4444X/4-344444144-1 1999 KEI349 function of line 1010 is also output. In this example the X origin is -50 and the increment is 5 *2 For the values of -50, -40, 40 and 50 the X X X incorrect Y value is given. This is because the value that is computed is -71 -4483 -44 -4497 outside the range of the Tiny BASIC's capabilities. After looking at this table -14 -9511 -A4 -T?4I the origins of the program can be changed so that values capable of being -14 -571 -1 used are generated. Another use of the table is to determine the values of the 14 -31 3 839 Y axis. 34 4149 44 -5I 11 54 -8919

A small program change in lines 1000 to subroutines and to the rest of the memory 1999 allows discontinuous functions to be space including IO ports. The format for generated and plotted as in listing 4. These using USR is: lines are the ones that contain the function D = USR (P,L,A) to be plotted. Instead of using a simple where P is the address of the machine expression, conditions are set up to deter- language subroutine, L is a variable passed mine the starting Y value of the graph on through the X and Y processor registers, line 1060, the upper and lower limits be- and A is a variable passed through the tween which the graph will oscillate on lines processor's accumulator. Upon exiting from 1020 and 1000, and the risetime and fall - such a user subroutine and returning to Tiny time of the graph on lines 1040 and 1051. BASIC, the high order eight bits of D are By examining lines 1000 to 1999 in listing 4 taken from the Y register and the low order it can be seen that the graph is independent eight bits of D are taken from the accumu- of X but is a function of its own previous lator. The D, P, L and A values are in value. decimal. If you want to use the entire graphing Two subroutines addressable by the USR routine as a subroutine you may want to function are included in Tiny BASIC. These renumber each line. Be sure that there are no statement number conflicts with your are the PEEK and POKE routines. The PEEK reads the routines and that all GOTO, GOSUB, and routine byte at location L, converts this byte to its equivalent LIST statements are properly changed. As an decimal and sets D to this value. The POKE routine alternative you can use statement numbers loads the low order eight bits of A into the from 2000 through 32767 and put a "GOTO memory location (first line number of your routine)" at specified by L. The PEEK routine is located at P = 532 the statement number 1. for KIM version and the POKE is located at You will notice that no unnecessary routine decimal address P = 536. The addresses blanks are included within each statement. for the TIM version are decimal addresses P = This makes it slightly more difficult to read 4116 for PEEK and P = 4120 for POKE. For the program but does conserve space. Each the 6800 these addresses are P = 276 for blank requires a byte of storage. At an PEEK and P = 280 for POKE. average of 2 blanks per line, this saves 90 With these routines you can read and bytes. As shown in listing 1, the program write into your computer's IO ports. Set L requires about 650 bytes of programmable to the port address, decimal, P to the PEEK memory storage. address and execute The USR instruction allows a Tiny BASIC program access to machine language D= USR (P,L).

:NUN 2. -$4. 2

1A31 NEM fME E11Af104 10 ìE .+I.IIfEU IS 1314 YX4X14.1-34X*X4244-1 Listing 2b: This is a run of the program under the 2 command using the same 1999 NEIViN

origin and increment values as in listing 2a. The function to be graphed, X Y

however, is still a cubic. Rearranging the order of operations helps avoid -SA 26485 value falls outside the -4a -24881 overflow errors. With this equation the only that ability -31 -9511 of Tiny BASIC appears when X = -50. -24 -3241 -14 -S 71 4 -1 IA -31 23 839 3.1 4149 41 11279 54 23849

www.americanradiohistory.com :4UN 3. -25. 1. -104. 4

1944 NEM THE E4U47IOA f0 14E PLOTTED 15 1414 7:9.2.x/4-39.3..2.2-I II114 8ElU44

-144 3 144

X. -25 -2, -23 -22 -21

-I9 Listing 3: The plot of the cubic equation whose table of values is shown in -I R -17 figure 2a. The graduations on the Y axis are from -100 to +100. A caret is -li -IS found on the X axis from the values of -25 to -5. This mark indicates that -14 -13 the point on the graph is less than the Y origin, in other words is less than -11 -11 -100 for this example. If the value of Y is equal to 0, a plus sign, +, will be -14 value Y 0, -9 printed on the X axis. If the of is greater than an exclamation point, !, will be printed on the X axis, and a plus sign will be printed at the _7 < < value. -5

-3 -2 -I

7- 3

7 Y causes a pulse of width 1728 ps ( 8 * 216 ) to 9 a be generated at PB7. PB7 must be set up as 1 an input (not output) and the 6530 timer 2 3 must be dedicated to this function. 4 ] i To return to the TIM monitor the Tiny 7 BASIC program should execute this se- R 9 quence of statements: <4 21 D = USR ( 536, 0, 0 ) 22 23 D = USR ( 536, 1, 96 ) 24

25 . D= USR(0) The first instruction loads 00, the 6502 BRK software interrupt instruction, into location 0000. The second in the The port data is loaded into D. Set L to the instruction above sequence loads 96, 60 hexadecimal, the 6502 decimal port address, P to the POKE ad- RTS return from instruction, dress, A to the value to be transferred and subroutine last execute into location 0001. The instruction causes Tiny BASIC to jump to the sub- D = USR ( P, L, A ). routine at 0000 where the instruction exe- This causes the value of A to be written into cuted by the 6502 causes the TIM monitor the port. to take over. To return to Tiny BASIC, just By using the PB7 pin on a 6530, very have the TIM monitor execute the instruc- accurate pulses from two microseconds to tion at 0001 by typing "G" at the console.. about a quarter of a second in width can be If the sequence of instructions above was generated directly from Tiny BASIC. If L is executed from a Tiny BASIC program by set to the base address of the 6530 timer, preceding each instruction with a line num- then the addresses L +12, L +13, L +14 and ber and commanding RUN, the next instruc- L +15 determine a factor by which A is tion in the user's Tiny BASIC program will multiplied to get the pulse width. These executed factors are: be when returning from the TIM monitor. Saving and reloading programs from pa- Address Pulse Width per tape or magnetic tape is easy with Tiny L + 12 1 * A BASIC if you have a debugged version of the L +13 8 * A interpreter. The procedure is to save the L + 14 64 * A program by typing LIST, turning on the L +15 1024 * A paper tape punch, and pressing the RE- TURN key on the Teletype. To reload the If the 6502 is using a one megahertz clock, program press LINE FEED, load the paper executing the line tape into the tape reader and turn the reader

D = USR ( 536, L + 13,216 ) on. The LINE FEED command suppresses

www.americanradiohistory.com :RUN 3 3. I. 3 I Listing 4: Plot of a sawtooth function. The function is independent of X but 330 L =25 is dependent on the previous value of Y. This type of graph may be plotted 313 REM L IS THE LOWER LIMIT 323 M =45 by changing lines 1000 through 1999 from those shown in listing 1 to those 033 REM M IS THE 10 /ER LIMIT 04.0 s =4 shown at the top of this listing. These changes allow you to specify the Y 053 REM S IS THE RISETIME value that the graph should start at, the upper and lower 351 REM THE FALLt IME IS I //M -LI limits between 060 R =12 which the graph will oscillate, and the rise and fall times of the graph. Using 070 REM N IS THE START 19G Y 941 le: 383 1FX =T Z= IN -LJ /S this type of evaluation technique a wide variety of discontinuous or 393 Y =SZL 1.3.3 Z =Z1 oscillating functions can be generated. II3 IFY. =M 2 =3 999 RETUR9

Y = 3 25

X= output from the interpreter to allow more a than one line at a time to be read in without interfering line prompts which can cause the 3 4 input through the tape reader to lose 5 6 synchronization. If the LINE FEED com- 7 Y mand does not suppress line prompts then 9 a you may have a bug in the interpreter. In the

2 KIM version check hexadecimal locations 3 06C7 and 06CB for 13 hexadecimal, X off, 4 5 and OA hexadecimal, LINE FEED, respec- 6 7 tively. These bytes may be reversed. If they x 9 are, switch them and try again. In the TIM 23 21 version check locations 14C7 and 14CB. In 22 both cases the lower location should 23 contain 24 13 hexadecimal and the higher location 25 26 should contain OA hexadecimal. Only tapes 27 28 shipped before September 1976 should have ?9 33 this problem. 31 32 To obtain a copy of the Tiny BASIC 33 for your machine, send a 34 interpreter descrip- 35 tion of your system along with a check for 36 37 $5 to Tom Pittman, itty bitty computers, 38 39 POB 23189, San Jose CA 95153. In return 43 41 you will receive the interpreter on a paper 42 43 tape and a user's manual. The 6502 micro- 44 processor, are 45 TIM, KIM, and 6530 available 46 from MOS Technology Inc, Morristown PA, 47 48 as is a line of KIM -n products which can be 49 53 assembled into a complete computer.

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www.americanradiohistory.com Peripheral Vision impacts your computer.

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www.americanradiohistory.com A Software Controlled 1200 bps Audio Tape Interface

Often a piece of equipment is designed audio recorder's existing electronics. Re- which will perform perfectly well in the taining the original audio electronics allows mode of its intended operation, but which continued normal use of the audio medium can also perform in ways not necessarily when you're not using the computer. This intended by the designer. An example of type of modulation is often generated from such a situation is the AC -30 audio tape a 4800 Hz clock source and a UART (uni- cassette interface subsystem described by versal asynchronous receiver -transmitter) or Gary Kay in his article in December 1976 ACIA (asynchronous communications inter- BYTE, page 98, and manufactured by face adapter) integrated circuit interfaced to Southwest Technical Products Corporation. the computer's bus to do the shifting out of

In a box accompanying that article, I noted data. Gary assumed an ACIA or UART the possibility of running Gary's design would be used when he designed the AC -30. considerably faster than the nominal The same clock which is divided by 16 in the 300 bps rate of the "BYTE" or "Kansas UART shifts the data out to the modulator, City" standard for audio cassette recording. and is used by the modulator to generate an

Since making the comment, I have inte- output waveform; on receipt of data from grated the AC -30 into my homebrew Motor- tape, the receiver section of the DART or ola 6800 system and have worked out the ACIA uses a clock at about 4800 Hz which details of this high speed use of the AC -30. is derived from the tape data. The logic in The Kansas City standard uses an AC the AC -30 which is used to generate and Carl Hel mers coupled redundant phase encoded method decode the waveform is only dependent Editor of recording which takes advantage of the upon the 1200 Hz and 2400 Hz frequencies

Figure 1: Timing of various interface signals. This diagram shows audio and TTL logic level signals for 300 bps and 1200 bps data referenced to the same 4800 Hz clock shown at E. On output, the timing of the clock governs generation of the waveforms, and on input the waveforms of A or C are used to regenerate clock data which averages 4800 Hz but with some jitter. The waveforms of A and B, respectively, show filtered audio and equivalent redundant Manchester I encoded digital data for a

300 BPS A FILTERED AUDIO

300 BPS DATA - START BIT O I 9 300 BPS PE

I 300 BPS '15 14 13 12 II 10 9 8 7 6 5 4 3 2 I O 15141312 II 10 9 8 7 6 5 4 3 2 O ST30 VALUES IO 9 300 BPS BITC VALUES

1200 BPS C FILTERED AUDIO

1200 BPS DATA - START O O O p 1200 BPS PE J U L

1200 BPS j--.13 2 I O 3 2 1 0 13 2 I 0¡3 2 I O¡3 2 I O 13 2 1 O 13 2 I O¡3 2 I 0 5T30 VALUES 9 18 17 16 j5 13 BITC VALUES 14 I I I I I E 4800 Hz CLOCK I LJ U LJ LJ U If l

www.americanradiohistory.com which arc derived from the 4800 Hz output encoded signal and the goal was to use the clock by frequency division in toggle flip AC -30 without any hardware modifications flops. in its circuit. The fact that it is only the 1200 and With this analysis of the situation, and a 2400 Hz frequencies on the tape which mental picture of what is seen in figure 1, I count when modulating or demodulating the set out to make an interface which would data is what makes this trick of 1200 bps drive the AC -30 at 1200 bps. Since I am a

I recording with the AC -30 possible. Figure 1 software person at heart, and since wanted shows the typical waveforms of the redun- to allow the possibility of eventually dis- dant phase encoded format at the beginning pensing with the asynchronous communica- of a 300 bps character transmission from the tions format by means of a new program UART or ACIA, and for an entire character design, I decided to leave out the UART or transmitted by a suitable algorithm in the ACIA chips and make a simple hardware asynchronous data format at 1200 bps. For interface for a programmed data format 300 bps transmissions, a logical 0 bit in the driven by interrupts. tape record consists of four complete cycles The Hardware: A Dedicated Port of 1200 Hz and a logical 1 bit consists of eight complete cycles of 2400 Hz. The and Real Time Clock switching between the two frequencies is In order to do a software simulation of a synchronous with the zero crossings so that data transmission format, some form of when the digital square wave signals gener- timing must be generated, both as the ated by the logic are filtered in the AC -30, 4800 Hz clock source for output through and by the act of recording on magnetic the AC -30 and to synchronize data with that tape, the results coming back into the clock or the tape derived clock on input. demodulator are smooth sine wave ap- Within the context of my own system, and proximations (see figure 1 A for the 300 bps bearing in mind more general uses of the version). In the 1200 bps version, we technique as well, I chose to use a separate eliminate most of the redundancy from the timing source driving the processor's non - redundant Manchester code by using only maskable interrupt (NMI) line as the means one complete cycle of 1200 Hz for a logical of synchronizing the software to the time 0 bit, and two complete cycles of 2400 Hz base. On output, the NMI line would have to for a logical 1 bit. If we were to use a true be driven by a 4800 Hz clock source; on

Manchester I phase encoding method (see Ira input the NMI line would have to be driven Rampil and Jack Bremier's article in March by the derived clock provided by the AC -30. 1977 BYTE, page 38), a 2400 bps rate The output clock source is a simple 555 would be possible by eliminating one more oscillator, IC9 in figure 2. This was set up level of redundancy. But the design of the with a variable resistor and a timing capac- AC -30 prevents generation of the true phase itor such that 4800 Hz was well within the

300 bps signal. The time ordered sequence of data starts with a "start" bit followed by several data bits. The waveforms of C and D show a complete character transmission at 7200 bps both as filtered audio (C) and redundant Manchester I encoded digital data (D). Above B and D are shown verbal descriptions of the data being transferred. Noted below signals B and D are the values of the variables ST30 and BI TC during output operations (see listing 7 and procedure 6).

1 14 13 12 10 15 14 13 12 II 10 9 8 7 6 5 4 3 2 i 0 115 14 13 12 II 10 9 8 7 6 5 4 3 2 0 115 II 9 8 7 6 5 16 8 7

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www.americanradiohistory.com Figure 2: The hardware needed to add this general purpose high speed AC -30 interface. The logic includes address decoding for the addresses in listing 7 and table 1, latched output from location 760 for control and data transmission purposes, drivers and receivers for RS -232 lines, an oscillator time base for output interrupts, as well as interrupt control logic and an open collector driver for the nonmaskable interrupt line. For those who use a commercial 6800 system, the bus pins should be allocated to the equivalent backplane pins of your system, and address decoding should be altered to fit your system. The names used in commercial products are usually similar to the Motorola documentation from which this system was designed.

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www.americanradiohistory.com tuning range. The .01 pF disk ceramic ca- LUGN AI A2 H? 21M0 > URO $2000 ?nnn pacitor C2 which I used as part of the 000 AC-30 INTEHhACE HuUfI.VES frequency determination network for the 2nnn 20n11 "BYTE STANDARD" INTERFACE Surf.AH5 oscillator may not have been the best choice 2000 ALSO CALLED "KANSAS CITY ", "CUIS" ruH.GMI ?nnn HUT A HOSE by ANY UTHEH LAMME STILL SOELLo for insensitivity to temperature and long 2n1U1 2nnn UESION HY UAHL HELMEHS. ED1fuH. BOT. term frequency stability, but previous ex- 2000 perience with 555 oscillators of this type 2n00 uENEHAL AC-30 lu UESIUNEU UECE.'mEH 26 1976 ?()01) TAPE 200A Lu(:AfIuN 02U rILE="AC-30 lu" proved stable over the course of nearly a 2000 2000 year of use in a slower tape interface which 2n00 THIS SET Jr HUUTINES HUNS AT 300 uH 1200 BPS 2000 AT 300 BPS. IS "BYTE ". "KANSAS CITY" uH "CUIS" runNM) had been mass storage method o. my primary 0000 AT 1200 BPS, IS 1200 BPS HEVUNUANT MANCHES(EH I 2000 0.0 PHASE ENl:ub119L until now. 20n0 THE VARIABLE "HATE" UEIEHMINES SPEED uF oATA 2nnn os. After the oscillator is wired, it can be 200n EOUAfES tuned to 4800 Hz by several methods. One nn5n >ST3u EOU 151) uUrPUT SIT STATE 0051 >UITV EQU 1,51 uUTPUT b1I VALUE Cu uH I) method is to borrow a friend's frequency 0052 'BITC LOU 152 uUIPUT 81f CUUNI 0053 »DAM EOU 153 LEFT DATA s TRAILER meter, or use an oscilloscope with pre- 4 >DATH EOU 154 01uHT DATA SPAHI' BIT 200no50 IN AHTICLE. "Dn1" HEhEHS Tu bu'H uF Ad,VE sumably accurate calibration of its time 'NXUA EQU SSS NEXT DATA (2 BYTES) 0057(0Sti >LELA EQU sS) DELAY COUNT (2 BYTES) base. I used a simple interrupt driven pro- nn54 >RATE EOU SSO DATA HATE gram in the processor to count the number 20n0 300 BPS VALUE =16 1200 bPS VALUE =4 OnS4 'HALF EOU SSA HALF HATE of processor cycles between clock interrupts nln >AC30 LOU 5160 AC3U DATA OUTPUT ANI) INPUT AUUHESS 0161 >ACuu EQU $161 OUTPUT NMI INTERRUPT ENABLE ADDRESS since I don't trust my oscilloscope's calibra- nlh3 >ACUr EOU 5163 NMI INTEHHUPT UISAHLE AUUHESS n13Á >MILI EQU SIDA MILI(b) - B MILLISECuND DELAY tion and don't have a frequency counter, but 21)011 o. MILI IS A l'IAINU LuUP IN MUN1TUH 0004 >NMIV EOU 14 N.1í AUUHESS VECTOR do have a crystal controlled processor clock. 2000 JMP UP CUVE AT LOCATION $3 ALLOYS WHITA'LE VECIVH 002E >FLA( LOU 52E MUNITuH'S INPUT uH OUTPUT THANSrEH ('LAO 0015 >MEM EQU SIS 4UNITUH'S EVULVIN6 DATA PuINTEH 0033 >ERHS EOU $30 MVNITUH'S EHRUH COUNT FIELD IN VEH1,1 2000 Listing 1: An assembly of the AC -30 inter- 2000 >. THE FULLUWIN) JUMPS SIMPLIFY PATCHING INfu MuNITUH 2000 . UUHINU INITIAL TESTING by PHOVIUINL FIXED ENTRIES face routines. The origin of this assembly 2000 7E no 00 >UPEI JMP UIUP 0003 7E 00 00 >HEAD JMP UIHU was chosen as hexadecimal arbitrarily 2000 2005 7E on 00 'WRIT JMP 1111QH to simplify relocation. In actual use, the 2009 7E 00 00 >VHFY JMP U1VY 200C '/E no 00 >GLUS JMP UICL routines were assembled to end up at the 200F 7E 00 00 >UPE2 JMP U200 2012 >. top of the previous code limits for 2.012 0. AC-3O NMI INTERRUPT HANDLER 2012 >CY30 EOU the author's IMP 6800 monitor and text 2()12 46 51 > LDAA BITV 2014 RA FE > UHAA i)E editor programs. (IMP, which resides in write 2016 H7 01 60 STAA AC30 2014 7A 00 50 o DEC ST30 protected memory at locations 1000 to 2nIC 27 00 BEO NEXB 201F: 30 RTI 1 FFF, stands for "Interactive Manipulator 201F 4r 'NEXB CLRA Program.') The addresses of FLAG, MEM 2010 01 2020 77 00 53 ASH UATL and ERRS used here are set by the structure 2023 76 UO 54 RJR OATH 21126 24 00 BCC CYZN of IMP - as arguments in different versions 2028 4C o INCA 2024 47 51 >CYZN STAA BITO of this set of routines, any old address would 2027 01 2020 96 52 o LDAA BITC do. The lO address locations reflect the 2n2U 27 00 BEO CYZH DECA hardware figure 1, and is a one 2021 4A of MILI 2030 97 52 CYZH STAA BITC millisecond delay loop program resident in a 202E 01 2032 96 54 LUAA RATE random piece of ROM which fills up part of 2034 97 50 STAA ST30 2036 38 HTI the bootstrap ROM of the system. In the 2037 2037 system in which this algorithm was used, the 2037 AC-30 MONITOR HUUTINES 2037 NMI (and other interrupts) vector to jump 2037 > instructions in programmable memory in the P037 > WRITE AC-30 300 BPS 2037 >U1WR EOU . first 12 bytes of address space. 2007 20 37 2037 96 52 LDAA BITC IF BIT COUNT > 0 THEN WAIT 2039 26 FC > BNE U1 WR 2038 DE 55 > LUX NXUA 203U UF 53 > SIX DATL s NXUA 203F 86 OB > LDAA 111 2041 97 52 o STAA BITC s 11 (SET BIT COUNT]] 86 FF' > LIMA s'F Number Type +5 V GND -12 V +12 V 2043 2045 97 55 > STAA NXUA (SET TRAILING BIT PATTERN] 2047 DE 15 LUX MEM IC1 74154 24 12 2040 AS 00 LDAA O.X IC2 7402 14 7 2040 97 56 STAA 5(04 *1 s= MEM (DEFINE NEXT OUTPUT] 2041) 'TA 00 56 > ASL NXUA+I IC3 7430 14 7 2050 74 00 55 > ROL NXDA s= SHL(NXOA) [INSERT START BIT] IC4 7400 14 7 2053 39 > RTS IC5 7404 14 7 2054 2054 O. 1200 BPS UPEN IC6 7410 14 7 2054 86 04 >U2UP LDAA 14 IC7 7401 14 7 2010 20 54 IC8 7400 14 7 2056 97 59 STAA RATE 2058 20 00 o BRA UUUP I C9 555 8,4 1 205A o. IC10 DM8833 16 8 205A >. 300 BPS UPEN IC11 DM8833 16 8 205A R6 10 'UIUP LDAA 116 IC12 DS1489 14 7 2001 20 5A 205C 97 59 STAA HATE IC13 DS1488 - 7 1 14 205E 96 59 'UUUP LOAA RATE IC14 74100 24 7 2059 04 2060 47 > ASRA 2061 97 5A > STAA HALF

www.americanradiohistory.com Listing 1, continued: Masking the Unmaskable

2063 7D 00 2E TST FLAU IS IT OUTPUT? Driving the NMI line for interrupts has 2066 26 00 > BNE UIOU one potential problem with a 6800 pro- 2068 7E 00 00 > JMP UIIu Ih NUT THEN INPUT OPEN 2068 > cessor: The hardware of the microprocessor 2068 > OUTPUT uPEN 206B 86 Eh >UIUU LLAA I$EF TURN itself has no way to turn off the source of 2067 03 206U 87 01 60 . STAA AC30 UN the interrupts. When I am not using the tape 2070 86 FF LDAA ISFr THE I 2072 B7 01 60 > STAA AC30 MUTUNI interface, don't want to have any inter- 2075 CE C3 50 > LUX I9999.9999.9999.9999r9999b (1L: S0.000) rupts. When I am listening to I 2078 DF 57 SIX ULLA input data, 207A CE Fr Fr > LUX ISFh }r don't want interrupts from the output clock. 207D DF 53 STX UATL 207F DF 55 STX NXUA When I am recording the data, I don't want 2081 96 59 LOAM RATE 2083 97 50 STAA ST30 any spurious interrupts from the input clock 2085 97 52 STAA BITC 2087 CE 00 00 > LUX 00101 SET UP INTEHRUPTS logic of the AC -30. Thus some switching and 208A DF 04 STX NAIV is 208C 7F 00 51 > CLR BITV masking logic in order. 208E 4F CLRA In figure 2, IC1, IC2 and IC3 are used 2090 7F 01 61 . CLR ACOU 2093 4D >UIU4 TSTA together to decode several addresses by 2094 27 FD NEO 0104 2096 39 > RTS combining selection of the address with 2097 > 2097 > OUTPUT UPEN INTERRUPT VMA (valid memory address) and the pro- 2097 DE 57 .UIU1 LDX ULLA 2088 20 97 cessor's (1)2 signal. Three of these addresses, 2099 09 VEX 209A 27 00 > NEO GONE hexadecimal 0161, 0162 and 1063, are not 209C DF S7 STX ULLA 209E 3B RTI 209F .GONE LOU 2098 03 209F CE 20 12 > LUX ICYJO 20A2 DF 04 STX NMIV 20A4 86 01 > LDAA 01 NUIES UN USE ur THE AC -30 WITH SOPEHSCUPE MULEL C -104 2046 97 51 STAA BITV 20A8 30 TSX 20A9 63 02 CUM 2.X LEAVE OPEN HANOUP TF.*PE:PAfUFF. SENSITIVITY 20AB 39 RTI 20AC . WHEN USEL IN A OuLL NASEMEHT (ESTIMATED fEMPEHATUhL 20AC > 300 BPS CLOSE Jh 55 -60 LEuREES FAHRENHEIT) THE HECUkbS uN TAPE .EHE 20AC 7D 00 2E >UICL TST FLAU UFTEN UEREAUAbLE. THE SUSPECTED CAUSE uh THIS 200D 20 AC PHENOMENON IS CHANUES IN LINEAR UIME6S1uNS Ur TAPE. SINCE 20AF 26 00 BNE UIUC AUJUSTIN¢ THE TAPE SPELL/ Tu HUN SIANLAHU VALUES CORFU 2081 7E 00 00 > JMP UIIC TPE PRObLEF.. THE ALJUSTMENT WHICH WUFAEU wA5 AbuUf 1-22 2084 > SLUwER THAN NuHMAL by THE C-1O4'S W AL. WHICH IS CunSISlEnl 20H4 . OUTPUT CLUSE WITH A ,ONTRACTIuN Ur THE LINEAR UTAENSIuNS uh THE TAPE 2084 96 52 .010C LDAA BITC DUE TO THE LUWEN SYSTE /. tE:APERAtuKE. 2080 03 2096 26 FC BNE UIOC WAIT FUR END LAST CHR 2088 DE 55 LDX NXUA 209A DF 53 STX DATL SENSITIVITY Tu "TuNE" ANL "VULU.IE" Cu6iiuLS 20BC DF SS SIX NXDA 208E CE 00 6E > LDX 11:0 THE PLAYHACH HF:LIAdILIrY IS ErrECTIVELY INLEPENLENf 2001 OF 55 > SIX NXDA OF THE VOLUME OF PLAYRACA uVEH A hAHUE CVVEHINL fat 20C3 86 O8 >U1U2 LDAA 111 CE6Th:H :Jr THE VOLUME SCALE ur THE HECuHUEH (J 10 d uN 2005 97 52 STAA BITC ITS APRITRARY CA1.I :HA(I:H SCALE). HUWEVEk THESE WAS 2007 96 52 >UIU3 LDAA BITC CUNSIOERABLE SENSII'IVIfY T0 THE TONE CONThUL SETFINU. FC 20C9 26 NNE U11.03 WITR THE uPTIMAL CUHTHUL dEIRU Tu.AHU THE " -" SLUE wk 20CB DE 55 LUX NXDA O Is THE C -104'5 HANUE Or -5 T0 5. 20CÚ 09 DEX 20CE OF 55 STX NXUA 2000 26 Fl BNE U102 2002 7F 01 63 > CLR ACJF TURN UFF NMI Uh:Nh.HAI. SUM.IARY ur HESULfS AS ur UANJAkY 27 197'/.+. 2005 86 OF LDAA 550E 2007 B7 01 60 > STAA AC30 TURN UFF AFTER UNE MUNIH Ur USE. ThE 1N1EHFAC. HAS WUW(EL FF 201A 86 > LDAA ISFF THE RELIABLY AS THE PRINCIPAL :1ASS STURALE DEVICE IN AY SYS1E, 200C B7 01 60 > STAA AC30 MOTOR AFTER IT WAS ASSEMHLEU AT A LuCATIUN WITHIN MY MuNltuk 20DF C6 FA LUAB 5250 PHUuHAn WITH THE EXCEPfIuN ur THE TEMPERATURE SENSITIVITY 20E1 37 PSHB WHICH WAS CUNEO NY uPENINU THE NAS &1ENf HEAT )(MASTERS. NNO 20E2 BD 01 38 > JSH MILI THE TuNE SENSITIVITY WHICH WAS CUHEL by r1NOINU THE hIUNT 20E5 33 PULB ANUN SETTINU HADOE. Nu ENHUNS IN HEAL, uH VEH1rY uPEhAflunn 20E6 BD 01 38 . JSR MILI HAVE BEEN ENCUUNTEHEL. THE 24 BIT CHECn SW1 USED IN THE 20E9 39 RTS 6uNITuN a:HIVINU THESE PHULHAMS IS THE PRIMARY VEHIFICATIDN 20EA > ur THE HEAD OPERATIONS. WHICH IS AUUMEnTEU UN VERIFY UPERAfiuN2 20EA . INPUT OPEN Hy THF: HITE by BYTE CUMPARISuN Uh TAPE [MIA Tv MEMORY URTA. 20ER 86 BF .U110 LDAA IfBF 2069 20 EA 20EC B7 01 60 > STAA AC30 20EF 86 FF LDAA ISFF 20F1 B7 01 60 > STAA AC30 20F4 C6 FA > LUAB 1250 THIS TEXT WAS PREPARED USINO THE TEXT EDITUH PkuUHAM dUILI INIu 20F6 7F 00 51 > CLR BITV MY P6191TUR. THE FIRST ITEM WRITTEN ANU UEbUUUEO USINU JACM 37 20F9 PSHB EHMEHICHS' ASSEHNLEH DESCHIHEO (PART I) ELSEWHERE IN THIS ISSUE 20FA ND 01 38 > JSR MILI ur BYTE. CTH 1/27/7i 20FU 33 PULB 20FE BU 01 38 > JSH MILI 2101 CE 00 00 > LUX 00111 2104 DF 04 STX NMIV 2106 7F 01 62 > CLR AC60.1 2109 39 HIS 210A > AWAIT START 210A B6 01 60 .U1í1 LDAA AC30 2102 21 OA 211E 84 01 ANDA 11 210D 84 01 > ANUA II 2120 26 00 BNE Ul1B 210E 26 00 BNE U11A 2122 7A 00 50 > DEC ST30 2111 96 SA LIAR HALT BIT TIME 2125 27 00 BEO U1IO 2113 97 50 STAA ST30 2127 38 HT1 2115 CE 00 00 > LDX /UII2 2128 START VERIFIES 2118 OF 04 STX NMIV 2128 96 59 >UIIO LUAA RATE 211A 38 >U1IA RTI 2126 01 2110 09 212A 97 50 STAR ST30 2119 > 212C 86 08 LORA 18 2118 > VERIFY START 212E 97 52 STAA BITC 211B B6 01 60 .U112 LDAA AC30 2130 CE 00 00 > LUX I0:13 2116 21 1H 2133 OF 04 > STX 9111 V

www.americanradiohistory.com implemented as actual memory locations at Listing 1, continued: all. Instead, the address selection outputs of 2135 38 > hT1 2169 7U 00 51 >UIRD T5T dITV IC1 for these addresses are used to control 2136 > FALSE START 2004 21 69 three flip 2136 CE 21 OA >UIIB LUX I0111 216C 27 FU > BEO UIRU flops which determine the source 2121 14 216E 96 53 > LUAA UATL of the NMI interrupt generated by this 2139 OF 04 > STX NAIV 2170 7F 00 51 > CLR B1TV 2138 38 > HT! 2173 DE 15 > LDX MEM circuit. The most important flip flop is 213C BIT HEAD STATES 2175 A7 00 STAA 0.2 213C 7A 00 50 >0113 DEC 5130 2177 39 RIS formed by IC6a and IC6b. This is the 2131 21 3C 2178 711 OU 51 >UIVY 'CST B1TV 213E 27 OU > 8E0 UIIU 200A 21 78 interrupt mask flip flop, which is set (allow- 2141 38 HT1 2178 27 Fb BEO UIVY 2142 96 59 >UIID LUAA RATE 217U 96 53 > LDAA DATL ing interrupts) by a reference to hexadecimal 2140 01 217F 7F OU 51 > CLH B1TV 2144 97 50 > STAA ST30 2182 DE 15 > LUX MEM addresses 0161 or 0162. is This flip flop 2146 7A 00 52 > DEC BITC 2184 AI 00 CMPA 0.X 2149 26 > BNE cleared by either a system reset or a refer- 00 UIIE 2186 26 00 EINE DIVE 21411 CE 00 00 > LUX I11114 2188 39 RTS ence to location 0163. The system reset 214E OF 04 > SIX NM1V 2189 DE 33 >UIVE LDX ERRS 2150 B6 01 60 >U11E LUAA AC30 P187 01 aspect is quite important, since it would not 214A 05 2188 08 > INX 2153 46 > HUM 218C DF 33 > SIX ERRS be too useful to have the system power up 2154 96 53 > LDAA DATL 218E 39 RTS 2156 46 HORA 218F 7F 01 63 >UIIC CLH ACuF with these interrupts enabled and no inter- 2157 97 53 > STAA uATL 2082 21 BF rupt handler in memory, and when 2159 3H > RTL 2192 86 7F > LUPA IE7F" develop- 2I5A ONE STOP 81T 2194 B7 01 60 > STAA AC30 ing software for the interface it helps to be 215A 7A 00 50 '0114 DEC 5130 2197 86 FF LDAA ISFF 214C 21 5A 2199 87 01 60 > STAA AC30 able to reestablish normal interrupt free 215D 27 00 > BEO Ul1F 219C 86 FA > LUAA 5250 215E 38 > Nil 219E 37 PSHB operation by pushing reset. 2160 CE 21 OA >U1I1, LUX SUlll 219F BD 01 38 > JSR MILI 215E 01 21A2 33 > PULB The flip flop formed by IC8a and IC8b is 2163 OF 04 > STX NM1V 21A3 BU 01 38 > JSR MIL! 2165 73 00 51 > CUM B1TV 21A6 39 HIS set by reference to address 0162 and is used 2168 3B > Nil 21A7 > END to select the AC -30's tape derived clock as the source of interrupts. The flip flop SYMBOLS: AC30 0160 ACOU 0161 ACLF 0163 BITC 0052 HITV 0051 formed by IC8c and IC8d is set by reference CLUS 200C CY30 2012 CYZN 2029 CYZR 2030 DATL 0053 to address 0161, and is used to select the DATA 0054 VELA 0057 ERRS 0033 FLAI, 002E LUNE 209E HALF OO5A MEM 0015 MILI 0138 NEXB 201E ,MIV 0004 4800 Hz oscillator as the source of inter- NXUA 0055 UPEI 2000 uPE2 200F RATE 0059 HEAD 2003 ST30 0050 UICL 20AC U111 210A U112 2116 0113 213C rupts for output use. Both of these interrupt 0114 2I5A UIIA 211A 01111 2136 UIIC 218E Ul1D 2142 011E 2150 UIIF 2160 0110 20E2 0110 2128 0101 2097 selection flip flops are cleared by a reference 0102 20C3 U103 2007 0104 2093 UIUC 2084 0100 2066 UIUP 205A UIRD 2169 UIVE 2189 UIVY 2178 0191-. 2037 to location 0163. In building this circuit for U2UP 2054 UUUP 205E VHFY 2009 WRIT 2006 some other processor, you'll probably have a different set of 10 addresses. Modification of the address selection logic (and the software Table 1: Summary of the addresses and commands used in programming the of listing 1) will probably be required. AC -30 interface of figure 1.

Output Latch and Interface Input Hexadecimal Address 160, symbol "AC30" in listing 1: The rest of the circuit in figure 2 consists Input from the four RS -232 receivers of IC12 is available in the low order bits of the output latch and RS -232 level shifting of data referenced at location 160. The low order bit, bit 0, is assigned to buffers associated with address 0160. the AC -30 by wiring IC12 pin 13 to the pin identified as "To Computer's RS -232 Input" in the AC -30 wiring diagram. High order bits are grounded Writing data to location 0160 sets the value to define unused logical zero inputs. contained in the 8 bit 74100 latch, IC14. Output from the four RS -232 drivers of IC13 is available in the low order bits The four high order bits of this latch are of data written to location 160. The low order bit, bit 0, is assigned to the used to drive the AC -30's motor control AC -30 by wiring IC13 pin 11 to the pin identified as "To Computer's lines directly as TTL signal levels. (See table RS -232 Output" in the AC -30 wiring diagram. 1 for a listing of command codes corre- The high order bits are used to control the two motor control flip flops of the sponding to the wiring of figure 2.) The low AC -30. Forcing the RS -232 output to remain at logical 1 (the negative order four bits are wired to a DS1488 line RS -232 state), the following command codes are used (hexadecimal): driver needed to convert levels to TTL EF = Turn on output motor All codes assume negative going RS -232 levels. The low order bit drives the DF = Turn off output motor pulses activate commands (see RS -232 output to the AC -30, with the BF = Turn on read motor AC -30 documentation for 7F = read motor settings of the options). remaining three lines available but unused at Turn off i present. If at some later date it becomes When setting data in the low order bits, the high order data sent to location necessary to program a communications 160 should be masked by a logical sum (OR) with hexadecimal FO. interface to some other RS -232 device, this Hexadecimal Address 161, symbol "ACGO" in listing 1: hardware now lies ready and waiting in my Any reference to this address turns on the 4800 Hz NMI interrupt source. system. The latch is written by combining the RW with the processor's line (inverted) Hexadecimal Address 162, symbol "ACGO +1" in listing 1: address selection signal to generate a clock Any reference to this address turns on the NMI interrupt source derived from pulse. the tape data via the receiver section of the AC -30. For inputs from the external world, the bus interface gates simply listen to data lines Hexadecimal Address 163, symbol "ACOF" in listing 1: when the address is selected. The low order Any reference to this address turns off all NMI sources in this interface, as four bits of an input word are defined by the does a system reset.

www.americanradiohistory.com logical unit identification. The control struc- INITIALIZATION ture of the monitor is not the subject of this (BITV =0) article, but its effect is felt in the requirement of five generic IO routines which must START be written to interface any given unit such as BIT INPUT 0 0 the AC-30: SEARCH OPEN: initialization of IO operations is performed by calling an OPEN pro- INPUT F 0 INPUT = 0 cedure; the monitor data item FLAG determines whether the unit will be opened for input or output processing. ST 30 f 0 WRITE: when output is required, WRITE is called each time a byte of data is to be transferred from the address in

ST30 = 0 pointer MEM to the peripheral. READ: for input to memory, READ is 72 called each time a byte of data is to be Figure 3: The finite state BT transferred from the peripheral to the machine for input. The in- READ BITC t 0 STATE / / address in pointer MEM. put decoding is performed VERIFY: to check the accuracy of by a "finite state ma- crucial files, a form of the read opera- chine" implemented in BITC = 0 tion called VERIFY compares input software. The state of the data to the contents of memory at the input decoder is set by the address in pointer MEM; an error choice of NMI interrupt STOP BIT count, ERRS, is incremented if vector. This diagram shows STATE necessary. the conditions under CLOSE: when IO is complete, the which transitions are CLOSE routine is used to turn off the made, but omits any refer- ST30 = 0 peripheral after making sure detail ence to the detailed pro- transmission operations are done. cessing. See procedures 7.0 to 7.3 and listing 1 for The choice of these five generic IO operations complete details. This infor any given IO unit is a fairly typical put state machine is four RS -232 compatible input lines which are practice when implementing the systems initialized by the OPEN converted to TTL levels by the DS1489 software of a computer. It is particularly routine and it is termi- receiver circuit, IC12. The low order bit is helpful when implementing new interfaces: nated when interrupts are committed to the AC -30's RS -232 output The control structure of my monitor is turned off by the CLOSE line by wiring of the cable, leaving the other thoroughly debugged already, so when I routine. three low order bits open for later use with wrote the new routines and they bombed

an RS -232 terminal as noted above. The high the first time around (as often happens) I order input bits are presently wired to knew for sure where the problem was. ground, but if it ever becomes necessary to add a single bit TTL level input port to the Specifying the IO Operations computer, these bits can be committed to The details of the IO operations the that use by wiring them to a suitable for external connector. AC -30 are shown in this article in two forms. One form is listing 1, a detailed set of code implemented for the 6800 and assembled With Hardware Defined, the using Jack Emmerichs' assembler program. Software Follows Suit The second form in which the IO operations The intent of this whole exercise is to are given is in a higher level "pseudo code" provide a set of routines for writing and form as eight self contained procedures. reading data from the AC -30 within the These procedures are written from the context of my existing monitor and text assembly as a form of detailed commentary editor program, IMP 6800 ( "the Interactive on the algorithm, and can be used by owners Manipulator Program "). This monitor proof the other processors as a starting point vides a general IO control structure which for coding new versions of the routines. accesses detail byte data transfer and control In the notation of the programs in the routines for any given IO unit. When an IO procedures, square brackets [] are used to logical unit is selected by an appropriate enclose extended commentary and opera- command, the control structure references tions defined in words. Variable names and the detail IO routines by looking up their labels are the same as those used in listing 1. addresses in a pointer table keyed by the With a few minor exceptions the procedures

www.americanradiohistory.com Procedure 1: OPEN routines. The OPEN routines are used to set up output or input operations, depending upon the state of FLAG, a variable which should be set to 0 for input, nonzero (example: hexadecimal FF as in listing 1) for output. Output OPEN operations consist of turning on the motor, then recording a leader (using the output interrupt of procedure 5), then initializing the interrupt handler for output operations. An input OPEN consists of turning on the input motor, then waiting a half a second before initializing the input interrupt which scans for the asynchronous data format used by this software. On leaving the OPEN routines, the software which uses this IO discipline can proceed to the details of byte by byte data transfer using WRITE, READ or VERIFY.

1.0 Entry U2OP [1200 bps data rate initialization] ; 1.1 RATE := 4 [interrupts per bit] ; 1.2 Go to 1.5; 1.3 Entry U1 OP [300 bps data rate initialization] ; 1.4 RATE := 16 [interrupts per bit] ; 1.5 HALF := RATE / 2 [set up half bit period value) ; 1.6 if FLAG = output value then do [an output open procedure] ; 1.6.0 [turn on the AC -30 output motor]; 1.6.1 DELA := 50000 [set up output write delay count for 10 seconds] ; 1.6.2 DAT := S'FFFF' [initialize data output buffer to null data]; 1.6.3 NXDA := $'FFFF' [initialize next data as null data] ; 1.6.4 ST30 := RATE; 1.6.5 BITC := RATE; 1.6.6 NMIV [nonmaskable interrupt vector] _ [address of output open interrupt service routine, procedure 51; 1.6.7 [clear "open done" flag, the accumulator] ; 1.6.8 (turn on output 4800 Hz interrupt source] ; 1.6.9 Wait until end of leader [after DE LA count is exhausted] ; 1.6.10 return; 1.6.11 end; 1.7 else do [an input open procedure] ; 1.7.1 [turn on the AC -30 input motor] ; 1.7.2 BITV [data ready flag] := 0; 1.7.3 wait 0.5 seconds; 1.7.4 NMIV [nonmaskable interrupt vector] = [address of input start bit search, U1111; 1.7.5 [turn on input `4800 Hz tape derived interrupt source] ; 1.7.6 return; 1.7.7 end;

Procedure 2: The WRITE routine. This routine must be preceded by an output OPEN operation which initializes the interrupt service of procedure 6. It can be called over and over again until the data to be written is exhausted. Each WRITE call transfers one byte from the location addressed by variable MEM to the output file. The software which uses WRITE is responsible for incrementing and keeping track of MEM when a block of data is being written.

2.0 Wait until BITC [bit count] is equal to zero; 2.1 DAT [2 byte output field] := NXDA [next output, computed by previous call] ; 2.2 BITC := 11 [1 start, 8 data, 2 stop bits minimum] ;

2.3 NXDA := $'FF00' I ( @MEM) [move data at MEM into new output string along with null trailing bits] ; 2.4 NXDA := (arithmetic left shift of NXDA] ; 2.5 return;

Procedure 3: The READ routine. This routine must be preceded by an input OPEN operation to initialize the input interrupt service procedures. It is called over and over again until enough data has been transferred. Each READ call transfers one byte from the tape into the location addressed by variable MEM. The software which uses READ is responsible for incrementing and keeping track of the address in MEM, and for determining how long a block of data is being read. READ coordinates operation with the input interrupt service routines through the variable BITV which is used as a flag.

3.0 Wait until BITV = $'FF' [synchronize with flag set by interrupt service] ; 3.1 ( @MEM) := DAT [move input byte from buffer to address in pointer MEM] ; 3.2 return;

www.americanradiohistory.com Procedure 4: The VERIFY routine. This routine works exactly like READ Using Interrupts with one exception: Instead of dumping the input data into memory at All the IO implemented in this approach MEM, compares data the data in memory and location it the input to uses the interrupt from the AC -30 or the increments the error counter ERRS if there is any difference. As with READ oscillator of IC9 to time operations. Thus WRITE, the software which calls is responsible incrementing and VERIFY for there are three interrupt service routines MEM and keeping track of the data being checked. specified, as procedures 5, 6 and 7. The output open interrupt service routine of 4.0 Wait until BITV = S'FF' [synchronize with flag set by interrupt service] ; procedure 5 has the simple task of counting 4.1 if ( @MEM) not equal to DAT then ERRS := ERRS + 1 [count the differences] ; 4.2 return; down DELA interrupts as set by the output OPEN procedure, after which it will set up the normal output interrupt service and signal the end of the leader. The normal Procedure 5: The output OPEN interrupt service routine. This procedure is output interrupt service routine counts used to count down a delay value initialized in DELA when OPEN begins its down the number of interrupts per bit, and processing. OPEN ultimately terminates when this interrupt routine finds a when necessary shifts a new bit out of the zero value in DELA and signals the OPEN routine via the value in BI TV. output buffer, DAT, to be sent to the AC -30. It also counts bits and signals the 5.0 DELA [leader interrupt count, 16 bits] := DELA - 1; WRITE procedure that it is ready for the 5.1 if DELA = 0 then do; 5.1 .0 NMIV := [address of output data transfer interrupt service, CY30] ; next character. Figure 1 shows the progres- 5.1.1 BITV := 1; sion of values of ST30 and BITC during 5.1 .2 [signal end of output leader delay] ; 5.2 return from interrupt; output. The input interrupt structure is much more complicated. There are four states to Procedure 6: Output data transfer interrupt service. This routine, which is the finite state machine which handles data initialized as the interrupt service routine at the end of the OPEN procedure, input, as shown in figure 3. These states are does the detail work of transferring data to the AC-30 from the computer. implemented by the current value of the The variable ST30 is used to count down the interrupts within each output NMI interrupt pointer, which selects one of bit (see figure 1), and the variable BI TC is used to count the number of bits in the four input routines of procedures 7. The a character being transmitted. BI TC is also used as the flag to signal to conditions for change of state are noted on WRITE that a character is done, so its counting down is halted at zero by the transitions in figure 3, but details of each line 6.4. Whenever a bit is completed, the count of interrupts per bit is state should be extracted from the pro- reinitialized in variable ST30. The variable BI TC is reinitialized by WRITE cedures. The input interrupt algorithm first when a new output word has been defined. Data is right shifted out the low enters a start bit search state of procedure order bit of a 2 byte field called DAT in this procedure, identified as DATL 7.0; when the start bit is found, it is verified and DA TR in listing 1. in the second state of procedure 7.1 by checking to make sure that it remains low for half of a bit period (marked by counting 6.0 [output data bit] := BITV [latest bit value] ; 6.1 ST30 [output waveform state] := ST30 - 1; down the value in variable HALF). When the if is zero 6.2 ST30 not then return from interrupt; start bit is verified, the data transfer state is 6.3.0 BITV [next bit value] := [low order bit of 2 byte output field DAT] ; entered and a total of eight bits are shifted 6.3.1 DAT := [2 byte arithmetic right shift of DAT] ; 6.4 if BITC greater than zero then BITC := BITC - 1; into the input buffer DATL. After eight bits := RATE ; 6.5 ST30 [number of interrupts per bit transmitted] are shifted, the algorithm enters the stop bit 6.6 return from interrupt; state of procedure 7.3 for one bit period, where a flag is altered to signal that data is follow the logic of the various sections of ready. Within 1.5 bit times of the flag listing 1, but the order of the procedures change, the READ or VERIFY routine must

differs. Listing 1 reflects the order in which transfer the data from DATL to its destina- the routines were actually written, while the tion in memory or an alternate buffer area. procedures are numbered in an aesthetically This timing requirement of 1.25 ms for nicer arrangement. 1200 bps data or 5 ms for 300 bps data is In interfacing to the monitor, the only due to the fact that the first bit of the next difference between 300 bps and 1200 bps is character will be shifted into DATL 1.5 bit in the definition of the number of interrupts periods after the stop bit state is executed. per bit, a value which is defined in the OPEN The time tolerance can be increased to a full procedure for each data rate. Thus there are character time (9.2 ms at 1200 bps) if pro- two entry points in the OPEN procedure, cedure 7.3 is modified to transfer the con-

corresponding to logical unit 1 (300 bps) tents of DATL into a buffering byte, for and logical unit 2 (1200 bps) of my monitor. example DAT R. The WRITE, READ, VERIFY and CLOSE Some Comments on the CLOSE routines are shared between the two logical unit designations, although the names used Routines... only reflect unit 1. The CLOSE routine given in this version

www.americanradiohistory.com of the software is far from perfect. It might Procedure 7: Input data transfer service routines. These four procedures even be called a bit "inelegant." Any good constitute the four states of the data input "state machine" which acts like programmer will see some rather obvious the receiver of a typical UA RT or ACIA chip. The start bit search state (7.0)

holes in the system: I really don't need four finds a start bit which may be verified by the start bit verification state of seconds worth of interrecord gap after data 7.1. If the start bit was good, eight data bits are transferred by the input bit is written at 300 bps. Similarly, for input read state of procedure 7.2. Finally, one stop bit time is marked by

operations, I should have allowed the motor procedure 7.3 and the receipt of data is communicated to READ or VERIFY to remain on for a period of time equal to by changing the state of BITV. Then the start bit search resumes. See figure 3 the null period which would have been for a state diagram of this process. generated by the output CLOSE operation

for the same block. Given manual manipula- 7.0 [start bit search interrupt service, U1 11 ] : tion of tape position using the mechanical 7.0.0 If input data line is zero then do: 7.0.0.0 ST30 := HALF [set up delay for a half bit's worth of interrupts] ; position counter, this CLOSE algorithm is 7.0.0.1 NMIV :_ [address of start bit verification interrupt service] ; adequate. But if you intend to do tape to 7.0.0.2 end; tape editing with two cassette drives and 7.0.1 return from interrupt; 7.1 [start bit verification interrupt service, U1121: probably want to motor control, you'll 7.1.0 If input data line is not zero then do [false start logic) ; improve the CLOSE algorithm to allow more 7.1.0.0 NMIV :_ [address of input start bit search, U1111 ; reliable electronic positioning via motor 7.1.0.1 return from interrupt; 7.1.0.2 end; control. 7.1.1 ST30 := ST30 - 1 [count down HALF bit times] ; 7.1.2 if ST30 := RATE; 7.1.2.0 ST30 := RATE; Does It Work? 7.1.2.1 BITC := 8 [initialize one byte's worth of bits] ; Yes, but 1200 bps Is Still Too Slow! 7.1 .2.2 NMIV := [address of input bit read interrupt service, U1131 ; 7.1.2.3 end; Since getting the software described here 7.1.3 return from interrupt; into the state seen in listing 1 and patching it 7.2 [Input bit read interrupt service, U1131: ST30 := ST30 - 1 [count down RATE states per bit] ; into my monitor program December 26 7.2.0 7.2.1 if ST30 = 0 then do [sample bit and shift into data word] ; 1976, this software has been my main mass 7.2.1.0 ST30 := RATE [set up for next bit] ; storage IO method. In a month of intense 7.2.1.1 BITC := BITC - 1 [count down the bits) ; 7.2.1.2 if BITC = 0 then NMIV :_ [address of stop bit interrupt service, U1141; use, I have yet to drop a bit (although while 7.2.1.3 DATL = [right rotate of DATL with carry defined by input bit value] ; testing I had to experiment to find the right 7.2.1.4 end; cassette recorder volume level range on 7.2.2 return from interrupt; 7.3 [Stop bit interrupt service, U114] : My homebrew system has re- playback). 7.3.0 ST30 : = ST30 - 1; cently grown to 24 K of programmable 7.3.1 if ST30 = 0 then do [restart start bit search] ; 7.3.1.0 NMIV = [address of start bit search, U111 ] ; memory with 12 K bytes of text editor 7.3.1.1 BITV [data ready flag for input) _ $'FF' [indicate data ready] ; string area, 4 K bytes for Jack Emmerichs' 7.3.1.2 end; assembler program (sec April and May 1977 7.3.2 return from interrupt; BYTEs), 4 K bytes for assembler output strings, and 4 K bytes for my monitor data operations are complete, CLOSE and text editor programs. I have found this Procedure 8: CLOSE routines. After all new 1200 bps data rate to be an indis- routines are used to turn off the motor and clean up the last details of input pensable time -saver compared to my older or output. See text for some comments about the design of this routine, hardware method which ran at about which could be improved considerably. 200 bps. Since the software described here works at 300 bps as well as at 1200 bps, I 8.0 if FLAG = output value then do [an output procedure] ; is zero; can now load and write cassettes using the 8.0.0 Wait until BITC [bit count] equal to 8.0.1 DAT := NXDAT [transfer last character to output field] ; physical format of the Kansas City standard. 8.0.2 [write 1200 null bits by letting output interrupts run] ; This of course finally achieves the real 8.0.3 [turn off AC -30 motor control]; [turn interrupt source] ; purpose of buying the AC -30. 8.0.4 off output 8.0.5 [wait 0.5 seconds for motor to turn off] ; With this interface I can load the as- 8.0.6 end; sembler program in 50 seconds, and com- 8.1 else do [an input close procedure] ; 8.1 .0 [turn off input interrupt source] ; define the string area in pletely text editor 8.1.1 [turn off AC -30 motor control] ; about 150 seconds. It lias really speeded up 81.2 [wait 0.5 seconds] ; the software development operations which 8.1.3 end; 8.2 return; are the real joy of a computer applied to personal needs and goals. Of course, having accomplished this is not capability in the form of an electronically enough: My next challenge, in design as of controlled file system with 2 million bytes this writing, is a 3M drive controller inter- on line, 40,000 bps data transfer rate and faced to a $500 surplus drive purchased 43 second maximum access time to any From Boston's American Used Computer given block of data. But for the next six

Corporation via their back door, The Com- months or so, I anticipate frequent and puter Warehouse Store. When this project is reliable use of this 1200 bps modification to done, my system will have some real IO the AC -30's purpose in life.

www.americanradiohistory.com Artificial Intelligence:

Is It? What a If you are typical computer hobbyist, you have probably spent (or will spend) a fair amount of time playing games - computer games, that is. Perhaps you have written computer programs to play space war, backgammon, even chess. What techniques are used in programming computer Richard L Rosenbaum games, 61 -04 Little Neck Pkwy particularly those requiring "intel- Little Neck NY 11362 ligent" decisions by the machine? The answer to this question is in the realm of artificial intelligence. Perhaps you are trying to program a microprocessor to recognize or interpret signals from a video camera, or would like to 11111 11111 11111 11111 11111 11111 automatically translate Morse code to 11111 11111 11111 11111 11111 11111 printed characters. Both of these problems 11111 11111 11111 IIIII IIIII II concern artificial intelligence, specifically in the field of pattern recognition. a) A typical nim board set up. b) A typical first move. What is artificial intelligence? For that Decimal Binary Decimal Binary matter, what is intelligence? These questions 15 1111 15 1111 can easily lead us into a philosophical 15 1111 3 0011 debate, but that is not the purpose of this 12 1100 12 1100 discussion. My interest is how artificial intelligence, frequently referred to as Al, can c) Unsafe second move. d) Safe second move. help us solve problems such as those just Decimal Binary Decimal Binary outlined. What these problems have in corn- 0001 0001 mon is the substitution of a computer 4 0100 o 0000 (artificial mechanism) for what are ordi- o 0000 o 0000 narily human tasks (generally assumed to require intelligence). So for the sake of e) Last move -1. f) Winning move. expediency, let's define artificial intelligence Figure 1: One version of the game of nim starts with three piles of 15 as the mimicking of human behavior and counters as shown in figure la. Players take turns removing any number of decision making by computer. counters, at least one, from any one pile. The player who takes the last Today, work in artificial intelligence is counter loses. In the case illustrated in figure lb the first player took three divided into a number of areas. Two of them from the last pile. Figures lc and d illustrate some techniques used in have been mentioned: game playing and developing an infallible play of nim. The first step is to represent the number pattern recognition. Others include generalized problem solving, natural language corn - of counters in each pile in binary. Then you must determine the number of is prehension and translation, and robotics. in each binary column. If the number is odd, as in figure lc, then you are in These will be examined in order. an unsafe position. You should make your move so as to leave an even number of 1 s in each column as shown in figure 1 d. This is known as a safe Game Playing Programs position. A point is eventually reached, as in figure le, where there are only two piles left and only one of them has more than one counter. The winning It is probable that once the beginning strategy is to take all of the counters from the pile with more than one. This computer hobbyist learns basic programming causes the other person to take the last counter, as shown in figure 1f. Using fundamentals, the first attempt at a big these methods, an unbeatable game of nim can be developed. program will be an entertaining one. How

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www.americanradiohistory.com many of us, once we have BASIC up and So we need an evaluation function. The running, quickly type in our copy of Star quality of this function will strongly Trek? We all have some interest in computer influence how good a game the computer games. can play. In 1967, A Samuel wrote a While many games use artificial intel- program to play checkers. In it, he used an ligence concepts in their programming, not evaluation formula that took into account all of them do. For instance, Star Trek such parameters as number of pieces, usually consists of a program that keeps number of kings, how far the kings were track of time, energy levels, scores and other advanced, etc. Samuel, however, did not parameters. The only decision to be made is know how to weight the various items to

generally, "Which way do I fire ? ", which determine their relative importance. So he only requires use of a simple formula. Of made a set of trial values and incorporated course, there are exceptions where some into the program a mechanism that changed super program simulates the alien cunning of these values if it was losing, in order to try a Klingon commander. to find an optimum strategy. In this way, he Artificial intelligence techniques are re- wrote a program which "learned" to play quired, however, for the automation of most better checkers! traditional multiple player games. These Of course there is more to playing a game range from the simple binary strategy of nim than just evaluating positions. We must (see figure 1) to the complexities of chess. generate trial moves in some orderly fashion. The case of nim illustrates one extreme of an The most efficient way to do this is to make intelligent program: the perfect player. The a tree of possible moves as shown in figure 2 game is simple enough to develop a fast for example. This figure is called a tree technique to determine the best move. Such because of the way it resembles an upside is not the case in chess. The important point down tree with branches. here is that both chess and nim are deter- As can be seen, trees can rapidly expand ministic; ie: if you have enough time, you as they grow downward. The tree shown in can go through every possibility that can figure 2 has 1.2 x 1056 branches. With the arise. games as However, with complex limited memory space of a typical micropro- as chess, a program would take a tremendous cessor, we must find some way to minimize amount of time to check all the possible its size. One way is to copy the human moves. This is where artificial intelligence player, and not expand any branches that do techniques come to the rescue. not look promising, ie: do not have a high Let us examine how a human player evaluation. Other aspects of artificial intel- makes decisions in a game such as chess. This ligence concern optimization of the evalua- technique, saying, "How would I do it ? ", is tion, speeding up tree generation, and mini- invaluable in artificial intelligence work. mizing other memory requirements. Often, Obviously, we do not go through every possibility. What we do instead is to make trial moves and evaluate the board situation at that point. If the situation is too dan- gerous, we discard that possibility and check (15) (15) (15) others until we make a decision.

(15) (15) (14) (15) (15) (13) (1) (15) (15) (0) (15) (15) /I\ /I\ Figure 2: This is the beginning of a game tree for the game of nim as discussed in figure 1. Only a few of the brunches are shown for the sake of clarity. Using (15) (15) (12) (14) this version of the game (15) (15) (13) (1) (15) (14) (0) (15) there are 45 different ways \ /I\ /I\ to play the game! -/ I / I \ / I \ / I \ 52

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www.americanradiohistory.com Figure 3: A syntactic analysis of the sentence, "This game is played by two people on the computer." This particular parse of the sentence, resolving the sentence into its components, means that two people are engaged in playing a game that somehow involves the use of the computer (the adverb use of the SENTENCE phrase "on the computer" to modify "is played").

NOUN PHRASE VERB PHRASE

THIS GAME VERB PREPOSITIONAL PHRASE (ADVERB USE) PREPOSITIONAL PHRASE (ADVERB USE)

1 IS PLAYED BY TWO PEOPLE ON THE COMPUTER

one only stores a small local region of the prerequisite of any attempt to make tree at any one time, using rules to generate comparisons. additional segments. Problem Solving Pattern Recognition Problem solving may appear to cover The influence of computer aided pattern everything under the sun but within artificial recognition is affecting us more each day. intelligence it refers to a specific set of tasks. Our checks have funny digits printed on In artificial intelligence, a problem is said to them, grocery items have strange stripes; you exist when we are in an initial state, desire to also might have run into forms that required reach a goal state, and 'have a limited set of you to write characters exactly as indicated. operations that can be used to get there. A portion of artificial intelligence concerns Game playing is actually a subset of this, in itself with these tasks. that the initial state is the present position, Pattern recognition is generally a problem and the goal state is a win. Another example of classification. We have either a single item is theorem proving, in which the initial state which we wish to describe as having certain is given (remember your geometry ?) and the characteristics, or we have a group of objects operations are the various axioms. which we wish to break into subgroups. The There have been many attempts to principal problem is determining if a parti- develop general methods for these types of cular object is in a certain class of objects. problems. In fact, an early one was called Hence, the field extends beyond merely GPS, General Problem Solver. The authors

recognizing characters on a piece of paper. of this program, A Newell, H Simon, and J Potentially, artificial intelligence techniques Shaw, developed many of the techniques in could help classify medical problems based this field. The simplest one was a brute force upon symptoms, the field of computer aided method, similar to our discussion of check- diagnosis long found in science fiction litera- ing every possible move in a chess game. ture. They called this the "British Museum algo- Unfortunately, much of the work in this rithm" in reference to the fact that a field involves higher mathematics which are monkey placed in front of a typewriter will beyond the scope of this article. However, eventually write all the books in the British some elementary principles may help you Museum. So much for that idea! conduct some investigations, perhaps in Of all the work done, the most popular computer analysis of video signals. A funda- idea was embodied in a program called the mental technique is to break your recogni- Fortran Deductive System. This program tion problem into the simplest subproblems would take the initial and goal states, and possible. For instance, consider the problem develop a set of differences. It then would of analyzing faces. One would have to methodically apply the various operations in generate parameters for subclassifications an attempt to reach the goal. The difference such as color of eyes, hair, etc. In this way, it had from the brute force approach was each face is assigned a set of basic values, a that it knew which operations affected

www.americanradiohistory.com The Digital Group adds character(s).

64, to be exact. The Digital Group's computer Write cassette system systems have a lot of character uses a digitally synthe- already. Just one quick look at sized frequency shift any of our products in their system, derived from TV unique custom cabinets con- system's master crystal firms that. But we believe it oscillator never hurts to add a bit more. Mis'r Read cassette system So, the Digital Group has added easily aligned using the character in a big way to give an write system as an align- added dimension to the opera- i_e'p4- ment aid. tion of our video -based computer systems. We are pleased Runs at 1100 baud to announce our new TV readout with a 64- character line. (100 characters /second) -loads It will give your system a great deal more capability. Give 16K in 3 minutes it more character, if you will. 512 TVC to 1024 TVC Upgrade Kit: Here are the specifics on the Digital Group TV Readout As always, when the Digital Group extends the capabilities and Audio Cassette Interface: of our systems, it doesn't mean obsolescence for any products. We are offering an upgrade kit for present Digital 1024 Character TV Readout Group system owners who wish to go to the longer line 64 characters horizontal by 16 lines length. This kit uses most of the IC's from our TVC --F read- 7x9 character matrix (effectively 7x12 due to char- out. No unsoldering is required; all new sockets, capac- acter shifting) itors, resistors, PC board and other necessary parts are 1K on -board RAM for buffer storage - requires supplied. no main memory- completely independent Prices: 128 character ASCII TVC -64 -Full 64- character TV Readout & Audio Cassette Upper case alpha Interface: alpha with base line extenders Lower case (g, Kit - $140 Assembled - $205 1 P, Y) Numbers and extended math symbols TVC- 64UPG- Upgrade kit from TVC -F: Greek alphabet Kit - $65 Software driven cursor - forward and backward Compatible with most microprocessors; Interfaces If you already own a Digital Group system, our 64- charac- with 1 8 -bit parallel output port ter line will definitely enhance its operation. If you're just Timebase may be driven with an external timebase looking, you might want to keep in mind that the Digital Group has a lot of characters. (may be synchronized to TV camera, TV set, etc.) Readout timebase available at connector (can be Write or call now for details on our new 64- character TV used for graphic driver, etc.) readout and all our other exciting products. White characters on black, and /or black on white; software selectable Plugs into standard dual 22 -pin TVC connector on Digital Group Systems Improved Audio Cassette Interface: the 6° O tal Reliable FSK recording technique 1- Uses standard unmodified audio cassette recorder box 6528 denver, colorado 80206 (303) 777 -7133

www.americanradiohistory.com which differences. By the way, any tech- stood. This method has a "hopefully it will nique that "intelligently" reduces a problem work" attitude about it. Figures 3 and 4 in complexity so that computation time is illustrate this technique, showing how a reduced is called a heuristic. single sentence can be broken down into different meanings. These methods are also Natural Language Processing applied to the design of computer languages, their interpreters, and compilers. In the early days of modern computers, the early 50s, one of the great optimistic hopes was to have automatic machine trans- Robotics lation of text. It was thought that all you This subject is last for good reason. The would have to do is have enough memory to design of robots is largely based upon the store a dictionary. Today there are not many preceding topics. For vision, if it is capable knowledgeable people who would make such of it, a robot would use pattern recognition a boast. techniques. For performing tasks, problem The problem with writing a translating solving is involved. Robotics is an applica- system is the immense complexity of natural tion of artificial intelligence to hardware of language. English, for example, is full of mechanical systems as a control element. potential ambiguities. Does "Time flies!" mean a comment about how time is going by Conclusion quickly, or does it mean a command that we Artificial intelligence probably offers should start chasing flies with a stopwatch? something for every programmer ... cer- One . can think of hundreds of such tainly if you like to play games. But there are sentences. other aspects that are just briefly touched Figure 4: Another parse of A related problem is natural language upon here. If we are building a large library the sentence of figure 3. comprehension. Wouldn't it be nice if we of information, perhaps we would like to use This particular parse is could converse with our processors in an English -like inquiry system. The computer evaluated as meaning that English instead of BASIC or assembly lan- directed medical diagnosis could be ex- two people are on top of guage? Unfortunately, the same problems tended to auto maintenance, or even com- the computer (adjective are faced in this task. One way to alleviate puter repair. Whenever you want some of use of "on the computer') the problem is to limit our speaking vocabu- your thinking done for you, automate it engaged in playing lary. Monitors often do this to an extreme, and are with artificial intelligence. a game. Both the parse of limiting us to specifics such as examine and figure 3 and this one are deposit. The most successful approach for REFERENCES valid and demonstrate a larger systems involves syntax directed major difficulty that is methods. This means that each sentence is 1. Gelerntner, H, "Realization of a Geometry Proving Machine," Computers and Thought, encountered when trying broken down until its meaning is under- McGraw -Hill, NY 1963. to use computer evaluation of English or other 2. Gries, D, Compiler Construction for Digital natural languages. Computers, Wiley, NY 1971.

3. Hunt, E, Artificial Intelligence, Academic Press, SENTENCE NY 1975.

4. Newall, A, and Simon, H, Human Problem Solving, Prentice -Hall, NJ 1972.

5. Samuel, A, "Some studies in machine learning NOUN PHRASE VERB PHRASE using the game of checkers," Computers and Thought, McGraw -Hill, NY 1963.

THIS GAME VERB PREPOSITIONAL PHRASE (ADVERB USE)

IS PLAYED PREPOSITION NOUN PHRASE

ADJECTIVE NOUN PREPOSITIONAL PHRASE (ADJECTIVE USE)

TWO PEOPLE ON THE COMPUTER

www.americanradiohistory.com Polymorphic Systems 11K BASIC

Size: 1 1 K bytes. Scientific Functions: Sine, cosine, log, exponential, square root. random number. x to the y power. BASIC Formatted Output Multi -line Function Definition String Manipulation and String Functions Real -Time Clock Point - Plotting on Video Display Array dimensions limited by memory The handle for the tool. Cassette Save and Load of Named Programs Multiple Statements per Line Renumber Memory Load and Store 8080 Input and A microcomputer without software is a tool Output If Then Else Input type - ahead without a handle. PolyMorphic systems BASIC Commands: RUN, LIST, SCR, CLEAR, REN, CONT Statements: LET, IF, THEN, ELSE, FOR, NEXT, GOTO, ON, EXIT, is the handle on the POLY 88; this provides the STOP, END, REM, READ, DATA, RESTORE, INPUT, GOSUB, RETURN, PRINT, FILL, OUT. interface between user and computer. Our Built in Functions: FREE, ABS, SGN, INT, LEN, CHR$, VAL, STR$, ASC, SIN, COS, RND, LOG, TIME, WAIT, EXP, SORT, CALL, BASIC fits the POLY 88 like a finely balanced EXAM, INP, PLOT. handle fits a quality tool. PolyMorphic Systems Systems Available. The POLY 88 is available in either the kit or Basic is an extremely efficient way to program. assembled form. It is suggested that kits be attempted only by persons familiar with digital circuitry. The following is a list of the It makes possible the immediate use of the systems available. POLY 88 for a range engineering, System 1: is a kit and consists of the Poly 88 chassis, CPU and wide of video circuit cards only. Requires keyboard and TV monitor for scientific and general problem solving. In operation. $595. System 2: Consists of System 1 with the addition of the cassette conjunction with either System 7 or System 16 interface circuitry- requires cassette recorder. $690. PolyMorphic Systems BASIC is the reliable and System 3: System 2 with 8K memory card, BASIC and assembler cassette tapes. $990. ready to go microcomputer tool on the market. System 4: Also a kit, but containing in addition to System 3 a No more waiting for the long- promised keyboard, cassette deck and TV monitor. $1350. System 7: Consists of an assembled and tested POLY 88 with 8K of software system. Among our best BASIC memory, keyboard, TV monitor, cassette recorder, 8K BASIC and features: graphic plotting function, tape save Assembler cassette tapes. $1750. System 16: Consists of an assembled and tested POLY 88 with 16K and dump with named files, time function, and of memory, keyboard, TV monitor, cassette recorder, 11K BASIC self -explanatory error messages. We believe and Assembler cassette tapes. $1995. the best tool - the POLY 88 - must have the best handle: PolyMorphic Systems BASIC.

460 Ward Dr Santa Barbara. CA 93111 (805)967 -2351 PolyMorphic Systems

9iT SEIM SM-nV?:81aTM211a

2E-1rs POINT OUT SMI-21v1111 cu ro 121 a

www.americanradiohistory.com Have you written Software The Altair 8800 computer was the first micro for your produced for the general public and remains number one in sales, with more than 8,000 mainframes in TM the field. The wide acceptance of the Altair computer and its rapid adaptation to many diversified appli- Altai cations has truly turned the dream of the affordable computer into a reality. Yet the machine itself, remarkable as it is, represents only the beginning. The right Software, Computer? tailored to meet a user's specific requirements, is a vital part of any computer system. MITS wants to insure that Altair users everywhere have the best applications software available today and in the future. For this reason, a new MITS subsidiary, the ALTAIR SOFTWARE DISTRIBUTION COMPANY, has been formed. Its purpose: to acquire the highest quality software possible and distribute it nationally through Altair Computer Centers. That's where you come in. The ASDC will pay substantial royalties to the originators of all software accepted into the ASDC library. If you have written business, industrial or commercial use software for the Altair 8800, ASDC wants to hear from you. It is the aim of the ASDC to stimulate and reward creativity in producing useful software that makes those dreams of "computers for everyone" come true. The ASDC will select only software that measures up to its high standards for system design, coding and documentation. The software will then be further documented and distributed through Altair Computer Cen- ters around the country. For more information on how to submit software to the ASDC, ask your Local Altair Corn puter Center for an ASDC Software Submittal Packet or contact the ALTAIR SOFT WARE DISTRIBUTION COMPANY.

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see next page for a listing of Altair Computer Centers

www.americanradiohistory.com lower order creature, then perhaps a ALTAIR COMPUTER CENTERS robot mouse or dog. Divide the big Ask BYTE project into many small ones, each with its own well defined goal so that you can watch your creation evolve and grow as BEAVERTON, OR 97005 you add each new ability or function. 8105 SW Nimbus Ave. MORE ROBOT REACTIONS 15031-644-2314 Man did not reach his present level in BERKELEY, CA 94710 In reading your January 1977 issue one jump or one day - neither will the 1044 University Ave. noticed a letter from Dean Blondefield Homo Robotus. (4151- 845 -5300 /page 140/, asking about books about To the staff SANTA MONICA, CA 90401 of BYTE: Thank you for 820 Broadway building your own robot. an excellent publication. (2131.451 -0713 In the December 1976 issue of Scien- DENVER, CO 80211 tific American (in the "Book Review" James F Ward 2839 W. 44th Ave. 3121 Chestnut Rd (3031- 458 -5444 section) a review may be found of a Carrollton TX 75006 ALBUGUERGUE, NM 87110 book entitled Build Your Own Working 3120 San Mateo N E. Robot by David L Heiserman, Tab 15051 -883 -8282.883 -8283 Thanks for on excellent letter. The Books, Blue Ridge Summit PA. TUCSON, AZ 85711 Tab book on robots, Build Your Own 4941 East 29th St From the description in the review Working Robot by David L Heiserman, is 16021-748-7363 this would appear to satisfy at least some LINCOLN, NB 68503 good as far as it goes and is an excellent of Mr Blondefield's interest. 611 N 27th St. source of ideas. It is just the starting Suite 9 1402)- 474 -2800 R S Schlaifer point, however, and antedates (very LITTLE ROCK, AR 72208 1500 Rollin slightly) the advent of microprocessors 2412 Broadway South Pasadena CA 91030 as flexible control elements for the 15011- 371 -0449 practical experimenter. [It is available TULSA, OK 74135 5345 East Forty First St. through our book service, BITS Inc. I 110 The Annex ROBOT LITERATURE RESOURCES 19181-664 -4564 HOUSTON, TX 77036 I would like to pass along to Dean MORE ON ROBOTS 5750 Bintliff Drive Suite 208 Blondefield of your January 1977 "Ask (7131-780 -8981 ... FROM THE "UNITED STATES VA BYTE" column, page 140, and any other RICHMOND, 23230 ROBOTICS SOCIETY" 4503 West Broad St. interested BYTE readers, the few 1804)- 355 -5773 "bytes" of information I have con- We were much interested to see the SPRINGFIELD. VA 22150 6605A Backlick Rd cerning robots. letter in the January 1977 BYTE /page 17031. 569.1110 There have indeed been too few 140/, from Mr Blondefield in Hayward, CHARLESTON, W. VA 25301 articles and books published about my seeking a robotics organization more Municipal Parking Budding Suite 5 robots, as favorite subject of the editor concerned with individual effort that 13041- 345 -1360 claims. A few of the few were: Popular with institutional and "industrial" EAGAN, MN 55122 Electronics, December 1958, January robots. 3938 Beau D'Rue Drive 1959, and Popular Electronics, March 16121 -452 -2567 As you will realize, we are engaged ANN ARBOR, MI 48104 1962. The robots described by these chiefly in a search, at the moment, for 310 East Washington Street articles were very primitive in nature but methods, hardware and experience that 13131- 995 -7616 would be useful to someone starting out WINDSOR LOCKS. CT 06096 will clarify the status of robotics. We are 63 South Main Street because they clearly demonstrate simple persuaded from some years of work in 12031.627 -0188 cause and effect situations, and provide a closely related fields that the keys to PARK RIDGE, IL 60068 mechanical test bed for further experi- development machines 517 Talcott Rd robotics - to of 13121- 823 -2388 ments. A series of manuals on home that have behavioral characteristics like ST. LOUIS, MO 63130 construction of robots was published by those of animals, making many of the 8123 -25 Page Blvd 1314)-427-6116 a company called Electric Brain Enter- same judgements in the same ways - prises, in Utah, about 1960. The first of have already been discovered and that it DAYTON, OHIO 45403 (5131- 252.6785 these manuals, Robots I, is dedicated is only necessary to apply a diversity of largely to the mechanical problems ideas in a single working system to create BURLINGTON. MA 01803 which home 120 Cambridge St the builder may encounter. a "robot" of considerable capability. 16171-272-8770 I never received the additional manuals We don't expect overnight success in ALBANY, NY 12211 in the series so I have no idea what they the search. Probably some decades of 269 Osborne Road (518(- 459 -6140 contained in the way of information. activity are ahead of us before robots of The latest NEW YORK. NY 10018 work to come across my true science fiction capability are avail- 55 West 39th St desk is Build Your Own Working Robot, able, but for the time being we'd be 12121- 221 -1404 by David L Heiserman, published by Tab dazzled by an artificial system with the ATLANTA, GA 30305 Piedmont Road Books, Blue Ridge PA 3330 Summit 17214. behavioral characteristics and apparent 14041- 231 -1691 This book of 234 pages published in intelligence of an ant - never mind an TAMPA. FL 33614 April 1976 is by far the best I have ever approach to human behavior. It's a long 5405 B Southern Comfort Blvd. 1813)-886-9890 read on the subject. I can recommend it hard road. to anyone with a clear conscience. When the United States Robotics I firmly believe that in less than 20 Society was formed last summer, we had years, for about the same price as a no idea whether or not as many as a middle sized car, you will be able to dozen people would be interested purchase a machine to do most of your enough to participate, but we have taken housework. In less than ten years you the necessary steps to become a formal will be able to purchase, for about nonprofit corporation, set up carefully $1,500 of today's dollars, a primitive by lawyers to achieve a Federal tax robot lawnmower. exemption when we have the resources To Mr Blondefield, and to anyone else to pursue it. who has ambitions to build the Homo Here's a point, by the way, on which Robotus, I would give only this small bit we take issue with your reply to Mr of advice: Man evolved on this planet ASOC one step at a time: Evolve your robot 3330 Peachtree Road. Suite 343 the same way. First model a simple Continued on page 149 Atlanta. Georgia 30326

www.americanradiohistory.com Designing the

I the small Jack Emmerichs When first became aware of 8465 N 51st St systems industry, I was particularly in- Brown Deer WI 53223 terested in finding out what software had been developed for personal computers, HIERARCHY especially software that would run on a minimal system configuration without much optional hardware. One of the most useful software products for such small systems is LEVEL 1 an assembler to relieve the programmer of the tedious job of programming in machine

language. I found no assemblers, however, that would run on a small machine configuration. SUBFUNCTION LEVEL 2 required at least 8 K 10 Most assemblers bytes of memory (which was beyond my initial budget projections). As two pass assemblers, many of the existing products also required that source programs be SUBFUNCTION LEVEL 3 SUBFUNCTION the 21 23 entered twice so that all symbols in source code could be resolved. This may be difficult or cumbersome if a system does not have IO devices that can easily handle high volumes of data. Furthermore, none of the NETWORK assemblers that I found could be used interactively because of this two pass design. For a minimum system without offline file storage, this can be a major problem. In

LEVEL 1 TOTAL many cases several IO interfaces were re- SYSTEM quired to handle the input source code, printed listing, and the generated object code (machine language). Finally, most of the assemblers then available provided all the LEVEL 2 SUBFUNCTION SUBFUNCTION bells and whistles available in much larger 10 20 programs designed to run on large timesharing systems. These large assemblers (called cross assemblers) are much more

complex than I felt a small system assembler LEVEL 3 SUBFUNCTION SUBFUNCTION SUBFUNCTION needs to be. I therefore decided to write a 21 22 23 small but powerful assembler that would run on what to me was an affordable machine. This article is a description of the design and construction of such an assembler using LEVEL 4 SERVICE SERVICE structured programming techniques. ROUTINE A ROUTINE B The first thing to do in any development project (though it is unfortunately often skipped in small projects) is to define the Figure 1: The top chart shows the structure of a single hierarchy diagram. program's specifications. For this project the The functions at each level are broken down into subfunctions at the next requirement was to develop a memory ser - lower level. The relationships are shown as a simple tree structure. The dent M6800 assembler which would: bottom chart shows the structure of a network diagram. Here routines may be common to more than one high level function, and the structure of rela- Assemble source code written in a free tionships can become much more complex. General subroutines that are format subset of the M6800 assembly common to many functions may be shown as a separate structure. language as described in the Motorola

www.americanradiohistory.com "Tiny Assembler"

Defining the Problem publication M6800 Microprocessor Programming Manual. Operate completely within the first 4 K of memory including all tables, these is a function to convert English -like buffers, and other memory mnemonic instructions into machine Ian - requirements. guage operation codes (opcodes). This is Completely assemble source programs complicated in the M6800 by having the in one pass to minimize IO operations. opcodes for some instructions vary with the Require no more than one IO interface accumulator or type of addressing used. This using the Motorola MIKBUG monitor. information is developed as each line of Support interactive operation. input is processed, so the parse and translate Facilitate modification and customi- functions must work together to develop the zation through the use of structured correct opcode. The second function re- code. quired at level 3 is to process assembler Have sufficient capacity to be able to directives that control the assembly process assemble itself so that no other soft- from the input stream. These may include ware would be required to generate such operations as reserving sections of modified versions of the assembler memory, setting up constants, assigning program. values to symbols, changing the program counter, and whatever else be defined After the design criteria were thus set may The required down, and before the program coding was in the language. third function level is a started, it was necessary to define the at this the maintenance of table of user symbols with their associated functions that would be needed to meet the defined values. Entries may be added the table, above specifications. Functions were defined to or retrieved from as the parsing from the highest level down to the lowest, it routine directs. The final function at this level is an and were related to each other through hierarchy and network diagrams (see figure 1). The first series of functions that we SIMPLE ASSEMBLER STRUCTURE shall consider here are those that are common to all assemblers. These functions are LEVEL discussed in more detail in the article "Jack ASSEMBLER PROGRAM and the Machine Talk" by Robert Grappel and Jack Hemenway, published in the August 1976 BYTE, page 52. Figure 2 shows how the network diagram PARSE START CLEANUP worked out for an initial conception of the Mainline End of 2 Initialization assembler. At the top level the assembler is Scan Input Job shown as a single function, level 1. Below this on level 2, the first major function is usually a table initialization and house- Handle Maintain Generate Per form keeping routine (START) that need not be Assembler 3 Op Codes Symbol 10 closely examined here. The second major Directives Table function is to parse and process each line of incoming code with its labels, mnemonic instructions, operands, and comments ERROR (PARSE). The final major function is usually 4 Generalized a termination and reporting function which Error Routine again need not be closely examined here (CLEANUP). At the next lower level, level 3, several Figure 2: This is a simple network diagram showing the primary functions functions must be defined which will be required by assembler programs in general. The error routine is common to all called from the parsing routine. The first of other functions.

www.americanradiohistory.com IO routine which receives source code from to achieve the generation of dummy- code an input device, and writes listings and and later patches, two specific problèms generated code to output devices. must be considered: What kind of opcodes The last level in this structure is shown and addressing formats must be handled, and here as a generalized error handling routine how are expressions containing a forward that flags and describes any ambiguities or reference handled? errors in the source code. This can be First, consider the relationship between described as a general service routine, and opcodes and addressing modes. For the may be invoked from any function detecting M6800, opcodes are one byte in length, and an error. may vary with the accumulator or mode of Several aspects of this project required addressing being used. The operand may be a Editor's Note: the addition of new functions or modifica- one or two byte address value which is a ditions to existing functions within this struc- rect reference to a location in the first 256 At the present time ture, and will be treated here in some detail. positions of memory (zero through 255), an (January 1977) Jack Em- The most severe functional changes were the extended reference to any position in merichs' assembler, de- result of requiring the source program to be memory, an offset from the index register, scribed here and in the processed completely in one pass. or an offset relative to the address of the second part which follows The problem of making the assembler a next instruction. It may also be one or two next month, is my princi- one pass type in general is: What is to be bytes of data immediately following the pal means of assembling done when the incoming code references a opcode. As the incoming instruction con- programs for my home - symbol that is not yet in the symbol table taining the forward reference is being proc- brew 6800 based system. but may be defined later on? This is known essed, the addressing mode being used is I've very successfully used as a forward reference and is quite likely to usually well defined and indicates a unique it to assemble its own occur in almost all programs of nontrivial opcode and instruction length. This is not patches to fit my system, a length. the case, however, when the instruction text editor which is now The solution to this problem will require making a forward reference is not relative, part of my old hand coordination between the assembler program immediate, or indexed. It can then be either assembled monitor, an ex- and a loader program. The loader is run as a direct (one byte) or extended (two bytes). tensive music text editor separate operation that converts the object The difference depends entirely upon program, and two differ- code developed by the assembler into an whether the final resolved address is greater ent versions (so far) of a executable program in memory. In this case, than 255 or not, and at this point the multiprocessing music in- the assembler will generate one, two or three address value is not known. Therefore, I terpreter program to drive bytes of object code for each line of source established the following convention: When my synthesizer peripher- code. It will also generate the address in no addressing mode is specified in a forward als. After having suffered memory where these bytes are to be loaded. reference, extended addressing will be systems software with- When a forward reference is made, assumed since it can refer to any position in drawal pains for over a "dummy" code will be generated instead of memory. Some efficiency may be lost by year, it is great to get my the normal object code. This dummy code is not allowing the shorter form of addressing "fix" of this intoxicating simply an address or offset with a value of here, but most forward references are not to elixir.... CH zero. The address of where the final address locations in the first 256 locations anyway, is to be loaded will be generated and saved in so the restriction is not a severe one. /Using a table. When the reference is later resolved, an equate (EQU pseudo operation) to define the correct object code must be generated a page zero address ahead of its first use with an address which will cause it to neatly solves the problem when using the

overlay the original dummy code putting in assembler . CH/ the correct value. If several references have The second problem is the handling of been made to a symbol by the time its value arithmetic expressions containing a forward is resolved, several sets of addresses and reference. It will require a solution built patches to the dummy code must be de- upon the logic developed so far, and will veloped. The opcode which is developed and require additional coordination between the put out with the dummy code will never be assembler and the loader. If the loader changed. The operand will be the dummy combines overlaying code with whatever is value to be patched. The loader required to already in memory instead of using it as a properly handle this type of generated code replacement, the dummy code can be used will be shown in detail next month. [Such a to contain part of the information needed to loader program is effectively a second resolve such an expression. This requires that "assembly" pass; however, by making the the loader clears memory before starting the output routine include a loader and using loading process and can correctly combine extra memory as we've done with Jack's all single and double byte values. An expres- assembler, the entire process can be carried sion with a forward reference is best illus- out within memory nearly instantly ... CH] trated by an example. Before considering the functions needed To load accumulator A with the address

www.americanradiohistory.com Set Forward Reference of five less than the sum of Y and Z (both unknown at this point) in table 1, the (start at beginning of forward reference table) following code could be used: DO UNTIL (past end of table)

: IF (current slot is an empty slot) THEN EXAMPLE1 LDAA TABLEZ +Y +Z -5 (store pointer to symbol in symbol table)

. (store current address) The expression (TABLE1 +Y +Z -5) is (store type of reference) (return) evaluated as far as it can be, and the value of ELSE (TABLE] -5) is put out as the dummy code. (increment to next slot in table) When Y and Z are resolved (in any order), ENDIF ENDO arc each as a value. they put out correcting (signal error since forward reference table is full) The loader then combines all three values (return) (TABLE1-5, Y and Z) to arrive at the final value. If the loader simply adds each correc- Listing 1: Set Forward Reference Routine. tion to what is currently in memory, a This routine is called once for each reference certain amount of caution is required when to a symbol that is not resolved in the sym- using the minus sign ( -) or symbols with a bol table and is not being used as a label. negative value. A further consideration is that the assembler can only check the range of relative or indexed offsets for each functional requirement. A routine is needed occurrence of dummy or correcting code. to generate the correcting object code when When these are combined by the loader, the value of an item in the new table is they may exceed allowable offset ranges. It resolved. This routine must search the entire is up to the programmer to see that they do forward reference table for pointers to the not exceed the limits. Since the require- newly resolved symbol and generate a cor- ments for handling forward references have recting reference for each. The address at been examined, and methods of achieving which the dummy code was generated is these requirements have been developed, the retrieved from the table and used as the first new functions required by this assem- location for the correcting reference. If the bler can now be considered. previous reference was a relative instruction, The first major change is a new functional the difference between the previous address requirement. A routine is needed to record and the resolved address is calculated and a all pending forward references in a table. single byte is put out. If the previous The table must contain a pointer to the reference required a one byte address (in- symbol that was referenced, the address in dexed or immediate one byte), one byte is the source program where the reference generated. If it required a two byte address occurred and dummy code was generated, (extended or immediate two byte), two are and the type of reference that was made generated. As each correcting item is com- (one byte or two, absolute or relative). Each plete, its position in the forward reference time the routine is invoked, a new entry is added to the table. If the table is full, an error condition is raised. The table size was Resolve Forward References arbitrarily set at 25, which has proven to be more than sufficient if the source program is (start at beginning of forward reference table) properly organized. (/n writing a new DO UNTIL (end of table) IF (this reference to symbol table = current symb) THEN version of my monitor and text editor (save current address) program (about 1500 source statements) (current address = address from forward reference table) IF (relative addressing) THEN with lack's assembler this has proved to be (calculate relative offset) the case ... CHI The Set Forward Refer- (write it out) ence routine has the logical structure shown : ELSE . : : IF (two bytes required) THEN in listing 1. Note that in this structured (write out symbol's high byte) programming notation there is only one : ELSE : : ENDIF logical entrance and one logical exit from (write out symbol's low byte) each function. The logical exit (return) may : ENDIF have several physical locations, however, to (clear table position for future use) (restore current address) used. use reduce the amount of code [The of : ELSE structured pseudocode such as that shown in ENDIF (increment to next table position) listing 1 for program design was discussed in ENDDO the article "Programming for the Beginner" (return) by Ronald Herman published in the June 1976 BYTE, page 22.1 Listing 2: Resolve Forward Reference Routine. This routine is executed each The second major change is another new time a symbol flagged as unresolved in the symbol table is used as a label.

www.americanradiohistory.com table is cleared for future use. Therefore, a the symbol is used as a label, the current source program may have as many forward address is entered into the symbol table and references as it needs, but the number of returned as the label's value. Resolve For- forward references pending at any one time ward Reference cannot be called at this time is limited by the size of the table. If any because the current instruction may modify pointers to the symbol table are found at the the value of the symbol just resolved by end of the assembly, the undefined symbols equating it to a user defined value. Resolve are printed as potential errors. The Resolve Forward Reference must be called after the Forward Reference routine has the logical current line of source code has been com- structure shown in listing 2. pletely processed. Now if another label for The third major change is a functional this symbol is encountered, a duplicate label modification. A routine has already been error condition is raised. defined to maintain the symbol table, but To avoid using a separate byte of memory now it will also be required to recognize for the unresolved flag for each symbol in symbols that are unresolved, and to de- the symbol table, a zero address is used to termine when the new functions developed indicate an unresolved symbol. This allows a above must be called. The first time an zero value to be normally returned for such unresolved symbol is used, it will not be symbols as required by the above logic. The found in the symbol table, so it must be only effect this will have on source code entered into the next available slot. If there programming is that a label at location zero is no available slot, a symbol table full error cannot be resolved. Therefore, a symbol condition is raised. Set Forward Reference should not be defined at or equated to zero. will then be called and a zero address Each reference to it would add an entry to returned. Additional references to this the forward reference table and soon fill it symbol will now be found in the table. up. Instead, a decimal value of zero should Because each is flagged as unresolved in the be used. The Maintain Symbol Table routine symbol table, Set Forward Reference is now has the logical structure shown in listing again called and a zero address is returned. If 3. These functional modifications enable the assembler to completely process a source Maintain Symbol Table program in one pass. At this point, the functional requirements for processing with (start at beginning of symbol table) DO UNTIL (past end of table) only one IO interface can be considered. IF (current symbol = incoming symbol) THEN Logically, each program to be assembled : IF (incoming symbol is a label) THEN has three basic sets of data to be handled: . : IF (table address = zero) THEN . . : (load symbol into table) the source code used as input to the assem- . . : (set symbols to be resolved condition) bler, the object code developed by the . . : (return table address) assembler, and a program listing showing the . : ELSE

. . : (signal error, duplicate symbol definition) object code that is generated for each line of . (return) source code. Physically, an IO interface is . : ENDIF : ELSE usually used to read and write data_to or : : IF (table address = zero) THEN from one external device. The problem of : FORWARD ADDRESS) (call SET handling three logical sets of data on one : (return zero value) : : ELSE physical device has been solved by com- : (return table address) bining the generated object code with the : ENDIF listing. This reduces the data handling re- : ENDIF ELSE quirements to one input file (source code), : IF (current table slot is an empty space) THEN and one output file (the combined listing) : (load symbol into table) which the single interface can easily handle. : IF (incoming symbol is a label) THEN (return current address) The generated object code and its associated : ELSE address that the loader uses are already . . . : (call SET FORWARD REFERENCE) . (return zero value) produced on the left side of the listing as . . : ENDIF shown in listing 4. Therefore, it is only . : ELSE (increment to next slot in symbol table) necessary to provide a way for the loader to

: ENDIF directly read the listing to find the data that ENDIF it needs. ENDDO (signal error, symbol table full) How the listing is made available to the (return) loader will vary with different physical configurations, and there are unlimited vari- Listing 3: Process Symbol Table Routine. This routine is called each time a ations in possible hardware arrangements for symbol is used. If the symbol has a resolved value it is returned to the calling small systems. This assembler was initially module, otherwise a zero value is returned. written to run on an ASR model Teletype

www.americanradiohistory.com Sample Listing Listing 4a: Combined list- LOCN B1 B2 83 ing as seen by the user. The generated code shown 0001 CE 00 20 >CLEAR LDX =TBL LOAD IX WITH START OF TBL under the headings 87, 82, 0004 6F 00 >LOOP CLR X CLEAR TBL LOCATION 0006 08 > INX INCR TO NXT TABLE POSN and 83 are to be loaded 0007 8C 00 30 > CPX =TBL +LENGTH END OF TABLE? starting at the address 000A 26 F8 > BNE LOOP IF NOT, DO IT AGAIN shown under LOCN. This was generated at BYTE using lack's assembler as with both tape reader and tape punch tern's configuration. If the input is coming modified for Carl Helmers' control characters enabled. A permanent from a tape file, input operations must stop homebrew system. machine readable copy of the listing can be to allow the generated code to be put out produced on paper tape during the one pass because the Motorola MIKBUG 10 routines operation. The listing, however, must be cannot support concurrent input and out- modified to enable the loader to find the put. If stopping the input is not feasible for required data when reading this tape. a given system, additional routines may have In the 4 K version of this assembler, items to be written to overcome the MIKBUG that the loader needs can be surrounded by limitations. For interactive operation, there special nonprinting characters that can be is rarely a problem as the assembler is recognized while scanning the listing. This usually faster than the user. For a truly isolates the needed items from source code, minimum system, the source code can be headings, comments and other extraneous entered by hand from the terminal, and the items. These characters must not appear in generated object code can be copied from any other context within the listing, so the combined listing and loaded, again by control characters (which are not valid as- hand. In this case, no intermediate files are sembler input) are the most logical choice. required at all! To the loader, then, the listing shown in The functional changes necessary to allow listing 4a would appear as shown in list- the assembler to operate with only one IO ing 4b where the '(' and ')' represent non - interface are handled as modifications to the printing characters used to signify the start existing 10 routine to enable it to create the of an address, and the end of any bytes to listing as shown above. Specific changes may load respectively. The high level form of the differ for various system configurations, and logical structure for a loader which would be will not be shown here. We have now able to use such a listing is shown in considered functional modifications to ac- listing 5. commodate our requirements that the as- The combined assembly listing is pro- sembler operate in one pass, and that it use duced by starting each line of source code in only one IO interface. The final requirement the middle of the page. The carriage return which will modify some of the original at the end of each line returns the current functions is that it run in only 4 K of print position to the front of the line. The memory. generated code is then printed in front of The first thing to do is to look at all the the source code. Before prompting for the functions available in existing M6800 assem- next line of source code, a line feed is issued blers and eliminate alternate ways of accom- to position the paper for the next line. The plishing things. In a tiny assembler, alter- result is most interesting to watch on the nates are usually expendable overhead. For Teletype since one normally expects a line example, operands for the A and B accumu- feed at the beginning or end of a line. The lators may optionally be separated from the loader recognition characters are combined mnemonic instructions in 8 K assemblers with "punch on" and "punch off" charac- (for example, LDA A instead of LDAA). ters to keep all unwanted items off the This has been changed to require that the 'A' object tape. and 'B' be attached to the mnemonic which There are 10 timing considerations worth eliminates an additional scan for the mentioning that apply regardless of a sys- accumulator operand. The choice of entering Listing 4b: Combined listing as seen by the loader. The generated code and Loader's View of the Listing associated addresses are separated from the rest of LOCN B1 B2 B3 the listing by special char- (0001 CE 00 201 >CLEAR LDX -=T B L LOAD IX WITH START OF TBL acters shown here as '(' (0004 6F 00) >LOOP CLR X CLEAR TBL LOCATION and T. This is a simulation 081 I N X INCR TO NXT TABLE POSN (0006 based on part (a) of this (0007 8C 00 301 > CPX TBL +LENGTH END OF TABLE? I000A 26 F8) > BNE LOOP IF NOT, DO IT AGAIN listing.

www.americanradiohistory.com Figure 3: The Final Assembler Structure. This is a detailed structure diagram of the assembler as it was actually written.

www.americanradiohistory.com data in decimal, hexadecimal, octal or binary Loader Structure form has been reduced to decimal and DO UNTIL (end of listing) hexadecimal. Alternate indicators of data DO UNTIL (character read is a 'l') type (eg: using a leading '$' or a trailing 'H' (read character) IF (character is null) THEN to indicate hexadecimal) are restricted to (stop) leading indicators to simplify parsing rou- ELSE tines. Other such redundancies can be ENDIF ENDDO eliminated whenever a significant amount of (read address into index) code is needed to support multiple ways of DO UNTIL (character read is a 'l') (read character) doing the same thing. IF (character is a blank) THEN The next area where space can be con- (read a byte from two hex characters) served is in table structure optimization. The . (add incoming byte to indexed address) IF (carry bit is set) THEN largest table is the symbol table, so symbol (increment byte beyond indexed address) size has been reduced from six characters to : ELSE four. The first three and the last one : ENDIF (increment index) character of a label of any size over four are ELSE combined as the character string entered ENDIF ENDDO into the table. This matches the four charac- ENDDO ter size of the mnemonic plus accumulator (stop) instruction mentioned above, and the four Listing 5: Logical structure for a directed loader capable of processing the character format of a hexadecimal address. listing shown in listing 46. See listing next month for the implementation a The input routines may therefore be built of loader based in part on this structure. around a standard four character format. Instead of using a binary search in the operand translation table, a hash index into The final method used to save space is to the opcode table based on the mnemonic's simply eliminate functions that are of first letter is used. /See Terry Do /hoff's limited use and require significant code to article on hashing techniques on page 18 of implement. There is no provision for multi- January /977 BYTE.) This keeps the num- plication or division in the expressions with- ber of table entries searched to an average of in an instruction's operand. Multiple ad- 4.5 per opcode, and reduces the length of ditions or subtractions are possible, however, the stored mnemonic. By combining this and can often be used where multiplication access method with routines making use of and division are usually found. There are no the M6800's opcodc structure, all of the I I4 provisions for naming programs or for select- four character mnemonic instruction and ing options in generating the combined assembler directives can be kept in a table listing. Some error checking, such as invalid keyed by 79 two character strings. address or byte overflow, has been com- The next area where space can be con- pletely eliminated. The code generated is as served is in the simplification of complex compact as possible to fit in small machines, routines at the possible cost of some effi- but is not relocatable. If it is desired in ciency or function. Because the symbol table another location, it must be reassembled. in this assembler is smaller than those in full The result of all this compaction effort is scale assemblers, and because we've got a an assembler whose basic executable code dedicated personal machine to work with, fits within 2170 bytes, and will run com- complex hashing routines can be dropped in pletely within 4096 bytes of programmable favor of a simple sequential search which memory with a symbol table capacity of burns a bit of computation time. Many 200 symbols. Modifications have been made complex error detection routines have been to almost all of the existing functions to simplified to catch the most common occur- accomplish the above changes. This com- rences of a problem. All physical 10 opera- pletes the functional additions and modifications are accomplished through the Motorola tions required for the assembler defined by MIKBUG monitor rather than through the project specifications as shown in figure uniquely written routines. 3.

In the next issue of BYTE, we'll continue Jack's article on his "Tiny Assembler" with his discussion of coding the assembler. The second part includes object code and information on patching and relocating the program.

www.americanradiohistory.com ,r oar E FZRST ,.- T Cps E R Z` >E 0.-1 4k X 0.aiAs& HomeCo1

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www.americanradiohistory.com MICROCOMPUTERS4K X ;,,i-kAMI -I

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www.americanradiohistory.com Establishing the CHU Dynasty

Let lt All Hang Out Stephen B Gray Amateur Computer Society 260 Noroton Av Darien CT 06820

Much time is taken up at computer club stripes; and so on. The mathematically meetings, and especially at computer con- minded reader will note that the lower limit ventions, with people asking each other what (in units of K =1024 bytes) is 2 raised to a machines they have, how much memory, power equal to the total number of stripes what peripherals, and so on. Much time and rockers. So three stripes and two rockers could be saved if there were some faster way indicate that the wearer has at least of communicating this information, and one 25 = 32 K bytes of semiconductor memory possibility is the Computer Hobbyist Uni- in his or her computer, and perhaps more. form, or CHU, for the purposes of adding For the memory fanatic with 128 K up to one more incomprehensible acronym to the 256 K bytes, there's the first sergeant's vernacular. insignia, with three stripes, three rockers, The basic requirements for the CHU are and a diamond. Incidentally, no stripes on that it be inexpensive, readily obtainable and the upper sleeve indicates up to 2 K -1 bytes lightweight. The one garment that fits all of memory. these criteria is the white lab jacket, with long sleeves and a button or two in front, Service Stripes also known as an intern's jacket, available A diagonal stripe on the lower left Army everywhere $9 to $22, with an average for sleeve indicates three years of service. On the price $13. of CHU, it indicates how many years the As for insignia, the most widely available wearer has had his or her computer up and type is military, and Army stripes are well running. Although someone with an suited to the job. The resulting combination Altair 8800 might want each stripe to indi- provides a pleasant uniformity that helps cate a year, it's better to let the three year make for a more homogenous group, as well period stand. After all, anybody who's had a as toning down flashy the dressers and Scelbi 8H, or Mark -8, or RGS 008A running improving the appearance the slobs. of since they were first available will be entitled to wear a single three year stripe by Stripes for Memory Spring of 1977. And if the stripe were to Since many computerniks seem proudest stand for only a year, the CHU sleeve could of how much memory their machine has, it get terribly cluttered by 1984. follows that Army noncom stripes are There are other sleeve decorations that best used to indicate the amount of semicon- could be used, but which might only add to

ductor storage. As figure 1 shows, the the clutter. There's the short horizontal bar number of stripes indicates how much for six months overseas, which might be memory the wearer's computer has. For used to indicate that the wearer has operated instance, if his Altair 8800b has at least a hobby computer in a foreign country. The 2 K bytes and as much as 4 K -1 (ie: 4095) Unit Citation might be used by computer bytes, he wears one stripe on each sleeve; clubs to indicate some sort of group merito- from 4 K bytes to 8 K -1 bytes, two stripes; rious action, such as designing a com- from 8192 bytes to 16,383 bytes, three puterized course selection system for the

www.americanradiohistory.com local high school, or working out a method for beating the local roulette wheel operation to help supplement club funds, or calculating how much beer should be ordered for an all -night programming session.

Maker Patches A A Now that your staff sergeant's stripes 2 K to 4 K -1 bytes 4 K to 8 K -1 bytes 8 K to 16 K -1 bytes (Private, first class) (Corporal) (Sergeant) have identified you from a distance as a BMOC (Big Man on Computers), a shoulder patch, worn at the top of the left sleeve, identifies the maker of your computer. These colorful patches, similar to the Army patches that identify a soldier as belonging to the Seventh Division or the Fifth Army, show the computer manufacturer's name in a distinctive and artistic design. Such patches could be sold by IMSAI, MITS, Southwest, etc, or packed with each computer kit. To make, they cost less than $1 each in large quantities. A arises a manufacturer ñ slight problem if offers more than one computer, such as the t MITS Altair 8800b and 680b. There are two solutions for this ambiguity. A different patch could be made up for each, with the 16 K to 32 K -1 bytes 32 K to 64 K -1 bytes 64 K to 128 K -1 bytes model number included; or a rectangular (Staff sergeant) (Sergeant, first class) (Master sergeant) patch, bearing only the model number, could be made for sewing on right under the maker's patch. Another problem comes up if the CHU wearer has, say, both an ETC -1000 and an EBKA 6502 Familiarizor. He or she can easily wear the ETC patch on one shoulder and the EBKA patch on the other. The question arises: Should the memory stripes show total memory, or should each set of stripes show only how much memory is in the computer whose maker's patch is on the same sleeve? It all depends on whether he or she minds having an unequal number of stripes on the two sleeves. Pl;ysicists, mathe- maticians and other lovers of symmetry may become emotionally hung up on this issue. 128 K to 256 K -1 Meritorious Service Stripes If the CHU wearer has more than two (First sergeant) Unit Award (Three years each) computers, he or she has two solutions: either stacking the makers' patches one below the other on the sleeve, or sewing the extra ones on the front of the jacket - but not just above the breast pocket area, because that's where we put the Peripheral Pins and Data Decorations. Overseas Service Bars Peripheral Pins (Six months each) Now that you've been identified from afar as the owner of a Southwest 6800 with 8 Kbytes of memory, something is needed to show what you've got attached to your computer. A simple solution is to use zapped 14 pin or 16 pin ICs, lettered in white, Figure 1: Representative military stripes adapted with semantic redefinition inserted into a narrow strip of P pattern to help CHU computer addicts.

www.americanradiohistory.com Name Tags Name tags are often used in the Army. The CHU version is a dead MPU IC, without pins, with your name lettered on it, worn above the Peripheral Pins over where the right breast pocket would be if lab jackets had one. (Dan Meyer, head of Southwest Technical, wore a 6800 MPU IC on his shirt at Personal Computing 76 in Atlantic City last fall, with DAN and SWTPC lettered on it, partly inspiring this article.)

Data Decorations

The area above the left breast pocket is reserved for Data Decorations, which are for meritorious action above and beyond the call of duty. There's the black- and -blue ribbon for those who successfully fought the "Battle of the 66 Wires" on the original Altair 8800, and the very rare blue, grey and brown ribbon worn by that gallant handful of pioneers who captured Hill 680, only to Artwork credit: Lest there be confusion, this drawing was lose it when it was retaken. executed by Sandra Gray, no There are also software decorations, relation to author Stephen B although this area is somewhat amorphous, Gray. since what is a difficult feat for one-hobbyist might be a snap for another, just as in hardware achievements. It's up to each hobbyist to decide if he or she is enough of a hero to merit this or that Data Decoration. There might be a software ribbon for the Vectorboard, and somehow pinned on the person who wrote his or her own assembler, right side of your jacket front, opposite the or Tiny BASIC, etc. left breast pocket. The lettering might read If a ribbon refers to a numbered piece of TELETYPE equipment, the resistor color code can be ASR 33 used for the ribbon colors, such as blue, grey or and brown for the 680. Cryptic types can SOUTHWEST simply wear a 680 ohm resistor, attached to CT -1024 Vectorboard. or even C ROM EMCO Scratch Built and Homebrew TV DAZZLER Actually, a colorful dot pattern could be There are some situations not covered so used for the Dazzler, without any lettering. far. What about the hobbyist who prefers to Or different shapes of thin plastic could build his or her computer from scratch? be used to more readily identify various What does he or she use for a maker's patch? If there's enough demand peripherals, such as one in the shape of a for them, they television screen, for video output, lettered could be supplied by the integrated circuit with something like manufacturers, such as Intel, Motorola, SONY Zilog, etc. Or again, by a computer store CVM -115 chain. For the real hard -core Or a bit of black plastic, shaped like a scratch builder, Philips cassette, to show you use cassette who scorns microprocessors as the easy way storage, perhaps lettered with the name of out and designs his or her own processor the cassette deck you're using. For floppy from TTL or ECL integrated circuits, a " homebrew" patch could be designed, disk, a circular piece of plastic, lettered with perhaps on the style of a mountaineer's the maker's name. For a printer, perhaps just still, or witch's cauldron. a rectangle with the maker's name lettered on it. And so on. A pin could also be used to Far identify the maker of your computer, in Out addition to the shoulder patch, for faster For the hobbyist who is really into face -to -face identification at club meetings. computers, and especially vice versa, the

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www.americanradiohistory.com ultimate CHU add -on is a 100 pin printed fringe type who has a COMCHU, and espe- circuit board edge, protruding from the cially to those who prefer a GI jacket and back of the jacket, just above the shoulder trousers. blades. A copy of an Army plastic helmet liner For the lunatic fringe, there's the com- could be made of the same material used in puterized CHU, or COMCHU, with a SC /MP PC boards, printed wiring could be applied, or other small board in one of the side and the whole thing turned into something pockets, controlling the flashing of LEDs like the battery powered Intersil Intercept and other devices inside insignia or pins or Jr, with keyboard on top, display in front, whatever, producing a Christmas tree effect. and batteries in the rear. The curved surfaces CAUTION: The COMCHU, if worn in pub- might be too much of a challenge to a PC lic, is a sure ticket to a rubber room. board designer, so perhaps some of the curves might have to flattened. This would Other Insignia make the CHO (Computer Helmet, Official) Many other types of insignia could be look even more futuristic and science borrowed from the military, but again, they fictionish. The full uniform CHU /CHO would only clutter up the CHU. There's the combination would be enough to stop a fourragère, a braided cord worn around the digital clock, as well as get you in trouble if left shoulder scam as a unit decoration. worn outdoors. There's the Combat Infantry Badge, worn above the over the breast ribbons left pock- Belt Buckles and Tie Pins et. And there're branch of service pins, worn on the lapel to indicate Infantry, Corps of The CHU is meant only for wearing to computer club meetings or to Engineers, Ordnance, etc. With a little computer imagination, these could all be used, but the conventions, as it's a little too odd to wear effect would be more gaudy than anything in public. However, there are several ways of else. This applies especially to medals, which letting people know you're a computernik, are expensive to make; it's much neater to without the CHU. And they can be worn wear the equivalent ribbons. with the CHU, too. Same for officer's insignia, such as bars, If there's enough demand for them, belt oak leaves, eagles and stars. They look good, buckle equivalents of the maker's shoulder but not when mixed with enlisted persons' patches could be offered by MITS, Poly- stripes. For those who insist, such insignia morphic, OSI, etc. These can be either the might be used to indicate rank or seniority flat laminated plastic multicolored type, or cast metal bas in a computer club. relief. Or the belt buckle could be a miniature replica of the front Other Jackets panel of your Astral 2000 or PCM -12, or a replica of a SC/MP or KIM -1 in its entirety, The hawks among us may prefer a mili- either as a laminated photoreduction, or in tary jacket, to go along with the military cast metal. The Cromemco TV Dazzler insignia, rather than a lab jacket. The catch would be a natural for a multicolored is that a GI jacket is apt to cost more, and mini -photo laminated belt buckle. isn't as easily and widely available. it And Tie pins offer a variety of possibilities. looks rather odd worn civilian if with Perhaps a miniature Continental Specialties trousers. If you want to go whole hog and LP -1 Logic Probe, or an 8080 processor, or a wear uniform trousers and jacket, along with DB -25 connector. Or, once again, a mini- stripes and decorations, you in might get ature of a front panel or a PC board. trouble with the MPs. However, if a full uniform is your thing, then you might go all the way. Get a web belt, a holster, and start The CHU Counter toting a Replica Models copy of a .45 Although maker's patches are perhaps automatic, with a light pen cleverly built best supplied by the computer manu- into the barrel. The ammo pouches could be facturers, all the rest of the CHU insignia used to hold program cassettes for trading could easily be made up by one of the with other software thieves. computer store chains, or by one of the manufacturers of military insignia. Com- Headgear puter stores could have a CHU counter, or Since interns and lab technicians seldom if CHU shelf, displaying the various stripes, ever wear hats, almost any type of headgear decorations and pins. The best display would would look odd with a CHU. However, be a CHU in maximum configuration, with continuing in the military vein, there is one jacket, full set of stripes, chestful of pins, item that might appeal to the same lunatic and a bouquet of decorations.

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www.americanradiohistory.com A New Journal for Computer Music Lovers ...

John Snell, a computer person with a specialization in music, has just decided to Reviews start a new journal of information for the computer music person. This journal is called, quite naturally, the Computer Music the design of a digital oscillator control- journal and is published by John through led by a small computer. It can output up the facilities of PCC. The address for the to 256 low distortion sine waves with journal is 1010 Doyle St, Box E, Menlo Park independent control of amplitude, fre- CA 94025. According to John's letter, which quency, and phase. I will also print an accompanied some descriptive copy, the first article on high speed multiplication. I issue was expected early in 1977. The have designed a TTL (74LSXX) circuit following is John's description, quoted from which will compute a 16 to 32 bit his letter: product every 75 ns. I may also include a computer music reading list if there is The first issue of Computer Music room. I will also probably print an article Journal includes an excellent comprehen- by Steve Saunders on multiplicationless sive introductory article on computer FM synthesis of natural timbre. music in general, written by Andy Moorer at the Stanford Al laboratory computer The price of a subscription to the Computer music project. Also included is an article Music Journal is $14 per annum. We've by Dexter Morrill on high quality already signed up for one and expect con- trumpet algorithms. l will print several of siderable interest on the part of BYTE my own articles in this issue. One is about readers in general.

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www.americanradiohistory.com Early Indications of Technology in Roman Military Arts or Plexitus

E E Barnes Star Route Parkesburg PA 19365

Sometimes an individual is about to bring solved this problem by attaching food to the about an invention which could change the lightened onager bolts and having these fired world, but is never noticed. We often say at the isolated detachments of his legion. that this man was born before his time. This was moderately successful since his Omnius Plexitus, legate of the XIII legion, casualties were light and the process spurred was such a man. Stationed with his legion in other developments. Unfortunately the fact the rough country which later became that he had fired upon his own men was Bulgaria, he improvised in order to survive. used later during his court -martial in Rome. Genius struck like lightning one day as he This Idea Has a Lot of Impact watched his artillery crews practicing. One of the pieces of semi -portable Roman siege Plexitus reasoned that such a bolt should equipment was called the onager or ass, be able to carry a man, but the major because of its kick; this was a sort of huge difficulty he faced seemed to be predicting crossbow which fired a heavy bolt or arrow the point of impact of the missile (and man). perhaps six feet long. During this particular After devoting much study to the problem, practice session, the cable release mechanism he was able to define 28 variables which became stuck and a legionnaire climbed atop directly influenced the flight of the missile. the device to free it. Free it he did, but only There was basically no limitation upon after he was astride the bolt to obtain payload size; he merely built a bigger leverage. Arrow and man sailed out as one crossbow.1 He had an onager scaled up and across the treetops. History does not record one was built concurrent with his attempts the fate of this early pioneer, but this is the at aiming. first historical incident of a man going aloft The first man known to fly was an aide to on an unpowered, heavier than air con- Plexitus, Dominic Idiotus. Idiotus (from trivance. This observation was not forgotten whence comes the common technical term) by Plexitus. was apparently offered a transfer if he would Plexitus was faced with supply problems agree to attempt a flight in the Plexitus in the hilly terrain in which his men were machine. In July of 248 BC he mounted the operating. They were widely spread out over bolt and was propelled 280 yards into a local the backs of ridges and across gorges. Sup- plying these detachments became rather 1During the supply operation early in the development of the Plexitus machine, some of the troops serious because the number of men which received their pay in the same way as they did had to be dedicated to carrying food seri- their food, attached to the onager bolts. A few scholars trace the roots of the word "payload" to ously reduced those carrying spears. Plexitus this event.

www.americanradiohistory.com swamp, from which he returned dirty but eight days because of its complexity and smiling. Exit Idiotus. some errors resulted from men in the morn- During the fall of 248, the machine was ing not remembering the positions which refined and experimentation continued. they had held the night before. Plexitus Plexitus found that most of the variables proceeded undaunted and merely repeated affecting his machine were products appear- the calculation and then took an average of ing in powers of one or more. (This in itself the different answers which he obtained.3 is a major accomplishment considering the His work was interrupted several times by state of instrumentation with which he had the hillsmen who took unfair advantage of to contend. For example, humidity was his scientific preoccupation by attacking. It found to change the tension of the bow was during this first retreat that the first string. The only means the Romans had for Plexitus computer was lost to the numerous measuring humidity was by counting the but unappreciative locals. number of crows made by a cock in the Thus Plexitus was the first to use the early morning. Plexitus apparently ran abacus in the West. Unfortunately, it lacked through a lot of chickens in his calibration portability, requiring over 7000 men and attempts. One of his men complained in a 34 acres in its operation. However, this is letter of all the chicken the men were forced not the disadvantage that moderns might to consume.2) Anyone who has ever think since the ancients had plenty of time attempted to multiply in Roman numbers and space. A pre- Christian timeshare facility will appreciate the difficulty of raising a could have developed where Romans could number to a power greater than one and have taken their problems to the machine, then finding the product of 28 of them. 3In standing all day, the legionnaires apparently took to shifting from one foot to the other, and The Roman Abacus when not actively moving about, to digging with the toes of their sandals in the sand. This was quite He finally resolved this difficulty by useful the next morning in determining the position the men had held the night before. This moving over half his legion to a huge space is the first mention of permanent memory in the which was cleared for this purpose and using literature. The holes in the calculating field suffered from men as markers in what became a kind of one operational disadvantage. When it rained, the huge abacus. Men moved about in position holes filled with water and the men had a distaste for standing in water, so he would begin the day upon orders from their squad leaders. Primi- with the complement of the number which the tive, but it worked. field had held at closing time the night before. Plexitus outlawed the scuffling with the toes Unfortunately, the calculation took over once he found the reason for his rather curious answers. Even good things had their problems. Some say that the water was not the reason for 2Some believe that later Roman soothsayers who Plexitus outlawing this practice, rather it was attempted to predict the future by looking at the traced to a comment made by a centurion who intestines of freshly slain chickens were attempt- had a villa near Actium. This individual observed ing to reproduce the actions of Plexitus' com- that this looked like an efficient way of plowing a puter, but were working from garbled, word -of- field and would he do some calculations on his mouth reports. land near Actium next spring.

www.americanradiohistory.com much like the Greeks did at Delphi. There the direct result of esprit de corps while are even some who suggest that Pompeii was others blame it on a reactionary attitude of attempting to use one of the Plexitus facil- those who did the calculations. Although ities during the later Roman civil wars; even normally the second log could be saved by this group is splintered with one faction quick action on the part of Plexitus, much saying that he never got it working. The time was lost. There are rumors among some other faction suggests that in fact he did, scholars of this period who trace the since he lost the battle and the war to battering ram to these acts, but this cannot Caesar. be supported; we only know that Roman During this time the XIII legion was numerals were not normally carved in them, forced to fight for its life, since the experi- at least not one to a million.4 ments had weakened the men; an individual does not use the same skills standing motion- The Last Days of Plexitus less a day as he does a in field all carrying Plexitus, because of overwhelming odds, time Plexitus shield and sword. About the had now lost nearly all of the province lost the province under his had half of which he had been sent to manage and was he was finally able to a command, complete now with his back against the sea. He then second super crossbow. This machine he launched his most extensive airborne opera- used to launch several groups of men in tion against the Bulgarians, firing over half a sharp, tight counter attacks behind the lines thousand men across the enemy lines, fully of the enemy. These were quite successful armed. The effectiveness of this attack and he won this battle. The retreat of the cannot be determined since those who had enemy resulted from the complete surprise been air launched, after regrouping, rebelled of this airborne tactic; whether these and joined the Bulgarians. Bulgarians were concerned over being At this point, the Legions XV and XVII flanked by legionnaires or were fearful of arrived from across the Adriatic and Plexitus being flattened during their descent is not was recalled in disgrace to Rome. His legion known. It is difficult to obtain information was in shambles and the remaining men were concerning the injuries which his men assigned to other units. For the rest of the sustained during this airborne operation days of the empire, no legion ever again used since a series about this time of rebellions that number of Plexitus' command, a broke out amid the tradition bound ranks of shadow which extends even to the present his command. These were unsuccessful, but day. Some say that he attempted to flee, but they weakened more his battle still strength. was apprehended only after there had been a malfunction in his machine.5.6 Plexitus Was an Exponent of Later, he fled Rome and joined the Logs Calculating With Carthaginians and became involved in arming Lack of manpower caused by attrition as a portion of their navy. Someone has sug- well as commitments required to hold the gested that Plexitus was the most patriotic battle lines forced Plexitus to improvise Roman of all since the numerically inferior again. He moved from the biological com- Roman fleet was able to overwhelm that of puter concept (an example of a kind of the Carthaginians which had been under reverse evolution, but Plexitus had distrac- Plexitus' direct control, a fleet equipped tions) to the physical by evolving a slide rule with a number of advanced weapons. But no using two large logs with a flattened face one can say. The last mention of him is apiece. This is an early example of miniatur- ambiguous. Some say that he was attempting ization since only 40 or so men were man- powered flight as opposed to his earlier required to operate it. This freed up many attempts, since the reference is quite definite individuals for fighting and yet allowed the in its description of his being covered with calculations to continue on predicting feathers. Critics say that he had just been impact points. Plexitus proceeded with his tarred. work despite distractions from outside his camp (since the Bulgarians were active again) 4Unfortunately Plexitus never stumbled onto scientific notation. Multiplying two 5 or 6 digit as well as those from within. Some say that numbers together must have resulted in an Plexitus could have gone much further impressive pile of sawdust. except for the actions of the men who 5Others say that this was not the case; his legionnaires wanted him to attempt to flee - via operated his slide rule. These operators his machine -and he was stopped by the legate of would, upon the first indication of an attack the XV who demanded his surrender. by enemy, pick up one of the logs making 6His contributions were largely forgotten at his trial. The only other reference ever made to his up the calculating device and rush to the innovation was about three years after his trial scene of combat and throw it into the when someone suggested that the Plexitus flying machine should be used as a punishment for cases enemy lines. Some account for this as being not serious enough to warrant crucifixion.

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Computer Components is dedicated to serving the needs of the computing community. We offer a complete line of computers and computer related products. We will ship anywhere in the world. Satisfaction guaranteed. Hours: Terms: Tuesday- Friday 10AM to 9PM Call or write for discounts. We pay Saturday, Sunday 10AM to 6PM shipping on UPS orders over $25. All CLOSED MONDAY others add $2 for postage and handling. We are authorized distributors for the following companies: IMSAI INTELLIGENT SYSTEMS POLYMORPHIC SYSTEMS CROMEMCO TARBELL KIM1 TECHNICAL DESIGN LABS SOLID STATE MUSIC VECTOR GRAPHICS RO -CHE SYSTEMS CONTINENTAL SPECIALTIES VECTOR ELECTRONICS SAE TEXAS INSTRUMENTS SIGNETICS NATIONAL SEMICONDUCTOR ADVANCED MICRO DEVICES SAMS BOOKS HAYDEN WILEY ...and more on the way. Always ask. www.americanradiohistory.com static programmable memory card you'll Get Yourself a Z -80 Reference Card employ some coordination of the Fred McNeill, Box 6305, Denver CO processor wait line with what computer 80206, sends us a copy of this Z -80 designers call "address anticipation processor reference card which he has logic." key to this address anticipa- The constructed from the Zilog documentation strategy is to assume that in most tion, and is selling for $3. The card is Wh81'$ cases the next address generated to a given bank of memory will be the previous address plus 1. This is certainly true in programs when executing contiguous segments of code between New? jumps; it is likely to be true in many data access situations where sequential operations such as linear searches, block moves and block IO transfers reference a Anticipation is Half the Fun continguous block of memory space. So what the Cromemco card does is to assume that in any given 4 K bank of memory implemented with its new 4KZ card, the next address will always be the old address plus 1. On this assumption the card starts a memory cycle ahead of the availability of the address from the processor using a local 12 bit address counter. If it turns out that the processor address in the low order 12 bits is the same as the anticipated value, then there can be immediate access and completion of the memory cycle for the 21 L02 circuits used in the board - with no processor wait states. If on the other hand the next address is not equal to the anticipation address, a wait state is generated and the counter is updated with the new nonsequential low order address value. If used with the fast Z -80 proc- printed on heavy letter size stock with a essor card which Cromemco also makes, fold. The number base orientation of the there will thus be a mix of slow and fast card is octal, and the information is How do you make a relatively slow cycles depending upon whether or not carried in somewhat condensed form, so memory part run fast enough to keep a the next low order address reference to some mental gymnastics are required to 4 MHz Z -80 processor busy most of the the card is one plus the old address. use it. time? If you use a little ingenuity such as When used with a slow 8080 or Z -80 at If you use a Z -80, you may find this that found in Cromemco's new 4 K 2 MHz, no wait states are ever generated card a handy accessory.. since the memories are always fast enough. THE SLOPPY DISK DRIVE The new Cromemco memory card is designed for convenient installation at Where to Get a 3M Drive ... I thought you would like to know we any 4 K byte memory address boundary, The National Multiplex Corporation, have a computer store in Cincinnati with with bank address selection via a slide 3474 Rand Av, Box 288, South Plainfield a rather interesting article: a sloppy disk switch mounted on the board (a bit NJ 07080, is presently advertising an in- drive. more convenient than using soldered expensive 3M drive product for the per- I assume it is used with PPP or NNN jumper wires.) Called the 4KZ board, sonal computing market. The drive is ap- transistors, "surprise pak" DIPs, and the this product is available in kit form from proximately one fourth the price of new famous Signetics WOM. computer stores or the factory at $195, drives previously available, and operates Perhaps some of your readers would or assembled for $295. Delivery is with phase encoded data at rates of up have other precision (106 ppm) uses for quoted at five days after receipt of to 9600 bps. Motor control, record and it. order. Cromemco is located at 2432 play mode are under control of software Rd, Mountain CA Sincerely on the lookout for such Charleston View in your computer or a set of switches on gems. 94043. the device. The device interfaces to any William R Stock computer with a serial IO port. The 1125 Lois Dr current price of $220 includes elec- Cincinnati OH 45237 tronics of the phase encoder board How to Make the Z -80 Slave to a NOVA (accepts clocks at 16 times or one times Documentation: The following clip- SAI Comsystems Corp, a subsidiary the data rate), and motor control. Ac- ping was found in the Cincinnati En- of Science Applications Inc, 4060 Sor- cording to the press release, delivery will quirer, /an 13 1977, on page D -1: rento Valley Blvd, San Diego CA 92121, be four weeks after receipt of order. At recently announced the availability of a 9600 bps, with an 8 ips (20 cm per fast cross -assembler for the Zilog Z -80 second) tape speed, the 300 feet Make -it- yourself computer kits, books microcomputer chip that runs on the (91.4 meters) of tape on this drive can and printer and video kits are sold at Digital Data General NOVA and ECLIPSE line be read or written (assuming no block Design, 7696 Camargo Rd. Instructions are of computers under the RDOS operating overhead) in 450 seconds (7.5 minutes). available on how to put the computer kits to- system. This cross -assembler was written Multiplying 450 seconds by 9600 bits gether. There is software, sloppy disc drives in assembly language for Scientific per second and again assuming no for- and almost anything the novice or profes- Applications Inc to allow speedy assem- matting overhead, the raw bit capacity sional would need. The shop Is open from 9 bly of large, in- house, Z -80 systems of this drive is 4.32 million a.m. -5 p.m. Mondays -Saturdays or by ap- bits per pointment. programs used in new intelligent termi- track, or a cartridge capacity of 17.3 mil- nals developed by the firm. lion bits on four tracks. Dividing

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MODEL 3M3 $199.95 2SIO(R) CONTROLLER $190.00 (Price Increases to $220.00 effective 1 April 77)

MODEL 3M3 Featuring the radically new "Uniboard" 2510(R) CONTROLLER (Bootstrap Eliminator) method of construction for data cartridge drives. The major This is a complete 8080, 8085, or Z80 system controller. computer makers are changing to cartridges at a rapid pace It provides the terminal I/O (RS232, 20 ma., or TTL) and because of the freedom from binding and greater data the data cartridge I /O, plus the motor controlling parallel reliability. Operates in the phase encoded self -clocking I/O latches. One kilobyte of on board ROM provides turn mode which provides greatly enhanced freedom from speed on and go control of your Altair or IMSAI. No more variation problems and allows 100% tape interchangeability bootstrapping. Loads and Dumps memory in Hex on the between units. terminal, formats tape cartridge files, has word processing Uses the 3M Data Cartridge, model DC 300. This and paper tape routines. Best of all, it has the search cartridge contains 300 feet of .250 tape in a sealed plastic routines to locate files and records by means of six, five and container. Using four tracks you can record nearly 2 four letter strings. Just type in the file name and the megabytes of data on a cartridge. recorder and software do the rest. Can be used in the BySync (IBM), BiPhase (Phase Encoded) or NRZ modes Specifications: Full software control of record, play, fast with suitable recorders and interfaces. forward and rewind. LED indicates interrecord gaps. EOT $190, wired and tested. - $160 0, Kit form. and BOT are sensed and automatically shut down recorder. Feedback signals send reset and inter-record gap signals Audio Cassette Interface (ACI) This is the phase encoding on the back to the computer so that software searching for board used in the 3M3. Additional components use recorders in KC inter -record gaps at high speed can be accomplished. Can board enable you to audio the standard the new PE 2400 baud) systems. Can also be used also be operated manually by means of the switches on top or (2400 you have an Intel I/O Required if which parallel the software control signals. for Tarbell if 8251 chip. you use an audio cassette with the 2S10(R) above. $199.95 until April 1, 77. $220.00 after April 1, 77. $50, wired and tested. $35, form. Includes Phase Encoder Board (ACI) - Kit For 6800 Users: Software programs and I/O board for SWTP are under development. Limited software available For 8080, 8085 and Z -80 users now. Ask for 6800 data with $3.00 Documentation Comes complete with software listing for the programs in package. These programs will provide full software control. the 2S10(R) ROMs. Can be controlled by any of the commonly used I/O boards. Send for complete documenta- CARTRIDGE AVAILABILITY: Cartridges are made by tion and interfacing instructions on 3M3 and 3M, ITC, Wabash and others. They are available at all 2SIO(R) ($3.00). These programs provide full software computer supply houses and most major computer service control. centers. We can supply them at normal current list prices.

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OVERSEAS: EXPORT VERSION- 220 V - 50 Hz. Write Factory or: megatron, 8011 Putzbrunn, Munchen, Germany; Nippon Automation 5 -16 -7 Shiba, Minato -Ku, Tokyo; Hobby Data, FACK 20012 Malmo, Sweden; G.Ashbee, 172 !field Road, London SW 10 -9 AG; The Computer Place, 186 Queen St. W., Toronto, Ontario M5V 1Z1, Canada. For U.P.S. delivery, add $3.00. Overseas and air shipments charges collect. N.J. Residents add 5% Sales Tax. WRITE or CALL for further information. Phone Orders on Master Charge and BankAmericard accepted. NATIONAL MULTIPLEX CORPORATION 3474 Rand Avenue, South Plainfield, N.J. 07080, Box 288 Phone (201) 561 -3600 TWX 710- 997 -9530

www.americanradiohistory.com 4.32 million bits per track by the mented error detection and correction 3600 inches per track, the density is methods used such as hamming codes, 1200 bits per inch (470 bits per cm) on cyclic redundancy checks, or checksums. each track. Dividing 17.3 million bits by However, using 2.16 million bytes as an 8 bits per byte, again assuming no over- order of magnitude, this could for ex- head, the total cartridge capacity of the ample hold 16,000 names and addresses drive is 2.16 million bytes. The actual of 133 characters each, 43,000 lines of figure will be smaller due to overhead of source text averaging 50 characters per interrecord gaps and any software imple- line, and so on. Very useful.

A 2650 Single Board Computer 2048 bytes of programmable memory of which 768 are available for programming with the balance (1280 bytes) dedicated to the display, one 8 bit input port and one 8 bit output port. The board con- tems software in ROM, and program- tains sockets for an additional 3 K of mable memory for user programs. The PROM programming, which can include board also features control logic and the firm's editor and assembler PROMs displays to aid in debugging of programs. which cost $200 for a set. A BASIC To complete the system, you'll need a package is also available on cassette tape power supply of 5 V at 600 mA (or 10 V for $20, as is a $20 tape version of the at 200 mA with 5 V at 400 mA for the editor and assembler package. To use LED displays) and a terminal with cur- this computer, you'll need to supply a rent loop (Teletype at 110 to bps) or video monitor (or modified television), RS -232 interface (110 to 1200 bps). an ASCII keyboard, a power supply (5 V The board contains a total of at 3 A) and probably some extra 256 bytes of programmable memory memory interfaced using DIP plug con- using RCA's CDPI822 256 by 4 bit nectors on the board. The 2650, itself, is memory integrated circuits. Wired, but one of the unsung heroes of the micro- not stuffed, are positions which can processor marketplace, a rather powerful accept 30 additional CDP1822 circuits machine with characteristics and address- for a total on board memory of 4 K ing modes well worth investigating by bytes. The ROM system monitor consists the serious personal computing of 512 bytes contained in one 512 by enthusiast. 8 read only memory. Jeff Roloff, whose company is called bit CDP1832 The in- Central Data Company (POB 2484 program features include memory of Station A, Champaign IL 61820) has spection and modification, initiation user programs, and full interfaces to the sent along this picture of a new $325 Interested in COSMAC communications terminal. The monitor's single board computer which uses the Evaluation Boards? working memory is contained in a Signetics 2650 processor. This board One of RCA Will Fix You Up with part which is an 80 character by 16 line video 32 byte CDPI824 memory includes These Kits for $249 Direct or from generator (upper case 64 character separate from the user memory. Since Your Nearest Distributor ... whole is CMOS, re- ASCII built -in) with a user program- the system power mable set of 64 characters (8 by This kit of components will allow the quirements are quite low, allowing RCA add the finesse backup for 8 matrix) for nonstandard character engineer or advanced homebrewer to put to of battery As a machine code sets. Also on the board are a 300 bps up a CDP1802 processor. It contains a memory contents. device, the Kansas City standard cassette interface, a printed circuit board, byte input and level test and checkout 1024 byte PROM monitor program, output ports, a terminal interface, sys- CDP185020 board kit has controls in-

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LIGHT AND SMALL: BABY! 1 weighs less than 10 lines. Any page of memory may be displayed and edited. pounds, is 14.75 inches wide, 10.625 inches deep and The 128 character set includes UPPER and lower case 3.625 inches high. Its attache case is slightly larger, letters, and lower case ypeeK. Four additional special leaving room for the powercord, video and cassette characters control the DMA functions to hide or flash cables, cassette tapes, recorder, and paperwork. your message or to obtain 100 percent processor time. POWER FUL MICROPROCESSOR: The 6502 processor EXPANDABLE RANDOM ACCESS MEMORY: Uti- has 13 addressing modes and 56 instructions. A single lizing at least 4K bytes of the low power consumption bus structure, engineered for high reliability and ease of and high -speed 2102 type chips, an additional 8K or 4K use, gives it excellent versatility, expandability, and plus an expansion card can be added inside the system. flexibility. The expansion card has two 50 pin connectors to enlarge EASY PROGRAM DEVELOPMENT: Firmware (soft- the system. ware in ROM) lets you enter and debug your programs MODULAR EXPANSION: With the expansion card, you through the keyboard and list them on the video may add up to 60K bytes of memory or connect and monitor; lets you dump it to an audio cassette at 1200 control any peripheral of your choice through the baud for future use and exchange with other systems. buffered bus, and through the four bidirectional COMPLETE MONITOR IN FIRMWARE: No time -con- interrupt driven parallel ports, the RS232 serial port, suming loading of the monitor is required. Firmware and the 20mA loop serial port. Connect printers, controls the unit completely. Turn on the unit and its typewriters, tape drives, disks, floppy disks, additional firmware will run the system until you enter a new processors, your railroad, or whatever else you may program in RAM or plug in up to four other ROMS or need. PROMS. It controls the keyboard, video, and tape COMPLETELY ASSEMBLED, TESTED, AND BURN- interfaces. ED IN for 168 hours at high operating temperatures. ULTRA RELIABLE KEYBOARD ENTRY: The unique FULLY WARRANTED for 90 days on parts and labor. keyboard with its 62 keys features ultra reliable solid MAINTENANCE CONTRACT available at the end of state "No Switch" switching (no moving contacts), the warranty period on a yearly basis for your BABY! 1 N -key roll over, tactile feel with a clicking sound when a at a cost of less than 20 cents a day. key is depressed. Its MTBF (Mean Time Between COMPLETE SOFTWARE SUPPLIED: A monitor stored Failures) is at least six years of continuous use, at least in 1K ROM, and programs stored on a cassette include twice the life of an electromechanical keyboard. TINY BASIC, music, shooting stars, and a version of the HIGH-SPEED AND FLEXIBLE TAPE INTERFACE: powerful TECO TM text editor of Digital Equipment The advanced 1200 baud cassette tape interface is under Corporation, and more. monitor control. You can write a program to simulate is a Equipment other speeds, techniques, and formats. Now you can TECO trademark of the Digital Corporation. read or write tapes for exchange on other systems! Any cassette recorder can be used. Two sets of cables are supplied, one for standard, the other for reverse polarity recorders. The system program provides a two to one STM Systems Inc. ratio between ones and zeros, and loads at 1200 baud Specialists in Technology for Microprocessors 4K bytes in less than 90 seconds. INDUSTRY COMPATIBLE VIDEO OUTPUT: The P.O. BOX 248 N.H. 03057 video signal is EIA compatible 1 volt peak to peak. The MONT VERNON, flicker free DMA (Direct Memory Access) design 603 -673 -2581 displays 7 by 9 dot characters in 32 columns and 16

85 www.americanradiohistory.com - dee for yourself the reasons why: - 1. MICROPROCESSORS: New Directions 9. MINICOMPUTERS: Structure and for Designers by Edward A. Torrero, #5777 -6, paper, Programming, by T.G. Lewis and J.W. Doerr, 1975, 144 pp., 81/2 x 11, illus., $10.95. #5642 -7. cloth. 1976, 288 pp., 6 x 9, illus., $12.95. 2. GAME PLAYING WITH COMPUTERS lo. PATTERN RECOGNITION by Rev. 2nd Ed., by Donald D. Spencer, #5103 -4. cloth, 1976, M. Bongard, #9165, cloth, 1970, 256 pp., 320 pp., 6 x 9, illus. $16.95. 6 x 9 illus., $14.90. FUNDAMENTALS AND APPLICATIONS 11. DIGITAL SIGNAL ANALYSIS by a Samuel D. Steams, #5828 -4, cloth, 1975, 288 pp., 6 x 9, by Sol Libes, OF DIGITAL LOGIC CIRCUITS illus., $19.95. #5505 -6, paper, ($6.95), #5506 -4, cloth, ($9.95), 1975, 192 pp., 6 x 9, illus. 12. BASIC BASIC: An Introduction to Computer Programming in BASIC 4. COMPUTERS IN ACTION: How LANGUAGE by James S. Coan, #5872 -1, paper, by Donald D. Spencer, #5861 -6, Computers Work ($7 95). #5873 -X. cloth, ($9.95), 1970, 256 pp., 6 x 9, illus. paper, 1974, 160 pp., 6 x 9, illus., $5.50. 13. ADVANCED BASIC: Applications 5. COMPUTERS IN SOCIETY: The and Problems, by James S. Coan. #5856 -X. cloth, Wheres, Whys and Hows of Computer ($8.95), #5855 -1, paper, ($6.95), 1976, 192 pp., 6 x 9, illus. by Donald D. Spencer, #5915 -9, paper, ($5.50), Use FUNDAMENTALS: A #5916 -7, cloth, ($7.50), 1974, 208 pp., 6 x 9, illus. 14. FORTRAN Short Course by Jack Steingraber, #5860 -8, paper, 6. PROGRAMMING PROVERBS by Henry F. 1975, 96 pp., 6 x 9, illus., $4.95. Ledgard, #5522 -6, paper, 1975, 144 pp., 6 x 9, illus, $6.50. 15. DIGITAL TROUBLESHOOTING: 7. PROGRAMMING PROVERBS FOR Practical Digital Theory and Trouble- FORTRAN PROGRAMMERS by Henry F. shooting Tips by Richard E. Gasperini, #5708 -3. Ledgard, #5820 -9, paper, 1975, 144 pp., 6 x 9, illus., $6.50. paper, 1976, 180 pp., 81/2 x 11, illus., $9.95. 8. COBOL WITH STYLE: Programming 16. DIGITAL EXPERIMENTS by Proverbs by Louis J. Chmura, Jr., and Henry F. Ledgard, Richard E. Gasperini, #5713 -X, paper, 1976, 192 pp., #5781 -4, paper, 1976, 144 pp., 6 x 9, illus. $5.45. 8'/2 x 11, illus., $8.95. - Write for 15 -day examination copies of any of these books! At the end of 15 days, please remit payment accompanies order, we pay postage and plus postage and handling, or return the handling. Outside USA, cash must books and owe nothing. Prices subject to accompany order - include $2.00 per book change without notice. If payment for shipping and handling. Hayden Book Company, Inc. 50 Essex Street, Rochelle Park, New Jersey 07662 phone: (201) 843 -0550

www.americanradiohistory.com eluding a RESET button to initialise the system, Continuous or single step operation, and displays of various information in LED devices. A prototyping area measuring 6 by 4 inches (15 by 10 cm) allows the user to adapt this system on a custom basis. irtiscd10141 RCA Solid State is located at Route 202, Somerville N) 08876, and as noted above, this kit is available for $249 direct or from your nearest RCA distributor. Its probably one of the best NCR ways to take advantage of the 1802 instruction architecture in a homebrew TERMINAL SYSTEMS DIVISION - DAYTON computer project. DAYTON, OHIO

Come and join Terminal Systems Division - Dayton. Our Engineering is a Some Information on Refreshing Staff leader in the design and Dynamic Memories Is Available implementation of Financial Terminal Systems. We have from Texas Instruments much to offer you - a career opportunity, a quality environment in which to work and live, and exceptional Texas Instruments has published a 12 personal benefits. Dayton, Ohio is a progressive page application summary bulletin entitled Introduction to Refreshing TI 4 K midwestern area, small enough to be friendly but large Dynamic RAMs. Bulletin MOSA3 intro- enough to offer outstanding communities with excellent duces refresh principles and their imple- housing, educational facilities, and cultural activities. mentation. It also compares static and dynamic RAMs in terms of speed, power consumption, refresh requirements, rela- PROGRAMMER /SYSTEMS ANALYST tive costs and power supply requirements. Various kinds of simple refresh Knowledge in the area of microprocessors and circuitry are outlined and block dia- minicomputers based on realtime operating systems. grammed, including transparent, cycle steal and burst methods. Hackers and Participate in the design and implementation of mini and homebrewers looking for engineering in- micro based realtime operating systems in a distributive formation on use of dynamic memories network. should write to Texas Instruments Inc, Inquiry Answering Service, PO8 5012, M/S 308, Dallas TX 75222. Attention: Bulletin MOSA3 Literature. SOFTWARE SYSTEMS DESIGN Provide technical expertise and leadership in the areas of realtime terminal control and batch operating systems. Don Tarbell's New Prototyping Board ... Analysts for state -of- the -art design in terminal operating systems and to provide technical leadership in software architecture.

SYSTEMS ENGINEERS Requires the development of concepts and specifications for new systems for financial terminal systems. Requires the ability to analyze and participate in hardware and software development programs. Basic educational qualifications for these positions are a BS or MS in EE, CS or Math and 2 to I -lere is yet another product for the 7 years experience. Altair bus. Don Tarbell, Tarhell Elec- tronics, 14 -1 Miraleste Dr =106, Miraleste Join our winning team. Submit your resume and CA 90732, has just announced this new prolotyping board for use with Altair salary requirements to: ,und compatible computers such as the Robert L. Opalek IMSAI 8080, Sol, Poly 88, etc. The Employment Department board is designed with interleaved power Terminal Systems Division -Dayton and ground for the standard logic vol- NCR Corporation tages, and lias a position for a 5 V regulator (lower right side of the photo). Dayton, Ohio 45479 The board is intended for use with point to point solder connections, wirewrap, or any combination. The board will accept 33 1.1 pin integrated sockets, or smaller counts of 16, 18, 24 and 40 pin N C R sockets plugged into its pattern of pre - drilled holes. The price is $28 per board. An Equal Opportunity Employer

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101 BASIC Computer Games edited by Ahl spent considerable time collecting David H Ahl, Creative Computing, Morris- this potpourri of games on his travels to town NJ 07960, 248 pages softbound. $7.50 various schools as well as from submittals in plus postage. response to an advertisement. Game authors range from seventh graders in California to 107 BASIC Computer Games, edited by PhDs in England. David H Ahl, is not only the first collection The games run the gamut from extremely of games all in BASIC, but a uniquely simple to more complex; but most require educational book which provides both a no special knowledge. To solve the game complete listing and description of every categorization dilemma, Ahl has simply game along with a sample program for each. listed the games in alphabetical order. But in As Ahl points out in his book, educators the appendices, he has outlined some family generally agree that games are highly motiva- groupings, such as logic, plotting and matrix tional and promote learning by discovery. games. What better way is there to learn about A BASIC speaking computer is the only Newton's second law than by simulating an equipment needed to play any of the games. Apollo lunar landing in ROCKET? Or to However, Ahl suggests that a grid or learn about logic by playing BAGLES? You quadrille paper be used to play four of the can even increase your vocabulary while matrix games and that one of the supple- playing SYNONM or improve your writing mental diagrams included in the appendices skills in BUZZWD by learning how to be used when playing QUBIC, a game of tic compose computer speeches with the latest tac toe in a 4 by 4 by 4 cube. Most of the buzzwords. games also run in standard BASIC with any For those interested in more exotic exceptions noted under the game title. games, there's CHEMST, in which the player Due to the addictive nature of the games, tries to dilute the fictitious kryptocyanic computer enthusiasts should be reminded acid; CHOMP, which involves eating a cookie not to skip meals or sleeping in favor of while trying to avoid the poison piece; and playing ANIMAL or FOOTBL. HELLO, in which the computer dispenses 101 BASIC Computer Games is available advice on such problems as sex, health, in a 248 page softbound edition for $7.50 money or a job. plus $.75 postage from Creative Computing, Computer enthusiasts with a sense of POB 789 -M, Morristown NJ 07960, and humor will find many entertaining games in from BITS Inc. the book with such challenging objectives as Linda Blocki delivering pizzas successfully, PIZZA; doing 1706 Silver SE, Apt 27 a silly profile plot of an ugly woman, UGLY; Albuquerque NM 87106 and finding the happy hurkle beast hiding in a 10 by 10 matrix, HURKLE. The names alone of many of the games TV Typewriter Cookbook by Don Lan- are intriguing enough to invite further inves- caster. Howard W Sams & Co, Indianapolis tigation. FIPFOP, SPLAT and ZOOP are IN 46268, 1976. $9.95. sure to send hobbyists running to their computers. FIPFOP is a solitaire logic game Don Lancaster's TV Typewriter Cook- dealing with changing a row of Xs to Os. book provides comprehensive coverage, not SPLAT involves opening a parachute at the only of the problems of generating character last possible moment. ZOOP, otherwise displays on a home TV set, but of a known as the BASIC programmer's night- host of related topics as well - memories, mare, is designed to imitate the system keyboards, cassette recording methods, commands of a BASIC compiler, except that modems, and hard copy devices. His book is it gives totally meaningless and frustrating one of the most valuable yet to appear for results. the electronics and computer hobbyist.

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www.americanradiohistory.com Some of the chapters in this book appeared mended Elements of Programming Style (see as articles in the earliest issues of BYTE BYTE volume 1 number 1), is to teach (September 1975 - January 1976, March good programming practice by presenting a 1976), and several of them won awards in series of practical programs, each of which our BOMB (BYTE's Ongoing Monitor Box) provides lessons in program design and contest. If you've been looking at some of implementation. All of the programs are the TV interface products on the market and general purpose tools which are used by the have wondered how they work; or if you'd authors in their everyday work; in fact, like to know more about programmable read many of them were used to help prepare the only memories, UARTs, keyboard encoders, text of this book. The programs form a TV bus transceivers and other fancy ICs, this is comprehensive set which is designed to be as TYPEWRITER the book for you. easy as possible to use. The code is inter- COOKBOOK Don is one of the few writers who not leaved with explanatory text which de- BY BOB S *MCBSlfr only presents circuits, but explains what's scribes, not only how each program works, really going on in them, and what design but why it was designed and implemented alternatives exist. The book starts with that way. basics, like how TV scanning works, and The programs are written in a structured how data is represented in the ASCII, version of FORTRAN, called RATFOR (for Baudot and Selectric codes. Successive chap- "rational FORTRAN "). RATFOR simply ters describe memories (both random access provides control structures such as nested and read only) and buses; timing, sync IFs and WHILE -DO and REPEAT-UNTIL signals and composite video for display looping constructs. The remaining state- generation; and cursor and update circuits. ments utilize a subset of ANSI FORTRAN Next Don digresses for two valuable chapters features that should be found in nearly all to deal with keyboards and encoders, serial FORTRAN implementations. The last chap- data handling, UARTs, cassette recording, ter of Software Tools presents, nat- modems, and telephone characteristics. Then urally enough, a RATFOR -to- FORTRAN his attention returns to the main TV type- translator. writer problem as he describes methods for There are two ways to use this book to interfacing to the TV itself (both direct develop software for personal computers: video and RF entry), color techniques, and First, the RATFOR source code could be graphics. The book concludes with a discus- hand translated to the assembly language of sion of hardcopy alternatives, including one or more of the popular microprocessors. some useful, if sketchy, information on the This would be a lot less work than designing possibility of converting a Selectric type- such tools from scratch, and should make writer for computer use. debugging a far less formidable job. Second, This book has been out for some time, a "Tiny FORTRAN" compiler or interpreter and should be available through many book- could be developed which would make it stores and retail computer outlets (also possible to mechanically translate or inter- through BITS). Many of our readers may pret the programs on a very small machine. already have this book. Those who haven't Only the subset of FORTRAN required by seen it would do well to check it out. RATFOR would have to be implemented. The only drawback to this approach is that Software Tools by Brian W Kernighan and P some of the programs presume the existence l Plauger, Addison- Wesley Publishing, of a "nice" operating system (the authors Reading MA 01867, 1976. $8.95. use UNIX on the PDP -11), which is sadly lacking on most existing personal computers. This book could be the jumping off point To assist in the second approach, the for creation of a great deal of useful soft- RATFOR source programs in machine read- ware for personal computers. Its great able form can be obtained from the pub- strength is that it contains well written, lisher. Write to Linda Banks, c/o Addison - thoroughly documented, tested and working Wesley Publishing Company, Reading MA programs for many of the most desired 01867, (617) 944 -3700. The cost is just $25 home computer applications: a very power- plus $1.67 postage for an IBM/360 com- ful text editor, a text formatter for docu- patible 9 track, 800 bpi, odd parity, ment preparation, a macro processor, and a EBCDIC coded magnetic tape. We'd like to SNOBOL like string pattern matching pro- hear from all the system hackers out there gram. Also included are general purpose who pursue this approach. sorting programs, a file management pack- Daniel Fylstra age, and a variety of useful utility routines. Hamilton Hall C -23 The purpose of this book, which was Harvard Business School written by the authors of the highly recom- Boston MA 02163

www.americanradiohistory.com S e \`0\e' k ` I a /l Q \b\e v I S(( \ \ \ S ke S` \r¢ SÌ be m g m v 1 d \\y ra . COI ° 0eK r y \rk° Ok P ß k\\\y e p0e SA b ' S é e aS C° eede N b - VW,ca\e e k° e JP\ AO a e t ,\° ° d ces e\ d S l \°\° S cacd ßeP ati\(p ô e aP P °\,\ S »\e s(a d s\a kep sP As 2.(\ o e e r ` eS ¢ d a\caw e +psèete` . sa ay 5 \\\ Wa o ()It \s n+a dP° poR`P y , odsd ° em5sp se. \ P P \b(a6a d o°r¢ a 0- 0°\ae 8e \° F \Sy oPd \ad yo . ds a\¢00.-0 Kas d ° 0 N d 0os \ oP e \ eG°e a c ¢ 0ó5 oo& écPdsepa' a S Ps Js Poad yses a 166 aéd M .4.00.6s aJd ode1O ¢< P ge ee J 9 0\ Pey \O°,N Pvop amgSteR`d e\ \, \\J tiyP ce \ Nels Pom SZ , \ 0< ` 39s , r r sP¢¢ pe°Mad s \\ 034' omed` to ` i `t¢\ a <,at y O Sa°te @ Seet VP? Ote l° s 0° PG EtG vP P- N 0y N1G ,0\ \ aP d m 9 \°P0M \ ` è s o E G1AGN g Syg.° \¢ Pß ce 4\ , " t OM9 OM 6PG AS eS1 f` 1\ QS ed \K5 2 < @ SSNO t,4 \ Grw(e``0a a Qw dOd OV4 1-PPS s°óNVd toi P) _100.t» 0.00 45 0etaa ¢°Na ^°e4o Q\ pp° \° ,óQ, o "-G\Ny/QNe \a00sao 0 Mas 90 Q www.americanradiohistory.com Why Aren't There Any Altairs

on Arcturus II?

Henry Melton flattering picture. Only the correct predic- 7307 E Riverside Dr tions are remembered, and even those Lot -13 weren't outstandingly accurate. Nobody pre- 78741 Austin TX dicted such a complicated first moon flight, with command modules and orbiting stages,

I have been writing science fiction for descent and ascent staged landers. Few some time now, and I've been reading it stories gave the first moonship an onboard forever, so it doesn't strike me as being very computer. None included television cameras. odd that I'm now into computers. If you But no one worries too much about that. mention your computer to a friend, you're After all, one person sitting at a typewriter likely to get a HAL joke back. It's an can't really compete with a team of engi- automatic association: Computers and neers in working out the best way to put a just seem to go together. It's man on the moon. A science fiction writer As in all prophecy, only science fiction logical too. For as long as I can remember, isn't a true prophet; all he or she can do is the correct predictions are the science fiction stories I read had ideas. choose a possible future to write about. J ust remembered, and even Spaceflight, nuclear power, robots and a as the human race, by its actions, chooses a those aren't outstandingly hundred other marvels were accepted fea- possible future in which to live. If a writer accurate ... compare the tures of those adventures. A good science knows humans well enough, he /she can actual nature of the first fiction yarn would drag me off to some second guess the race and look like a pretty moon flights with the strange time and place where there would be fair prophet. Such is the way of the game. predictions. far too much going on for me to ponder over Looking back at the hundred million the particular space drive involved, or to words of science fiction I have read to date, puzzle about the program that might be I think I have gotten a good return. Future running beneath the robot's polished skull. shock holds no terror for science fiction

But when I got back to Earth, how things readers. No new technological marvel can had changed. So many marvels seemed so sneak up and go boo. The science fiction possible in what had been such a drab reader has seen it all before. mundane world. Or, rather, almost all of it. Well, the moonflights and the nuclear There does seem to be a big black gap in power plants and the Viking Lander robots this flood of prophecy. The science fiction happened. Everyone speaks of today as reader who is familiar with the common being a science fiction world. And, in a picture of a computer as portrayed in sense, the wonders of today were spelled out science fiction is due for a big shock when years ago in the books and magazines of he /she runs up against the powerful lit

www.americanradiohistory.com That is frightening in itself. What is wrong Particularly in physics, some stories have with science fiction that something so tech- come out in the science fiction magazines nological as a revolution in computers could before the original research on which they go unheralded? Are science fiction writers were based has even made it to the profes- losing their touch? Is technology developing sional journals. Science fiction can still make Future shock holds no too fast for them to keep up? its claim to be the literature of ideas. terror for science fiction An overview of modern science fiction, But, Alfred Bester's excellent novel, The readers. however, indicates that this gap seems to be Computer Connection, has a room sized a strange, localized thing. In other areas of malevolent computer trying to take over the human knowledge, science fiction is still world. Roger Zelazny's "Home Is The riding high on the far edge of the barely Hangman," which has just won the Hugo possible. Interstellar ramjets, galactic core award for the best science fiction novella of explosions, Kerr black holes, gene grafting, 1975, has the main character hunting down just about any conjecture of physics, cos- a possibly murderous robot, before the mology, biology or whatever, is likely to be robot can find his creators. Isaac Asimov's found in a modern science fiction story. "The Bicentennial Man" follows a robot,

www.americanradiohistory.com caught us all off guard. Poof! There it was, a gadget with major sociological implications in the is a small one ... sci- Yet, this gap literature in everybody's pocket, and nobody had ence fiction can still make its claim to be the really predicted it. I can remember only one literature of ideas when it talks about the social old story that used pocket calculators, and implications of black holes, the people dynamics of a even then, they were finely machined, runaway relativistic acceleration in an interstellar motorized slide rules. The story was good, ramjet, or what to do about a murderous robot. though. It explored what a world would be like if everybody had forgotten that math could be done in one's head. If the story had come out only five years ago, it would have been hailed as a prime example of the originally designed to be a butler, in his life- predictive value of science fiction. But no long quest to become a human being. modern story had even considered the con- Now, these are good stories, some of the cept. best of the past couple of years. But the That was a shock for the writers; and computers and robots in them are no more signs that this stagnation is breaking up are If a writer knows humans sophisticated than those in science fiction starting to appear in print. But why was that well enough, he /she can stories of twenty years ago. mental block there at all, and why has it second guess the human Science fiction has had its stereotypes. persisted for so long? Was it just a fluke?

The two computer types constantly used are I race and look like a pretty don't think so. I'll tell you why. either the huge device, something that would A quick look at all the computer fair prophet. Such is the of have been a good university computer back stories that have come out since computers way of the game. in the sixties, except for its disconcerting and science fiction writers discovered each tendency to chuckle evilly when no one is other back in the forties will show one looking, and the robot. The robot, more- dominant theme: artificial intelligence. over, usually has some kind of magical (ie: A writer of fiction stories has to be Asimov's positronic) brain that is really concerned with people. Even a gadget story nothing more than technological handwaving is only a story inasmuch as it affects people. on the author's part to let him have a human For a writer to write anything worth read- brain sized computer inside a human looking ing, he /she has to consider the characters robot body. above all else. When the intelligent com- The real shame is that these stereotypes puter first appeared on the science fiction haven't changed in the twenty years that scene, everybody took the concept to they have been used. A reader of BYTE can heart. sit down with one of today's science fiction The intelligent computer made a beauti- books and rest his /her reading arm on top ful character, from the storyteller's point of of a logic machine considerably more sophis- view. The full range of personalities, from ticated than anything he /she is likely to en- purely logical to insanely demonical,were all counter in the pages of the book. It is a available for use, and all essentially believ- shame, if for no other reason than some able. Believability is a prime quality in otherwise good stories are going to be un- science fiction. It has to be there if the story palatable to a lot of personal computer is going to be any good. And anyone can owners. This mental gap in science fiction believe a computer with a bad case of writing really shows up in some places. misprogramming. Can you imagine what Spock would have And so the computer became part of the The personal computer is done if there had been a microprocessor stable of characters available for a science here now, with a potential in his tricorder as there should have been? fiction writer, right up there with human to open up society to pri- The more one thinks about it, the clearer beings, mythological creatures, and aliens vate initiative in a manner it becomes that science fiction writers are from the planet [The symbolic almost unprecedented in really behind schedule when it comes to name of your favorite mythical planet is a parameter to be user a history, and nobody wrote computers; actually behind the times, when supplied by the of they should be well ahead. It is a blank spot science fiction writing program.] A com- a story predicting it. Are in science fiction, and it has been there for puter was a character. The concept became science fiction writers years. It might have stayed blank for many so fixed that writers forgot that real com- losing their crystal balls? more years if it hadn't been for the inven- puters exist because they are beautiful tools. tion of the microprocessor. The only people And while science fiction writers told their who can notice that blank spot are those tales of pensive robots and planet killing who know better. In other words, only you Berserker machines from some war lost long

and I and the people we talk to. ago and light centuries away, the macro- But there are signs that the writers are computers begat minicomputers, and minis

waking up. I think the pocket calculators begat micros. Out of the same labs came the

www.americanradiohistory.com pocket calculators, which jumped out on the hours tapping touchtones on his phone? market and gave us all a little taste of future Shades of stories we've read about in shock. Computerworld! In this story, Brunner When the intelligent com- The shock has done some good. Some of introduced the concept of a tapeworm to puter concept first ap- the better writers are already into the swing the science fiction readership. peared on the science of things. Take two examples: You must A tapeworm is a software life form. It fiction scene, everybody read The Mote In God's Eye by Larry Niven lives in memory space, eating processor time. took the concept to heart. and Jerry Pournelle, and Imperial Earth by And they exist. I've seen them. So have you Aha, here's another type Arthur C Clarke. In both of these novels if you've watched a program blow up, using of character! everyone has a pocket computer. These a video display as a window into your gadgets are pocket sized with large memories memory space. I've watched about five and very easy to program. They can store naturally occuring species in a friend's 8080. text, graphics, and sound, occasionally tying If you are doubtful that they are alive; go into larger computers by radio, thus serving back and reread the definition of life and as diary, library, calculator, and who knows think again. what else. This pocket computer is such a Exciting things are starting to happen as logical development that you can bet that science fiction takes another look at com- other writers will pick up on the idea. Here puters and what they can do. But you only Definition: A tapeworm is is a beautiful tool in science fiction, and not can determine how fast these stories can a software life form. It a hint of an evil chuckle out of it. come out. You can't wake up a writer if you lives in memory space, Here is another example: Shockwave haven't met him /her. So put on your BYTE eating processor time. The Rider, by John Brunner, extrapolates a tee -shirt and go to the next science fiction etymological roots its world where any computer can be reached convention and meet the people. Talk about of and programmed from any telephone. (This your machines. name lie in the theory of is an extrapolation ?) In this future world, The computer as a beautiful character generalized computability, the programming genius with the right pass- will never go away; you can be sure of that. ie: the theory of Turing word is like the one eyed man in the country But the beautiful tool is here, and all it takes machines. of the blind. What can be forbidden to the is for science fiction writers to realize it. man who can change his identity, profession, Then, finally, you might see an Altair on and financial status, with just a couple of Arcturus II.

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www.americanradiohistory.com Navigation with Mini -O

Part 3, Software

Richard J Salter The previous two articles on Omega program is now continuing with the develop- Avionics Engineering Ctr Navigation and the Mini -O design by Ralph ment of navigation software to provide the Ohio University W Burhans /February 1977 BYTE, page 62; pilot or navigator with more direct data Athens OH 45701 March 1977 BYTE, page 701 have presented readout in the form of course deviation and the basics of the Omega system and the indications of distance to go. hardware required for a minimal Omega An outgrowth of the program's airborne receiver interface to microprocessor systems. Omega receiver research is the Mini -O In this part we will present the software system. details for phase- tracking loop filters and The Mini -O interface, operating at a methods for output of the data as filtered 40 Hz sampling rate, is a spin -off of an lines of position (LOPs) for selected station earlier investigation using a 100 Hz sample pairs. This type of data output would be rate and a more expensive temperature directly usable in the simpler forms of compensated crystal oscillator clock oper- marine navigation receivers with a digital to ating at 2.611200 MHz (10200 X 28 Hz). analog converter driving a low cost Rustrak (See reference 3). In this investigation, both type of chart recorder. ground and in- flight measurements of actual The original concept of the Mini -O Omega phase data were collected. The data Omega receiver by Ralph W Burhans has base was then used as the input for a been augmented by the contributions of a software (FORTRAN language) simulation number of individuals from the Ohio Uni- of the Omega sensor processor functions. versity Avionics Engineering Center, Omega This simulation analysis, performed on project team. These include Dr Robert W actual off -the -air Omega data, proved the Lilley who first suggested the concept of the feasibility of software methods of manipu- Memory Aided Phase Locked Loop (see lating Omega data at a lo.w interrupt rate. reference 1) and also originated the basic idea of the software based Omega sensor Digital Phase Locked Loops processor in the early stages. Kent Chamber- lin perfected the Memory Aided Phase A very simple form of digital phase Locked Loop in practice in 1974 with an locked loop has been presented in part 2 of all -TTL hardware version described in ref- this series where a pair of exclusive OR gates erence 2. The design has subsequently been provide a phase detector for comparing the converted to CMOS logic and implemented filtered 40 Hz signal obtained from a down in a number of prototype receivers in our counter, with the phase of the signals ob- lab. These CMOS digital hardware sensors tained from the type D flip flop used as a have been prepared by Ohio University mixer (see figure 7 of part 2). This is what under the sponsorship of the NASA Langley we call an increment-decrement type of Research Center program in air transporta- binary phase locked loop where the 40 Hz tion for eventual use by the general aviation output is being continuously generated from community. 215 Hz - 29 and 214 Hz _ 29 depending on The basic goals of this NASA sponsored where the incoming noisy edges are with program have been to provide the general respect to the divide by 29 counter output. aviation pilot with some alternative naviga- This provides a very effective low pass filter tion aids for use on a world wide basis from for the 40 Hz signal with a lock up time of a the Omega VLF signals. The feasibility of few cycles which is comparable to the 14 Hz low cost Omega data sensor methods for bandwidth of the analog RF front end airborne use has been demonstrated in a filtering. For the interested reader, a number of Ohio University test flights. The thorough treatment of digital phase locked

loo

www.americanradiohistory.com Photo 1: Authors Richard Salter (left) and Ralph Burhans (right) shown with the Mini -O receiver loops is available in reference 4. comparators provides a bandwidth of about equipment driven by a

The Memory Aided Phase Locked Loop 1 /10th of an Omega cycle. This only allows KIM -1 processor seen at is a more complex digital filtering system. In the tracking loop to move about 30° from the right. the hardware version, the output of a tempera- the previous phase value during a single time ture compensated crystal oscillator operating slot (using a tracking window of 625 ms per at the Omega reference frequency of 26 X time slot). 10.2 kHz is divided in a 6 bit binary divider Selected pairs of the 6 bit numbers ob- chain, and the outputs of all six stages are tained from the memory aided phase locked compared with the six most significant bits loop after each time slot can be subtracted, of an up down counter which represents the thereby generating Omega lines of position current Omega Phase estimate. This com- values. The subtraction as performed in parison yields a pulse at the point in time of hardware uses parallel arithmetic adders as coincidence of the two 6 bit numbers. The two's complement subtractors and appropri- locked pulse is in turn fed back to the phase ate latches to store the data for the selected detector which compares the time of arrival stations. of the locked pulse to the time of arrival of the next incoming Omega zero crossing. This phase detector is similar to the one previously discussed, and it outputs an incre- REFERENCES or decrement signal to the loop ment 1. Lilley, R W, "Binary Processing and Display counter. Concepts for Low-Cost Omega Receivers," Jour- The memory aiding feature allows a single nal ION, Volume 22, Number 3, Fall 1975. loop (in software here) to track the signal 2. Chamberlin, K, "Binary Phase Locked Loops phase in all eight Omega time slots by for Omega Receivers," Proceedings of the periodically (ie: every ten seconds) loading Second Omega Symposium ION, Washington the phase estimate from a particular time DC, November 1974. slot back into the loop counter when it is again time to begin tracking that particular 3. Lilley, R W, and R J Salter, "Simulation Analy- sis of a Microcomputer -Based Low -Cost Omega In time -multiplexed time slot's signal. this Navigation System," Proceedings of the fashion a single loop and eight words of National Aerospace Symposium of the ION, memory can do the work of eight separate Warminster PA, April 1976. phase locked loops. 4. Reddy, C P, and S C Gupta, Class of All Using the memory aided phase locked "A Digital Phase Locked Loops: Modeling and loop, a quite narrow bandwidth digital filter Analysis," IEEE Transactions on Industrial for the phase information produced by the Electronics and Control Instrumentation, Omega front end can be achieved. Ten bits November 1973. of up down counter filtering before the 6 bit

101

www.americanradiohistory.com 40 Hz INTERRUPT léió

4049 (CMOS) A15 414 A13 412 MINI-O All RECEIVER A10 GENERATES PHASE 4002 A9 SAMPLES A8 a ADDRESS FLAGS A7 BUS 4049 UNUSED A6 ADDRESS AS LINES A4 V A3 L A2 Al AO TRISTATE ENABLE D7 TIME SLOT D7 17 07 C> C> FLAGS "A" INITIALIZE D6 I6 06 fl c. D6 D5 I5 05 olC> D5 04 D4 1 I4 04 fl I C> DATA 03 D3 6 -BIT I3 03 C> C> BUS D2 D2 PHASE I2 02 aIo DI DI II 01 oIo Do DO IO 00 D 1 NOTE: ALL MISC INTEGRATED 4508 TRISTATE CMOS I CIRCUITS ARE CMOS LATCH (PART OF FIG.7 IN PART 2 OF THIS SERIES)

TIMING DIAGRAM FOR FLAGS 07 LOOP ENABLE 625 I~ D6 "A" INITIALIZE -0I ms D5 MSB PHASE LOOP ENABLE 04 A STATION A D3 I.25s D2 I~ DI DO LSB PHASE lOs

Figure 1: Using memory mapped IO ports. In small systems, where little memory address space is committed to programmable memory resources, it is possible to use the high order address lines to partially decode IO ports. This technique is applied here to show how the KIM or JOLT computers address the Mini -O receiver's eight bits of input data. There is one hitch with this form of lO address decoding: Since the low order address bits AO to All are not used, all addresses from hexadecimal 8000 to 8FFF are equivalent in this particular case. In the logic of figure 3, a similar ambiguity of addressing finds hexadecimal 9000 to 9FFF treated identically as the output analog value latch.

With the phase locked concept thus de- monitor service routine calls in place of scribed as a primer for the software tracking JOLT's TIM monitor calls. system to be presented, the remainder of Memory Mapped IO this article concentrates upon the specifics of the microprocessor interrupt 10 and the In the name of system simplicity and low Omega sensor processor software originally cost, the data input and output decoding used with a JOLT Microprocessor System. technique known as memory mapped IO is The JOLT system is a product of Micro- sometimes used. As mentioned previously, computer Associates and is based on the the JOLT system includes a peripheral MOS Technology 6502 CPU chip. The basic interface adapter chip (PIA) which can be JOLT system, incorporating the 6502 CPU, used for 10. However, in a small dedicated 6530 -004 Teletype Monitor ROM, and system with only one or two interrupts to ASR -33 and RS232 Teletype interface hard- service, the generality and sophistication ware (also a PIA which is not used in this provided by a PIA can become an expensive application), is available on a single 4-1/2 X luxury - especially when one realizes the 7 inch printed circuit board for $150 in kit simplicity inherent in a memory mapped

form. Photo 1 shows a KIM -1 processor by input latch. MOS Technology; the programs shown in The memory mapped input circuitry is listings 1 and 2 will work with any 6502 illustrated in figure 1. As used with the processor based system by using appropriate microcomputer interface described by Ralph

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www.americanradiohistory.com Burhans last month (see figure 7 in part 2 of FROM 09 OUTPUT OF 4040 (FIGURE 7, PART 2 OF THIS SERIES) 20µs PULSE this series), the memory mapped input hard- (40 Hz) ware consists of a NOR gate, inverter and a tristate latch. The NOR gate and inverter are used to decode the four most significant IRO address bits, and the decoder output enables the Omega data onto the data bus by TO 6502 enabling the tristate latch when the Omega data port is addressed by interrupt service routine software. When the microcomputer TO CLOCK INPUT OF 4508 LATCH, (FIGURE 7, PART 2 OF THIS SERIES receives the 40 Hz I RQ from the Mini -O AND FIGURE I OF THIS ARTICLE ) interface, the service routine needs only to say "load accumulator with data from Figure 2: Since the IRQ signal of the microprocessor is a level sensitive one, it memory location 8XXX" to accept the new is necessary to shorten the pulse out of the Omega receiver shown in last

Omega phase data. Note that since the I RQ month's article. A method appropriate for noncritical applications is use of an is a level sensitive input the I RQ signal must RC time delay. This RC delay developed by a 200 pF capacitor and 47 k be conditioned into a short pulse so that it is resistor provides u pulse width of approximately 20 µs on the IRQ line. In not serviced more than once. It is necessary applications where critical timing is involved, this method is not to add the circuitry in figure 2 to figure 7 of recommended. part 2 to obtain this IRQ pulse. Since only the four most significant address bits are decoded in the memory will result in enabling the Omega input latch. mapped input port, any attempt to address In effect, 4 K bytes of potential memory the 4 K locations encompassed by 8XXX space have been delegated to this one input port; however, since the 16 bit address bus permits addressing up to 64 K bytes, this apparent liberal use of memory space is of

WRITE 4049 A15

A14 N

MICROPROCESSOR 4002 (EG: 6502) AI2 4049 All

4011

UNUSED ADDRESS BITS 4049 DIGITAL TO ANALOG CONVERSION BY RESISTOR NETWORK

D7 I IR I D7

ANALOG vv OUTPUT L___J VOLTAGE RL r

Figure 3: An output interface mapped to memory locations 9000 to 9FFF (hexadecimal). This is a simple 8 bit output port which drives a 6 bit digital to analog conversion using a weighted network of resistors. When the Mini -O programs of listing 1 and 2 store data at memory locations in the address range decoded by this port, it will be latched and appear as an equivalent voltage at the output jack. This interface is one simple way to drive a strip chart recorder monitoring the results of the Omega signal processing.

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www.americanradiohistory.com ------INTERRUPT n; - r --- --I I PREVIOUSLY

-I STATION PRINTED I I CYCLE READ THIS CYCLE T_J1I1 O I PHASE L- - -J / SET UP FOR NEXT / PRINT CYCLE

TMSLCTR YES OLDE NA B YES

NO NO

OLDENAB O (PREVENT SECOND SMAPLL PRINTING)

DISABLE (RETURN FROM IRO INTERRUPT

)

SELECTED PHASE ANLGPORT DISPLAYED AS SELECTED ANALOG VOLTAGE PHASE;

PRINT CURRENT REFERENCE PHASE

PRINT PR NT CARR AGE SPACE RETURN, LINE FEED

INTERRUPT BREAKS THIS ONE INSTRUCTION LOOP TEMPORARILY, DOES ITS PROCESSING AND RETURNS TMSLCTR: TMSLCTR+I;

Figure 4: The design of an interrupt driven Omega data processing program. (RETURN FROM l This is the flowchart of INTERRUPT J the program found in listing 1, which implements the software memory aided phase locked loop algorithm. The circled num- no consequence in a small system. Further- output with the microprocessor "write" bers are referenced in list- more if memory space becomes a valuable signal, and the data bus latch does not need ing 1 by notations to the commodity, a thrifty alternative is to simply to be a tristate device. The outputs of the left of the address column. decode more address bits. The additional latch are converted from digital to analog hardware required is a NOR gate, NAND using a resistor network. This analog output gate and inverters. can be used to drive a chart recorder or The memory mapped output technique is meter indicator. very similar to the input scheme just de- Interrupt Service Routine scribed, and it is illustrated in figure 3. Again, the four most significant bits of the When the Omega data samples are entered address bus are decoded and used to clock a into the microcomputer from the Mini -O latch which latches up the data on the data interface (one sample every 25 ms), they are bus. The only differences from the input contaminated with noise and require fil- circuitry are the NANDing of the decoder tering in order to extract a good estimate of

1 oa

www.americanradiohistory.com Station =A B C D E F G H

Table 1: SMAPLL filtered Omega Phase 27 21 2F 29 13 2C 3E 1 n Data. This is a sample the of Teletype 27 21 2C 03 13 2C 3'3 1 ï: printout of the program in listing 1. Each 29 21 31 2D OF 2D 33 17 line of the table is the result of one 2A 22 34 2C OF 30 33 1D 10 second frame of Omega phase data com- 27 22 35 2E 13 33 3:; 1 D pared to the internal clock. The phase 26 25 37 23 12 33 00 1C differences are printed as two hexadecimal 24 25 39 31 11 37 00 IA digits for each time slot, corresponding to a 6 bit number. Note that the data in the 25 25 3A 33 11 37 04 10 columns lettered A, B, E, F and H is quite 25 24 33 33 OF 33 09 1D random due to the low strength of the 25 24 32 35 OC 35 OC 1= signals. However, the data in time slots C,D 26 IF 04 37 39 37 11 20 and G can be seen to be quite systematic: It 25 21 07 37 03 '1- 20 increases in value as a phase difference 23 23 09 3ra OA 35 15 20 between the internal clock and the incoming 2A 20 05 39 OD 3A 14 1E signal. By taking pairs of these well- defined 2C 22 07 3C 13 39 17 lE station measurements and forming dif- 23 24 09 3C 13 33 19 IC ferences such as C -D, G -C or G -D, the result 29 23 OD 3L'. 14 37 13 19 is a relatively constant value of the line of 2A 21 15 position phase difference estimate for that OD 3F 35 16 IA station pair. For example, forming the dif- 23 23 OF 01 14 35 13 19 ferences between station pairs G and C 26 23 OF 01 11 34 13 1S yields a fairly constant difference 12 average 29 23 12 02 11 33 IC 13 over these 24 measurements. (The mean 23 21 14 33 17 30 20 16 square deviation is 3.) These observations 23 21 14 05 15 2D 22 14 were made at 10.2 kHz at 14:20 EDT July 2D IF 14 04 14 2D 21 14 19 1976.

the true phase. This is the function of the From this chart it can be seen that the software version of a memory aided phase routine must also output a filtered data locked loop: This closed loop digital filter word at the end of each time slot. The data accepts the noisy phase measurements and output takes the form of printed numbers provides averaging so that its output is a on the Teletype, and the memory mapped better estimate of the true phase. output latch with its digital to analog con- The data format presented by the Mini -O version provides a means for obtaining an interface is also shown in figure 1. Of the analog voltage to drive a chart recorder. eight bits in each data byte, two are control Tracking Loop Software flags and six are phase data. The most significant bit, D7, is a control signal flag If the D7 control bit indicates that the which goes high to indicate when the 625 ms data is within a 625 ms time slot window, Omega measurement time slot window is the routine must then perform loop filtering present and data should be tracked by the on the data via the software version of the software filter. The D6 flag is also controlled memory aided phase locked loop. This by the Mini -O timing hardware, and it is routine is illustrated in flowchart form in forced high by the Mini -O when the A time figure 5. The incoming phase data is slot occurs. Bits D5 through DO are the compared to the stored reference phase phase data to be tracked. word. If the incoming phase is ahead of the When an interrupt is received by the reference phase, the difference will be microprocessor, the interrupt service routine positive and the loop counter must be must load the new data byte, test the incremented. Likewise, if the incoming control bits, and perform loop filtering to phase is behind the reference phase the the phase data bits (assuming the control difference will be negative and the loop bits indicated good data). Note that the counter must be decremented. The only microprocessor could be busily performing exception to this procedure is when the any main routine when it is interrupted: In phase is near the "edge of a lane" (ie: the our example the main program will be a data points are close to 0 or 63) in which simple idling loop, but it could conceivably case the opposite increment or decrement be a more general program of use in the must be effected. vehicle being navigated. A flowchart for the The loop counter, which is incremented interrupt service routine appears in figure 4. or decremented by the phase detector out-

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www.americanradiohistory.com Hex Address Hex Code Label Op Operands Commentary o 0000 AD 00 80 START LDA (PHASE Load data byte from phase measurement input; © 0003 10 44 BPL PMEAS If high order bit zero then go print measurement; 0005 A2 80 LDX #$80 © 0007 86 EO STX OLDENB OLDENB :_ '10000000' [set old enable flag) ; 4O0009 OA ASL 000A 10 04 BPL SMAPLL If this is reference time slot O5 000C AO 01 LDY #1 then set the 000E 84 El STY TMSLCTR time slot counter to 1; 0010 " Begin software memory aided phase locked loop algorithm details O 0010 4A SMAPLL LSR 0011 29 3F AND #$3F 0013 85 D6 STA PHASE PHASE :_ [bits 0 to 5 of input (low order/1; 0015 A6 El LDX TMSLCTR 0017 B5 D7 LDA,X OLDPHREF (TMSLCTR) 0019 4A LSR 001 A 4A LSR (DI 001B 85 D7 STAA PHIREF PHIREF := OLDPHREF (TMSLCTR) /4; 001D " This adjusts for 4 increments or decrements in loop below 001D A5 D6 LDA PHASE 001F 18 CLC 0020 E5 D7 SBC PHIREF DIFF (in accumulator) := PHASE - PHIREF; 0022 10 19 BPL CKGT32P If DIFF > 0 then go check range, positive; 0024 A5 D7 LDA PHIREF 0026 18 CLC 0027 E5 D6 SBC PHASE DIFF (in accumulator) := PHIREF - PHASE; 0029 A8 TAY 002A A9 F6 LDA = INC,X Patch INC,X opcode 002C 85 3A STA IDSW2 into increment or decrement switch location; 002E A9 D6 LDA # DEC,X Patch DEC,X opcode 0030 85 37 STA IDSW1 into increment or decrement switch location; 0032 98 INCTST TYA Begin sequence to test and increment; 0033 C9 20 CMP 32

I 0035 10 03 BPL IDSW2 If I DIFF > 32 then go to IDSW2; 0037 XX D7 IDSW1 DEC or INC Decrement or increment OLDPHREF (TMSLCTR); 0039 40 RTI 6.9 003A XX D7 IDSW2 INC or DEC Increment or decrement OLDPHREF (TMSLCTR); 003 C 40 RTI 6.6 003 D A8 CKGT32P TAY 003 E A9 D6 LDA ::DEC,X Patch DEC,X opcode 0040 85 3A STA IDSW2 into increment or decrement switch location; 0042 A9 F6 LDA =1NC,X Patch INC,X opcode 0044 85 37 STA IDSW1 into decrement or increment switch location; 0046 4C 32 00 JMP IN CTST Go to test and increment sequence; 0049 A5 EO PMEAS LDA OLpENB 004 B 10 20 BPL DONE If previous enable flag was 0 then skip printing; 004D AO 00 LDY i.0 004 F 84 EO STY OLDENB OLDENB :_ [reset to prevent double printout] ; (1-( 0051 78 SEI [mask off interrupts) ; 0052 A5 DB LDA OLDPHREF (4) a) 0054 8D 00 90 STA ANLGPORT [analog port output := selected OLDPHREF) ; 0057 A5 D7 LDA PHIREF Print current reference phase 0059 20 B1 72 JSR WROB using JOLT's TIM hexadecimal routine; (3 005C A5 El LDA TMSLCTR 005E C9 08 CMP #8 If TMSLCTR < 8 0060 10 06 BPL SPCESI then type space and increment TMSLCTR; 0062 20 8A 72 JSR CRLF Print carriage return, line feed with TIM; 0065 4C 6B 00 JMP INCIT 0068 20 77 73 SPCESI JSR SPACE Print space using TIM routine; 006B E6 El INCIT INC TMSLCTR TMSLCTR := TMSLCTR + 1 [onward to next station] ; 14 006D 40 DONE RTI Wait for next interrupt from Mini -O hardware; 006 E main routine is an endless loop interrupted o n occasion ... 15 006E 4C 6E 00 MAIN JMP MAIN

Symbols: (other than labels)

00D6 PHASE temporary storage of 6 bit phase value 00D7 OLDPHREF origin for indexed references to old reference phase 00D7 PHIREF current 6 bit reference phase derived from table reference 00D8

OLDPHREF data values, indexed by TMSLCTR values 1 to 8

OODF OOEO OLDENB flag (values hexadecimal 80 or 00) OOE1 TMSLCTR current station index, 1 to 8 for stations A through H 8000 IPHASE input phase and flag data port from Mini -O peripheral 9000 ANLGPORT output analog data port for meter or chart recorder

Note: Location 0053 is the low order address of a phase reference value which will be displayed on the analog output channel when printing is done.

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www.americanradiohistory.com CSMAPLL

Listing l: The Mini -O PHIREF: processing program. This OLDPHREF routine implements a (TMSLCTR) /4, software memory aided phase locked loop. The bulk of the code is an interrupt DIFF: PHASE - response routine, starting PHIREF at address 0000. Before entering the program, the IRQ interrupt vector of YES the JOLT or KIM -1 system must be set to point to location 0 and IRQ must

be enabled. The entry DIFF: PHIREF- point is an endless loop at PHASE location 006E.

IDSW : IDSW : DECREMENT INCREMENT put, performs the loop filtering. The length IDSW2: IDSW2: /--6.S INCREMENT DECREMENT of this counter determines how much integration is provided by the SMAPLL routine, / and it also sets the tracking speed of the / loop. The proper choice of loop counter length is the result of an important engineering design tradeoff: If the loop counter is made too long, the noise cancelling charac- NO(<) YES ( >) teristic will be enhanced but the tracking speed will be too slow to adequately track 6.9 the signal. On the other hand, if the loop r counter is made too short the loop tracking //\\ IDSWI // \ IDSW2 speed will be increased at the expense of -d desirable noise filtering. - The six most significant bits of the loop INCREMENT DECREMENT DECREMENT INCREMENT counter make up the filtered reference phase PHASE PHASE PHASE ' . PHASE which is used to measure the next incoming phase word. It is also stored at the end of L J L_ J each time slot so that it can be used to preset the loop at the beginning of the particular time slot ten seconds later; hence, the term "memory aided" phase locked loop. During the 625 ms gap following each time slot, this reference or "locked" phase (END l SMAPLL J can be sent to both the Teletype printer and analog chart recorder for recording single station phase or for measuring clock offset. Figure 5: The detail design of the software implementation of a memory A typical output is shown in table 1. These aided phase locked loop. The circled numbers here refer to listing 1. The dot- reference phase words (eight total, one per ted line boxes surrounding the two increment or decrement switches are an time slot) can be subtracted to form the elaborate representation of the concept of a program which patches itself by phase differences which define lines of posi- changing operation codes. tion (LOPs) on an Omega map. Of course, this too can be output to a recording device.

local clock as in the Mini -O interface, the Software and Output Options SMAPLL phase reference outputs can be The SMAPLL interrupt service routine used to determine the receiver's clock error. listing for a 6502 system is given as listing 1. Similarly, any lab standard oscillator can be Omega and other VLF signals are of interest calibrated and adjusted to cesium atomic to time frequency scientists and lab experi- clock accuracy by this technique (since the menters because of the frequency stability Omega signals are locked to a cesium ref- of the transmitted signal. When these signals erence at each transmitter). Table 2 illus- are referenced against a receiving system's trates this method of clock offset determina-

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www.americanradiohistory.com tion and the program of listing 1 was used to operators or backpackers. In order to plot a obtain this output. line of position, the segment of the program Another common use of Omega signals is in listing 2 must be substituted into listing 1 that of position fixing. In order to obtain a beginning at location 0052. The LOP output position fix, the phase differences of two obtained with this program and plotted on a station pairs (two LOPs) are plotted as an Rustrak chart recorder appears in figure 8. intersecting grid on a map and their inter- In order to compare the operation of the section defines the receiver's position. This software version of a memory aided phase technique is suitable for use by small boat locked loop and a conventional hardware loop system, the routines were run in a JOLT microcomputer side by side with an all hardware Omega sensor and processor. The Station =A BC DE F G H lines of position outputs of both systems 23 00 19 25 23 29 39 OA were plotted on a dual trace Rustrak chart 1F 00 IA 29 lE 2E 3A Ott recorder in our lab. This chart appears in IF 31 1D 213 ID 30 3F 013 figure 6 with the software system output on 21 04 23 2E 13 33 C5 013 the bottom. As can be seen from this chart, 21 09 29 2F 13 34 OA 07 the software system tracks the Omega signal IF 0>:1 2B 33 13 34 OC 06 in very similar manner to the hardware 1E 11 32 35 13 35 12 03 system. 20 15 36 33 11 34 14 05 Future Software 23 19 39 39 OE 37 15 01 23 113 3;3 3C 13 3D 13 3D Line of position outputs and phase versus IF IF 39 3D 16 3D 1E 3F clock information can serve the boat opera- 23 25 3A 01 1 3F 1L 3F tor and time frequency experimenter respectively, but airborne navigators need position 22 23 33 113 01 21 J2 data in a more suitable form (such as 21 2D 0/4 35 12 25 03 04 cross-track error, miles- to -go, etc). Develop- 1D 2D 09 07 2'3 01 r24 32 ment of the necessary navigation software to 1r 32 OD OA 23 3D 25 01 enable the accomplishment of these tasks IF 37 013 or 22 3D 21 30 with an inexpensive, commerically available 1C 3C JD op- 25 3:: 2F 3'L 1J 39 11 27 30 31 33 13 3r 13 15 27 35 35 33

1ú 3C 14 1 2 32 35 33 ,7 1:3 3F 15 23 39 w 713 One Omega Cycle time 1C 03 1C l ..l 271 32 Clock Offset = Time to Change 11: 3F 1E 1i 35 2c 3F 34 One Cycle 1E. 33 1F IF 3i1 29 02 33 = 1 /10200 seconds 1D 35 21 23 3n 30 32 290 seconds lE 0A 25 24 3 ;3 Pr) 34 3A 20 OF 29 23 00 3:? 09 34 1F OF 2r. 23 32 32 33 34 09.80 X 10-5 1C 14 21". 01 37 O3 34 2.90 X 102

1 3 14 22 23 3F 33 33 35 17 14 2n 33 32 3A 011 35 3.38 X 10-7 1!; 12 2C 34 32 37 on 3r 1 17 12 2F 3 C3 37 op 34 .32 1:3 10 31 3A 3.i 11 3/1 Table 2: Local clock offset determination. 1 12 33 J5 35 1:2 33 By measuring the amount of time needed for 15 32 3F Ü° 35 11 3/1 phase to change one complete cycle, relative 19 13 35 34 0 3 /1 13 33 to the local clock, it is possible to measure 13 1/4 37 05 03 35 14 32 the difference between your local clock 13 12 33 03 34 17 30 reference and the Cesium atomic clocks used to calibrate the Omega system at its world 19 12 3D 03 10 77' 13 .- r+ wide network of stations. The calculation is 1C OF 3F OF 12 2r, 1C shown here, along with data taken from 21 OF 12 10 34 2D 1A 2F 10.2 kHz stations at 10:30 EDT July 20 21 10 03 15 15 IF 32 1976. This is one way to achieve the 24 313 OC 15 15 29 1C 30 ultimate in personal measurement of time 25 V J OF I(, 16 27 1li using your computer and an Omega receiver.

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www.americanradiohistory.com Hex Address Hex Code Label Op Operand Commentary

0052 E0 04 PATCH CPX .4 Is old TMSLCTR = 4 [selected station D index] ? FO 0054 18 BEp DIFCALC If so then go to DIFCALC [calculate difference] ; 0056 EA NOP Fill space; 0057 ENDPTCH Return to previous code;

006E A5 DA DIFCALC LDA OLDPHREF (3) 0070 4A LSR 0071 4A LSR

0072 85 D3 STA TPHAZ TPHAZ := OLDPHREF(3) /4 [get C phase] ; 0074 A5 D7 LDA PHIREF 0076 18 CLC 0077 E5 D3 SBC TPHAZ DIFF := PHIREF - TPHAZ; 0079 30 08 BMI NEGAT If negative then go to NEGAT; 007B OA OUTDIFF ASL 007C OA ASL Shift left to correspond to DAC output bits; 007D 8D 00 90 STA ANLGPORT [analog output port := difference phase] ; 0080 4C 57 00 JMP ENDPTC Jump back in line; 0083 69 40 NEGAT ADC -540 [convert to positive difference] ; 0085 4C 7B 00 JMP OUTDIFF Go to OUTDIFF [and display value] ; 0088 4C 88 00 MAIN JMP MAIN

Additional symbols (other than labels): 00D3 TPHAZ temporary byte used in phase difference calculation

Listing 2: An alternate version of the software memory aided phase lock loop for use in plotting a phase difference value versus time. This patch to listing 1 was used in preparing the chart of figure 6. It o-LL calculates the phase difference, between oz oz stations selected by the choice of addresses 100 D8 to DFat address 006F, and the choice of a station index 1 to 8 at location 0053. (The T_ ranges in each case correspond to station cn LOP 6-bit w h-C-G -- selections A through H.) The setup shown J --CMOS hardware MAPLL - U here picks the C-D station pair. In preparing U figure 6, the constants were set up for the I= - G -C station pair. With this patch, the main z -- w entry point is now at location 0088. U ------_-- --

-----. _ _. _ -, i 7. - .L r ...i :-- . - . . . microprocessor is a continuing effort at Ohio _ o University. The microcomputer has made a I cc.. o low cost Omega Navigation System a very j' _ -_ --__ - real possibility and BYTE readers are advised ) ? s ) J to stand by for navigation software as it is o.... perfected. oz oz 100

Figure 6: Comparison of the Mini-O software mem- N w ory aided phase locked loop J U rC-G LOP 6-bit ---_ (listing 1) with a com- > U -1--,-JOLT software SMAPLL - parable hardware version I __:_ z in older (more expensive) w ._ U -- equipment. The two sets - ______-___1.,_------of equipment were run _ simultaneously beginning ¡I- : .r , .i,..:--:_--... ° á.r-_=_ .. at 3 PM EDT on July 16 =_. + o 1976 with the 2 channel _-r_. _ - chart recorder running at =1 >- c) J 7 > one inch per hour. Timing d-2ü75 calibration is shown at the bottom of the chart. 0300 0400 0500 0600

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www.americanradiohistory.com Microprocessor Update: 8008

Robert Baker For the newcomer to the microcomputer 15 Windsor Dr world, the 8008 was one of the first 8 bit Atco NJ 08004 VDD INTERRUPT microprocessors to be developed. Figure 1 READY shows the pin assignment of the 18 pin D6 /I dual -in -line package while figure 2 shows a /2 D5 block diagram of the central processor unit 04 SYNC BUS 03 SO (CPU). Typical prices for the 8008 CPU are 02 SI STATE currently under $20. DI S2 Figure 1: The pinouts of The 8008 is a single chip, MOS, 8 bit CPU DATA DO VCC the Intel 8008 processor. that communicates over an 8 bit data and

Figure 2: Internal organization of the 8008 processor. DO-D7 BI-DIRECTIONAL A DATA BUS V DATA BUS BUFFER (B BIT) (B BIT) INTERNAL DATA BUS INTERNAL DATA BUS A A v ti V

I TEMP. REG . I TEMP REG INSTRUCTION STACK ACCUMULATOR REGISTER (8) MULTIPLEXER (8) e)I V 1 FLAG PROGRAM COUNTER e IFLIP -FLOPS (14 ) REG (8) U LEVEL NO.1 w C (14 ) J REG (8) INSTRUCTION ARITHMETIC DECODER ¢ LEVEL NO.2 D LOGIC AND V+ (14) REG (8) UNIT MACHINE 1- Z LEVEL NO. 3 E (ALU) CYCLE a ENCODING a (14) REG (8) Y LEVEL NO.4 o H (8) 4 (14) REG (8) N LEVEL NO.5 L (14) REG (8) LEVEL NO.6 SCRATCH PAD (14)

LEVEL NO. 7 J ( 14) ADDRESS STACK TIMING AND CONTROL

POWER 9V SUPPLIES +5V STATUS INT READY SYNC CLOCKS

111 0I SO SI 52 INT READY SYNC ,

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www.americanradiohistory.com MINIMUM INSTRUCTION CODE MNEMONIC STATES D2 D8 125 134 133 D2 131 DO DESCRIPTION OF OPERATION REQUIRED Table 1: The instruction (t)Lrlr2 15) 1 1 D D D S S S Load index register r1 with the content of index register r2. 171L,M set of the Intel 8008, re- 181 1 1 D D D 1 1 1 Load index register r with the content of memory register M.

(7) 1 LMr 1 1 1 1 S S S Load memory register M with the content of index register r. produced from Intel's No- (3)Lrl (8) 0 0 D D D 1 1 0 Load index register r with data B ... B. vember 1973 B B 8 8 8 8 8 8 8008 central

LMI (9) 0 0 1 1 1 1 1 0 processor Load memory register M with data B ... B. unit User's Man- B B B B B 8 B 8 INr ual, pages 8 and 9. (5) 0 0 D D D 0 0 0 Increment the content of index register r (r / Al. DCr (51 0 0 0 D D 0 0 I Decrement the content of index register r (r 4 Al. Accumulator Group Instructions

The result of the ALU instructions affect all of the flag flip -flops. The rotate instructions affect only the carry flip -flop. ADr (51 1 0 0 0 0 S S S Add the content of index register r, memory register M, or data

ADM 1 1 (BI O 0 0 0 1 1 B ... 8 to the accumulator. An overflow (carry) sets the carry ADI IBI 0 0 0 0 0 1 0 0 flip flop. B B B B B B B B

ACr 15) 1 0 0 0 I S S S Add the content of index register r, memory register M, or data

ACM IM 1 0 0 0 1 1 1 I B ... B to the accumulator with carry. An overflow (carry)

ACI 181 0 0 0 0 1 1 0 0 sets the carry flip -flop. B B B B B BBB

SUr (5) 1 0 0 1 0 S S S Subtract the contant of index register r, memory register M, or

SUM (8) 1 0 0 1 0 11 1 data B ... B from the accumulator. An undarflow (borrow)

SUI (81 0 0 0 1 0 1 0 0 sots the carry flip -flop, 813 B B B 8 8 8

Sir 15) 1 0 0 1 1 S S S Subtract the content of index register r, memory register M, or data

SBM (81 1 0 0 1 1 1 1 1 data 8 ...El front the accumulator with borrow. An underflow

OBI (8) 0 0 0 1 1 1 0 0 (borrow) sets the carry flip-flop.

B B B B B B B B MINIMUM INSTRUCTION CODE MNEMONIC STATES DT Di D5 D4 D3 02 Di lb DESCRIPTION OF OPERATION REQUIRED

NDr (51 1 0 1 0 0 S S S Compute the logical AND of the content of index register r,

NDM (BI 1 0 1 00 1 1 1 memory register M, or data 8 ... 8 with the accumulator. NDI 181 00 1 0 0 1 0 0 8 B B B B B B B

XRr 15) 1 0 1 0 1 S S S Compute the EXCLUSIVE OR of the contant of index register

XRM (8) 10 1 0 1 1 1 1 r, memory register M, or data B ... B with the accumulator.

XRI (8) 00 1 0 1 1 0 0 B 8 B B B B B B

ORr 161 1 0 1 1 0 S S S Compute the INCLUSIVE OR of the content of index register

ORM (BI 1 1 0 1 1 1 r, memory register m, or data 10 B ... i with the accumulator .

ORI 181 0 0 1 1 0 1 0 0 B8 BOB BOB

CPr (5) 1 0 1 1 1 S S S Compare the content of index register r, memory register M,

CPM (B) 10 1 1 1 1 1 1 or data B ... B with the accumulator. The content of the

CPI 181 0 0 1 1 1 1 0 0 accumulator is unchanged. B B B B B 8 8 8

RLC (51 0 0 0 0 0 0 1 0 Rotate the content of the accumulator left.

RRC (51 0 0 0 0 1 0 1 0 Rotate the content of the accumulator right.

RAL 15) 0 0 0 1 0 O 1 0 Rotate the content of the accumulator left through the carry.

RAR (51 0 0 0 1 1 0 1 0 Rotate the content of the accumulator right through the carry. Program Counter and Stack Control Instructions

(4) 1 JMP (11) 0 X X X 1 0 0 Unconditionally jump to rerrtory address 83 ...133132 . . . 02. B2 B2 8282 B2 B2 8202 X X 83 8383 B3 83 B3 (5) JFC (9 or 111 0 1 0 Cq C3 0 0 0 Jump to memory address 83 .. 8382 ... B2 if the condition 82 132 132 B2 02 132 132 B2 flip -flop c is false. Otherwise, execute the next instruction in sequence. X X 83 03133 83133 B3

JTc 19 or 11) 0 1 1 Cq C3 0 0 0 Jump to memory address 83 ... 8302 ... 82 if the condition 82 82 02 o2 07 02 02 B2 flip -flop c is true. Otherwise, execute the next instruction in sequence. X X B3 B3 B3 133 83 133

CAL (11) 0 1 X X X 1 1 0 Unconditionally call the subroutine at memory address 83 ... 02 132 132 82 B2 B2 83 02 0302 -... 132. Save the current address (up one level in the stck). X X 03 133 03 83133 83

CFc (9 or 11) O 1 0 Cq C3 O 1 O Call the subroutine at memory address 03 ... 0382 ... 82 if the 82 132 132 82 B2 82 82 132 condition flip -flop c is false, and save the current address (up one X X B3 133 83 133 133 133 level in the stack.) Otherwise, execute the next instruction in sequence.

CTc (9 or 111 0 1 1 Cq C3 0 1 0 Call the subroutine at memory address 83 ... 8382 ... 82 if the

132k 02 82 o2 112 02 132 condition flip -flop c is true, and save the current address (up one X X B3 B3 83 83 133 03 level in the stack). Otherwise. execute the next instruction in sequence.

RET (5) 0 0 X X X 1 1 1 Unconditionally return (down one level in the stackl.

RFc (3 or 51 0 0 0 Cq C3 0 1 1 Return (down one level in the stack) if the condition flip -flop c is false. Otherwise, execute the next instruction in sequence.

RTc (3 or 51 0 0 1 Cq C3 0 1 1 Return (down one level in the stack) if the condition flip -flop cis true. Otherwise, execute the next instruction in sequenca.

AST (51 0 0 A A A 1 0 1 Call the subroutine at memory address AAA000 (up one level in the suck). Input /Output Instructions

INP (8) 0 1 O 0 M M M 1 Read the content of the selected input port (MMM) into the accumulator.

OUT (6) 0 1 R R M M M 1 Write the content of the accumulator into the selected output port (RRMMM, RR / 001. Machine Instruction

HLT (41 0 0 0 0 0 0 0 X Enter the STOPPED state and remain there until interrupted.

HLT 141 1 1 1 1 1 1 1 1 Enter the STOPPED state and remain there until interrupted. NOTES: 11) SSS - Source Index Register These registers, ri, are designated Alaccumulator -0001, DDD = Destination Index Register 1 810011. C(0101, DI0111, E(100). H11011, L(110). (2) Memory registers are addressed by the contents of registers H & L. (31 Additional bytes of instruction are designated by 13BBB8BB8. (41 X - "Don't Care ". 15) Fleg flip. laps are defined by C4C3: carry 100-overflow or underflow), zero 101- result is zero), sign (10 MSB of result is "1 "1, parity 111 -parity is even). Continued on page 160

111

www.americanradiohistory.com The diversity in The Best of The Best of Creative Computing - Vol- ume 1 can only be described creative as staggering. The book contains 328 pages of articles col. putiRd and fiction about computers, Volume I Edited by David H. Ahl games that you can play with computers and calculators, hilarious cartoons, vivid graphics and comprehensive book reviews. Authors range from Isaac Asimov to Sen. John Tunney of California; from Marian , Goldeen, an eighth -grader in Palo Alto to Erik McWilliams of the National Science Foundation; and from Dr. Sema Marks of CUNY to Peter Payack, a small press poet. In all, over 170 authors are represented in over 200 individual articles, learning act vities, games, reviews and stories. THE BEST OF BYTE - VOL. 1 This 328 -page book has 108 pages of articles on computers in education, CAI, programming, and the computer impact on The Best of Byte - Volume 1 is a 384 -page blockbuster of a book society; 10 pages of fiction and poetry including a fascinating which contains the majority of material from the first 12 issues of story by Isaac Asimov about all the computers on earth linking up Byte magazine. 146 pages are devoted to "Hardware" and are after a nuclear war to support the few remaining survivors; 15 cram full of how -to articles on everything from TV displays to pages of "Foolishness" including a cute cartoon piece - joysticks to cassette interfaces. The section on computer kits called "Why We're Losing Our War Against Computers "; 26 pages describes building 7 major kits. But hardware without software on "People, Places, and Things" including the popular feature might as well be a boat anchor, so there are 125 pages of "The Compleat Computer Catalogue" which gives capsule "Software and Applications" ranging from on -line debuggers to reviews and lists sources for all kinds of computer -related games to a complete small business accounting system. A goodies; 79 pages of learning activities, problems and puzzles; 29 section on "Theory" examines the how and why behind the pages continuing 18 computer games including a fantastic circuits and programs, and a final section "Opinion" looks at extended version of the single most popular computer game - where this explosive new hobby is heading. Super Star Trek; and 32 pages of in -depth book and game reviews The Best of Byte - Volume 1 is edited by Carl Hel mers and David including Steve Gray's definitive review of 34 books on the Basic Ahl and published by Creative Computing Press. Price in the US language. is $11.95 plus $1.00 shipping and handling ($12.95 total); foreign

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One of the best ways of exploring future scenarios of computer usage is through fiction. so Creative seeks out material from the best authors - Isaac Asimov. Frederik Pohl. Arthur C. Clarke to name just a few. as NO RISK GUARANTEE well as many others who are destined to be the best You may cancel your subscription at any time for of the next generation. any reason and we will refund the balance without 4 question. Creative Computing's book David H. Ahl.Publisher reviews are honest and timely. Were not owned by a big book publisher to whom we owe loyalty. nor do we depend upon advertising FOR FASTER RESPONSE for our revenue. Hence. not only do our reviews pull no punches. but we also rank order similar books You can phone your subscription orders to us at (like all 34 books on the BASIC language which we (201) 366-5617 Our lines are open from 9 am to4:30 reviewed last year). Creative reviews virtually every pm EST. computer book of interest to educators. hobbyists. and general laypeople, even including vendor r manuals and government pamphlets. SUBSCRIPTION ORDER FORM Term Foreign An Type USA extensive resource section will Individual 1 -Year S 8 S 10 save you time and money. 3 -Year 21 c 27 400 Every issue of Creative carries 40 or more short Lifetime 300 resource reviews evaluating periodicals, booklets. Institutional 1 -Year 15 15 hardware. terminals. couplers, peripherals. software 3 -Year 40 40 packages, organizations, dealers, and much more. New Renewal Every entry has a brief description. evaluation. and the name. address. and phone number of the Cash. check, or M.O. enclosed 6 vendor. You'll save valuable time seeking out this information, much of which you'd possibly never BankAmericard Card No come across. 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www.americanradiohistory.com Guess who just bought our new Microfloppy for $1095 including software? Plug-compatible iCOM - the leader for $1095 We've been building Floppy iCOM's brand new Micro - Disk Systems for microfloppy° is specifically designed computers for nearly three for the personal computer years. Thousands of our user. It's smaller, using the systems are operating per- new 51/4 -inch diskette, and is fectly in the field. Many major priced at only $1095 including computer manufacturers have disk drive, power supply, incorporated our Floppy Disks cabinet, controller /interface into their systems. We deliver, card, all cables and connec- and we'll be around to give tors, plus, on diskette, iCOM's you service whenever you new FDOS -M software, may need it. You see, we're a including assembler, editor, division of Pertec Computer and file manager. And for a Corp., one of the largest and limited time you also get an most respected manufact- 8K Disk BASIC package at no urers of peripherals, microsystems, Much faster than a cassette data entry products, and data extra cost. Floppy This compact, economical processing systems. Best of all, iCOM's Microfloppy° is Disk System is 10 to 15 times faster fully assembled and tested. It's 100% than a cassette. Programs can be So you don't need to risk getting compatible with Altair, IMSAI, Poly 88 loaded in seconds, a source program burned by a fly -by -night company. and other microcomputers using the of several thousand characters can Order an iCOM ®Microfloppy° and be Altair bus format. be corrected and a new file stored on sure of getting the best. diskette in less than a minute. Any of See iCOM's Microfloppy° now at up to 175 files can be reached in your local computer store. Or contact 'Offer good through April 15, 1977 1.5 seconds. us for the name of your dealer. IUM mICROPEPIPHEPIILS 6741 Variel Ave., Canoga Park, CA 91303 U.S.A. a division of Pertec Computer Corporation (213) 348 -1391 TWX 910 -494 -2788

www.americanradiohistory.com TliE COr.1PUTEß BOO Continued from page 32 SMALL COMPUTER SYSTEMS SOFTWARE AMATEUR RADIO EQUIPMENT

1455 -A So. 1100 E. Salt Lake City, Utah 84105 Phone: 801 -466 -7911 bibliographic information about a manu- script and the second containing the present working text buffer. Or consider the problem of remembering one section "WE TAKE THE of code while editing o program electronically - then altering a second por- OUT OF THE 11JCFIU tion at a different place. The idea of multiple text editing windows via separate displays is a very powerful concept which is well worth exploring. As to split screen displays where lines are intended to span several screens, there is a fundamental problem.- The gap between the display tubes interferes with one's scanning of the text... CH

YET ANOTHER DEFINITION OF THE WORD BYTE ... AND BAR CODE COMMENTS

In reference to Thomas P Bishop's One Of The Nations Largest Over 1600 Square Feet Of Sales letter /page 77/, published in November Full- Service Computer Stores. And Service Facilities. 1976 BYTE: One of my pet quirks is labeling things. Like so many authors of WHEN YOU WRITE FOR OUR CATALOG AND ENCLOSE S1 TO today's computer texts, I put a label on HELP DEFRAY THE COST OF HANDLING AND MAILING, everything. I would, however, like to clarify the meaning of the term byte; so, HERE'S WHAT YOU GET: in that connection, I have a bit (eight to be exact) of information. According to 1. A CERTIFICATE GOOD FOR 52 ON YOUR NEXT Donald E Knuth, the father of many of PURCHASE today's algorithms, a byte is not related to IBM (it is about the only thing in the 2. THE COMPUTER BOW EASY TO UNDERSTAND computing world which isn't) but rather CATALOG COVERING it is a universal concept. IMSAI The basic unit of information is u THE DIGITAL GROUP byte. Each byte contains an un- POLYMORPHIC SYSTEMS specified amount of information, SOUTHWEST TECHNICAL PRODUCTS CORPORATION must be capable of holding at but it TECHNICAL DESIGN LABS least 64 distinct values. That is, we ETC. know that any number between 0 and 63, inclusive, can be contained in one byte. Furthermore, each byte TO HELP YOU contains at most 100 distinct values. 3. THE COCIPUTER BOOM "EASY GUIDE" On a binary computer a byte must PICK THE RIGHT SYSTEM, PERIPHERALS, COMPONENTS, therefore be composed of six bits; on AND SOFTWARE FOR a decimal computer we have two digits per byte. THE BEGINNER THE ADVANCED This is an item of information which THE EXPERT is invaluable, or should be invaluable to THE SMALL BUSINESS Mr Bishop, since I have just relieved his "plight." Furthermore, Mr Helmers 4. A CURRENT LISTING OF PRESENTLY AVAILABLE should also be pleased, since now an explanation has been found for the name SOFTWA RE of the magazine he created. PUBLICATIONS I am extremely pleased with the PERIPHERALS quality and quantity of BYTE, and I would like to say "keep assembling, 5. INFORMATION ON REPAIR SERVICE, LOW COST compiling and interpreting these fascinating bits, bytes and words of data," CUSTOM PROGRAMMING AND OTHER SPECIAL SERVICES. ie: good work, and keep it up! One last question: Do you know of any company presently manufacturing a AT THE YOUR WRITTEN QUESTIONS hand -held scanner capable of reading the COMPUTER BIM future bar codes which will be published ARE HAPPILY RECEIVED AND PROMPTLY ANSWERED by BYTE?

R H Beinert 223 Du Rose Ter WE ALSO STOCK A COMPLETE Madison WI 53705 LINE OF AMATEUR RADIO EQUIPMENT

See the letter by W Buchholz (Feb- ruary 1977 BYTE, page 144) and note BANKAMERICARD MASTERCHARGE

115

www.americanradiohistory.com also that your quote from Knuth makes and I look forward to every issue. I toyed with the idea of getting my no reference to the origin of the term phoned Mr Grappel to thank him per- computer a code proficiency certificate but simply generalizes the definition to sonally, but I'm sure he'd just as soon from W1AW when it copied a minute mean any mouthful of data with greater have the $100 award. solid at 20 words per minute. That was than 6 bits in a binary representation. I enjoyed this article because it des- much better than normal. The receiver The scanners have not yet been pro- cribed a simple starting point for what noise was quiet and the W1AW signal duced in commercial form, but we have can be an almost unsolvable problem. was quite strong. been contacted by several firms in- The biggest obstacle in any accomplish- Incidentally, the only ICs used in the tending to do so. The first firm which ment is usually getting started. I sus- improved audio processor are a pair of achieves the $20 scanner (or at least the pected there were others who thought NE555s (U33, U32) and an LED. Out- same order of magnitude price) capable about such an idea but let the possible put is in the right sense at pin 3 of U33. of transforming bars as small as complications keep them from writing Missing pin number 7 on U32 must be 0.01 inch (0.25 cm) in width into TTL that first line of code. I've made some tied to pin 6 or it will never work. level signals will most likely get very changes to the program but I really Please keep up the good work of good publicity as the prize for winning appreciated being pointed in the right BYTE. I hope these next three years are the race. We intend to support the direction. Thanks to all. half as interesting as the first. with good starting with concept, software In my conversation Mr Grappel, Bill Bennett K3TNM with lack Emmerichs' assembler pub- he suggested a replacement for the all 1908 Foxhound Ct lished in this issue of BYTE and inter- important audio input processing circuit Severn MD 21144 preter and monitor software as well as designed around the NE567PLO tone

miscellaneous applications, fun and decoder. I had very little luck with these PAPER- decoder noise games. As a rule of thumb, tone chips. Low immunity COMPUTER COURSES WANTED BYTESTM products will be distributed seems to be their problem. Mr Grappel in both source listing and object bar said the one in QST, November 75, I completed three years of active code forms unless specific arrangements page 15, looked much more promising. duty in the US Army approximately to the contrary are mode by program built this unit up and had considerably 2 -1/2 years ago. During this 2 -1/2 years, authors. more success. The unit in the QST article I have been keeping an eye out for an by Thomas Riley uses a bandpass filter educational program in which I could CODE DECODED which I have not yet incorporated and ... apply my VA benefits. COMMENTS ON MORSER still have obtained good results. The Since I am very interested in owning signal still has to be pretty clean but the a personal computer with CRT, disk I hope I'm not too late to get my Schmitt trigger or the OST circuit has drives, etc, etc, and learning about the vote in for Grappel and Hemenway's much more immunity than the tone principles of the processor and all of its October 1976 article, page 30. I believe decoder. When the filter is added I supporting and peripheral equipment, I it was the best I've ever seen in BYTE expect to see more improvement. I would like to find a course to which I could apply my VA benefits along these lines. Do you, one of BYTE's readers or advertisers, know of such a course or VECTORBORD® TENTH /TENTH HOLES MOUNT: courses? DIPS, SIPS, KL /PS, CHIPS If a company could develop such a PINS, POSTS, POTS, PADS Save Work - Time - Money course around its computer and periph- RCs, ICs, PCs, SCs eral kits, it could expand its market to those who are very interested in personal Pattern "H" 8800V MICROPROCESSOR PLUGBORD size computers, but do not have the knowledge and /or funds to own one at 0.1 " F- T28 Fits the present. .062" .042" I would appreciate any help from T1 Holes Dia. anyone who could get me in contact with such a course. John A Whitney 3644 Parkway PI Shreveport LA 71104 Dia.

1802 USERS CLUB WANTED

(Component Side with Added Sockets) I just received the November BYTE. Pattern "P" Has 100 contacts on 0.1" centers, is 10" wide by 5.313" Wow! Some good coverage of video high. Has heavy tinned back -to -back buses, overall 0.1" graphics. Keep the "display" articles spaced 0.042" hole pattern. Socketed models available. coming. (There may be a few that felt there was too much emphasis on W I D E S E L E C T I O N O F SI Z E S AND MATERIALS graphics; but on the other hand, I'd MICRO- VECTORBORD® "P" - 0.042" TERMINALS - Complete selection of wager the majority could stand a lot holes match DIP leads. Epoxy glass, or wire wrappable and solderable push -in more.) glass composite, terminals for dia. holes paper, copper clad. Also 0.042 "and 0.062" I'm one of those "homebrewers" and 1 /64 "to 1/16" thick and 10 "max. width. - plus wiring tools available. am in the midst of getting my computer VECTORBORD "H" - For larger termi- PLUGBORDS - For solder or wrap wire act together. It will be housed in an nals, leads. Available in epoxy glass sheets construction 2.73" to 10" wide and 4.5" attache case, use an RCA 1802 proc- 4.8" to 8.5" wide and 8.5" to 17" long. to 9,6" long. With holes .1"x .1", .1 "x essor, 4 K (minimum) or prorammable 1/32" and 1/16" thick. .2 ", .2 "x .2 ", or loaded with IC sockets. memory, a keyboard, TV and cassette recorder interfaces, of course. Every- It tera turc Send for complete thing possible will be CMOS logic to ELECTRONIC COMPANY, INC. minimize power supply requirements, 12460 Gladstone Ave., Sylmar CA 91342 with either 110 VAC or battery power. (213) 365 -9661 - TWX (910) 496 -1539 I was someday going to get into 41575 personal computing; then the August

116 www.americanradiohistory.com 1976 BYTE bit me with Suding's television display device. I studied it thoroughly to learn all the required signals to generate television video. Then

I converted the design to my requirements: CMOS wherever possible, a single supple character generator using +5 V only 21 L02s for memory, etc. My result now takes 26 chips instead of 32, cost $45 in parts including the crystal and wire wrap board (found in a surplus shop) and draws only 5 V at 250 mA. Now, a question: Is there anyone out there using the RCA 1802 processor chip or is it too new for the hobbyist? Could you print a short request for responses from any 1802 users? I think this may be of interest to many others besides myself. Harley Shanko COMPLETE Apartment 209 15025 Vanowen St FLOPPY DISK SYSTEM Van Nuys CA 91405 FOR YOUR ALTAIR /IMSAI ON USING BURIED GOLD $699 I don't own an Altair 8800 or whatever (yet), but I do have an SR -52 of my That's right, complete. very own and I was pleased to see "The The North Star MICRO -DISK SYSTEMTM uses the Shugart Gold in the SR -52," by Clif Penn, Buried minifloppyTM disk drive. The controller is an S -100 corn - page 30, and "Desk Top Wonders," patible PC board with on -board PROM for bootstrap load. It page 92, in the December BYTE. When I can control up to three drives, either with or without heard about the hidden goodies in the interrupts. No DMA is required. SR -52 three months ago, I wrote to Texas No system is complete we provide the Instruments and received a prompt reply without software: a with a printed sheet giving much the PROM bootstrap, file -oriented disk operating system (2k same dope on the registers as in Clif bytes), and our powerful extended BASIC with sequential Penn's story. Although the first level of and random disk file accessing (10k bytes). the stack is addressable as R60, it actually Each 5" diameter diskette has 90k data byte capacity. cannot be used if you are doing any BASIC loads in less than 2 seconds. The drive itself can be arithmetic with dyadic operators (plus, mounted inside your computer, and use your existing power minus, times, divided by, y to the x supply (.9 amp at 5V and 1.6 amp at 12V max). Or, if you power or x root of y) because the num- prefer, we offer a power supply ($39) and enclosure ($39). ber on the left hand side of the operator Sound unbelievable? See the North Star MICRO -DISK is written into the first level of the stack at local For a high (register 60). So in most cases only R61 SYSTEM your computer store. -performance BASIC computing system, all you need is an 8080 or Z80 to R69 arc available. This I found from personal tinkering. computer, 16k of memory, a terminal, and the North Star Would it be possible to publish the MICRO -DISK SYSTEM. For additional performance, obtain address of the SR -52 Users Club and up to a factor of ten increase in BASIC execution speed by 52 Notes? For that matter, I think it also ordering the North Star hardware Floating Point Board would be a good feature to publish a list (FPB -A). Use of the FPB -A also saves about 1k of memory by of users' groups for the various micro- eliminating software arithmetic routines. computer systems and programmable Included: North Star controller kit (highest quality PC calculators. board and sockets all IC's, regula- The big advantage of programmable components, for and power calculators is that they are portable. But tion for one drive), SA -400 drive (assembled and tested), are they inexpensive in terms of comput- cabling and connectors, 2 diskettes (one containing file DOS ing power per dollar? Polymorphic Sys- and BASIC), complete hardware and software documentation, tems offers a ready to run system with and U.S. shipping. an 8080 based processor, 8 K memory, video interface, cassette interface, key- MICRO -DISK SYSTEM $699 To place order, send check, money order or board, television monitor, cassette re- (ASSEMBLED) $799 BA or MC card #with exp. ADDITIONAL ea. corder, BASIC and an assembler for DRIVES $425 date and signature. Uncer- 51750, or about six times the list of an DISKETTES $4.50 ea. tified checks require 6 SR -52. The Poly 88 is faster by several FPB -A $359 weeks processing. Calif. times and has several times the program- (ASSEMBLED) $499 residents add sales tax. ming capacity, not to mention the ability to handle nonnumeric data, and can be expanded. I would say you get more NORTH STAR COMPUTERS, INC. than times the computing power. six 2465 Fourth Street There are certainly less expensive systems Berkeley, CA in ready to run or kit form available 94710 from other manufacturers. Texas Instruments, I've heard, has á

117 www.americanradiohistory.com super SR -52 desk top machine called the mable calculators. Those programmable cheaper, too. It seems to me that this SR -61. Could you run a product descrip- calculators that are not keyboard pro- idea could be expanded for mathematical tion on it in a forthcoming issue of grammable only are programmed by modeling and simulation, beyond its BYTE? magnetic cards except for some of the original use for industrial routines. "super" calculators such as advanced William R Hamblen David W Johnston members of the HP -9800 series. Mag- 946 Evans Rd POB 3781 netic cards are small and easy to lose. Nashville TN 37204 Washington DC 20007 They are expensive as compared to your new form of printed software. They can- BITTY? SR -52 Users Club is at 9459 Taylor- ITTY not be duplicated as easily as printed ville Rd, Dayton OH 45424, (513) software. They can lose a bit or two over 233 -3698, and publishes 52 Users Notes I'm writing you in regard to your a long period of time, but printed soft- monthly. September issue editorial, "Come One, ware should last longer and it should be Come All! ", page 6. more obvious when something is wrong In your article you mentioned Ted A CALCULATOR USER'S with a printed program, also cheaper to Nelson and his "itty bitty machine COMMENTS replace. A low cost optical reader is corporation." I would like to know how needed to make the idea of machine I can communicate with Mr Nelson. As a member of the SR -52 Users readable printed software economical. Could you please send me his mailing Club, I was pleased to read "The Buried I have recently been reading Compu- address. Gold in the SR -52" by Clif Penn, ters at Large by Charles J Sippl and Your response to my request would page 30; also "Desk Top Wonders - Robert Bullen (Bobbs -Merrill, NY 1976). be greatly appreciated, as I don't know Shooting Stars," page 92; and letter Starting at the beginning of chapter four, when or if I'll get your magazine again. "New Product: Snob Detector" by Craig "The Robots are Coming - and Giants Pearce, page 53, in the December BYTE Too," there is a description of a robot Ira Ford 19826 48th Av W ,;16. I hope you have more on the SR -52 that can learn routines by having the as well as other programmable calculators operator run the machine through a L -9 such as the SR -56 and the HP -25. routine manually, once, and the machine Lynnwood WA 98036

I think that the idea of machine read- has "learned" the routine and can repeat able printed software on page 12, etc, of it as it was done the first time. In doing See the advertisements for itty bitty the same issue of BYTE is a great idea this the robot has "written" a program and Dato Domain beginning in January and should be a great help in the produc- and developed an algorithm for the rou- BYTE on page 63. tion of low cost software. It should also tine. It has done this a lot quicker than a be a good idea for software for program- human being could do it and a lot WHERE'S A TWO ADDRESS MACHINE?

Will there ever (in the next few years) be a two address microprocessor on the

market? I have been using (in school and in work) several of the NCR Century series computers, which by the way are WANT TO HOOK UP two address machines, for the past five years. I have also used single address

machines (ie: Altair 8800, IBM 1 130 and

CHI 2130), but generally I have found A CIRCUIT QUICK? them a pain to work with after the NCRs. I just can't see the point of having a set The PB -100 is only one of our of 78 hardware commands to perform family of solderless Proto -Board memory to register, register to register breadboarding units, designed to and register to memory functions when help you assemble, test and modify a set of 39 memory to memory com- circuits as fast as you can push in or mands are sufficient. OK, I'll admit it pull out a lead. Preassembled is unfair to compare a medium scale sockets with durable 5 -point computer with a mini or microprocessor, terminals provide low- resistance but, the NCR line was developed for the interconnections you can arrange 1968 sales market without the LSI tech- and re- arrange at will. niques now in use. There is place for Resistors, capacitors, transistors, both the single and double address in DIP's, TO -5's, LED's etc. plug machines, but I feel the ease in program- without damage to leads. And ming of a two address processor makes it jumper connections, where required, far superior to a single address processor.

are lengths of #22 AWG solid wire. I am not putting the single address

Models from 630 to 3060 tie -point machines down, but I feel they are for (6 to 32 14-pin DIP) capacity the same people who would prefer to use available. For more information, see an RPN calculator when there is an AOS 100. 760 your CSC dealer, or write for our Proto-Board' solderless calculator available. Let the machine tie Kit, catalog and distributor list. -points. $19.95* work for you! Anyway, I haven't bought

a micro yet because I am waiting; I have CONTINENTAL CORPORATION SPECIALTIES a feeling it will be a long wait, for a two addressmachine.CAN ANYONE HELP ?? Jon Kirkpatrick Fullerton CA =0=EASY DOES IT 44 Kendall Street. Box 1942 New Haven, CT 06509. 203 -624 -3103 TWX 710- 465 -1227 Want u two address machine? Take a West Coast office: Box 7809, San Francisco, CA look at a microprogram oriented archi- 94119. 415- 421 -8872 TWX: 910- 372 -7992 tecture using contemporary bipolar © 1976, CSC Mfrs. sugg. list microcontrollers such as Signetics 8X300 or A MD 2900 series parts. Then do your

118

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MICROCOMPUTING FOR HOME AND THE SMALL BUSINESSMAN

The professional publication bringing microcomputing technology to the hobbyist, small businessman, educator, engineer and student. Every issue edited to bring technology and people together in the simplest manner.

INTERFACE AGE is packed with HARDWARE ARTICLES - Product profiles, comparisons, applications, modifications and construction projects. SOFTWARE ARTICLES - Microcomputer development software, short software routines, application software, off -line software storage formats, software communication standards and access to the microcomputer software depository for all INTER- FACE AGE readers. TUTORIALS - Fundamentals of micro processors, basics for microcomputing, professional to technical transition information, understanding software, elementary math for computing. NEW PRODUCTS - Manufacturer profiles and latest product releases. USER COMMUNICATION - UPDATE - devoted to club and organization announcements and activities. - LETTERS TO THE EDITOR - Reader forum for expression of opinions and feedback on articles and features. MICRO- MARKET /FIFO FLEA MARKET - Low cost /no cost advertising for the new marketeer /garage sale enthusiast.

If you need to know how to get started in microcomputing or need the valuable software once your system is completed then INTERFACE AGE is a must for you. Don't Delay - Subscribe Today!

INTERFACE AGE MAGAZINE

I P.O. Box 1234 12 Monthly Issues: Cerritos, CA. 90701 $10 U.S., $12 Can. /Mex., $18 International CHECK MONEY ORDER Name Address

I City State Zip Country MAKE CHECK PAYABLE TO: INTERFACE AGE MAGAZINE J www.americanradiohistory.com own microprogramming and machine THE ETYMOLOGY OF HAM? zine in hopes that someone near to me architecture design to make a usable sys- with an operating computer will contact tem out of the parts. In the October BYTE, page 20, you me? I would like to see one running and published a letter from Bryan Patterson. talk with someone as interested as I am ROLLING ROBOT QUERY In Mr Helmers' reply, he stated "ham" who has some experience with his own came from the tendency to "ham it up" equipment. I am a ham radio operator, on the air, as in the usage of "ham WA2T01, and can be reached almost any 'N`- ESiWiEp EDIí1eS Of f7E. actor." The term "hams" came from the time through the Gloversville 10 -70 re- fact that in the early days of amateur peater or Cobleskill 01 -61 repeater. W98T CAu bJ Ttat /.-x ,tïaS r Also, if there is anyone in my area Ìtl[J radio, the government was trying to ,_¡¿ ,d7lkT eliminate the use of radios for hobby (50 miles west of Albany NY) who k, VA...D C AE,SFRhAN purposes, and the four operators of one might be willing to help me get into this, TAO, 3(a:,tS of the first stations that led the fight I would appreciate a phone call or card. aIJDZ.éy10Su against the government were named Thank you for your interest and Harriet, Arthur, Mark and Stanley; thus, cooperation. the term hams came from the first letters Jim Faliveno . VEEa A pRo7Ear Fct re .hJE7F.Y. .", of their first names. It then evolved into Caroga Lake Stage v N.( RoRtotrXMl UEIT 5oESrrR. its present meaning of a radio amateur. Gloversville NY 12078 Y 1N LG tAr.t/iFD (518) 725 -2012, evenings ,TV A TMP T4AT dry.Si ItAryr,( George j Valaitis 14A., 647 Linkfield Rd `'Aaul AN) .,... RE ñ, fosN To Not MY Pota C.PJ. Watertown CT 06795 THE PERSONAL COMPUTING DIRECTORY, ANYONE? WANTED: COMPUTER PERSON (AND OTHER TOPICS)

me to congratulate you on I have subscribed to your magazine Allow since the first issue and find the world of your excellent journal. It's the only I've ever anxiously waited microcomputers fascinating. As yet I publication haven't built anything or purchased any for every month. I have a proposal: Someone like hardware. I am still undecided as to what to do, what to buy, what to build ... yourselves should publish a directory of computer hobbyists. You might call it but I would very much like to get into this. something like Register 77. The directory would list anyone owning, having See page 58. Would you print this in your maga- access to, or just interested in computers. It might also list clubs. The directory could be organized so that one could "key" on a person's name, address or microprocessor. Each name entry could contain information about the Make the HAL Connection person. The following is an example of the information that might be contained, using myself as an example. 8080A MPU 24 lines of 1K Monitor /Debug Parallel I/0 (8255) Name: Software in Hardware "front Larry J Leone t Age: 2708 EPROM or t panel" on board 22 2 -3624 PROMs Optional Address: On board space Accessories: 48 Second St CRT Terminal for: 4K ROM .ti Masury OH 44438 `; Board, BASIC (2708), 2K RAM in Phone: EPROM, Audio (2102A -4) (216) 448 -1252 Lassette Interface, Occupation: TTY Current Loop or 7K RAM Expansion Board/ Senior electrical engineering RS -232C serial I/O (8251) EPROM Programmer, Power Supply. student, Youngstown State MCEM -8080 from$375 (2 -3624 ROM /1K RAM) orS445 as shown (2708 EPROM /2K RAM) University and solve your lab Languages: or OEM computer problems FORTRAN, SNOBOL 4, 1. the 24 lines Connect to of Parallel I/O puter system elements are incorporated in BASIC, PL -1 and ASCII or Baudot Serial I /O. this fully assembled, tested single -board System: 2. Connect to processor bus to add mem- computer. Some unexpected features of Constructing 1M6100, 1 K RAM, ory expansion board /EPROM program- the HAL MCEM -8080 are: hardware "front access to IBM VM /370 -145 mer, I/O devices, or our unique CRT panel" which allows setting a breakpoint Interest: Terminal Board. and manual control of the computer; 1K Artificial intelligence, robotics 3. Connect to our power supply or use ROM Monitor /Debug Software (with user I would imagine that many of the your own. callable, Intel®compatible I/O routines) people that would submit their names to Lab users and OEM's will - alike find solu- which greatly simplifies program develop the directory would have access to a key - tions to their computer problems with the ment; Parallel and Serial I /0 on the board; punch. If you set up a card format then MCEM -8080 computer. All essential corn- and very reasonable prices. they could send you the cards and all

Cal I or write for further information on the HAL Connection. that you need to do is feed them into a You'll be glad you did! card reader and let the computer do the work. HAL COMMUNICATIONS CORP. CI I don't believe there should be a wall Box 365B 807 E. Green Street, Urbana, III. 61801 between large and small computer sys- I Telephone (217) 367 -7373 tems, because they all work basically the

same. I think some articles should be

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www.americanradiohistory.com about research work with large systems, how they are being used, and how they perform certain operations or functions. What I'm getting at is why reinvent the wheel when one can copy it; or, in this case a small system can mimic a large one. These kinds of articles should transmit stimulating ideas to the computer hobbyist. Concerning the controversy over which micro is the best micro, I say any 1A11`A1.1.1 micro is better than no micro. I happen to be the proud owner of an IM6100, although if I had the money I would have a Z -80 with 64 K, but that's LIFE. Less I'm building my system from the micro Bread, up a little at a time; therefore it will most likely be incompatible with every Box. other system, me More but that doesn't bother either because it's all mine. I'm just happy to have something that was only a dream to anyone five or more years ago.

I don't care how advanced a micro is; what more can one micro do over another in 4 K or less memory? At least

I can get a mountain of cheap software made to run in 4 K for my system. Not everyone can make that statement. Re- member a computer is only as good as its software. A word concerning the Morse code articles of the October issue: I wouldn't \d\lllllAAt t\t11/40\\\\\\ be subscribing to BYTE if I wanted to read that type of article. I think the articles should have been spread through several issues or better yet sent to the New, complete Breadboarding /Interfacing Station. appropriate magazine. I'm not criticizing Only $241.50! the contents of the articles since I only We took our economy And to top it off, monitor the glanced at them and quickly became Breadbox IV kit and did a buss with LED or 7 segment uninterested in the topic. I'm sure you complete design number on displays, add an LR -6 /K LED didn't mean this to happen but I know several friends who feel the same way. it ... to add accessories and indicator outboard -4 To help you from doing this, I am give you far more hardware individual LED's with driving willing to attempt to write an article if for the buck. circuits ($10.00 each). And you could suggest some topics that your For example: It plugs directly LR -4 /K seven segment display readers want to read about. into your Altair/lmsai buss outboard with driver /decoder At any rate, I do like the way you without special adapters ... ($19.00 each). group similar articles into one issue. Keep up the good work. Gives you almost 3,000 connections for bread- So bug out to your local Larry I Leone boarding ... Power supplies computer store now and save 48 Second St ( +5 15V) built in substantial bread on this E &L Masury OH 44438 & +/- ... Available in kit or assembled deal. Or write us for the PS: Concerning the photo on page 96 of format. All that for just $241.50 store nearest you. the December issue: I would guess it to each in kit form. *Suggested resale price (U.S.A.). be conductive foam used to ship ICs like inquiries invited. CMOS. Dealer Problem: Flow do you explain to the kids that are growing up in a world of III n® clocks rotates t digital that something I I clockwise? ¡Good point ... Consult a physics text and talk about the right - E &L INSTRUMENTS, INC. hand rule and the cross product ... 61 First Street, Derby, Conn. 06418 not exactly u perfect solution./ (203) 735 -8774 Telex No. 96 3536

It turns out that someone is busily ut work on iust such a directory. His name is Richard Gardner, und his address is Resources, P08 134, Harvard Square, Cambridge MA 02138. On a similar subject, PCC (Box 310, Menlo Park CA 94025) is preparing a Reference Book of Personal and Home Computing for release this spring. Contact Dwight McCabe for information on this $4.95 book.

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HELP: I need Issues 1, 2, 3, 6, 7, 8, 9, 10, and Lombard 60148 FOR SALE: Four Lambda regulated power sup- 12 of BYTE. Will pay any reasonable price. KENTUCKY plies Model LB -701 FM -OV. Input is 208 VAC Send list to Alex Novickis, 8358 Park Av, 5061/2 Euclid Avenue 3 phase, output is 0 -8 VDC at up to 300 AMPS. Forestville CA 95436. Lexington Asking $300 each. Harold W Norris, RFD =3, 606 -233 -3346 Milton VT 05468. 3028 Hunsinger Lane FOR SALE: 5 low power 4 K RAM boards Louisville 40220 502 -456 -5242 assembled and tested by E E. I'm using 8 K boards Readers who have equipment, software or other so for now and no longer need these, they're yours items to buy, sell or swap should send in a clearly WISCONSIN $100 each. S Edelman, POB 91, Ithaca NY 14850, typed notice to that effect. To be considered for 2221 E. Capitol 16071 272 -1279. publication, an advertisement should be clearly Shorewood 53211 noncommercial, typed double spaced on plain 414 -961 -2430 SWAP: Will exchange a March 1976 issue of BYTE white paper, and include complete name and May TEXAS in return for either the 1976 or June 1976 address information. These notices are free of in D 460 The Micro Store issue good condition. Kay, W Clapier St, charge and will be printed one time only on a space 634 S. Central Expressway Philadelphia PA 19144, (215) V19 -6648. basis. Insertions should be limited to 100 available Richardson, Texas words or less. Notices can be accepted from FOR SALE: Two new unused MFE 250B digital individuals or bona fide computer users clubs only. 71) cassette transports (see BYTE a15, page with We can engage in no correspondence on these and data; call, best offer. Also have Remex papertape your confirmation of placement is appearance in spooler with schematic, $25 plus shipping. Bug - an issue of BYTE. Book Ill, $10. Processor Tech's 5 K BASIC Please note that it may take three or four manuals and tape, $10. Assembled Morrow BYTE months for an ad to appear in the magazine. standard board, $100. Gary Alevy, 48D Clintwood GRv?FIC inc. F Ct, Rochester NY 14620, (716) 244 -1133. 717 LAKEFIELD RD., SUITE WESTLAKE VILLAGE, CA 91361

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www.americanradiohistory.com Microcomputer Glossary

David Price BCD: (BinaryCoded Decimal). 3901 Victoria Ln Binary: The base -two number system. The digits Midlothian VA 23113 are 0 and 1. They are used within a computer which represents them as the two states of an electrical circuit. The first five numbers (0 -4) are 0,1,10,11,100.

In this article I have set down definitions Bit: This is a contraction used to name one binary of several computer words which one is digit.

likely to see in BYTE. I didn't want this to Bug: A bug in a program is something which causes wind up being a full blown, unabridged the program to malfunction. A programming error. Byte: A group of The most common byte size dictionary, so I limited the list to words that bits. is 8 bits. I thought would be unfamiliar to most

"outsiders." The computer industry has a Chip: See integrated circuit. fascinating tendency toward the use of COBOL (Common Business Oriented Language): A abbreviations and acronyms. These words high level language heavily oriented to the use of are printed in capital letters, and are spelled files and record keeping. It replaces operation out within parentheses. codes of assembly level languages with a set of powerful "verbs" resembling common English. Compiler: A compiler accepts the statements of a high level language, then converts them to machine ACR (Audio Cassette Recorder) interface: Permits language. an ordinary tape recorder to be used to store Core memory: Many older computers utilize digital data. It is frequently used as a low cost memories of Ferrite or Lithium Magnetic cores. A replacement for a magnetic tape unit. core memory doesn't "forget" data. AD (Analog Digital) conversion: An AD converter CPU (Central Processing Unit). measures an input voltage, then outputs a digitally CRT (Cathode Ray Tube) display: A type of encoded number corresponding to the voltage. terminal which displays information on a television Alphanumeric: The set of graphic symbols con- like cathode ray tube screen. taining the alphabet (A -Z), the numbers (0-9), and special characters (such as punctuation). Data rate: The number of bits (or bytes, or words) Applications program: A program which does true of information transmitted over a communications problem solving, as opposed to an assembler, channel per unit time. compiler, monitor or other systems program. Debugging: Removing bugs (programming errors) ASCII (American Standard Code for Information from the program. Interchange). Disk storage: A type of mass memory which stores Assembler: Assemblers allow the programmer to data on a magnetically sensitive disk. write programs using easily memorized mnemonic DOS (Disk Operating System): A computer system instructions of an assembly language. which uses disk storage. Also refers to special Assembly language: A low level symbolic pro- software routines for driving a disk system. gramming language which was historically the first programming aid, and is the simplest type of EBCDIC (Extended Binary Coded Decimal Inter- language to implement. change Code). EROM (Erasable Read Only Memory): A ROM BASIC (Beginner's All purpose Symbolic Instruc- which can be erased and reprogrammed. The tion Code): BASIC is a widely used but simple typical contemporary EROM is erased by exposure beginner's high level language. Like all high level to ionizing radiation such as ultraviolet light. languages, it utilizes powerful statements, such as "10 PRINT A /B" instead of machine opcodes. Firmware: 1) Software which has been hard wired BASIC is typically implemented as an interpreter, into the computer by storing it permanently on which runs more slowly than would be the case ROM, 2) Microprograms written to emulate a with a compiled computer language. specific machine's instruction set.

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www.americanradiohistory.com Floppy disk: Disk storage which makes use of Octal: The base 8 number system. It is commonly flexible disks made of a material similar to mag- used when programming in machine language netic tape. Floppy disk units are slower and hold ( "375" is easier to remember than "011111101"). less data then hard surface disks. Opcode ( OPeration CODE): A bit pattern which Flowchart: A diagram representing the logic of a specifies a machine operation to a computer's computer program. central processor. Often listed in hexadecimal or FORTRAN (FORmula TRANslation): A computer octal notation. language useful in computational programming. Paper tape: A long strip of paper punched in a pattern decodable by the computer. Hexadecimal: The base 16 number system. It is commonly used when programming in machine Parallel IO: When input and output is sent or language. (FD is easier to remember than "1111 received with each bit having a single wire, the 1101".) transmission is called parallel. Contrast this to serial 10. Peripheral: The devices which perform detailed IC (Integrated Circuit). interfacing operations for the computer. These Instruction set: The repertoire of the instructions a include terminals, mass storage and the like. given machine can execute. A major component of Program: A set of instructions which instruct the a computer's design. The programs of one corn - computer to do a certain task. puter can't run on another computer if the two instruction sets aren't compatible. Programming: To write a computer program. Integrated circuit: A technique whereby many PROM (Programmable Read Only Memory): See electronic components can be integrated and mass "ROM ". produced on a single chip of silicon. Interface: A device which allows one type of Queue: A "waiting line" of tasks or data. electronic device to communicate with another. Interpreter: An interpreter accepts and executes a RAM (Random Access Memory): Generic term for high level language program. Unlike a compiler, microcomputer system memory. however, it executes programs on the fly, instead ROM (Read Only Memory): Memory whose data of producing machine language code. BASIC is a cannot be destroyed. common interpretive language. RS 232: An electronic interface standard for serial data communications. LED (Light Emitting Diode): LED displays are often used as digital output devices because of Serial IO: A method of transmission in which bits their low weight, cost, and size. are sent one by one. Line printer: A high speed printer connected to a Simulation: A computer program which models computer can print data at rates often exceeding some system, typically using mathematical tech- several hundred lines per minute (LPM). This is niques. achieved by printing a whole line at a time. Software: Computer programs. Looping: A programming technique used when a Star Trek: A computer game based on the TV single portion of a program is to be repeated many show "Star Trek." It involves destroying times. "Klingons" with an array of sophisticated LSI (Large Scale Integration): The most complex weapons. Also referred to as "Space War." form of an integrated circuit is made using LSI Statement: A single computer instruction, within a techniques. computer program. Subroutine: A subprogram within a larger program. Machine language: The lowest level of pro- Terminal: A device for communicating with a gramming. This is the only language the computer computer using a keyboard and an alphanumeric can understand without the assistance of an printer or CRT display. assembler, compiler or interpreter. Teletype: A terminal which prints information on Magnetic tape: Mass storage of data on mag- paper, manufactured by Teletype Corporation. netically sensitive tape, similar to that found in home tape recorders. Timesharing: A technique whereby a single computer can support several terminals simultaneously. Microprocessor: A microprocessor consists of all the electronics of a minicomputer miniaturized TTL (Transistor- Transistor -Logic). onto a single IC chip. TTY (Teletype). Mnemonic: A short word which stands for another TVT (Television Typewriter): An inexpensive word or phase, designed so that it is easy to form of video CRT display. remember (ie: "Jump to subroutine" might be abbreviated "JSR "). UART (Universal Asynchronous Receiver Trans- Modem (modulator -demodulator): Converts audio mitter): converts parallel data into serial form, or sounds into digital form, and vice versa. vice versa. MPU (Micro Processor Unit): Synonym for CPU chip. Word: A basic unit of computer memory.

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www.americanradiohistory.com Technical An Approach to High Level forum Languages for Small Systems

Donald J Stavely machine given these obstacles is to start by 1706 Banyan Dr writing a series of "system subroutines" Fort Collins CO 80521 which will perform the complex operations done in a few instructions on a large machine. A "floating point package" is a The prospect of high level languages for prime example. Calls to floating point rou- the computer hobbyist is exciting, though tines add structure, simplicity and compact- foreboding. Setting out to write a compiler ness to compiled code. Also, scanning, for a microcomputer is in many ways more search and block move routines simplify and daring than taking on a compiler for a full - shorten the compiler itself. blown computer, since the "distance to be In essence, what we have done in this traveled" from source to machine language approach is to augment the puny instruction is greater. The large machine programmer set and word length of our machine with has a vastly richer instruction set to work subroutines. Once written and debugged, with. Also, the data elements of the source these routines "bootstrap" us up to a higher language (ie: integer, real number, etc) can level of programming. We can now think in often be directly implemented as single terms of "scanning for the next blank" words on a large machine. For example, the instead of "load byte, compare to blank, FORTRAN expression REAL = REAL *PI conditional jump, increment pointer, etc, translates to a mere handful of IBM 360 etc." We think "floating point add" instead instructions, compared to perhaps a pageful of all that code to match the exponent, shift of 8080 or 6800 instructions. The instruc- the multiple byte mantissa, add it, then tion set and word length not only make the normalize it back. final object code simpler, they also make the Now, armed with a few kilobytes of translation process (ie: the compiler program) system subroutines, the compiler output simpler. If software complexity doesn't scare becomes mostly a series of calls to these sub- the small system user, then memory size routines, rather than directly executable ought to. Both the storage for the compiler code. Think of this situation as if the com- and for the compiled program is much piler is no longer outputting true machine greater for a small and simple processor. level code for your 8080 or 6800. It is out- The reasonable approach for a small putting code for a more sophisticated, higher

About the Author Donald l Stavely is an employee of the Hewlett- Packard Company, Ft Collins Division. He is a graduate of the University of Michigan, with a master's degree in Computer Engineering. In the letter accompanying this opinion, Don writes:

I intended this piece for the new "Technical Forum" section, which I think is a great addition to BYTE. The "Technical Forum" will encourage people (like me) who have something to say, but who don't claim to be experts and who don't want to take on a full article with its implied burden of proof.

The letter and the original copy of this "Technical Forum" entry demonstrate an excellent application of a people oriented computer: Don typed the article using a text editing and formatting program on a 9830 calculator and a 9871 printer, both products of Hewlett -Packard. The 9830 is called a `desk top calculator" but is in reality a general purpose computer with some biases towards calculation built into its high level language.

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www.americanradiohistory.com level machine implemented through subrou- have stack elements which could be tine calls. What has been gained by this defi- addresses, integers, floating point numbers, nition of a software machine design? First, string descriptors or logical values. the compiler is simpler because the level of Several things need to be said at this the outputted code is one step higher than point. First, the notion of an intermediate the real machine. Second, the object pro- level abstract machine is not new. More than gram code is much shorter since each call a few compilers have been implemented this replaces many machine instructions. What way. The IBM S/360 FORTRAN (G) com- have we lost? While the code is compact, it piler is written for a stack oriented machine requires the few kilobytes of system subrou- called POP. PASCAL, an ALGOL -like lan- tines in order to run. In terms of execution guage, also was written for an abstract speed, we have sacrificed the overhead of the machine. This concept is part of a broader subroutine setups, calls and returns. class of methods to divide the compiling task Let us now take this argument one step into two parts: a Language Dependent further. We have made the compiler easier Translator (LDT) and a Machine Dependent and the compiled code more compact by Translator (MDT). At what level and in what making our machine appear more sophisti- way this division is optimally made is the cated than it really is through run time sub- subject of current research. routines. What would we really like our Second, the idea of simulation or inter- machine to look like? A PDP -11? pretation of intermediate code often brings An IBM 360? Not necessarily like any con- to mind extremely slow and inefficient ventional machine. We would like a machine execution. This is certainly true when a con- with an instruction set tailored to compiling ventional machine simulates another conven- and running a high level language, with word tional machine. A 6800 simulation program lengths and data types appropriate to the of an 8080 machine is absurd. 95% of the task. We can define an "Abstract Machine" execution time would be spent in the over- which we would like to have, and then make head of instruction fetching, decoding and our microcomputer simulate this abstract setup. But a 6800 simulation of a 360 is not machine by writing an interpreter program quite so ridiculous, since most of the time for it. the 6800 would be grinding away at power- What would an interpreter program look ful arithmetic and logical routines. Defining like? As one would guess, there would be a an abstract machine whose "architecture" is main routine that would fetch the next suited to the source language and whose abstract machine instruction and increment instruction set is powerful compared to the a simulated program counter. Based on the real machine insures that most of the execu- instruction, the main routine would branch tion time is spent doing useful work. to the appropriate execution routine. The But now look at the advantages of the abstract "opcode," rather than being an in interpretive abstract machine for the ama- line subroutine call, would require only a teur computing experimenter. First, as was single byte - as an index into an instruction said before, the code is extremely compact. routine jump table. A single byte instruction might do some- In terms of architecture, we woUld like a thing like "take the floating point number at machine that is at least partially stack the top of the stack, convert it to an ASCII oriented. Stack machines are well suited for character string, and leave the descriptor in processing high level languages for several its place at the top of the stack." A fairly reasons. First, stack code is very compact sophisticated program would take up little and storage efficient, since most operations space, aside from the fixed overhead of the have implied operands, ie: the top one, two interpreter, string and numeric literals, and or three elements on the stack. Second, the the value area. No matter how big memory code generation portion of the compiler is chips get, it is safe to say that memory will greatly simplified since the parsing process always come dear to the computer hobbyist. directly implies stack operations. This Second, an abstract machine is a step applies not only to arithmetic expressions, toward real machine independence and soft- but also to string expressions, logic expres- ware portability. If you write an interpreter sions and nestable program constructs like for your 6800 and your friend writes one for IF- THEN -ELSEs, DO- WHILEs, etc. Third, his 8080, abstract machine code will run stack allocation of memory is nice for well on both. Also, if you later upgrade to a recursive subroutines and block structured 9900 or LSI -11, you don't have to junk all languages. The stack instructions would your software and start over - you just have operate on the actual data types defined in to rewrite the abstract machine interpreter. the language. The abstract machine for an The more powerful processor will make the ALGOL -like language, for instance, might interpreter shorter, simpler to write, and

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www.americanradiohistory.com faster at code execution. Machine independence should hold appeal to any serious programmer since it gives the ability to change and upgrade machines. Third, it is a structured, "one step at a time" approach to software development. If your system now only has a few kilobytes of programmable memory, you can work on the interpreter, play with various abstract machine architectures, and write small programs in the abstract "machine language." Later, with a little more memory, a resident assembler written in abstract machine code for the abstract machine would be an interesting and useful project. Still later, with more memory, on to FORTRAN, ALGOL and APL! If readers are interested, perhaps a basic abstract machine could be proposed and kicked around a little. Extensions to the instruction set and data types (like string or matrix operations) could easily be added later. Just how sophisticated and how language- specific the abstract machine ought to be is open for debate. I have played around with a simple one on my 6800 and am convinced it is the logical approach to Look for us at the West Cocst Computer Faire high level languages on micros. It would April 15 -17 in San Francisco. seem to be a natural for those people who have big plans for their small systems. Let's talk about a Real Bargain It's the Typewriter /Terminal from AJ Use it as a typewriter! We have hundreds of ready- for -lease, or Our AJ 841 features the heavy duty Selectric IBM mechanism to give ready- for -sale terminals that have you fast, dependable operation day after day. Use it in the office. Use been refurbished and repriced it at home. At our price, it's an economical typewriter. to make them a truly Use it as a terminal! outstanding The 841 incorporates our own SELECTRONIC bargain. mechanism that turns it into one of the most useful and reliable computer terminals on the market. Thousands are in operation today. Your choice of EBCD or Correspondence Codes, with APL as an option. It will interface with almost any IBM computer. If you can use an efficient, low cost computer terminal, here's your chance to get one for about the price of a good typewriter alone. If you're interested, call AJ Marketing at 408- 263 -8520, Extension 280, or write for more details.

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www.americanradiohistory.com Continued from page 9 (0.01 of units, remember ?) and to negate the rate of descent, where necessary, so that it Listing 1, continued: shows as a positive number.

Address Op Operand Label Mnemonic Commentary Detecting Input

007A 85 F9 FLY STA INH The KIM -1 monitor subroutine that lights 007C A9 02 LDA #02 } DECK: =02; [counter] the display gives us a free bonus: It also tells 007E 85 E1 STA DECK a key is depressed on the 0080 20 1F 1F FLITE JSR SCANDS look for depressed key; us whether or not 0083 FO 06 BEQ NOKEY if no input go to NOKEY: keyboard. To find out which key, we must 0085 20 6A 1F JSR GETKEY else go to GETKEY; call another subroutine in the monitor pro- 0088 20 91 00 JSR DOKEY go to DOKEY; 008B C6 El NOKEY DEC DECK DECK:= DECK -1; gram. 008D DO F1 BNE FLITE if DECK not equal to 0 go to If we discover that the user has input a F LIT E; I to 9, we first 008F FO DO BEQ LINK else go to LINK; thrust command, buttons 0091 C9 15 DOKEY CMP #15 A: =fuel mode ?; check to see that the motor is on and that 0093 DO 03 BNE NALT if not fuel mode go to we have fuel. Then we set the thrust, and NALT; 0095 85 EE STA MODE else MODE:= fuel mode; also calculate the acceleration as thrust 0097 60 RTS return; minus 5, where 5 represents the force of 0098 C9 10 NALT CMP #10 A:= altitude mode ?; gravity. 009A DO 05 BNE NAL2 if not go to NAL2; 009C A9 00 LDA #00 else mode: = altitude mode; The two other legal keys, A and F, set the 009E 85 EE STA MODE MODE: =A; display mode to altitude or fuel. The pro- 00A0 60 RETI RTS return; 00A1 10 FD NA L2 BPL RETI return; [illegal mode] gram sets a memory location which will be 00A3 AA TAX else X: =A; tested by the display routine. 00A4 A5 EA LDA THRUST A:= THRUST; The program doesn't need to worry about 00A6 FO F8 BEQ RETI if thrust: =0 go to RETI; 00A8 86 EA STX THRUST else THRUST: =X; when a button is released. Although the 00AA A5 EA THRSET LDA THRUST A:= THRUST; question can be quite important for pro- 00AC 38 SEC set carry; grams that must distinguish between, say, 9 GOAD E9 05 SBC #05 THRUST:= THRUST - 05; OOAF 85 E9 STA TH2 +1 TH2 +1: = THRUST; and 99 on the input, the lunar lander doesn't 00B1 A9 00 LDA #00 really care. If you leave your finger on the 00B3 E9 00 SBC #00 } A: =00; 00B5 85 E8 STA TH2 TH2: =00; button, it will keep on setting the thrust 0087 60 RTS return; over and over to the same value, without 0088 45 INIT affecting the flight. 0089 00 [initial height) 00BA 00 1 COBB 99 Coming Down 00BC 80 } (initial speed] OOBD 00 The program doesn't stop. If you run out oOBE 99 00BF 98 } (initial acceleration] of fuel, you will watch yourself freefall to 0000 02 [initial thrust] the surface. When you land, with or without 00C1 08 fuel, your rate of descent freezes so that you 00C2 00 [initial fuel] 00C3 00 can see how hard you landed. 00C4 00 )[mode] It would be easy to have the display change after you land, to show words such as "SAFE" or "DEAD." The KIM -1 display until we realize that both the altitude and is segment driven so that you can easily the fuel gauge will probably go right past the produce special combinations. zero mark, jumping directly from a positive The novice astronaut who would like to to a negative value; so a zero test is out. try his or her hand at flying this, or other, Instead, we take action the instant the craft should keep the following rules in number goes negative, restoring it to zero mind: and then taking whatever other action is 1. Always conserve fuel at the beginning called for. by reducing power to minimum thrust. 2. Don't let your rate of descent get Lighting the Display excessively high; with my program, it's The display is quite straightforward; in wise to steady up with a thrust value fact, the KIM -1 monitor program has a of 5 when your speed gets over 90 feet subroutine to do the job. per second. Depending on the display mode flag, all 3. As you get to lower altitudes, try to we need to do is to move altitude or fuel to balance your altitude against your rate the display area, together with rate of of descent. At 1000 feet, a rate of descent. Then we call the subroutine to descent of 500 feet per second will transfer it to the LEDs. bring you down in 20 seconds, which Of course, we must remember to drop the is reasonable. Keep that sort of last two digits from the displayed values balance.

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www.americanradiohistory.com Continued from page 6 High -Speed pages 106 -107 of the Ballantine Books Cassette Recorder paperback edition: Interface (The Stringy Disk)

The 'Sec was the standard size of all such units, determined by what could fit comfortably in the normal human hand. At a quick glance, it did not differ greatly from one of the small electronic calculators that had started coming into general use in the late twentieth century. It was, however, infinitely more versatile, and 111111lIIIIIIiIMlllllfll (illlllllllllül(IÍi?i!if Duncan could not imagine how life DIP-switch selection of speed from 800 to 12,500 baud would be possible without it. (1,562 bytes per second with tape speed of 71/2 inches Because of the finite size of per sec.). Max speed on a good cassette recorder is 5000 clumsy human fingers, it had no more baud. Bi -phase recording. controls than its ancestors of three Bi -phase recording; self -clocking, digital comparator. centuries earlier. There were fifty LEVEL indicator assures correct volume setting. neat little studs; each, however, had a SYNC indicator shows reception of sync byte. virtually unlimited number of func- Fully buffered with bus drivers. tions, according to the mode of Altair, IMSAI, Tarbell compatible: s -100 bus. operation -for the character visible on Includes all IC sockets, output connector, and pre- recorded cassette tape with sync code. each stud changed according to the Kit $120.00 Assembled, tested $165.00 Manual mode. Thus on ALPHANUMERIC, $3.50. twenty -six of the studs bore the letters of the alphabet, while ten DAJEN Electronics showed the digits zero to nine. On 7219 Springleaf Ct., Citrus Heights, Ca. 95610 MATH, the letters disappeared from (916) 723-1050 residents COD extra the alphabetical studs and were re- Ca add 6% sales tax $7.50 placed by X +, --, -, =, and all the standard mathematical functions. Another mode was DIC- TIONARY. The 'Sec stored over a MORE POWER TO hundred thousand words, whose three -line definitions could be dis- YOUR ALTAIR* played on the bright little screen, steadily rolling over page by page if desired. CLOCK and CALENDAR 12 AMPS @ 8v. (nominal) also used the screen for display, but for dealing with vast amounts of 2AMPS ±16v. information it was desirable to link the 'Sec to the much larger screen of At any line voltage from: a standard Console. This could be done through the units optical inter- 90 to 140 volts. face-a tiny Transmit- Receive bull's - Installs easily inside any Altair* 8800 or eye operating in the near ultraviolet. 8800a. As long as this lens was in visual range of the corresponding sensor on a Over voltage and over current protected. Comsole, the two units could happily

Conservatively . exchange information at the rate of designed and specified megabits per second. Thus when the 'Sec's own internal memory was satu- rated, its contents could be dumped only $90.00 into a larger store for permanent postpaid in the U.S.A. master charge keeping; or, conversely, it could be California residents add BANKAMERICARO loaded up through the optical link $5.40 sales tax. with any special data required for u particular job. PARASITIC ENGINEERING

The Minisec system's characteristics as en- PO BOX 6314 ALBANY CA 94706 visaged by this passage are not really so 'Altair is a trademark of MITS Inc.

133

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_A Dictionary of Microcomputing by Game Playing With Computers by Philip E Burton. In the opinion of BYTE's Donald D Spencer, published by Hayden. editor, Carl Helmers, "This is one of the What does it mean to play games using a best designed and executed dictionaries of computer? Read this book to get an computer related terms yet seen on the introduction into numerous recreational market. It is of particular relevance to those uses of the computer to program and play individuals who want a good general mathematical and logical games. Topics reference to numerous technical terms, include numerous mathematical problems, broadly covering hardware and software casino games, board games, unusual gam- fields as currently practiced?' This new bling games, and miscellaneous logic games. hardbound edition is part of the Garland Numerous BASIC language programs and Reference Library of Science and Technol- listings are included to show details. $16.95. ogy. $12.50. t

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t, _Software Design for Microprocessors. This stand alone guide to microprocessors has been designed by the people at Texas Instruments to convey knowledge to the first time user of microprocessors. This Scientific Analysis on the Pocket _Build Your Own Working Robot by excellent source book of computer concepts Calculator by Jon M Smith, published by David L Heiserman, published by Tab begins with an outline of the basic principles John Wiley & Sons. This book is another in Books. This book will not tell you how to of the general purpose computer, its a set of source books for mathematical build Robbie, the robot of Forbidden machine architecture, software, and meth- analysis using the contemporary products of Planet, or a classical android of science ods of addressing. It proceeds to discuss technology. It is oriented to the pocket fiction. What it will introduce you to is the how to build software, what is involved in calculator, yet it will provide you with problems of making a robot mobile device documenting what you've done once you've algorithms and methods useful with any called Buster Ill, using pre- microprocessor done it, the mechanics of programming, and personal computer which implements the TTL integrated circuits for all logic specific examples using the TI TMS -1000, scientific and analytical functions found on functions. It is a must book for background TMS -8080, TMS -9900 and SBP0400 de- a good pocket calculator. For a more reading, but much of the logic can be signs. You'll find a thick hardcover text- complete description, see the book review extremely simplified using today's micro- book filled with over 370 pages of useful on page 120 of the December 1976 BYTE; processor technology. Use this book as a information including a comprehensive or order its 392 pages of detailed technical first look at these problems from which you glossary of microprocessor terminology, information and review its use for yourself. can build further and more elaborate among several other detailed appendices. $13.75. solutions. Softbound, $5.95. $12.95.

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www.americanradiohistory.com much science fiction. Aside from the size SOFTWARE constraint and memory capacity, the functions of the Minisec as described can be TEXT EDITING SYSTEM accomplished by a well designed contem- TSC'S 6800 TEXT EDITING SYSTEM SURPASSES ALL porary personal computer system. The char- MICRO EDITORS. THE COMPLETE ASSEMBLED SOURCE LISTING NOT ONLY INCLUDES THE USUAL EDIT FEA- size a acteristic of fitting into the of hand TURES. BUT ALSO BLOCK MOVES. BLOCK COPIES. held object is not even necessarily a valid OVERLAYS. AN EXTENSIVE CHANGE COMMAND. AND engineering goal for such a powerful device. TABS. JUST TO NAME A FEW. THIS IS THE EDITOR Why? FOR THOSE WITH SERIOUS NEEDS. SL68 -24 $23.50 Have you ever considered the problem of 6800 8080 6502 typing text passages into a keyboard the size 8080 GAME PACKAGE I. PD80 -1 $19.95 of a calculator? Aside from the frequency 6502 GAME PACKAGE I. PD65 -1 $19.95 6800 GAME PACKAGE I. P068 -1 $16.50 and positioning idiosyncrazies of the stan- 6800 COMPLETE SOFTWARE PACK. P068 -3 $35.50 dard Roman alphabet typewriters we all use (which could be solved by training with the 6800 SOURCE LISTINGS Dvorak system), the design of the text SPACE VOYAGE. SL68 -5 $12.00 FLOATING POINT PACKAGE. SL68 -4 $6.50 keyboards is well adapted to the problem of MICRO BASIC PLUS. SL68 -19 $15.95 quickly typing text. I know that personally PROGRAM OF THE MONTH CLUB from the immense amounts of keystroking I RECEIVE 1 YEAR MEMBERSHIP INCLUDING A MONTHLY do, and anyone who works with computers NEWSLETTER DESCRIBING TSC'S LATEST SOFTWARE a at software level will have similar experi- RELEASES. UP TO A 157. DISCOUNT OFFERED ON ences. A major portion of the information FEATURED SELECTIONS. POM $2.00 processing operations performed with the ORDERING INFORMATION personal computer are now and will always PLEASE INCLUDE 3% POSTAGE. INDIANA RESIDENTS be accomplished using such text keyboards, ADD 47.. TAX (US FUNDS ONLY). CHECK YOUR LOCAL at least for the foreseeable future, barring DEALER FOR OUR PRODUCTS. (DEALER INQUIRIES invention of really efficient voice parsing WELCOMED). SEND $.25 FOR A COMPLETE CATALOG. the physical size constraint techniques. Thus 'FEETECHNICAL SYSTEMS CONSULTANTS .71, 1 a7 L is now and will probably remain at the level x y I. r murre INDIANA 47906 TEE of the size of a text keyboard's physical layout,. hardly a hand held size, but certainly a lap- perched device. Redefining of key interpretations is already accomplished automatically when a 16 K STATIC RAM command language is used with symbolic For ALTAIR / IMSAI / POLY 88 commands typed as text strings. However, having a changeable command keyboard such as Clarke describes is a neat idea. I ran $459 KIT into a specific case of such a keyboard when ASSEMBLED $529

I worked for a short time on an experi- mental digital avionics system design which projection displays to define dif- employed USES 4K STATIC RAMS - NO REFRESH depending ferent legends for key positions VERY LOW POWER - LESS THAN 1 AMP upon mode of operation during an aircraft's Z80 FAST - 200ns ACCESS TIME mission. It is a nifty concept, but a bit PROVISION FOR BATTERY BACKUP expensive at present. The model of the LOW PROFILE SOCKETS FOR ALL CHIPS Minisec keyboard is a very sensible extrapo- EACH 4K ADDRESSABLE TO ANY 4K SLOT lation of liquid crystal style display tech- HARDWARE /SOFTWARE MEMORY PROTECT nologies coupled with switchless capacitive FOR EACH 4K SPECIAL PAGING OPTION ALLOWS UP TO touch contact zones. 1 MEGABYTE ADDRESSABLE MEMORY the physical characteristics of Forgetting LOW COST the implementation, the logical charac- CONSTRUCTION MANUAL $1.75 teristics of multiple modes of operation are PAGING OPTION $9.00 quite realizable with present day personal QUANTITY DISCOUNT 5 BOARDS -5 %, computers, although not always in a pre- 10 OR MORE -10% packaged form as described by Clarke. For DEALER INQUIRIES INVITED example, the whole purpose of the ALPHA- NUMERIC mode is to allow text entry and OMNI SYSTEMS INC. command language style operations, if it is P.O. BOX 7536, UNIV. STATION meaningful to have such a mode at all. The PROVO, UTAH 84602 ASCII keyboard and the text editors ap- plicable to personal computers of today READER SERVICE NO. 198

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_Practical Solid-State Circuit Design by Jerome E Oleksy. A self study course in the design of semiconductor circuits from the TV Typewriter Cookbook by Don Active Filter Cookbook by Don Lan- simple transistor to the complex operational Lancaster. A complete guide to low cost caster. The chief chef of electronics Cook- amplifier. $5.95. television display of alphanumeric data, books concocts another gourmet appetizer. several chapters of which were published Run to this book when you need to find a -101 BASIC Computer Games by David ahead of the book in early issues of BYTE starting point for the design of a filter for Ahl. A treasure store of games and magazine. $9.95 use in an electronic application. $14.95. simulations, 101 all written in BASIC. It contains both a complete listing and a Digital Logic Circuits by Sol Libes. An sample run, along with a descriptive invaluable tutorial background volume on write -up. 256 pages. $7.50. digital logic, arithmetic, 10 concepts and _Altair Design developed by Ensor interfacing to analog devices; written by one Holiday. Projects in Sight, Sound & Sensation of the founders of the Amateur Computer _More Altair Design developed by Ens - by Mitchell Waite. Dedicated "to all space Group of NJ. This book acquaints the or Holiday. cowboys." Detailed theory and practice of reader with much of the terminology and __Altair Design 3 developed by Ensor seven fascinating amateur electronics pro- background concepts of digital hardware. Holiday. jects, along with a complete and detailed $5.98. Keep the loved ones busy while you use appendix on how to make PC boards. $4.95. your system ... give them any one or all of _Modern Operational Circuit Design by these computer generated Altair Design ___.Security Electronics by John E Cun- John L Smith. An absolutely essential intro- books to start them (or yourself) on endless ningham. To catch a thief, apply liberal duction to the use and application of hours of creative coloring. No other coloring doses of ingenuity and a modicum of systems. The book cleverness. Find out what's been in operational amplifier books are quite like these unique books. tried theoretical infor- conventional alarm you go contains both background $2.50 each. systems before mation and practical circuit suggestions off computerizing your home security sys- which can be used to advantage by the tem, though. $5.95, new second edition. experimenter. $22.00 (hardbound). ___Artist and Computer edited by Ruth Leavit. A visual treat, as you encounter Introduction to Biomedical Elect- Electronic Projects for Musicians by reproductions of numerous works by com- ronics by Edward J Bukstein. What's been Craig Anderton. "Even if you know nothing puter oriented artists and read about these done in robot doctors? Nothing so far. But about electronics, you can build preamps, works in their own words. $4.95. in terms of electronic aids to physicians and ring modulators, mixers, tone controls, min - practices of health researchers, consult this iampls, fuzzes and a dozen other inexpen- Linear IC Principles, Experiments, and background review of the field of biomed- sive musical projects." Furthermore, even if Projects by Edward M NoII. From basic ical electronics. $5.50. you couldn't care less about about musical principles to complicated systems, from applications, you can use this book to gain simple amplifier experiments to applications What to Do After You Hit Return of familiarity with electronic parts, circuit dia- in radio, TV and control systems, this book PCC's First Book of Computer Games. This grams and construction techniques, using can improve your knowledge of the way is PCC's first book of computer games, a the wealth of illustrations and tips found in circuitry of the analog world really works. compendium which includes descriptions of an extended introductory chapter for the $8.95. numerous games, and listings of 37 selected novice electronicker. $6.95. BASIC games. $8, new second edition.

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provide this mode of operation. The MATH i .I mode is simply extending the concept of a PRAMMER BASIC or APL or language X interpreter to allow its use with your personal computer to by XYBEK calculate programmed combinations of elementary and transcendental functions. DIC- An extraordinary 2k memory board TIONARY mode is a little bit more difficult, for your Altair- bussed computer primarily because as of today we do not yet * On -board 1702A PROM programmer have the technology to inexpensively store Space for 1792 bytes of read -only memory (seven (with random access) such a large vocabulary * 1702A EPROMs) with associated definition materials. But, * 256 bytes of RAM given a mass storage drive with 2 million or Supplied with one pre - so bytes on line (for example, a 3M car- * 1702A, programmed with stand -alone programming software - no sense tridge) and enough time to do the key - switches are used stroking, a personal information system (a la * Supplied with programming power supply dictionary) with a significant size can be * PRAMMER's own on -board clock makes it compatible built using equipment presently available on with almost any Altair- bussed system. the market. The CLOCK and CALENDAR * All read and write sequences are generated via an functions of the Minisec are so trivial to on -board micro- programmed state machine, thus implement that it's amazing it isn't standard eliminating all one -shots. on all personal computers which are assumed Send me PRAMMER kits @ $189 ea. (Calif. residents to be plugged in 24 hours a day: - It only please add sales tax.) BankAmericard & Master Charge O.K. takes dedication of an interrupt line driven Name by timing signals generated by frequency Address division from the crystal controlled clock of the processor. The interrupt routine updates Zip the real time as stored in an appropriate Call (408) 296 -8188 or write to: programmable memory location or loca- XYBEK P.O. Box 1631 Cupertino, CA 95014 tions, scaling and converting to 24 hour time if desired. As for connection to external larger Why Wait? information systems, the present day personal computer does not exactly use a fast ;ilg Y rra04 l4/10-S'rara. light interface, but it certainly can use a .rI NMI f.- modem and telephone link at 300 bps or so. ^ A mix amp WWI PINIr Modems are available in kit or surplus form IN..e! Lt-St at quite reasonable prices today, and are =M; WM MOM likely to be a drop in the price bucket compared to the costs of the timesharing services themselves unless you just talk to The Tarbell Cassette Interface your neighbor's computer. Plugs directly into your IMSAI or ALTAIR* The Future Comes Faster Than Anticipated Fastest transfer rate: 187 (standard) to 540 bytes /second What this all boils down to is the conclusion that the design and function of Extremely Reliable - Phase encoded (self - Arthur C Clarke's conception of the ultimate clocking) personal computer is a lot closer to reality 4 Extra Status Lines, 4 Extra Control Lines than he might expect. The actual dates he 37 -page manual included gives for the progress of technology into the

Minisec stage I do not recall, but I certainly Device Code Selectable by DIP -switch suspect that he put it further into the future Capable of Generating Kansas City tapes than the present day and the next few years. also But, then, one purpose of science fiction is No modification required on audio cassette to explore technological scenarios given an recorder author's defined set of outrageous premises. No one should believe that there is any Complete kit $120, Assembled $175, Manual prophecy about when the scenarios are $4 played if ever. Rather, the ideas and specula- TARBELL ELECTRONICS tions serve as inputs to the imaginations of 20620 S. Leapwood Ave., Suite P, Carson, Ca. 90746 the innovators of practical products as the (213) 538 -4251 technologies progress. Viewed in this light, California residents please add 6% sales tax Arthur C Clarke's concept of the Minisec ALTAIR is a trademarkltradename of MITS, INC.

137 www.americanradiohistory.com Adam Osborne's books An Introduction page) detailed volume which complements

to Microcomputers, Volumes 1 and 2, are a the information in the first volume. This is concise compendium of the technical details the volume which fills in many of the details of microprocessors at the component left out of the conceptual treatment in (engineering) level. These are the source Volume 1. Here you'll find 19 detailed books for the system designer who plans to chapters on the engineering and logical employ the microprocessor, or the advanced specifications of products made by 16 homebrewer who wants a dash of custom- different manufacturers, including in many ization not found in commercial products. cases reprints from the manufacturers' documentation as well as new materials

Volume 1 is subtitled "Basic Con- provided by the author. Published in 1976, cepts." This is the book which presents a it even includes such processors as the framework of ideas concerning the design MicroNOVA by Data General and the Texas and use of small computers implemented Instruments TMS -9900 as well as the older 8 with LSI. Topics include definitions of the and 16 bit machines. Organization is by microcomputer, fundamental concepts of design type, and where parts of several logic and numbering characteristics of manufacturers were intended for a given instruction sets, etc. $7.50. processor design such as the 8080, these are grouped into a single chapter. $12.50 Volume 2 is a much thicker (895

_ _ How to Buy and Use Minicomputers and Microcomputers by William Barden. People have often asked us where to turn to get an COMPLITER introductory book about computers POWER for personal use. One excellent place AND to start is How to Buy and Use Minicomputers and Microcomputers, HLIMAN William Barden Jr's instant summary REASON of the small computer revolution, JUDGMENT Digital Computer Fund- FROM published by Howard Sams in mid - TO CALCULATION amentals by Jefferson C Boyce. 1976. This is one of the first books The way to a world of learning is of the "general introduction to through books. A great place to start, computers" genre to be published and to return from time to time, is Computer Power And with an emphasis towards the small Human the classical textbook. This new Reason by Joseph Weizenbaum. This computer and personal computing as book from Prentice Hall is in- book is one be it is being practiced these days. the which should tended as just that. Topics covered purchased or read for several reasons. book, written for the novice as well include digital computer operation, If you're presently a programmer by as the expert, surveys the technical and concepts, a basic computer circuits details of the field in nine chapters trade or skill, you'll see philosophy Boolean algebra, implementing com- of computer use and abuse pro- and 10 appendices. This book is light puter in hardware, com- pounded. It's genuinely interesting, operations (but essential) reading for the experi- the computer and and provocative if you municating with enced computer person, and worthy definitely related schemes, reference the storm of letters, issues of coding of serious, concentrated perusal by coun- letters detailed discussions of the control the novice. $9.95. ter and counter counter letters section, memory functions, arithme- which this book produced in the tic and logic functions, input and Association for Computing Machin- How rouwcueo output functions of a classical com- ery's SIGART newsletters during MIIyICOMPUTERS R puter, a chapter on computer pro- 1976. If you're a novice to the field, MICROCOMPUTERS gramming and a final summary the tutorial and explanatory chapters chapter on the details of a typical of this book, which are aimed at the minicomputer design interpreted in layman, will serve as an excellent the light of the more theoretical background source which is also general concepts in the book. This eminently readable This includes an book is excellent background infor- excellent and low level explanation mation for the literate and well read of what an algorithm is, and how hacker. Order yours today. $15.95 computers go about executing effec- hardbound. tive algorithms. $5.95 softbound.

Send to: Check payment method: My check is enclosed BITS, Inc 70 Main St GO Bill my MC No. Exp. date Peterborough NH 03458 Bill my BAC No. Exp. date

Total for all books checked Name Postage, 25 cents per book Address - - _ for _ books Grand Total City State Zip Signature You may photocopy this page if you wish to leave your BYTE intact. Please allow six weeks for delivery.

www.americanradiohistory.com MULLEN COMPUTER BOARDS personal computer and its uses throughout the book Imperial Earth is a most inspiring BOX 6214, HAYWARD, CA 94545 input which designers of personal computers would do well to explore.

A CHALLENGE ... The Logical Squelch, a Noncommercial Product Occasional, functional specifications of REIAMIPIO neat ideas can be fun. Here is one which was dreamed up by yours truly and Judy Havey ISOLATOR while preparing the April issue. We both love to listen to classical music FM radio stations CONTROL g while working, principally WGBH and WCRB out of Boston MA. What we were BOARD 6117 talking about was the fact that while we g certainly appreciate the fact that advertising supports the commercial radio station 8 fast reed relays respond to an 8 bit word: Feed with its bit a and it closes, give it WCRB, we sometimes get just a bit tired of the relay associated "1" a "0" and it opens. Also, 8 opto- isolators accept an 8 bit hearing the same commercial or announce- word from the outside world and send it to your corn- ment over and over again. So, I said to puter for handshaking or Further control purposes. be a neat hack myself, wouldn't it to Especially suited for model railroad, burglar alarm, develop an audio input processor backed up audio switching, ham radio, music synthesizer, and auto- Y by an Al algorithm which has the following mated display applications, this board goes wherever

characteristics: you need a general purpose 1 /0 switching gizmo. Were proud of the design work and quality put into the signal Continuous digitization of this applications- oriented peripheral; and with it, you and characterization of the past "n" take care of that 1 /0 gap in your system. milliseconds by a set of numerical Acan in kit form only. California mail orders: constants reflecting the signal being OAvailableadd state tax. digitized. A manual switch input used for pATIBLE AVAILABLE BY MP "catching" various unwanted signals and storing the empirical parameters for the previous time period (goal: perhaps 16 to 128 bytes characterizing a segment of the signal with a high probability of uniqueness). 1NTE1. A monitoring algorithm which seeks a match between stored signal parameter Ohp u1ag_1644H- sets and the incoming pattern, perhaps UlPa1tÍ with a "criticality" parameter which it to tir... YOUR ALTAIR 8800 adjusts a fudge factor tolerance on the can't run well without match. When a match is found, the a correct, reliable C.P.U. clock. "squelch" signal is given to the output level control peripheral. A PARASITIC A level control peripheral which is ENGINEERING either full "on" or in a squelched clock fix kit is guaranteed to state, with a timing oneshot used to produce(P1 and(1)2 stretch the squelch period over an clock pulses, that adjustable time of a half to two meet Intel's specifications for the minutes or so. 8080. Installs easily on

Hole These are Ihe equal clock revelCome al the your Altair' 8800 or In this simplest conception, no attempt is BOBO es proopced by a Paruinc Engineering board. Clock F,. ICI 8800a C.P.U. made at fancy word recognition, or recognition of voice characteristics of announcers. Such embellishments would of course be only $15 BANNAMERICARD most desirable, but who knows what is postpaid in the U.S.A. possible until it is tried? Who'll be the first to build this logical squelch device and write ENGINEERING it up as an article for perusal of our other PARASITIC readers? ... CH PO BOX 6314 ALBANY CA 94706 'Altair is a trademark of MITS Inc.

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www.americanradiohistory.com the Green Oaks Inn, Fort Worth TX. For Bories," pictures and describes 200 re- further information contact Alton R placement and enhancement items for Goddard, publicity chairman, at AEDS use with Digital peripheral equipment, National Headquarters, 1201 16th St including media for disk and magnetic 13YT['$ 1311$ NW, Washington DC 20036, (202) tape drives; paper supplies, ribbons and 833 -4100. baskets for printers, plotters, terminals, paper tape and card readers; terminal Attention Education Users stands, chairs, tables and other convenience accessories. The 56 page color Catalog of Computer Supplies Available The fifteenth annual convention of catalog includes order blanks and is the Association for Educational Data A new catalog from Digital Equip- available from Communications Services, Systems will be held April 25 -29 1977 at ment Corporation, "Supplies and Acces- 444 Whitney St, Northboro MA 01732.

The Grapevine's Latest Goblet of Divine Juice According to the volcano of rumors and other premature enthusiasms, Jim MOO 18.0 Warren of Dr Dobb's Journal of Com- puter Calisthenics and Orthodontia (PCC OOP 8211 Box 310, Menlo Park CA) in a public utterance at a Homebrew Computer Club meeting January 19, there are some goodies in the works from Zilog. Dr Dobb himself (alias Jim Warren) says

10 SI that reliable reports indicate the Z -200 is Zilog's next product, a high level language stack machine which directly executes PASCAL constructs as its

10 11 If 11 14 IS 10 machine level language. It remains to be 711 71 74 seen whether this particular concoction 28 JAI a2 SO 81 74 VS IA 70 VP 18 is grounded in reality or the result of several stages of quite nonlinear amplification.

IS 16 la 1.14 20 21

22 21 24 141 .4 P7 VO Two Computers in Every Home, 10 11 Motherhood, Pizza, Apple Pie, et al

21 21 21 24 2S 26 2,7

71 111

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10 19 IM 21 21. 74

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.88

as This Bit was supplied as by Chuck Adams at The latest word we hear is that a firm Texas A &M University, with the name Computer Shack, tied up in some nebulous way with the people SO College Station TX. who bring you another kind of electronics oriented Shack, is planning to double or quadruple the present number OS Oft es 06 of computer stores in existence through

e. a nationwide franchise program (see ad- 110 a. 00 1111 vertisements in BYTE, as well as an ad 011 which has run in Computerworld several times). Here's one of the people responsible, Ed Faber, president of Computer Shack Inc, located at 14860 Wicks Blvd, San Leandro CA 94577.

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www.americanradiohistory.com BYTE on how to program these chips, In.r:t ,, ,i; which will be seen more and more IJttlltl ,i,r.7tt1, i.;.rillt frequently ,. l,l':Yt/. lg. 1 in personal computing circles ltrl;: tn uc ctt- over the next half year or so. The lusc', l 1 .,,nsits tn. It What's significance of the TI announcement is t'r) y mat- that it marks entry of alternate sources and 'e rtlat- Lc LT). 'ttu into a market which in the past has been _rior c-- r outer New? characterized by high initial production Yet o y;ttrt.led prices. At BYTE, we paid nearly $100 the dorsal for a 2708 several months ago (quantity rebel' lilla ob- 18'8 " one, from a distributor). As TI and all See RE; / the rest of the new 2708 sources corn - tBR:11N. ROM Programs Beget ROM pete their way down the "learning nce a tian- Programs ... curve," we can expect to see these prices ionding drop if past history is any clue. Don't be ,w usu- surprised if the cost of a completely rtellect; filling a Cromemco BYTESaver board .$)l uut Brain ! .t with 2708s (8 K worth in 8 chips) has dropped to about $400 within one year. frequently used programs; so the more Locally programmable EROM parts are vendors there are, the better the pros- quite useful to have around for storing pects for a reasonable price.

From Sweden: LYS -16 Memory address space for up to This new programmer for 2704 and -Telaw Göran Peterson, of AB Aero 64 K bytes. 2708 memory parts is an example of the Atew, Box 125, S -642 00 Flen, Sweden, 256 byte miniature operating creative use of a microprocessor to sends us a flier on a new small computer system including a 1200 bps serial engineer a system which has features product which his company has intro- interface for audio recorders. which would be difficult if not impos- duced. The product is the LYS -16, television interface (which obvi- previously. is sible to achieve The system designed by the Computer Society of the ously must be designed for the a microprocessor controlled programmer Linköping Technical High School in local power line frequencies). which allows the user to create, edit and Sweden, and available either in kit form manipulate data in a buffer memory or as a finished product. The technical The first deliveries are scheduled for using an RS -232 or 20 mA current loop specifications of this product include: the spring of 1977, and the price is listed (Teletype) terminal interface. In a hypothetical computer store PROM programming center, this programmer with its interactive command sequences would be connected to a terminal or one About of the demonstration computers of the Confused store, so that customers could edit and Printers? try out programs before committing them to PROM. One can conceive of the retail store selling time on the programmer at X$ per hour, with X set to amortize the cost of this $850 device and its terminal in a reasonable time. And of course the industrial and commercial firms who design products with microprocessors will find this device a most useful piece of equipment for the microprocessor design and production facility. The company which makes this device is Shepardson Microsystems Inc, 20823 Stevens Creek Blvd, Bldg C4 -H, Cupertino CA 95014. According to the press release, new products which MPI HAS YOUR ANSWER! include a multiple socket version of this TTY REPLACEMENT? THE SSP -40 programmer and additional programmers $575 The SSP -40 contains its own microprocessor for easy ç. on-, ec lunn with similar features oriented towards to your serial pore bipolar PROM products are due soon. LOW COST BUSINESS SYSTEM? THE MP-40 $425 The MP-40 connects to your parallel port for ASC17 data transler

MINIMUM COST FOR HOBBYIST? .. . THE KP-40 KIT $179 a Enough Finally, We'll Get Low The KP -40 KIT contains mechanism and minimum electronics for Price for the 2708 Connection to your parallel port texas Instruments has recently an- Allot our 40 series printers use the same reliable 5x7 impact dot matrix mechanism with up to 40 columns per line on ordinary paper with a print speed of 75 lines /minute nounced its entry into the 2708 EROM WELCOME UTAH RESIDENTS ADD 5% SALES TAX market with the TMS2708JL part. This MASTER CHARGE is an 8 bit by I K memory part with SEND FOR FREE LITERATURE 450 ns access. time, static operation and MICROPROCESSOR SYSTEMS AND PERIPHERALS TTL compatibility, in a 24 pin package which will plug right into many micro- mpi P.O. BOX 22101 /SALT LAKE CITY /UT. 84122 processor applications. We've got an (801) 566 -0201 article coming up in a future issue of

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www.americanradiohistory.com New and Used as 5900 Sw Crw (based on foreign exchange rates quoted in the December 15 1976 edition of the Wall Street Electronic Surplus Journal, this is equivalent to about $1357 in US currency). According to the flier, the company has about 180 CRT Terminals employees and plans to offer a floppy Peripherals disk option in the near future as well.

Electronic Assemblies Micro Cosmos PLEASE Components Robert Tripp, publisher of The Computerist, has announced a package of software for the KIM -1 system which he's selling for $10. According to his announcement, the features of this package, distributed on a KIM -1 cassette, Tape Drives - None include:

Higher than $1195 timer routines with 1 ms accuracy. a clock program displaying hours, minutes and seconds. an adding machine program with six digit addition /subtraction. a decimal to hexadecimal (and l vice versa) conversion routine. a drunk test program. and a much longer list of gim- micks and programs ....

He even claims to have a "high level language" as part of the package, and that the whole set of programs is designed to run in an unmodified KIM with minimum memory. The package is Keyboards 1 to be distributed with complete source listings, operating instructions for the demonstration programs, and instruc- Components - Power tions on how to write programs in the Transistors, Diodes, Resistors, Capacitors PLEASE high level form. Integrated Circuits - from Write Micro Cosmos, 210 Daniel 10 Cents Webster Hwy S, South Nashua NH Equipment Cabinets 03060. Transformers New Hobbyist System Supports Timesharing

The SIXTEEN /8, a new personal computer announced by Western Digital Send for a free catalog or Corp and The Computer Mart of Orange County CA, is the first personal system to our knowledge which supports full Call toll free 800 258 -1036 scale timesharing with multiple terminals in NH 603 885 -3705 and active jobs. The system offers an Come to our Showroom instruction set similar to the Digital Equipment Corp LSI -l1, but comes as two fully assembled cards which plug VOLUME AND INSTITUTIONAL DISCOUNTS AVAILABLE into an Altair or IMSAI backplane and permit the use of existing memory and peripherals. The price of the system with W RLDWIDE ELECTRONICS INC. software is $1295, and the source code for all software is available on floppy 10 Flagstone Drive, Hudson, New Hampshire 03051 disk for the cost of distribution. Send my free catalog to The SIXTEEN /8 hardware, micro- NAME: code and software were developed by Dick Wilcox, a Western Digital employee heavily involved in development of the ADDRESS: LSI -11. The new machine's microcode

implements essentially the PDP -1 I instruction set as seen from the assembly I'm especially interested in: language level, including the floating ONEW OTERMINALS point option; but the instruction en- O USED O PERIPHERALS coding is different and several PDP -l1 instructions have been omitted in order OAS IS O COMPONENTS to discourage the use of proprietary DEC O ASSEMBLIES software. A number of instructions have

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www.americanradiohistory.com been added which considerably enhance the power of the SIXTEEN /8: these include short immediate mode, multiple bit shift, and block move instructions; table indexed jump .uicl subroutine call instructions; "load effective address "; and instructions to save and restore registers on the stack. Typical instruction execution times for the SIXTEEN /8 range I rom 3 to 10 µs. To permit the use of existing 8 bit Your Mail Order Computer Shop... microprocessor memory and peripherals, the PDP -I I peripheral addressing struc- IMSAI 8080 kit with 22 slots (limited quantity) $599.00 ture was revamped to support 8080 style TDL Z80 ZPU (the one with full software available now) 242.00 10 transfers, and external demultiplexing Edge Connectorsand guides for IMSAI each 4.25 logic involving some 70 TTL chips was Edge Connectors and guides for IMSAI I O for 40.00 added to interface a 16 bit processor to Seals 8k RAM kit with 500 ns chips 225.00 an 8 bit bus. The SIXTEEN /8 also Seals 8k RAM kit with 250 ns chips 260.00 North kit 599.00 supports 16 bit memory, vectored inter- Star complete Micro -Disk System rupts, and multiple DMA ports. The software for the SIXTEEN /8 was WE TAKE MASTER CHARGE OR BAN KAMERICARD developed by a Dick Wilcox over period For phone and mail orders... BAMAAM[AICAAO of 4 I/2 years on a PDP -11/40 in his (Add 4% of TOTAL ORDER for service charge) Q+A.L7 back bedroom and has been sold to a TERMS: charges CPU large number o1 large commercial users. The Shipping - $10. per or units, $1.50 per kit, $2. minimum per order. basic operating system supports floppy Provided stock is available, we will ship immediately for payment by disk space management and a multi -user cashiers check or money order. file system; multiple interactive termi- Allow 3 weeks for personal checks to clear. New York State residents add appropriate sales tax. nals, each of which may control several PRICES SUBJECT TO CHANGE WITHOUT NOTICE. concurrently running jobs, and segmen- tation and overlay loading for user pro- For the best prices available on: grams. Operating system calls support IMSAI TDL NORTH STAR POLYMORPHIC device independent 10 for all programs NATIONAL MULTIPLEX SEALS ELECTRONICS and devices. User written drivers for special purpose devices are easily added CALL: (315) 637.6208 to the system. The timesharing facilities WRITE: P.O. Box 71 Fayetteville, N.Y. 13066 do not however, include virtual memory management or swapping to floppy disk; i nor is memory protection provided at present. tck Boards DO Something Program development software in- ct-Irr1 cludes a text editor, a macro assembler, a ì1. ion CL2400 linkage editor which combines separately p Real Time Clock assembled programs, and a symbolic F t 1' r U debugger which permits run time references to source code names. A power- $98 -Kit $135- Assembled ful BASIC compiler (not quite finished at the time of this writing in mid- If your system needs to know what time it is, our CL2400 is January) supports a wide range of the board for you. The present time in hours, minutes, and BASIC language features, 11 digit seconds is always available for input, and is continuously floating -point precision, and interactive updated by the highly accurate 60 Hz power line frequency. or speeds batch execution with esti- Need periodic interrupts? The CL2400 can do that, too, at any mated at 18 -20 times that of MITS 8 K of 6 rates. Reference manual with BASIC and assembly BASIC. An 8080 cross assembler is also language software examples included. provided with the system. Other software includes a line print spooler and a CRT based job status monitor. The PC3200 entire source code occupies about two Power Control System doten fully loaded floppy disks. Use of the system is likely to require PC3232 5299-Kit $360-Assm. substantial amounts of main memory. PC3216 S189-Kit S240-Assm. The basic operating system occupies 10 PC3202 $39.50-Kit S52-Assm to I I K bytes, and the BASIC compiler requires 12 K bytes; a practical system If your system needs on /off control of lights, motors, for a single user might well include 2 -1 K appliances, etc., our PC3200 System are for to 32 K bytes of memory: components Although the features described for you. Control boards allow one I/O port to control 32 (PC3232) this system seem quite incredible, the or 16 (PC3216) external Power Control Units, such as the SIXTEEN /8 was demonstrated recently PC3202 which controls 120 VAC loads to 400 Watts. Optically to members of the Homebrew Computer isolated, low voltage, current -limited control lines are Club in Santa Clara CA and appears to standard in this growing product line. be a reality. Deliveries should be under- way by the time this note is published. P.O. Box 516 Also planned for later introduction is a h...k La Canada, CA 91011 complete package using 16 bit memory Real World Electronics" (213) 790 -7957 and a selfcontained floppy disk drive, _

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www.americanradiohistory.com controller, and power supply. Inquiries Katella, #10, Orange CA 92667, (714) One place is a company called Power about the SIXTEEN /8 should be ad- 633 -1222, or to yoúr local Western One Inc, 531 Dawson Dr, Camarillo CA dressed to The Computer Mart, 625 W Digital representative. - Daniel Fylstra 93010. These people have a new "Disk Drive Series" of power supplies for use in single and dual drive floppy disk memory systems. The product is aimed at the OEM (Original Equipment Manu- Attention Floppy Users ... facturer) systems house which puts to- Here's a Power Supply Module for You gether custom products using floppies Suppose you decide to build a floppy and other subsystems. interface, such as the one Ken Welles These supplies will also prove to be a described in February BYTE. One of the good item for computer stores to carry factors you'll have to consider is the to augment independent handling of power supply for the floppy itself. This floppy disk component lines and inter- key component is not part of the price faces. Retailers should find the 2 year of the bare drive, but generally is in- factory warranty a useful selling point cluded if you buy a commercial floppy along with overload and overvoltage interface package. If you have the right protection. For individuals dealing direct

voltages and spare current capacity sit- and prepaid, the 1 to 9 unit prices range ting around in some other supply of from $69.95 to $120 depending upon your system, there is no problem, but model. If you're interested, write for the where do you go if you don't have a brochure on the disk drive series, Models proper supply? CP -162, CP -205 and CP -206.

The IMSAI Hard Copy Option ing double size characters for headings. This new $399 (kit, or $549 The controller features automatic line assembled) printer interfaces to an 8 bit wraparound so that output lines greater parallel output port. It is a selfcontained than 44 characters in length are printed unit with case, cable, power supply, on two or more lines with no software timing, control and character generation tricks. Since it is an impact printer it can logic. The interface is through a parallel be used with multiple copy forms using cable so it should be quite easy to install carbon or NCR paper. For further infor- through any parallel interface board. The mation on the IMSAI Printer, write to type font is a standard 64 character IMS Associates Inc, 14860 Wicks Blvd, ASCII subset, with the option of print- San Leandro CA 94577.

elvt atalc.4wrEd...L.t Ineerzy z vbrr

WHEN? WHAT? WHERE?

HUGE FLEA M.1 RKIST - HARDIVAR/i & SOFTWARE

General Registration - $4.00 (Student $2.00)/ Sales - $ 2.00 per spot FestinaI will be TRENTON si- iE COLLEGE EXHIBITS - DISPLAYS 'TECHNICAL TALKS CONTESTS Route 31 Apri130 /Slay 1. 1977 Amateur Computer Club Convention Trenton, ,Vea, Jersey beg' ' g at 10:00 a.m.

HOME COMP( "PING - PRIZES - .N:INI'FAC/'(!RIZRS BO( rum

Special IEEE Conference on Consumer and Hobby Application of Micro C,,u,,,,wr ! For further information: Can: Jaci Di Paoli, Write: TRENTON COMPLIER FESTIVAL 609.771 -2487 Trenton State College Trenton, ,V. J. 08625

144

www.americanradiohistory.com Computer Stores in Canada - How many are there?

Many stores have opened in Canada within the last year or so. Seven stores are known to us, and there are probably The Great quite a few more which we do not know about. We would appreciate our readers pEngioNg telling us about stores not listed here. International Pacific Computer Store 4509 -4511 Rupert St Vancouver BC V5R 214 (604) 438 -3281 Math On Keys

The Computer Place 186 Queen St W Book Toronto ONT M5V 1Z1 (416) 598 -0262 From Texas Instruments

Focus Scientific Do you need a numerical algorithm for calculating exchange 160 Elgin St rates in a hotel on a foreign trip? Or figuring those Ottawa ONT K2P 2C4 mysterious "points" when facing the sanctimonious charisma (613) 236 -7767 of a banker at mortgage arrangement time? This book is a compendium of simple explanations and step by step Computer Master Systems Ltd procedures for accomplishing numerical solutions to 69 Gloucester St numerous commonly encountered situations in daily life. Each entry is characterized by a statement of the problem, Toronto ONT M4Y 1 LB (416) 924-9789 including the elements of theory required, and the keystrokes needed to solve the problem on an algebraic entry calculator. First Canadian Computer Store Ltd This is an invaluable sourcebook of information for the 44 Elington Ave person who is inclined to manipulate numbers. $4.95, plus 35 Toronto ONT M4R 1A1 cents postage. (416) 482-8080 Send now to: Computer Hobby Shop BITS, Inc. Master Charge and 4812 16th St SW 70 Main Street BankAmericard Welcome. Calgary ALBERTA T2T 4J5 Peterborough N H 03458 (403) 243 -6776 Please allow six weeks for delivery. The Computer Shop 3515 18th St SW Calgary ALBERTA (403) 243 -0301

/ATM Subscriptions

Since our subscriptions have increased so greatly, we have decided to use a subscription service. This new service will make it possible to serve you better and faster.

According to theory, any systems transition is supposed to be smooth. However, if there should be some unexpected and unplanned problems, please bear with us during this transition period.

Please address all subscription correspondence to

BYTE Subscriptions PO Box 361 Arlington MA 02174 (617) 646 -4329

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www.americanradiohistory.com If you'd like to find out more about the Clubs and San Diego Computer Society, drop a note to POB 9988, San Diego CA 92109.

Newsletters Computer Ham? Check out AMRAD The Amateur Radio Research and Devel- opment Corporation is by, of, and for those people who are the vanguard in their hobby, Want to help your club reach out to the ham radio. Speeding up radio communica- nearly 200 computer groups around the tions often means the employment of country and the world, share information, computers. AMRAD is making an attempt at newsletters and valuable organizational organizing a regular newsletter which could experience? That's what this column is here conceivably be a boon to people of similar for. We'd like nothing more than to help interests. If it's going to work, they'll need your group benefit from the attention it will your support. Contact Amateur Radio receive from a writeup in a magazine that's Research and Development Corporation, widely read by people like you. People who 1524 Springvale Av, McLean VA 22101. are forming groups are invited to send details or questions. New clubs are especially Trenton Computer Festival welcome. We ask the more established to put Trenton NJ, the place where it all began us on their mailing lists. All correspondence for amateur computer festivals, is about to should be addressed to Peter Travisano, do it again on April 31 and May 1 1977 at BYTE, 70 Main St, Peterborough NH 03458. Trenton State College, Rt 31, Trenton NJ. It looks like this is going to be a good sized fair with 30 speakers, up to 90 demonstrators Personal Systems - San Diego and an outdoor flea market. Forums are Computer Society planned on microcomputers for home, radio amateurs, education and medicine, consumer It's always a pleasure to sec a job well applications of microprocessors, computer done and the San Diego Computer Society's robots, graphics, speech synthesis, publication Personal Systems does its job music, establishing amateur computer standards and well on a monthly basis. There's plenty here a computer club convention. for the thoughtful hobbyist to read through, Sponsors include a number of groups: think about and experiment with. Dr Lance Amateur Computer Group of New Jersey, Leventhal's first rate series, "The Micro - Philadelphia Area Computer Society, Tower" is always a treat, and there are Trenton State College Digital Computer plenty of other goodies. A recent issue Society, Institute of Electrical and Elec- carried what looked to be an interesting tronic Engineers Princeton Section and program in F -8 machine code called - the Department of Engineering Technology, Mastermind - a game of code breaking College. which will probably tantalize and challenge Trenton State It is expected that attendance will exceed the best of us. Someone finally did it, the 3,000. There will be amateur computing article many of us wanted to see, but were contests and awards, a Saturday night afraid to ask for, "The Complete and Utter awards banquet, programming copying ser- Idiot's Guide to Computer Programming," a vice, forum audio cassette copying service, reprint from a recent issue of the Homebrew service between hotels and motels Computer Club's newsletter. This should free bus and fest, activities for wives and kids, and save a lot of aggravation for people just free parking for up to 4,000 cars. breaking into computers. Of interest to anyone with the ability to For more information write Trenton Computer Festival, Trenton State College, get there is the West Coast Computer Faire Trenton NJ 08625. to be held April 15 through 17 1977 at the San Francisco Civic Center. According to Société d'Informatique Amateur du Québec Personal Systems, the Faire is expected to draw from 7000 to 10,000 people. There Computer buffs in Quebec will be glad to will be 50 to 100 tutorials, an exposition of hear of the formation of the first French homebrewed, exotic, and low cost systems, speaking computer club, Société d'Infor- components, and you name it, along with matique Amateur du Québec. Hobbyists commercial exhibits. In short, it promises to from everywhere in the province are invited be an incredible experience for those inter- to get in touch with Ricardo Talbot at ested in computers. (418) 522 -3349 during the day or (418)

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www.americanradiohistory.com 522 -4872 at night. Correspondence and Pop, is up and running again after a should be directed to him through IRISCO year's absence. In it is news of an informal du Québec Inc, 376 du Roi, Suite 304, forum for hobbyists to share information, Québec PQ 2W6. SIAQ looks forward to successes and mistakes. Neophytes are relations with all clubs in Canada or the US invited to come in and learn from veterans willing to forward their newsletter. so they won't have to reinvent the wheel. Bon chance. Most meetings include speakers and a "Random Access" period in which individ- South Florida Computer Group uals can obtain personal information and help from others in the group. Get in touch We came across this ingenious little ditty with SMUG at POB 161513, Sacramento, in volume I #9 of the South Florida CA Computer Group's newsletter reprinted from 95816. "Florida Skip" and thought we'd pass it on to you. Stony Brook NY Xvxn though my typwwritxr is an old We've just received word that a new modxl, works for it quitx wxll xcxpt onx group of hobbyists has formed on the 46 kxys wxll kxy. Thxrx arx that function campus of the State University of New York xnough, but just onx kxy not working at Stony Brook. The Stony Brook makxs thx diffxrxncx. Home -Brew Computer Club is an informal mx Somxtimxs it sxxms to that our group, both hardware and software oriented. group is my not somxwhat likx typxwritxr, Members have their own systems and the use all thx kxys arx working propxrly. You may of the school computer to experiment with. say, "Wxll, I am only onx pxrson. It won't To learn more about the Stony Brook makx that much diffxrxncx." But you sxx, Home -Brew Computer Club write to Ludwig for the group to bx xffxctivx nxxds thx Braun, Professor of Engineering, State activx participation of xvxry pxrson. University of NY at Stony Brook, Stony Conducted by So thx next timx you think you arx only Brook NY 11794. Peter Travisano onx pxrson and that your xffort is not nxxdxd, rxmxmbxr my typxwritxr and say to yoursxlf, "I am a kxy pxrson and nxxdxd vxry much!" Those people in the Fort Lauderdale - 1702A MANUAL EPROM PROGRAMMER Miami area should look into the advantage Features hex keypad, two of joining the South Florida Computer Club, digit hex address and two ) lib digit hex data display. Con-

410 NW 117 St, Miami FL 33168, . trols include load, clear, go! Ilia (305) 685 -1218. (step), key /copy, data in/ !, - z data out, and counter up/ U`.LQi 1$ eat Profile includes ¡ osou Society down. card Tulsa Computer high voltage pulse regulator, .,.' i ' 0000 timing, 8 bit address and 8 Some information on a going computer bit data drivers /receivers. Two 6'/" x 9" stacked cards with group in Tulsa has found its way to this spacers. Allows programming in 20 minutes - copying in desk. The Tulsa Computer Society has been 5 minutes. Requires +5, -9, and +80 volts. ASSEMBLED $299.95 in existence for nearly a year, meeting the KIT $189.95 last Tuesday of each month. Write: Tulsa NOW Computer Society, POB 1133, Tulsa OK The best of two worlds ... use our 1702 EPROM programmer 74101 or call Jerry Henshaw at (918) as a manual data /address entry programmer ... or connect it to your processor. 836 -7364. IMSAI / ALTAIR computer interface (requires 3 output ports, +1 input port) and software $49.95 North Central Ohio Briefcase unit with power supplies and interface connectors (assembled and tested only) $599.95 We're always glad to mention new clubs ANNOUNCING in these pages and the North Central Ohio Our NEW 16K Byte Pseudo- Static, IMSAI /ALTAIR compat- Computer Club is no exception; it's an ible RAM. Single card slot. Uses less power than equivalent low power RAM. All memory chips socketed. Uses all prime, organization for hackers in the Mansfield OH factory fresh ICs. High quality, two -sided, through -hole- area. For details contact Bill Hicks, plated circuit board. Crystal controlled, totally invisible 618 Teakwood Ct, Galion OH, (419) refresh system requires NO software management. Just plug it in and use like STATIC memory. 468 -7477 (home) or (416) 468 -8975 (work). Complete kit $349.95 Assembled, tested, and burned in $549.95 SMUG in Sacramento ASSOCIATED ELECTRONICS 12444 Lambert Circle Garden Grove, CA 92641 The newsletter of the Sacramento (714) 539 -0735 Microcomputer Users Group (SMUG), Push

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www.americanradiohistory.com continued from page 59 control, artificial intelligence techniques UPSIDE DOWN DATA ANYONE? and applications of microprocessor intel- I'm certainly not a computer expert; ligence. however, a very interesting and confusing Blondefield. The mechanics of the sys- The mechanical problem is a difficult aspect of the computer compatibility

tem are the major problem for experi- one when you change the context from has come to my attention. I understand menters now in robotics. Remember that that of my "tinkerer's.' point of view to a lot of time and effort has gone into we're talking aboyit preliminary, very the point of view of the production setting up a standard format for data basic devices. The problem for experi- engineer who wants to muss- produce u exchange; however, there seems to be menters is that its no fun at all to work reliable device, where reliable is defined some confusion in definitions, especially with systems that don't do anything, iii a matnner similar to Detroit's defini- for newcomers like myself and appar- don't move about and fend for them- tion of a reliable car: u neighborhood ently others: definitions of marks and selves even in a primitive way. It is specialist can fix the product without spaces, Os and I s, etc, at true logic levels extraordinarily difficult to design and totally redesigning it.... CH for users and experimenters. build a reliable "vehicle," even a wheeled device without reaching members... and that's a requirement if the work is really to deal with robotics and not only conventional electronics. That's where our effort is beginning - with the mechanics, to which an array of sensory and iudgemental circuitry may be fitted. Circuit design is proceed- CRT ing in parallel, of course, but the mechanical system is of paramount importance in the short haul. Without dwelling on the matter here, Terminals we have some unusual resources in the areas both of mechanics and circuitry. We expect to produce a satisfactory system - schedule indeterminate, cost Includes: indeterminate. We do hope to issue short 12" CRT; 64 -key keyboard; line driver /receiv- reports that may be of interest to your er; power supply; plastic cover and bezel readers, not only those dealing with microcomputer systems specifically. TTL input levels; 12.5MHz video bandwidth Glenn R Norris, President United States Robotics Society POB 26484 A high quality unit; ideal for microcomputer Albuquerque NM 87102 applications

Mr Norris sent along copies of appli- Fully assembled, not a kit cations forms for USRS, which is a nonprofit organization for the robot builder. The dues are S I 2 per atnnun. Only $195 in single unit quantities The point about mechanics depends (FOB Hampton, Va.; no COD) talon holy t oft view the problem. In my point 01 view, / sec' a readily construc- tible solution to the problem of making the walking robot device mechanically, first implemented as a test bed with WYLE COMPUTER PRODUCTS model aircraft servos, luter with stronger 3200 Magruder Blvd. mechanisms for u more practical device. Hampton, Va. 23666 (804) 838 -0122 / see the dynamic control of a moving mechanism as a really fun software challenge with elements of real time LIST YOUR C J aP-UTS& REM T.V. CAMERA & DISPLAY FAST SCAN SYSTEM INTERFACES FOR ALTAIR /IMSAI PLAY GAMES & LET YOUR COMPUTER TEACH YOUR COMPUTER TO READ, LET YOUR COMPUTER MAKE DECISIONS SEE THE BOARD DO SURVEILLANCE, ETC. BASED ON VISUAL INPUT SLOW SCAN T.V. CAMERA FAST SCAN T.V. CAMERA COMPUTER TO MONITOR r- INTERFACE TO TO COMPUTER COMPUTER INTERFACE INTERFACE D SLOW SCAN INTERFACE 5295 FAST Maximum Horizontal Resolution 115 D SCAN INTERFACE 545 230 115 TO Maximum Vertical Resolution 106 D COMPUTER MONITOR INTERFACE 245 212 106 D OSCILLOSCOPE Maximum Grey Scale 16 16 16 /PLOTTER DISPLAY INTERFACE 495 D BLACK AND WHITE T.V. CAMERA 300 Maximum Conversion Time 5 sec. 1/30 sec. 1 /60 sec. Minimum Memory Requirements' (8K <8K (8K D 12' T.V. /MONITOR COMBINATION 150 OSCILLOSCOPE /PLOTTER DISPLAY for random 4096 points or 682 line D SEND MORE INFORMATION segments with 4K RAM. (Requires 150 Kitt bandwidth oscilloscope.) Any T.V. camera can be used. Enclosed is my check /money order for:$ All equipment fully assembled and documented. Allow up to 90 days for delivery. Name: Not for maximum resolution Address: City: State chnvss or ENVIRONMENTAL INTERFACES Zip_ mi,ney n,rlert in P.O. Box 18011 Cleveland, Ohio 44118 (216) 371 -8482 Ohio residents please add 5.5% sales tax, thank you.

149

www.americanradiohistory.com I have (built) a 6800 based micro either. If you use a double pole switch speaker is connected to which contact of with a Bit Boffer 10 interface. A friend on this and the original line, you can the speaker jack. One way yields an of mine has a SWTPC 6800 with an read either polarity data just by throw- inverted signal, the other yields a normal AC30 SWT cassette interface. There the ing the switch. signal. Doti Gunter, of STM Systems,

problem starts! These similar computers I would like to congratulate you on a dropped by our office to show off some will not talk to each other, period! We very fine magazine. It carries more infor- of the latest additions to BABY and one tried exchanging tapes, tying the lOs mation than most assembly and user of his remarks in passing was that STM together, you name it; garbage, but no manuals of most companies in the elec- lias two different cords for plugging into data. Both systems are configured for tronics business. cassette drives when using their audio 300 bps Kansas City standard? We I personally dislike the term interface. if one cord doesn't work, they checked clock timing, amplitude, phase, "hacker." I've been in the business of recommend using the other cord which etc, and even looked at the data coming trying to upgrade electronics technicians switches the contacts on the miniature off both interfaces with a scope and the for 30 years and nonprofessional names phone plug which goes into the speaker data appeared to be perfect. Both sys- like hacker lower, rather than raise, the jack of the recorder. This reflects your tems would record and play back their status of people with enough skill to problem, which will be a problem for own tapes 100 %. Finally a ray of light: build and run a computer. any tape interface to audio recorders,

Listening to the tapes, the 0 and 1 I presently am writing an article on and may vary from unit to unit of the frequencies were different. Solution: my unique 6800 system, complete with same model recorder! Invert the data. pictures, and I hope to submit it to you That's right. Turn it upside down, in the near future for possible publica- and now they work. Seems like the tion in BYTE. I (we) would like to see Some letters to BYTE are standard is not so standard. So for all the more articles on 6800 software. I've run technical in nature and are others out there who don't have all the all the programs published in BYTE on best served by some form of response. We will try to facilities to find out why the system my system and sure hope to see more. answer as many such letters as doesn't work properly, and you can't Keep up the good work. possible. If you have a puzzle

read the 8 K BASIC or friends' tapes, I concerning some aspect of the Warren V Bell CET personal computing field, would like to offer an easy fix so Bit Service Manager, RCA Products write down a clear statement Boffers can talk to AC30s, etc. Solid State Electronics of your question and send it Two modifications are required: to: N1604 Smith St Either run all the data through an Ask BYTE Spokane WA 99207 Byte Publications Inc inverter, ie: TTL, CMOS, etc, before the 70 Main St Bit Boffer modulator to make a tape the The data still conforms to the Peterborough NH 03458. AC30 can read or vice versa. To read standard. You're complaining about a We will publish names and addresses individuals receive either the or detail the way the tape recorder is of data modify Boffer of making Inquiries unless you AC30 by adding a lead to the Q or Q wired, or designed, which definitely does specifically request us to omit output on the 4013 that was not pre- vary from recorder to recorder. It's a the reference. viously used, on the data out IC in matter of which side of the output

First Come pCOMPUTER PROGRAMMING First Served COURSE Free description and outline of Modu -Learn TM Home Study Back Issues of BYTE Course in microcomputer programming. Hundreds of pages of text with examples, problems, and solutions. Prepared by pro- About 600 July, 400 Aug., 1,000 fessional design engineers using the best software design tech- Sept., 50 Oct., 200 Nov. and 100 niques from structured program- THE PROM SETTER Dec. 1976 issues of BYTE. Orders ming and practical experience will be filled on a first come first with microcomputers. Presented READ /WRITE served basis until the supply is in a modular sequence of 10 1702A and 270R exhausted; we will partial ship and lessons oriented for the new ALTAIR /IMSAI COMPATIBLE return any monies in excess. programmer. Extensive reference NO EXTERNAL POWER SUPPLY Readers please send $1.75 for each material you will use long after you become an accomplished LET YOUR COMPUTER issue; this includes postage and microcomputer software designer. DO IT ALL handling. Much of the information in the course has been available only SOFTWARE INCLUDED Doubles as an 6 Bit Parallel I The Computer Place through costly seminars. Now you can purchase this complete 186 Queen St. W home study course for under KIT COMPLETE $165 ASSEMBLED $245 Toronto M5V 1Z1 Focus Scientific $50.00. Send for free descriptive brochure now. 416- 598 -0262 160 Elgin St. DELIVERY I,ESS 71 IAN (i0 DAYS Ottawa K2P 2C4 613- 236 -7767 SERVICESLOGICAL INCORPOR ATEO SZERLIP ENTERPRISES HARBOR CITY, CA. 90710 Dealers please inquire 711 Stierlin Rd, Mountain View, CA 94043 1415) 965 -8365 Calif. Res. Add 6% Sales Tax 416- 598 -0262 i

150

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www.americanradiohistory.com Personal Computing Its happening at the Dallas Convention Center

Big Plans for "Big D" Innovation and relevance are key words for the 1977 National Computer Conference, the first NCC ever held in the Southwest and the year's largest gathering anywhere of data processing users, computer professionals and computer hobbyists. More than 25,000 people are expected to gather in Dallas for a conference program of more than 100 sessions and the year's largest display of computer hardware, software, systems and services-plus the first National Programming Contest and a series of outstanding Professional Seminars. Largest Computer Exhibits Ever More than 250 major hardware and software companies will pack more than 1,100 booths into the Dallas Convention Center's modern 200,000- square -foot main hall. And additional space for the Personal Computing Fair & Exposition is on the next level for a totally separate exhibit by commercial producers of Personal Computing hardware and software. For information on exhibiting in either area, please contact Ms. Carol Sturgeon, manager, conference operations, National Computer Conference, 210 Summit Ave., Montvale, N. J. 07645, 201/391 -9810. Headquarters Hotel Personal Computing headquarters for the 77NCC will be at the Holiday Inn in downtown Dallas. Low -cost housing also will be available at Southern Methodist University. Fill in the coupon for information about NCC's Deluxe Travel Service, which can take care of all of your travel and housing reservations for you in one neat package. Or, contact 77NCC, c/o American Federation of Information Processing Societies, Inc., 210 Summit Ave., Montvale, N. J. 07645, 201/391 -9810. r For More Information!

To 77NCC c/o AFIPS 210 Summit Ave. Montvale, N.J. 07645

Yes, I am very interested in the 77NCC and the Personal Cumputing Fair & Exposition. Please keep me informed about the conference program, exhibits and all related activities and events, and please send me information about:

Exhibiting my personal computer system Exhibiting my company's commercial products /services Personal Computing Fair & Exposition events The first National Programming Contest Professional Seminars NCC's Deluxe Travel Service Low -cost housing at SMU And, I'd like to receive your bi- monthly newsletter, NCC ROUNDUP!

Name: Title.

Company /school

Street address.

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(1) L J

www.americanradiohistory.com Goes National during the 1977 MCC, June 13 -16

Personal Computing Fair & Exposition The fast -growing field of Personal Computing will share the national spotlight in June, when the 77NCC will recognize the dynamic growth and promise of the field with the Personal Computing Fair & Exposition. In addition to the commercial exhibits of Personal Computing manufacturers, dynamic displays and demonstrations of non -commercial individual and group -owned projects will be featured at the Dallas Convention Center. The success of other hobbyists can give you new ideas for your own systems, "how -to" tips and dozens of clever solutions to everyone's problems. You might even find a joint- venture partner with a kindred spirit. More than 100 non -commercial small computing systems are expected, featuring hardware and /or software implementations, games, recreation, music, art, amateur radio, scientific, miscellaneous and general applications. Prizes and awards will be given in all categories. Personal Computing Program Two full days of panel sessions on June 15 and 16 will provide an in -depth look at Personal Computing: Past, Present and Future; The Future of Retail Computer Stores; Hardware of the Computer "Hobby" Market; and Personal Computing Software. Leaders in the Personal Computing movement will appear on each of the panels to let you know the latest developments in the field, point out trends you'll need to be aware of -and answer your questions. Special Interest Sessions In addition to the panel sessions, special interest groups will be able to gather informally for "how -to" programs on building a kit, debugging software, using assembly language, I/O interfaces, cassettes and disks, software standards and so on, into the night. If the special interest group you want is not organized when you get there, we'll do our best to help you get one started! National Club Congress Is a national personal computing association needed? If it is, what does it do, how does it do it, and who does it? To find out what's happening -pro and con -club reps from across the nation will gather to exchange ideas and discuss issues related to club activities and programs. Make certain your club sends an official delegate who can speak for you and vote vis -a -vis a national organization, establishment of national hardware /software standards, a national program library and interchange, educational seminars, meetings, ad infinitum.

1977 NATIONAL COMPUTER CONFERENCE Dallas Convention Center June 13 -16

www.americanradiohistory.com Continued from page 17

! i;;-- `.. ^, i _ . ' 1"' '. yi"' L--. lit 4:.

Photo 5: A view with ranges from $100 to $1200, typically $400. Teletype Model 38 cover lifted of the author's Another light duty machine, same as Kleinschmidt Model Teletype Model 33 Model 33 but accepts standard computer TT-76A (military nomen- This light duty eight level ASCII machine forms. Has upper and lower case printing clature). This machine is a (see photo 3) is extremely popular in mini- and two color ribbon capabilities. paper tape punch and computer circles, and could be called the reader only, which standard Teletype." It is widely sold with actually types characters Teletype Model 40 new computer systems. More than 600,000 on the tape. Like the Model 33s have been sold. New Teletype The latest ASCII Teletype Corp machine Kleinschmidt in photo 4, Corp prices are: 33 RO, $649; 33 KSR, includes a line printer, keyboard, CRT dis- this unit contains a loop $765; 33 ASR, $1090; a used ASR typically play, etc. The high speed line printer with power supply. runs $700. this set is an 80 or 132 column, 300 lines per minute, heavy duty unit. Prices in the $1400 Teletype Model 35 to $2000 range. A heavy duty version of the light duty ASCII Model 33 ASR. New price is $3800. Kleinschmidt Kleinschmidt machines were manufac- Teletype Model 37 tured during the 1930s, 1940s, and 1950s in A heavy duty, 150 words per minute direct competition with the Teletype Corp, ASCII machine with a full 255 graphic and more recently by the Smith Corona character set. Other features include soft- Marchant Corp of Dearborn MI. This line of ware tab stop set, half line spacing, forward devices includes the following: page printer and reverse, etc. and keyboards (TT -117), paper tape reader

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www.americanradiohistory.com the microcomputer LOGIC DESIGN L INC an introduction to QUALITY Support for reality those who wish to dig deeply into digital design. now in canada: Pictured above is the new OP -80A imsai Breadboarding System, text- High Speed Paper Tape Reader from book on logic design, and OAE. This unit has no moving parts, will read punched tape as fast as you processor complete schematics for an can pull it through (0 -5,000 c.p.s.), cromemco elegant CPU that will run the and costs only $74.50 KIT, $95.00 tdl PDP8 instruction set .. $1095 ASSEMBLED & TESTED. It includes a precision optical sensor ar- and more 132 IC's $ 87 ray, high speed data buffers, and all required handshake logic to interface TTY Interface $ 20 The Computer Place with any uP parallel I/O port. 186 Queen St. W Memory $ 26/k To order. send check or money order M5V 1Z1 Toronto (include $2.50 shipping /handling) to 416- 598 -0262 Focus Scientific BOX 3991, UNIV. STATION Oliver Audio Engineering, 7330 Laurel Canyon Blvd., 160 Elgin St. WY 82071 No. Holly- LARAMIE, wood. Ottawa K2P 2C4 CA 91605, or call our 24 hr. (307) 742 -7977 M /C -B /A order line: (213) 613- 236 -7767 765 -8080

8080 Interactive DEBUG THE BETTER NOW AVAILABLE: A real -time pro - BUG TRAP gram debugger for all 8080 processors. Debug your code in one -tenth the time The Better Bug Trap is an it takes by hand. This is not a simulator Altair /IMSAI plug -compatible 32 K but a real -time programming aid that until now was only available on mini & board that extends system capa- PERSONAL macro computers. And it FITS IN 5K! bilities to facilitate software debugging and real -time proces- MINICOMPUTER FEATURES : sing. Capabilities include interval SYSTEMS. *Six I/O nodes- Mneumonic, single & timer, real -time clock, watchdog double byte numeric, ascii, or dis- timer, processor slowdown, and placed mnemonic & numeric. *Four user -defined breakpoints. clock with variable rates. Four *Relocatable to anywhere in memory. hardware breakpoint addresses K *User - controlled number base -binary, 32 CPU, octal, hex; any radix from 2 to 36. allow you to stop processing or Two CRT's, *Commands for displaying & modify- generate an interrupt at a breaking all registers -including PSW & SP. And Two *Search command with masking. point without modifying exist- Floppy Disk *Block memory move & fill. ing software. The board services *On -line calculator/expression eval'. its interrupt with a CALL Drives With *Displacement register for examing 262 K Bytes relocatable code. instruction to ANY memory Each. address you choose. All capabili- DEBUG 8080 To Order: ties may be set by software or (I) Specify: CUTS cassette $30 front panel. Write for free or Paper Tape $40 literature. or Manual Alonet $10 $180 assembled, tested, corn - For Details: or Descriptive brochure $ 1 ABBOTT COMPUTER CO. (2) Your hardware: Altair, lmsai, Sol,... plete documentation, software. (3) Send to: 57 Gregory Street Bay Area Timeshare MICRONICS, INC. P.O.Box 2298 Marblehead, MA 01945 Berkeley, CA 94702 PO Box 3514 617- 631 -8903 ¡refundable on purchase of program Greenville, N.C. 27834

www.americanradiohistory.com (a) (b)

Photo 6: Two views of the Creed 75 unit. In (a), the unit is shown with the and punch sets (TT -179) or a set designated teletypewriters for Spiegel in Chicago in the cover in place as it might the TT -100, which includes a page printer, early 1960s, which were eventually passed be seen in use. In the keyboard, table and power supply. These on to a company named Wilcox Enterprises second view (b) the cover units are fairly common although not in as in Naperville IL. has been removed, and the plentiful supply as their Teletype counter- The basic unit shown in photo 6 paper tape supply drawer parts. As with Teletype Corp, many other consists of a page printer, keyboard and opened for inspection. Kleinschmidt configuations were manu- paper tape punch, but no paper tape reader. factured for the military under various This machine uses a Baudot code at 10 nomenclatures such as TT -65, TT -98, characters per second. Some differences U-271, etc. For example, a Model TT -24 is from American machines are that the key- a 100 word per minute KSR machine. Photo board añd printer are mechanically linked, 4 shows a Kleinschmidt Model 150 KSR, ie: no loop supply is needed for local, which is typical of this line. My personal typewriter like operation. The printer is run typing paper tape reader and punch set is by activating a 24 VDC solenoid for space labeled "TT- 76A /GGC" and is shown in and another one for mark; thus there is no photo 5. Price range, $20 to $150. current loop. The keyboard output consists of five Lorenz parallel bits and one strobe bit to indicate character ready, although it can be rewired A German company which, like Klein - for serial operation. schmidt, has manufactured Model 15 KSRs Also available from Wilcox Enterprises and 15 ASRs. These machines are relatively are interface kits, programs, and erasable, rare in the US. programmable, read only memories which the for use with 8008 and Mite adapt machine 8080 systems. This New Haven CT company has manufactured small Baudot page printer and What Characteristics Should keyboard machines for use in submarines I Look For? and by the US Marine Corps. This device is Once you've found a Baudot machine and relatively rare on the surplus market. are thinking about whether or not to buy 'et, two items are of key importance besides Creed Model 75 Teletypewriter general mechanical condition; these are ITT Creed is the English counterpart of machine speed and character types. Teletype Corp. This company manufactured Basically these units were supplied with several hundred special Creed Model 75 three different kinds of character sets: corn-

156

www.americanradiohistory.com N Computer Marl NEW IN rOMPUTALKE new /orhT PHOENIX

LONG ISLAND ,?)o o:i Bits & Bytes AMPLIFIER Computer leasing available.

IMSAI,SWTPCo, Digital Group COMPUTER SHOP Processor Tech, Apple, OSI 6819 -C N. 21 st Ave. TDLZ -80, Seals, Cromemco, Phoenix, Az. 85015 Veras, Tarbell, Oliver s -100 BUS

Magazines, books, chips, CSR I sockets, connectors, terminals. (602) 242 -2507 SYNTHESISBYRULE SOFTWARE t IT'S ALL HERE WAITING FOR YOU SPEAK "KAAMPYUTAOLKER" FRIENDLY ADVICE TOO Featuring: MODEL CT -1 SYNTHESIZER 395.00 New York City EPA Micro -68 System CSR1 SOFTWARE SYSTEM 35.00 314 5th Ave. DEMONSTRATION CASSETTE 2.95 (32nd St) Micro Term -Act 1 Keyboard I.ALIE RESIDENrS006 SALES TA.

New York 10001 Video Monitors FOR Long Island WRITE INFORMATIVE LITERATURE 212- 279-1048 Books, Magazines COMPUTALKER CONSULTANTS 2072 Front St Tues. - Sat. P.O. BOX 1951, DEPT. B, 9:30 - 6:00 East Meadow NY SANTA MONICA, CA 90406 circle reader number 140 Thurs. - 9:00 516- 794 -0510

INVENTORY PHILADELPHIA COMPUTER MART RII PROGRAM Article Index features F or IMSAI with TTY for Hard IMSAI Copy output --Up to 112 alphabet- the digital group ic Files. Single user license $259.00 without hardware -- $59.00 Poly 88 with hardware & 8K minimum mem- TDL FREE ory "SEALS" National Multiplex Complete listing of all fea- For POLY88 for instant Video Dis- play of Inventory information. ture articles appearing in FORMS PROGRAM for Invoicing Volume I of BYTE - and general p urpose Forms work. September, 1975 thru De- ACCOUNTING - General Ledger - Personal cember 1976. Indexed for for IMSAI with TTY -memory orient- easy reference. Includes all ed.. Available April 15 Computer errata. UniWrite Minicomputer Accoun t- ing -Payroll- Forms Programs with Corporation To get yours, send a $.24 or without CA LSI -2 Hardware. stamped self addressed en- Phone: velope to: (215) 647 -8463 BYTE Index COMPUTER FRAZER MALL 473 -2323 70 Main Street SHOP IIIIIIII 603- Rt. 30 & 352 Peterborough NH 03458 Rt. 16B, Union, N. H. 03887 Frazer, PA 19355

www.americanradiohistory.com SUPPLIERS OF BAUDOT EQUIPMENT merciai, weather and stock market. Table 1 Among the companies which advertise tele- lists the characters which correspond to printers in the various amateur radio magazines, particular 5 bit Baudot inputs. Note that in computer journals and other "surplus" advertising all three cases, the letters, lower case, are spots are the following: the same, but the figures, upper case, are dif- Goodman, 5454 S Shore Dr, Chicago I L 60615, ferent; in fact some of them are downright (312) 752 -1000. Teletypewriter Communications Specialists strange! (Van's Electronics), 550 Springfield Av, Obviously the most desirable character Berkely Heights NJ 07922, (201) 464 -5310. set for microprocessor use is the commercial Andy Electronics Co Inc, 6319 Long Dr, or communications group, but don't let a Houston TX 77087, (713) 641 -0576. Typetronics, POB 8873, Ft Lauderdale F L stock market or weirdo weather font stop 33310, (305) 583 -1340. you! Replacement commercial keys are Lawrence R Pfleger, 532 W Wilson St #1, available for $0.50 to $1 each from most of Madison WI 53703, (608) 255 -2935. the sources listed. Atlantic Surplus Sales, 3730 Nautilus Av, Brooklyn NY 11224, (212) 372 -0349. There are four printing speeds associated Henry Holder, (817) 429 -3021. with these old machines, those being 60, 66, Don C Dando, Rt 4, POB 454, Liberty MO 75 and 100 words per minute. Table 2 64068. summarizes the data rates, bit pulse widths, BVE Enterprises, POB 73, Paramus NJ 07652. character speeds, etc, for each the Alltronics- Howard Co, POB 19, Boston MA of four 02101, (617) 742 -0048 speeds. More about how to increase machine Wilcox Enterprises, 25W178 39th St, Naperville speeds later.

I L 60540, (312) 420 -8601

This list was culled from the publications circa July 1976. No inventory or prices are listed since Next Month: Baudot tele- as one supplier (Goodman) put it in a conversation, printer information con- "I have hundreds of 15s and 19s now, but they tinues with a discussion of sometimes move slow, or sometimes fast, and I could sell 'em all tomorrow." In each case, where interfacing techniques and available, a phone number is listed so that the problems. latest availability can be checked.

OSBYTE KIL DO I HAVE TO TILL YOU AGAIN? IT ALL STAND BACK,5IR! MAWS BEGAN WHEN GRAMPA I ' ll SAVE YOU ! TODAY, K1L O'6YTE IS SPOTTED THE 51-IAKK TELLING CV ABOUT YET ANOTHER ADVENTURE OF HIS GREAT-RANI:0V ABOARD THE HAS.

EMPTYEYES KILT O'BYTE

(61040)1LAD NAD DUNCE WITH LO41- 5AARK5,50HE

CONSIDERED HIMSELF SOME-

THIN6 OF AN ICHTHYOLOGIST.

YSEE, CHIP, MK. EN GUARDE FOUL FIEND! gAikt FLOCK GOT AWAY WELIIL... WHAT BY PRETENDING I CANT PO YOU EXPECT HE WAS A PENIISC BELIEVE IN A CAKTDON ? ?9 I ATE SOUNDS \ olloyp THE FISHY QUr4CW WI-10L rOME2_,J THING

'GÜLP CK,oK

158

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www.americanradiohistory.com Continued from page 111 address bus and uses 2 input and 4 output counter (PC) and seven 14 bit words is used leads for control. Time multiplexing of the to store program and subroutine addresses. TTL compatible data bus allows control This allows up to seven levels of subroutines information, 14 bit addresses, and data to be to be nested while the 14 bit addresses transmitted between external memory and permit direct addressing of up to 16 K, 8 bit the CPU. bytes of memory. This addressing capacity By use of the "Interrupt" control line, can be indefinitely expanded through mem- normal program flow can be interrupted to ory bank switching using 10 instructions. allow servicing of slow 10 peripheral devices, The instruction set consists of 48 data while also executing the main program. The oriented instructions as shown in table 1. "Ready" command line can be used to Most instructions are single byte instructions synchronize the 8008 to the memory cycle while immediate data instructions require time, allowing any type or any speed mem- two bytes and jump instructions utilize three ory to be used. The "State" and "SYNC" bytes. With a 500 kHz clock, nonmemory outputs will indicate the state of the proc- referencing instructions are executed in 20 essor at any time during the instruction microseconds. cycle. Being a first generation microprocessor, The CPU contains six 8 bit data registers, the 8008 is slow and has limited capabilities an 8 bit accumulator, two 8 bit temporary and features. The availability and low price, registers, four flag bits, and an 8 bit parallel on the other hand, make the 8008 a good binary arithmetic logic unit (ALU). A mem- starting point for some home built computer ory stack containing a 14 bit program systems.

Information and diagrams courtesy of Intel Corporation, from their MCS -8TM User's Manual.

PROM: Space for 2K bytes, 1702A. Store /r, bootstrap loaders and monitors. RAM: 1K bytes, 2102LIPC, 450 ns, low power. NO NEED TO RELOCATE STACK WHEN ADDING MEMORY. CIRCUITRY: Replaces memory write logic on ALTAIRTm and Imsai front panels. REGULATORS: Two regulators. No need for regulated power supply. JUMP -ON- RESET: PROM program execution starts at any location in memory without interfering with programs in any other portion of memory. S -100 BUS; +8 and -16 VDC; P/C BOARD SOLDER MASKED BOTH SIDES WITH PLATED THROUGH HOLES; ALL SOCKETS INCLUDED. OPTIONAL FIRMWARE: 512 byte monitor for use with Tarbell tape interface on 2, 1 1702A PROMs. PROM /RAM KIT WITHOUT PROMS $ 89 RaVECCO and + OPTION A - SIO Rev. 1 or 3 P + S $129 GO - 2 eset + OPTION B SIO (MITS) $129 PROM /RAM + OPTION C - SIO 2 (IMSAI) $129 + OPTION D - Poly Video Interface $159 (Includes Video Driver) BOARD California residents please add 6% tax. IMMEDIATE DELIVERY FROM FACTORY from OR YOUR LOCAL COMPUTER STORE

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160

www.americanradiohistory.com Programming Puzzle:

An 8080 Bug in the Stack

Bruce A Dolan 2331 Cathedral Av NW Washington DC 20008

Instead of coding a subroutine call fol- With these two subroutines available, lowed immediately by a subroutine return, the most probable use is to protect intermediate results while a subroutine is invoked (for 10, for example). These might be used inside another subroutine, as follows, taking the JMP trick mentioned above: CALL SUBRX advantage of RET SUBRX: CALL SVREG SAVE ALL one could write

JMP GTREG ;RESTORE ALL AND RETURN

JMP SUBRX This doesn't work. Why not ? to save one byte of program storage space and avoid unnecessary stack manipulations. [Answer in next month's BYTE] But this practice has a price to be paid in frustrations; read on. Here are two subroutines that will first =I MI save, and then restore all of the working Mri processor registers and flags for the 8080. They are useful as housekeeping functions on entry and return from subroutines, to preserve register contents: ADM -3A IN KIT ;HOLD H,L FOR NOW SVREG: SHLD TEMP FORM XTHL ;PUSH H,L. GET RET ADDR 825°° PUSH PS W PUSH B All equipment PUSH D F.O.B. Dallas, Texas PUSH H ;PUSH THE RETURN ADDR Terms - check or money order with LHLD TEMP ;RESTORE H,L order RET Delivery in 30 days Customer should GTREG: POP H ;GET RETURN ADDR a contact Lear -Siegler POP D era° for maintenance , : POP B j% Warranted for 90 days POP PSW s Service contract XTHL ;RECOVER H,L. PUSH RET ADDR o available RET as° m

80 CHARACTERS /LINE 75-19,200 BAUD 24 LINES /SCREEN FULL & HALF DUPLEX The first of these (SVREG) pushes all ADDRESSABLE CURSUR ODD /EVEN /NO PARITY 9, 10, OR 11 BIT WORDS RS232 INTERFACE OR registers and flags onto the stack, and the 20 ma CURRENT LOOP second puts them all back. It is assumed that GET COMPLETE DETAILS WITH A DIRECT CALL: between "CALL SVREG" and "CALL 214 258-2414 TWX 910-860-5761 TELEX 73-0022 800 527-3248 GTREG" the stack has no net changes, so that the value of the stack pointer and the contents of the stack are the same for capitalp "CALL GTREG" as when "SVREG" equipment brokers finished. (The double register TEMP is I 930 N. BELTLINE IRVING, TEXAS 75061 ' located anywhere in programmable memory, 110 MIMEO and has no use outside of SVREG.)

161

www.americanradiohistory.com perpendicular to the page. Sample 4a decades. The idea of being able to appeared to be scanned reliably but publish machine readable software on PAPERBYTES' response was greatly reduced on the the printed page is, in my (and a few of oscilloscope. Samples 4b and 4d did not my friends') opinion, the biggest thing to reproduce well, having practically all hit the hobby computer scene since the Forum black print in areas of high 1 density. Altair 8800 and BYTE magazine. One problem encountered after a Of the formats presented, I per- great many passes of the various probes sonally prefer format 2 and think a was that the paper began to wear and the frame format is mandatory. The equal codes became scratched. Even so, the spacing of the data bits to assist manual A READER'S RESULTS OF slightly flattened sine waves generated reading of the data should be considered MAKING SOME TESTS... by the probe remained intact. Optimum when your final format selection is display was achieved with a scanning made. A frame format is required to

I read with interest the three articles speed of 5 to 15 cm per second. keep the data in manageable chunks and on bar code software in the December I am in agreement with Mr Banks to facilitate error detection. Some con- 1976 issue of BYTE. While awaiting that a need for better and cheaper cerns and suggestions I have are as arrival of my Digital Group system, I software dissemination exists. I support follows: decided to tinker with a simple way of adoption of the bar graph encoding reading the sample codes presented by method and urge acceptance of sample 1. Be sure to give complete plans (or Banks in his article /page 12/. 4e on page 17 as a standard. Certainly maybe manufacture a kit) for the First, I tried the examples suggested this simple investigation demonstrates reading wand with easily obtain- by Merkowitz /puge 77/. A suitably that a means of reading such a code need able parts. A single +5 V supply small lens proved very difficult to secure not be an obstacle to the home com- requirement would be nice, too. - however, one was found. The focal puter hobbyist. 2. Possibly include visual guide length was somewhat long and alignment Rick Bourgeois MD WASEVH marks on the edges of the pages was quite critical. Examples 2a and 2b POB 2746 or between frame lines to demark on page 78 were both constructed. Both Lafayette LA 70502 data bytes as an aid to manual visible light and infrared detectors were reading. used. Also, LED and incandescent SCANNING? BACKLIGHTED You've got the on a great idea, sources were tried. The incandescent BYTE don't let go. BYTE on to the (non) source with the infrared photodarlington I have read your articles on bar coded BITter and glorious end. detector proved to be the most sensitive. information transfer with interest. Might The persistent difficulty with the mecha- the construction of the document J Scott Williams nics of the lens system led to further reading device be simplified if the docu- POB 932 tinkering. The split fiber optics of ment were backlighted by a light table or Bellingham WA 98225 figure 1, page 77, was tried but con- such? (This would require that no struction of a homemade split fiber optic printing exist on the document's reverse NOT ALL REACTIONS ARE guide was tedious and lacking in ade- side.) The "lens" could simply be a pin FAVORABLE, WITNESS THIS: quate sensitivity upon completion. hole, as the light sourcing problem Next a pinhole lens was tried but would have been eliminated. The critical As one who is deeply involved in again adjustment proved difficult. angle of the reading device (due to home computing and who has been However, this did lead to the final probe reflections off of the ink and paper) reading BYTE since issue #1, I am that seems to provide a suitable alter- would also be gone. moved to voice my complaints about the native for the homebrewer to the com- garbage you've been including in several Jonathan L Bondy mercial probe. Instead of a lens, a linear recent issues. Garbage that serves only to Ketron Inc aperture was used. The slit was just the waste valuable space! Valley Forge Executive Mall width of the 0 bar in figure 4e on What's this /expletive deleted/ about 530 E Swedesford Rd page 17. "Machine Readable Printed Software ?" were Wayne PA 19087 Two semicircles of shim brass Is this supposed to be humor? I hope so. soldered to the end of thin wall 1 cm The suggestion to backlight the paper My M6800 computer is very bright, but inside diameter brass tubing to provide has been made by several readers. For it has never spent one cent for BYTE or the slit aperture. After blackening the magazine published and printed pro- anything else. People buy things and inside of the tubing with carbon black, grams, the main disadvantage is lack of people read BYTE, but get too heavily an infrared detector and incandescent use of the back side of the paper. into "machine readable printed soft- lamp were mounted inside a 1.5 cm Use of a source and sensor array such ware" and you will have to depend on length of the tubing right over the slit. A as the Texas Instruments TIL -139 part machines to purchase BYTE - people slightly smaller diameter 12 cm length of with an external imaging slit looks like a won't! The "BYTE standard" for mag- tubing was then press fitted over the very promising and inexpensive scanner netic tape data recording was widely detector, lamp and slit assembly with the for the front side of the paper. This accepted because we needed such a wires running up out of the end of the device, described on pages 167 and 168 standard. Not one of the computer handle. tubing of the TI Optoelectronics Data Book for hobbyists I know feels any need whatso- Tests were run on the samples pro- Design Engineers [available from BITS ever for a standard on machine readable vided in figure 4 of Banks' article which IncJ, has a source LED and receiver printed software. Perhaps it is an idea proved to be promising. The response of phototransistor mounted in a plastic whose time has not yet (and may never) the detector was monitored on an oscil- housing with an adjustment slot for come. Try printing software in the form loscope while making repeated passes positioning relative to the image being of source listings; they are people read- over each sample. Samples 4c and 4e scanned. able - and people are the ones who were read with ease, giving approxi- spend money. If you wish to sell mately 0.4 V peak peak to deflection. BYTE ON TO THE (NON) machine readable software, may I sug- Noise as observed on the scope was BITter END gest that you use "IlYTE standard" minimal both during bar code scanning cassettes and /or paper tape. and passes over sections of white page. Regarding the "Machine Readable Happy Computing! Handling of the homemade probe was Publishing Standard" in November 1976 /unintelligible signature/ not difficult, one only having to make BYTE: Yea team, go go go. If you can sure the slit was parallel to the code make this work you will have advanced Chattanooga TN elements and that the probe remained personal computing at least 2 or 3 light To each his (or her ?) own opinion.

162

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www.americanradiohistory.com THESC/MI ASC H KEYBOARD AT $ 95.00 SC /MP, the Microprocessor kit from National Semiconductor includes everything you need to build a completely functional microprocessor system - featuring the National SC /MP microprocessor - the low cost microprocessor for every application: Text Systems and Instrument Control; Machine Tool Control; Small Business Machines; Word Processing Systems; Educational Systems; Multiprocessor Systems; Proces Con- trollers; Terminal Control; Laboratory Instru- mentation; Sophisticated Games; Automotive ` Controller and Appliance Controllers. The kit, neatly packaged with all the corn- Ponents and literature you need, in a looseleat binder, includes: The SC /MP Microprocessor - a single -chip Central Processing Unit in a 40- pin, dual in -line package. Features static operations, forty -six instruction types; single -byte and double -byte, software controlled interrupt structure, built in serial input /output ports; bidirectional 8-bit TRI, STATER bus, parrallel data /port and latched 12-bit TRI- STATED ROM (Reg. address port. - 512 bytes (8 -bits /byte) of pre -programmed Read - $58.85) $53.00 Only- Memory containing KITBUG -a monitor and debugging program to assist in the development of your application programs, KITBUG This 63 key ASC II Encoded Keyboard kit was designed and manufactured provedes teletypewrite input /output routines and allows examination, by Electronics Warehouse Inc. Features: single 5 volt D.C. supply, utilizing modification, and controlled execution of your programs. RAM -256 only TTL logic elements bytes of static read /write memory for storage of your application (no MOS devices to blow), TTL drive capability (each programs. Transfers of data to and from RAM are controlled by SC /MP of the eight bits of ASC I I output will drive the equivalent of ten standard TTL and KITBUG. Teletypewriter Interfact Including buffer and drive inputs without external buffer drivers(, de- bouncing, upper and lower case capability for a 20 MA current loop interface. Voltage Regulator fully ASCII, 8 bit parallel output. In addition to the alphanumeric and symbol Data Buffer -providing interface between memory and bidirectional keys data lines. All the literature you need, including schematics and pro- available on a regular keyboard, the following keys are utilized: escape, gramming manuals. Timing Crystal -providing 1.000 MHz timing back -space, tab, line -feed, delete, control, shift -lock, shift(2 keys), here -is, signal. Plus all the passive components and circuit board with 72 pun control -release. edge connector required to build and interconnect your microprocessor system with external hardware Kit includes: 63 key keyboard, P.C. board, all required components and assembly manual with ASC II code list. Optional: 1. Parity bit - add $1.00 Aluminum enclosure 639.- SC/MP 2. Serial output - add $2.00 Note: If you already have this teletype keyboard you can have the kit without KEYBOARD It for $36.00 (reg. $39.85). Dealer inquires invited.

K IT National's new Keyboard Kit now gives There is a hole pattern for additional inte- SC /MP Kit users a low -cost input /output grated circuits on the SC /MP Kit PC card. capability. This new kit replaces the Tele- By following the simple instructions in the type* normally required by the SC /MP Kit SC /MP Keyboard Kit users manual, one and allows users to evaluate the SC /MP can add buffers, decoders, drivers, multi- CPU and to develop a variety of application plexers, etc. Simply replace the Kit Bug software. ROM (supplied in the SC /MP Kit) with the new SCMPKB ROM, connect the pre - The heart of SC /MP Keyboard Kit is a ROM assembled Keyboard cable connector to firmware package (512 bytes) called the kit card, and you are ready to go! $ 95. SCMPKB. The SCMPKB ROM replaces the "Kit Bug" ROM originally supplied with the National's Keyboard Kit comes complete SC /MP Kit and allows the effective use of with manual, all required integrated circuits, This is a great kit for engineers and com- the hexadecimal keyboard, to execute resistors, keyboard display cable con- panies who don't have access to a Teletype. programs, to examine or modify the connector assembly, wire wrap connectors, It is a low-cost teaching, learning, and tents of memory and the SC /MP registers, precut wires -even a hand -held wire wrap developing tool for hobbyists, professors, and to monitor program performance. tool. students, and electronics entrepreneurs of all levels. MINIMUM ORDER $5.00 SWITCHES Shipping & Handling:

10 Position rotary switch KEYBOARD or SC /MP - $3.00 + $.50 Insurance manuf. 4 by oak $1.00 per a l l others - $ 1.00

8 position, 1 off switch in TO5 can California residents add 6% sales tax. $.69 2 for $ 1.00 ELECTRONICS WAREHOUSE Inc. ROCKER SWITCH 1603 AVIATION BLVD. SPST normally open contact rating 6A 250VAC REDONDO BEACH, CA. 90278 solder S .50 ea $2.00 per 6 TEL. (213) 376 -8005

MINIATURE TOGGLE SWITCH WRITE FOR FREE CATALOG SPST P.C. MOUNT $.99 You are invited to visit our store at the above address

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1 1 * SPECIAL PRICES * 4007 .16 MEMORIES 74152 .90 HIGH SPEED 4008 .70 1 1 74155 .60 74H00 .20 Rams 4011 .16* 74157 .60 74H01 .20 2102 1 1.50* 4012 .16* 1 2102 -1 74160 .75 74H04 .20 1.70 4013 .30* Proms 74161 .75* 74H10 .20 4015 .80 1 1 82S23/S123 1.95* 74H11 .20 4016 .35* 74163 .75* 74H40 .20 TTL 4019 .70 1 74165 .80 74H51 20 7400 .12* 4020 .90 74173 1.25 74H52 20 7402 .14 4021 .95 1 74174 .75 74H74 .40 7403 .14* 4023 .16* 74175 .75* 74H103 .50 7404 .16* 74177 .70 74H106 .50 1 7407 .20 74180 .80 4025 .20* 7410 .12* 74181 1.50 LOW POWER 4027 .40 1 7420 .12* SCHOTTKY 4028 .60 7427 .25 74191 .85 74LS00 .29 4030 .35 1 74192 .70* 74LS02 .29 4040 .95 74193 .70 74LS08 .29 4042 .60 1 7438 .20* 74194 .85 74LS10 .29 4043 .75 7440 .12* 74198 1.25 74LS27 .30 4044 .70 1 7441 .65* 9602 .50* 74LS73 .45 4049 .35* 9300 .75 74LS75 .65 4050 .35* 7445 .60 9312 .70 74LS151 1.10 4066 .65 7447 .75 74LS153 1.10 4068 .35 7450 .14 SCHOTTKY 74LS157 1.10 7451 .14* 4071 .16 74S01 .25 74LS161 1.50* 7473 .28 4073 .16 74S02 .25 74LS163 1.50 7474 .28 4075 74S37 .40 74LS164 1.50 .16 7475 .40 4516 74538 .60 74LS174 1.10* .85 7480 .40* 4528 74585 2.00 74LS175 1.50 .75 74LS193 1.50 1 7493 .50 74S113 .80 74LS221 7495 .49 74S139 1.50 1.50* LINEARS 74LS251 1.50 1 74107 .29 74S140 .50 NE536T 2.75 74LS253 1.50 74109 .30 74S153 2.50 NE555V .43 74LS257 1.50 1 74116 1.50 74S172 4.50 NE556A .90 74LS258 1.50 74123 .45 74S174 2.05 1456V .75 1 74141 .80* 74S175 2.05* CMOS 1458V .52 74145 .75 74S181 4.50 4001 .16* 566V 1.25 1 74150 .60 745197 2.20 4002 .16 567V 1.35 74S257 1.50 74151 .60 4006 .90 540L 2.00 1 Order Minimum $10 00 Add $1 00 shipping and handling charge per order Californ a residents add 6 °° sales tax All orders shipped First Class within 24 hours 1 1

Order the famous lasis 6 volume Programmed Learning Course "Microcomputer Design is a Snap for 1 1 $99.50 and receive a special $10.00 credit on any group of IC's. 1 Satisfaction 100 °0 guaranteed C.O.D. Orders. Phone (day or night) 408/354-1448 PO BOX 2542B 1 ELTRON Sunnyvale, CA 94087 1 LFree catalog -Just send us your name and address ______mot __ -

www.americanradiohistory.com \W/e 'rre mallmna a case for 013 nuC = Iloo íiirnn 4qu43rment 000 BILL GODBOUT ELECTRONICS BOX 2355, OAKLAND AIRPORT, CA 94614 VCCciron = P//\Ihí enclosures There are no screws or fasteners to mar TERMS: Add S0c to orders under $10; over $10 add for 5% the lines of these beautiful enclosures. shipping & handling. BankAmericards /Masterchargea: call Has provisions for card guides, connec- (415) 562 -0636, 24 hours. Cal res add tax. No CODs. Thank you very much for your patronage.' tors, etc. on the inside. Available in black or computer blue with white front 1 panel; shipped unassembled. 1 /VP5- 17-17U 5.51 "H, 17.58 "W, 17.1 "D

Now you have a choice -- specify wire $79.25

wrap pins (illustrated) or solder - BODED 1 #VP7- 17-17u 7.26 "H, 17.58'W, 17.1 "0 tail with .250" row spac- 584.00 ing. For IILSAI and PM' #VP9-17-17U 9.01 "H, 17.58 "W, 21.6"D or Altair peripherals. gpol5g exact same size as IMSAI microcomputer. Wire wrap part n t x$96.50 S- I00WW. Solder - tail part 0 S- 100ST. CoIMMIEglroQ Ì WE #S-I00ST is ideal for STOCK MANY = the MAI motherboard. $ 0 EÁ\CIII III -- $22 FORR 5 j VECTOR PRODUCTS

10/81.95 ASSORTED VALUES. We picked up a a limited quantity of We have hatch of brand new, American made, trimmer high quality, multiconductor caps in assorted styles and values. flat cable. Unfortunately we (louse MULTI-CONDUCTOR WIRE numbered, so we're not sure of the exact 20 conductor (#28 stranded wire) 20 ft /$5.95 couldn't get as much as we values - - -and until we get them all tested 26 conductor ( #28 stranded wire) 20 ft /$7.50 wanted, so if you're inter- out, we're selling assortments at a super 28 conductor ( #24 stranded wire) 20 ft /$9.95 ested, get your order in soon. bargain. Lowest value caps go from 2 -8 pF; 20 ft Subject to prior sale. 34 conductor ( #28 stranded wire) /$9.95 highest value caps from 50 -60 pF. Ltd qty. NOMMOMMEIrMIMMEMMONIIIMMEMIIIIMMEMIIIIMMEIMIN EconoRom $17995 GIVE YOUR CPU A FRIEND: A HOME FOR PROGRAMS AND ROUTINES.

Our basic ECONOROM board is 4K X 8 worth of eraseable ROM, which you can program with any program or routine you want (or have us program it for you). Similar features and same quality as our ECONORAM-- -and also very low power: 5V @3/4A, -12V@ 150 ma. We offer several options:

BASIC ECONOROM BOARD (4K X 8) $179.95 SMALLER ECONOROM BOARD (2KX 8) $135.00 BIGGER ECONOROM BOARD (8K X 8; holds 8K BASIC) $269.95

8080 SOFTWARE BOARD (this is our 4K board, programmed with edit- or, assembler, and monitor routines for the 8080...a valuable first step if you're trying to get away from machine language programming. Info package available that describes the function of all $2.95 (refundable with order) $189.95 _ loom uu U uuu iuuuuuuuuuiuiiuiiinelEE NIB( u

,ho Adore U', L. -i r, c. Assoc i ates book on mia.rueumpu- 1 000OQII 1G DOO is Lg ters are recoenized as tops in their field. Lucid and complete, these are now available from us ppd GOOD CONNECTION in the USA, or buy all 3 books for 525 ppd. 25 PIN RS -232 CONNECTORS: sub - "AN INTRODUCTION TO MICROCOMPUTERS, VOL. I" book mini D type. 0?001. Clearly covers all the basics $7.50

"VOLUME 2" book #3001. Covers latest uPs and sup - Male plug with EconoRaml plastic hood, :ort ICs, replacing 100s of pages of data..512.50 part #DB25P "8080 PROGRAMMING FOR LOGIC DESIGN" book #4001. 53.95 Demystifies the art of programming $7.50 Female jack, mummummum part #DB255 OVER TWO YEARS OF EXPERIENCE SELLING 4K X 8 BOARDS HAS SHOWN US $3.95 EXACTLY WHAT YOU WANT IN A MEMORY BOARD KIT.

- -You want low power to stretch your power supply. Any company MORE can claim low power; not every company offers a spec to back it up. We guarantee current consumption under 750 ma, with the 741S00 $0.36 741.5139 1.38 average board falling between 600 and 650 ma. is 0.36 74LS155 1.38 Il 741501 - -You want S -100 buss compatibility...and Econoram is fully com- 74L502 0.36 7415157 1.25 THIS 1.85 patible. II 741SO4 0.42 74LS160 741508 0.38 74LS161 1.85 - -You want clean and unambiguous data transfer...which is why we ''COMETS I 0.36 1.85 buffered our addresses, data lines, and outputs long before the 741510 741.5162 74LS11 0.38 74LS163 1.85 other guys caught on. Taw.tar,y¡r¡/',M 1 1.38 741S168 1.87 guaranteed at 450 ns 741.S14 - -You want a fast board. By using memories FROM...l.. 1 0.36 1.87 74LS169 worst case over the full temp range, we can guarantee this boar. 74LS20 74LS21 0.38 7415174 1.38 to run at zero wait states (500 na or better). A 450 ns memory 74L522 0.38 74LS17S 1.35 also allows for any propagation delays in support circuitry. Mg 74LS27 0.38 74LS221 1.38 - -You want quality, and we deliver it. From the epoxy glass, dou- 741S30 0.36 7415240 1.88 ble- sided, plate through board...to the low profile sockets... 74LS32 0.38 7415257 1.25 the optimized thermal design... the DlPswitch address selector. É 741537 0.53 7415258 1.38 ICs... guarantee we offer on the low power Schottky support the 741538 0.53 74LS273 2.25 more. II parts used in Econoram... and 741S42 1.25 7415283 1.20 - -You want low cost. Because of our purchasing policies and quan- II 741S74 0.56 74LS367 1.00 tity buying, we can still deliver a board of this quality for 741S75 0.85 74LS368 1.00 under $100. You can pay less, and you can get less. But if you 741S109 0.60 7415377 1.88 want the best combination of value and economy...ECONORAM gives mil 741.S124 2.50 741.S378 1.38 you both. fi 7415125 0.75 811.S95 1.13 Yer 7415126 0.75 811596 1.13 ALSO AVAILABLE ASSEMBLED, TESTED, AND WARRANTED FOR ONE YEAR FOR 741.S132 1.50 811597 1.13 $129.95. DISCOUNTS ON ALL KITS AVAILABLE FOR GROUP PURCHASES. -11.8138 1.38 81LS98 1.13

www.americanradiohistory.com MICROPROCESSOR COMPONENTS

RAM'S DISPLAY LED'S CPU'S

21L02 1024 x 1 $1.58 8008 -1 8 Bit CPU $17.95 Static Type Polarity HGT. Price (18 Pin) (PMOS) MAN -4 Common Cathode .187 $ .75 1101 256 x 1 Static 1.00 8080A 8 Bit CPU 24.95 ILD -74 Logic Drive (8 Pin) 1103 1024 x 1 1.50 (40 Pin) (2us) (NMOS) Dynamic Opto- Isolator (8 Pin) 1.00 DL-707 Common Anode .300 1.25 2101 256 x 1 3.00 Static (lus) DL-747 Common Anode (Jumbo) .60 2.00 8080 SUPPORT DEVICES TIL-113 Opto Coupler (6 Pin) 2.00 2102 1024 x 1 1.50 Static (lus) TIL-302 Common Anode (LORR DEC) .27 1.00 8212 8 BIT S 4.25 2102 -1 1024 x 1 1.65 I/O Port Static (500NS)

8214 Priority 8.95 2107B 4096 x 1 6.50 Interupt Control Dynamic (200NS) TTL PRODUCT 8216 Bi- Directional 4.25 21078 -4 4096 x 1 5.00 Bus Driver Dynamic (270NS) 7400 .14 7441 .85 7496 .65 74160 .86 8224 Clock 8.00 2107B-6 4096 x 1 4.50 7401 .20 7442 .44 7497 2.00 74161 .62 Generator Dynamic (350NS) 7402 .20 7443 1.20 74100 1.25 74162 1.00 8255 Programmable 12.00 3107 256 x 1 2.95 7403 .20 7445 .89 74107 .76 74163 .76 Peripheral Interface Static (80NS) 7404 .20 7446 .87 74109 .35 74164 .80 3107A 256 x 1 3.50 7405 .20 7447 .69 74110 .50 74165 .90 ROM'S Static (60NS) 7406 .39 7448 .81 74116 2.00 74166 1.00 4050NL 4096 x 1 4.00 7407 .39 7450 .20 74120 1.25 74167 3.00 Dynamic (300NS) 7408 .20 7451 .20 74121 .34 74170 2.00 x 1 74S387 1024 Bit S 2.50 5261 1024 3.00 7409 .24 7453 .20 74122 .39 74172 9.72 Programmable Dynamic (400NS) 7410 .20 7454 .20 74123 .50 74173 1.25 MM5230 2048 Bit 1.95 5262 2048 x 1 3.00 7411 .20 7460 .20 74125 .45 74174 .85 DM8796 4096 Bit 10.00 Dynamic (365NS) 7412 .24 7470 .20 74126 .45 74175 .75 5280 4096 x 1 4.00 7413 .35 7472 .23 74128 .65 74176 .85 Dynamic (200NS) 7414 .70 7473 .26 74132 .95 74177 .85 PROM'S 7489 16 x 4 Static 1.50 7416 .33 7474 .29 74136 .50 74180 .75 8599 16 x 4 Static 1.50 7417 .33 7475 .39 74141 .80 74181 2.00 7420 .20 7476 .31 74142 4.00 74182 .90 82S23 32 x 8 Open $ 3.00 Collector (Schottky) 7422 .50 7479 1.50 74143 3.00 74184 1.65 MISC. OTHER 7423 .28 7480 .69 74144 4.00 74185 1.30 1702 A 2048 Bit 5.00 COMPONENTS 7425 .24 7482 .72 74145 .70 74186 5.00 (512 x 4) (lus) 7426 .24 7483 .75 74147 Erasable and 2.50 74190 1.00 7427 .24 7485 .90 74148 1.75 74191 .65 Electrically N8T20 Bi- Direc- $4.00 7428 .40 7486 .25 74150 1.00 74192 Reprogrammable tional One Shot .85 7429 .40 7488 3.50 74151 .70 74193 .85 1702AL 2048 Bit 7.00 N8T26 Quad Bus 3.25 7430 .20 7489 1.50 74153 .70 74194 1.20 (512 x 4) (LO -PWR) Driver /Receiver 7432 .28 7490 .39 74154 .90 74195 .55 (lus) Erasable N8T97 Tri -State 1.45 7433 .34 7491 .65 74155 .70 74196 .80 and Electrically Hex Buffer 7437 .28 7492 .39 74156 .90 74198 1.50 Reprogrammable 1488 RS232 Quad 1.25 7438 .28 7493 .39 74157 .70 74199 1.75 2708 8192 Bit 40.00 Line Driver 7439 .36 7494 .70 74158 1.75 74200 3.50 (1024 x 8) 1489 RS232 Quad 1.25 7440 .20 7495 .50 74159 2.25 74279 1.75 Erasable and Line Receiver Electrically D3207A Quad 2.50 Reprogrammable Bi -Polor to 8223 32 x 8 Open 3.50 MOS Level LINEAR Collector Shifter /Driver C-3404 6 Bit Latch 3.95 LM308N(8) Micro Power Op Amp S .75 12NS Output LM311N(8) Hi- Performance Volt. Comp. .95 SHIFT REGISTER'S Delay LM318N(8) Precision Hi -Speed Op Amp 1.95 P-3408A Hex Sense 6.75 LM324N Quad 741 Op Amp 1.00 MM506N Dual $ .89 Amplifier W /Latch LM339N Quad Comparator 75 100 Static P-4201 Clock 4.95 LM380N 2 Watt Audio Power Amp .60 P-2405 1024 4.95 Generator LM381N Low Noise Power Amp 1.95 Dynamic MM-5320 T.V. Camera 6.00 NE555V Timer .60 N2518B Hex 32 Bit 3.95 Sync. Generator NE566V Function Generator 2.00 N 2533V 1024 Static 3.95 MM-5369 Oscillator 2.00 NE567V Tone Generator 2.00 MM5013N 1024 Bit 2.00 Pre -scaler NE723CN Voltage Regulator .50 Accumulator MC-6850L Asynchronous NE739N Dual Hi -Perf. Op Amp 1.00 Dynamic DM8130N Ten Bit 2.25 NE741 CH Compensated Op Amp .45 MM5017N Dual 2.00 Comparator NE741CN Compensated Op Amp .35 500/512 DM8131 N 6 Bit 2.00 NE1458CN Dual Comp Op Amp .65 Dynamic Comparator NE3900N Quad Amp .45

MM5058 1024 x 1 2.50 Static TMS3002LR Dual 50 3.00

Static BAMMAMERIfaRO. master charge TMS3132NC Dual 144 2.00 JADE Co Static ELECTRONICS DISTRIBUTION CALCULATOR CHIPS NEW LOCATION 5351 W. 144th ST., LAWNDALE, CA 90260 MM5736 6 Digit Cal. $1.25 TERMS: CT5001 12 Digit Cal. 1.75 Add $1 .00 for shipping plus $.85 if COD Phone (213) 679 -3313 With Specifications California Residents add 6%. Sales Tax $20 minimum On BofA & M.C. Retail Store Opens February 21, 1977 Orders from Foreign countries add appropriate postage Hrs. 9 -7 MON. -FRI.; 9 -5 SAT.; 12 -5 SUN. www.americanradiohistory.com TTL1 r*Trr 7400N FAIRCHILD TECHNOLOGY KITS FAiRCHILID WIRE WRAP CENTER 51174009 16 5974594 25 HOBBY -WRAP TOOL -BW -630 5974019 16 5074609 22 50111540 I 00 PHOTO ARRAYS 9114020 21 5974100 45 597415511 99 51 00 1100040 9 Dement Tape Ready Array Battery Operated Sloe Cl 597403N 16 507422N 39 591741569 99 1192002 00 rr.pnr we D 00 1190p41 12. Firmem Card Reader Array Weighs ONLY 11 Ounces 557401 18 59747354 37 514741575 99 357 HO Common Camnae D'9'I ;5 1100042 ReNalne Oplu Coyle' 59171059 24 5974149 32 50741608 1 25 119000+ 0 8 H9Ir Common Cathode 090 2 00 Wraps 30 AWG Wire onto 5911069 SN7475N . 20 50 50741619 99 1100005 0 8 990 Common Anode 098 00 COUPLERS Standard DIP Sockets 10 25 inch) 5974079 29 5974765 32 50711678 99 ITU0050 3 Gener0 P18posr 0540 Couplers Complete with built -m bit and sleeve 5971089 25 597/799 5 00 59741649 110 1.1" HIGH DISPLAY ARRAYS E100051 Da01n91on Oplo Coupler

5974099 25 5914909 50 59741659 110 1100010 1211nu! 3't 21911 Clock OIs5 y 7 00 $34.95 5974109 18 51174829 98 SN711666 125 1100011 24 ]lour 4 Osa Clock 067151 8 00 MOS CLOCK CIRCUITS IOallelleS not mcludedl 5974119 30 597/839 70 50741671t 5.50 11K0400 09'141 Clink CArl111ar CICII 7 00 5974129 89 ICM00011 33 5074859 50741709 2 10 LED LAMPS t WIRE -WRAP KIT WK -2 -W 597413N 45 5514869 39 B 95 10 Red 116a01 Dx0'tal Clock Cule.Nar wan BCD 700 - 59741729 1100020 LED Lamps W 70 5074889 3 50 9174149 59141139 1 50 1100021 5 Wed Colored LED lamps 101 ONpuls 11CM70021 WRAP STRIP UNWRAP 51174899 2 49 s1K0402 5574161 35 59741746 125 1100022 10 LED Moumng cops 101 Dual ()me nm'lal Clock Cnrud 5 00 Tool for0 30 AWG Wire 9174909 15 5974119 35 59741755 99 1100023 5 Three Rece LED 9041/109 Adapters 100 with AC Output IFCM381741 Roll Ft. AWG 5974200 21 5974910 75 59741768 90 r1K0403 0ue.t moue 1110.141 Crock Clrcu.I 5 00 of 50 While or Blue 30 Wil 5074219 33 5974929 49 S9741719 90 PHOTO TRANSISTORS won DC Output 1Ì1M391 /DI . 50 acs each 1 2 . 3" A. 4' lengths - S07412N 19 5974939 49 SN741SON 99 1150030 51611 tens Photo Ira055996 I00 nK0+05 Dues Dove moan Clock Calendar 6 00 pre -stripped white wire 5074239 37 5974949 79 59741818 2 49 1150031 5 Round lens Photo Transistors 00 Cuctol HCM70151 597425N 29 5974950 79 59741829 95 1160032 3 141 lens Photo Damn5lons

50112611 29 5974969 89 557416459 1 95 1180033 3 Round Lens Prao Darlingtons NITS $11.95 55171279 37 5974979 4 00 59741859 2 20 Automat. Clock Ka 40 00 5974299 42 59741009 100 5974116N I5.00 WIRE WRAP TOOL WSU -30 91743051 16 59741079 39 59741879 6 CO s 125" Ma. 190' dia. 5974329 31 59741219 39 59741889 3 95 4111- 4111 WRAP STRIP UNWRAP -55.95 4109 Red 10 51 01111 Rea 1051 59740711 27 597<1229 39 55741909 I 19 51174384 77 59741239 50 51741919 125 56209 Green 4 51 46111 /teen 4 SI WIRE WRAP WIRE 30 AWG 50209 D,.tnde .1111 16110. 5.14799 25 59741250 61 59741929 89 J SI DISCRETE LEDS 51 - 91209 Fr mw 4 51 SCIII Orange 4 25 55 min 51.25 5050 5195 1001.52.95 100017 54744021 IS 59741269 60 511741939 89 51 51500 5474419 89 59741329 109 59741945 1 25 OSO.. Ella ASS" ola. 015.. 654. SPECIFY COLOR While Yellow Red - Green - Blue - Black - - 19/44251 59 59711369 95 5914195N 15 AC22 Red 10 51 .1526 Red 1O SI A1550 Red IO SI MODO 651

5914/311 75 1 15 RC22 4 4 4 59741419 9174196N 1 25 Green 51 00526 Glenn 51 x1551 Greer, SI

1 ININANE0 51744/14 75 59741429 4 00 50741979 75 8122 Yellow 451 x1526 Yellow 4 51 %CS5% yellow 51 LED CRIMPER TOOL (CS 51474459 75 4 4 451 1'16 CUTTER -8) 59741439 4 50 SN7419691 1 75 X122 Orada 51 xC526 Orange 51 XC556 Chyme 514/44654 81 Irla! 5/51.10 59741449 4 50 1 051.22 111 4,51 X1526 16.1, 4.51 XC556 Clear 59741999 75 751 PI1el Nose I serrated -)awl 5574479 69 S91741459 1 15 S0712009 5 59 SPECIAL XC556 Red 100/58.00 1000/560.00 SPECIAL Scissors Action Cutting 5914489 79 59141119 2 35 SN742794 90 - - 5974500 26 6 Bolt Cutters I4 -40, 5 -40. 6 -32. 8.32. 55111485 2 00 59740515 I 79 omp 51174515 1 11138 27 5974150N 00 59742840 8 00 01101 DISPLAY LEDS 10-32, 10.241 54745311 17 59741519 79 9742859 6 00 Crimp Stations i7mm Auto 22-20 lo TYPE - 59145411 20 59741539 09 59143619 .. POLARITY Hi 1501 001 011115 HT 12 -X0 elect ) 51114 1 Conlon And0e ep 300 I 75 MANY OTHERS AVAILABLE ON REQUEST 222 ::Ali 7 S r 7 Opt Malt. 300 495 400 I 95 -Up-Front Wire Cutting 20% Discount or 100 Combined 7400's 119 I Common Cae10a 125 3 i 00 300 Scissors ACtlon Stripping (No. 22 -201, Nn 10 MAN 4 Common Catan 1BÌ 195 01004 300 99 E04000 25 Ì+C0414 Crimp Stations Insulated 12w MAN 7 - Common Nade 300 175 DL Ì0l 300 Pr CD4001 25 CMOS 74C ION 65 1 12.10 elect.) Common Nade ¡peen 300 1 95 DL 728 500 1A4002 25 cOJ035 85 74C209 65 '.IÁ9 2V 101,0000 1 Nade ye110w 300 95 50041 Wm'55 600 1 50 Actual Size - 81/. length 611.1006 250 00+070 2 45 741309 65 '.I49 $8.50 5? Common Anodegran 300 99 00 747 n.x 600 7 75 C04007 25 CD4042 1 90 046429 21S '. 11'1x..1 I rn urn on 1nn1e 51 400 99 0l 750 Commonon C915555l55 600 2 40 000009 09 1041344 1 50 741739 1 50 ._. 300 150 0L 338 Cnn,mm, I.0145 110 50 001010 59 C01046 2 51 741.74 300 99 F11050 250 75 001011 25 2 75 74/909 J Oli CD4aÌ 595 Permacel Electrical Tape 99 r':DSO1 500 1 00 C01011 15 CD4049 79 0409511 2 0 1 00 3+ 47 500 IwAIcI X669 °o1151 Allere415e, Notimport CO:aI C-D1050 79 7+C10;9 1 2 III C0Á16 56 Cl/4051 2 95 ; -1151 2ál S1.25 per roll -59.95 per 10 roll package C0:07; I 15 CD0053 1 95 741151 4 00 :i (grs ATARI GAME BOARDS NEW AY -3- 8500 -1 TV GAME CHIP COA19 55 1134660 3 25 74157 2 15 .6 lead Dual In Line BOARD A - n': 16 Co4020 49 CD1p66 1 75 71C160 3 25 116155 60 each tnrsa91 IC 56.95 ea. Seleda51e Mows Ine nIIIII Is Mended lo In Gallery ZENERS DIODES RECTIFIERS C04022 r 25 C04069 45 741161 3 20 - - c 1 anse.lms, Iks,sl0rs ,perd and bal sae Bowered Mlnlmum number of TYPE VOLTS W PRICE TYPE VOLTS W PRICE 204023 25 C04071 15 74116:1 3110 [bodes. Cales. Clyslals.5wdco .n '.' ... manual Gan semce e,lernal rornoenenlo required 19746 3 3 400mm 4 100 104005 600 PIV I AMP 10 100 l'04024 1511 1,04081 s 7+1164 3 25 ..i n sounds tin complete smem 1N7514 5 I 40211 4 100 194006 800 PIV 1 AMP 10100 64025 75 104511 2 50 741173 2 60 DELUXE BOARD I n', .18 $9.95 ea. - . e - 1mn1: hockey 91752 5 6 400m 4 1 W 194007 1000 PIV I AMP 93 100 In1027 69 104518 741191 2 75 over 100 tam teusa5le IC s ONLY 5i . 7 50 Iquasli peor., 114753 6 40011 4100 193600 50 1001, fi t 00 114026 1 65 MCI4566 00 741195 2 75 c 1ou16101s 90.95011 0941111,11 0,64606 and Iwo eue 0.56/5 111754 6 8 400511 4 100 194148 75 15100 90 7410055 i' noes. $24.95 04029 7 39 8013041 450 Caps Crystals S.Ones. 1E05 etc 111959 0 2 400.1 8 100 147154 35 10m I? IDO 01010 65 741020 55 61114016 54 159658 15 40011, 4100 100305 75 25m 20 1 00 IC SOLDERTAIL LOW PROFILE (TIN) SOCKETS LM300H 80 1M13100 2 95 - 1515232 5 6 50011 28 144734 56 25 1 24 7549 50.100 t -24 .9 1M30111 35 191135111 165 195234 6 2 50001 28 114735 62 Iw 25 S 17 16 ;S 74 mit 5 38 37 1030109 35 LINEAR LMI1r4N 175 195235 6 8 500m 28 144736 68 Iw 2F pm 20 19 8 211 pm 45 44 19.430211 75 1081+560 65 195236 15 500m 28 144738 82 25 mn 21 20 36 pm 60 59 SB 9130451 100 LM310N 115 11014969 95 1N456 25 On 6100 194142 12 la1w UIn 19 78 27 10 m0 63 62 61 1M30511 95 0143739 25 LM15564 t 05 191458 150 Im 6'100 194744 15 6n 17 36 35 P0 .M3071N 35 1M37)N 00 1912111N 1 95 SOLOERTAIL STANDARD (TIN) 104850 180 An 6100 111183 50 1 60 1"r .030811 100 1.14313011 39 11,1290191 2 95 5 77 25 N 28 pIn 5 99 90 81 194001 S0 PN 7 AMP 12 100 141184 IO!" I 10 pIn ,!A308eN I 00 L81160155 05 1030659 69 21 ?5 36 inn 139 1 26 115 1144002 IW PII 1 AMP 12100 191,85 II' 50

WPM 1 1 1 ,5870911 I IO 103819 79 11439009 55 IS 37 30 =11 . inn 59 45 30 104001 200 PIV I AMP 12 00 161186 20 ,543095 g9 1M3820 19 1M39091 60 61 49 45 1514004 400 PN I AMP 12 100 119188 4-- 1155010 031000 I IS 03 143909 I 25 SOLDERTAIL STANDARD (GOLD) .51311H 90 1155109 00 101555671 185 5 10 T :4 p.0 $ 70 63 57 SCR AND F BRIDGE RECTIFIERS L1.131110 90 015310 00 MC5558V 90 mu 35 32 29 78 p'' 1 10 1 00 90 C360 1SÁ@ 4004 SCR 51 95 158318C9 150 905161 00 14752511 35 32 M inn 75 I 40 C38M 354@ 2039 SCR 1M71911 130 11E5401 00 19175355 1 25 47 41 10 pm 75 59 262326 I GA @ 2001% SCR 1.1.13205.5 135 915505 79 80388 4 95 IDA 1M320K-5 I 35 NE555V 39 1MIS150 49 WIRE WRAP SOCKETS (GOLD) LEVEL #3 MOA 9601 0. AV BRIDGE RFC 1 95 41 u J7 ?J pIn 51 05 95 17A SW 1 1913205.12 1 35 9E56013 5 00 75151CN 39 ont 545 85 MOA 980.3 On 2000 BRIDGE REC 95

open 119 se 3l lfl , 1 40 1 1113200.15 1 35 14E56113 5 00 75152CN 30 25 110

15 NE5628 7545309 39 55 1 2 JI ID pm 159 145 130 090209 45100 LM32015 1 5 00 RIPS 405 55100 TRANSISTORS Tri Ì5 68 62 a 11Th 1 6909 451 op 19132015 1.75 9E56511 125 7545419 39 P 175 55 1 40 MPS 406 55100 151561 35100 19.00 0sm, 103207-0 115 955659 1 75 7549115 79 151:190 00 III P111566 4Slea 7111 125 7549219 89 212221 455 01 LM3207-12 175 4E56600 663569 4 51 00 G7 MINATURE TOGGLE SWITCH 2N2212Á 551pC 1M720i-15 1 15 NE567N 1 95 75494151 89 1j, Plastic Push Button Switch 763206 Sft00 N403 797369 551 00 175 1415674 1 50 RCA LINEAR 10AWOSoIIAWIM- 5'Lola 713105 SSI W 1%4109 103201.16 2971694 S1 00 1111106 SS1 00 2'r5016 I ;5 1M703C9 5 CA3013 2 15 1M9001 24 II 5o (Wide) X .901R19M 8 -27 Tbread iJMT-221 DPOT on1oN/on 7X1+4 4S100 $1.95 163702 5f101 ALPO 5 s .. CA3032 2 56 LM323K 5 9 35 19170911 29 AMP @ 14 Voll- 1 AMP(_ 110 Voll 21029064 +5100 8 JA1T-223 DPDT 7630, 55103 716000 45100 1913249 30 1M709N 29 CA3035 2 40 1.9 on/none/on S1.75 1919014 55100 10 Up 14312+ S 65 215009 451 01 797575 5S, CO 1.913399 70 1M1109 79 CA1019 1 35 J 1081 01151 On Push Olt 59 49 JA1T-121 SPOT 00109/00 S1.50 1e31t5 51m 156119 5512, 130 793051 n, m 1M31055 )5 19171154 39 CA3a6 J -1882 Normally Open 59 49 110901 55100 2115136 551 d ORJMT-123 SPOT on/none/on $1.25 75]055 s 19 1.1434004 1M720H 55 CA3059 3 25 Al. 451003 216139 55100 )5 J 188 3 Normally Closed 59 49 X2955 SI CO '14305 4S100 215709 55100 1M3421-8 75 LM723H 55 CA3060 3 25 4X7955 51 75 941. 4 SI 00 716951 551 00 1M3100N2 3y 1M133N 00 C.A3080 BS 793191 521 CO 151 00 .0554115C9 151 On 293396 LM340K-15 35 1.9473951 1 00 CA7061 2 00 55100 CLIPLITE 8/$1.49r 355 CO 31 57 d 2 00 LDIP SWITCH ,-13405.18 95 1M141CH 35 CA3002 .174 5 0 51 00 -813400.24 i)5 1M741C11 35 143083 60 LED MOUNTING SYSTEM These SWIChes lealure 7 SPOT slide swam, III a 15434015 75 1 M7411JN 39 CAì0B6 85 Lse with X1556 LEDS molded dip They are ideally soiled CAPACITOR 50 VOLT CLRAMIC CORNER .5134014 75 1M107N 79 CA3089 3 75 1'LJ001010510I ,Ippllra9Ons 51.95 eM3.01.8 75 1911479 79 CA3091 10 20 DISC CAPACITORS I 10 49 50 -100 1-9 10 49 10:' L61340i.12 75 OA 74851 39 CA3123 2 15 ï, 10p 05 a 03 071.,1 05 04 035 11.13407.15 5 LM14BN 39 CA3130 I 39 50 PCS. RESISTOR ASSORTMENTS PER ASST. I S1.75 22 p 05 04 03 0007.,E 05 a 035 LM340T.18 75 15113039 90 CA3140 25 47 p 05 04 03 010 05 04 035 1.03401.24 75 15113040 19 CA7600 175 1 5 ea 100 p 04 1035001 00 19413059 140 914194 5 95 ASST. 77 OHM 33111'.' I11M 47019M 56 OHM 1 WATT 5, 50 PCS 05 03 012F 06 05 a RCA195 220 0 05 04 03 04)0 06 05 a 1M351CN 65 IMIlO)N 85 325 6B OM 82 13.15' '.. n 111191 120 OHM 1501NIM 410 p 05 a 035 11.1 12 09 075 ASST. 2 5 ea 180 OHM 220 OHM.' 130 1111M 174 WATT PCS 71923 74 LSI39 1.95 :TOM 00M 190 S. 50 100 VOLT SOUR 511M CAPACITORS ;415151 155 11502 74LS00 T 330 OHM 560 OHM WO OHM BOO 0111.1 IK 001m1 12 10 07 022m1 13 II 08 :9 I 11503 '+1115,1 89 0022 12 10 01 00101 21 17 13 ASST. 3 5 ea 125 1 SS I BK 2 2K 114 WATT 5. 50 PCS 41504 69 2419117 I 55 0047ml 12 10 07 Iml 27 23 17 741576 3 3K 3 9K 4 15 5 6K 6 80 15 795162 2 25 011111 I2 10 07 22m1 33 21 22 511 ?5 4 5ea ,OK 571 15K 1B1x WATT SO Pes 115116 29 5 Ì1f ASST. 1/4 5. e20'. DIPPED TANTALUMS (SOLIDI CAPACITORS 15015 Ì41.5a I 95 41510 149 I 35V 1 .Y a208 215 135 19K 4211 28 23 17 5 35V 30 26 21 49 101513 69 Ì445n0 915115 1.95 15 17 5 ea 354 28 23 2 2254 31 21 22 7415191 ASST. 5 560 68K 82K 100K 1200 4 WATT 5. 50 PCS 140514 :5 741590 t 25 69 2235V 28 23 17 33.25V 31 27 22 1500 1800 ;4L520 79 ;4L592 125 ;415191 2 85 0700 270K 1100 33.350 28 23 17 4 7'251/ 32 28 23 t 241526 151593 25 ;41519' 785 ASST. G sea 3900 4705 5600 6800 I.I. I71 WATT P. 50 PCS 47350 28 23 17 6 8.254 36 31 25 195 ]71577 N 79.595 7415191 2 85 68.35V 28 23 17 10125V 40 35 29 IM 1 2M 15M 1 BM '81 74528 ;41596 189 7415191 2 85 10'35V 28 23 17 1525V 63 50 40 S 3 3 0 5 114 1 ASST. 7 u. 7 7M 3M 9M 7M hM WAIT 5, SGPCS 740530 75 7445107 59 741519+ 09 MINIATURE ALUMINUM ELECTROLYTIC CAPACITORS 741532 ML512) 59 74151'11 189 Radial load ASST. 8R Includes Resistor Assortments 1 -7 (350 PCS.) S1 0. 95 e a . A+Ial Lead 11.540 9 795112 59 7+1557 4750V 15 13 10 47 25V 15 13 10 Ìíl52%,5 59 7415137 25 1 .'41551 29 $5.00 Mlnlmum Order - U.S. funds Only 50áe Shoots - 25- Send 35s 51amp lIr 19771 Cam1511 1 0 5011 16 4 I I 47.504 IS 14 11 7J.5t 36 1 59 74l52Ì9 :5555 29 Calllornia Residents Add 6% Sales Dealer Olseet81 Available Rapes! Pricing 3 3 50V 15 13 10 1016V 15 13 10 74L5135 I 89 7í1567n 95 - Ti. - i 4 7 25V 16 14 12 1 0 25V 16 14 II

10 15 13 10 1 16 14 II CLOCK 25V 0 50V CHIPS 10 50V 16 14 12 4 7 164 15 13 10 005309 6 0,0I BCD Oul04s Resel PIN 59 95 22.25V 17 IS 12 0 2 25V IS 13 10 605311 6 011'1 BCO Outputs 12 or 24 Hour 4 95 22'500 24 20 18 4 7 504 16 H I I 945312 4 DI¡I BCD Outputs I PPS Output 4 95 41354 19 I1 15 11,164 14 12 09 005314 6 0'ot t7 or 24 hour 50 0I 60 511 4 95 110505 25 21 19 10,250 15 13 10 0615416 4 0.01. A4101 I PPS Output fi 95 100125V 21 20 18 15,500 16 14 12 005318 shoe Clod Crap Ior Ise With IMM5001 59 9Si 9 95 ames 1001505 35 30 28 0250V 24 21 19 CU T1 6 001. Calrndat, Natur. 12 or 24 Not 595 ELECTRONICS 220254 32 26 25 100164 19 15 14 DATA HANDBOOKS 220504 15 41 30 100 25V 24 20 18 1021 -A HOWARD AVE.. SAN CARLOS. CA. 94070 Lir7400 Pin nm P. Moser son of 540007400 ICs 52.95 470'254 33 29 27 100.504 35 30 28 CMOS P.,. 0.11 Al 11..11.:1.011,00 01 4000 Sev,cs 1CS 52.95 PHONE ORDERS WELCOME - (415) 592-8097 10001164 55 50 45 220 164 23 II 16 Linear PHI 52.95 70 470250 31 ALL THREE IHANDBOOKS 56.95 All Adverlised Prices Good TMo April 220011611 62 55 28 26

www.americanradiohistory.com .'CRYSTALS MICROPROCESSOR COMPONENTS PanatroniCs %' `- - LOGIC ANALYZER KIT - THESE FREQUENCIES ONLY __" 8080A CPU 019.95 822P System [antioller - Bus Drive $10.95 lab shown . Feb Popular Electronics, Pert ~ Frequency CeselSlyle Prlca - 8212 8 Bit Input /Output 4.95 MC68001 8 Bit MPU 35.00 Troubleshoot any CYlA 1 000 MHz HC33'U $5.95 8214 Priority Interrupt Control 15.95 MC6820L Penult Interlace Adapter 15.00 CY2A 2 000 MHz HC33 U $5 95 type of digital Bus 011901 6 95 MC6810AP1 128 o 8 Static RAM 6.00 CY3A 4 000 MHz X01841 S4 95 8216 OPDIIectIonal system including CV7A 5 000 MHz OCIE U 54 95 8224 Clock Generator.0over 10.95 MC6830L7 1024 o 8 Bit ROM 18 00 Microcomputers CV12A 10 000 MHz HC18 U 54 95 CPU s RAM s or- Nw CY14A 14 31818 MHz HCt6U 54 95 813Bo m CVI9A MHz HCIE U S: 95 18 000 25( 8080A LA100 KIT GY22A 20 000 MHz HCIB U 54 95 2T02 Io::. 'S $189.00 CO30B 32 000 MHz HC18 U 54 95 2107 i 95 SRs MO More than 60 db Isolation 21t1 IF 95 TV ANTENNA SWITCH 2504 1024 Ornamc 5795 7489 Switches 300 ohm to OR-2260K8 Kit 527.95 XR-2206KA Kit 517.95 2518 Her 32 &T 70o B101 95 2519 He. 40 BIT 4 00 300 ohm E ns WAVEFORM TIMERS 2524 512 Dram, 2 49 Ala Switches 75 ohm eR -SSSCP s n 8599 GENERATORS 2525 024 0111wnm 6 0o to 300 ohm 91L02 2 75 H 205 5A 40 EXAR 011 420P 1 55 2527 Owl 256 BII 195 4 19 KR -556CP 1 71200 756 I RF coax connecting cable AR 2206CP 85 2529 Duo 512 B11 4 00 AR 93421 256 . I xA- 2207CP 3 e5 eeluELUREan 7556CP 320 2532 Wad BO BIT (16f1. I with RCA phono 1 IMM5262 2x a1 ,m, Iit' .R-2211CP S6 70 SR 2240CP 4 2U 2533 1024 &aid plyes suttee outman AR 4136 PHASE LOCKED LOOPS 7341 too 6 95 PROMS aR,1410CP S, 20 R 145E 3 85 111 210 520 74956'0 16 4 Rep 3 95 02A 21118 rama. S 995 141011, 70 .R1486 5 B0 6215 660 52,03 7018 fins 4. $6.95 IR 195 kR 1800P 1 70 .R-1489 480 561CP BARTS 132521 e UDen C sa xR 5 R 56;01 1 :O 879!21 3: . A Insole R 2567 2 99 2201 20 A5-5.1013 30A Baud 5595 5 00 749:8' 1024 ' 95 CB MOBILE MONITOR 3601 756.4 Fast 395 Hear the highway action ROM 8 Off -on volume Control 2708 BK Etnom 34 95 2511 c- CONNECTORS CI,, 5995 6301.1 1024 In ,Slate Bipolar 749 Internal mount antenna 7516 Cna 0, 10 95 6330.1 256 00111 Collector 13,20111 2 95 3P. 9 -voll battery powered PRINTED CIRCUIT EDGE -CARD 195 6331.1 256 TrrSSle &pdar 2 95 156 Spacing -Tin -Double Read -Out Portable - attaches to visor Bifurcated Contacts - Fits .054 to .070 P C. Cards 23- Channel operation GEMINI -68 The Unique Microprocessing System Long range reception 15 0 PINS (Solder Eyelet) 51.95 18 á6 PINS Eyelet) S2.49 MIRel'& ROM (Battery not included) (Solder 61120 PIA Actual - 4 x 3 A 1'7 22 .1.1 PINS Eyelet) caso RAM Size $9$9.95 7 (Solder 52.95 Standard Ra -Sse, YOM Fully 50 100 1 100 Spacing) PINS (Solder Eyelet) 56.95 Curtest Lop 4'h" Beaty Ip Port Buffered and DIGITAL 25 PIN -D SUBMINATURE Boards - STOPWATCH Tristalable &Rn1 E &al LED 00011 sop.* ese -. DB25 PLUG Dual 22 53.25 Address and Imes to 59 .mute¢ 59 59 secours pin edge Crytul Contra , lame Base 0025 SOCKET 54.95 Data Buses Connector Three 5loowdtcles m One FULLY Times Survie Event - Spi S 11110, NOT A 5x45 .215 x90 iFIC315 DIGIT DVM K. Isnl. ASSEMBLES cryai s 3 Pende CNN KIT 1 .,rWlk vl..d C1Hx-B1aWM \ Iti" w ia16 uuA eunm. Kit - $39.95 WwPwer MAM Assembled - 549.95 STAND ALONE CPU HOARD - Iles 384 bytes of RAM on board semi CO 015,232 ano 20 ma [sent loop. Heavy Duty Carry Case 55.95 (1111 1114654 eneel memory acuss TONAL WM In son -ware - 5,1.1 able echo back rapab,nty Pam SA,CPU B oard $27as .7.95 Stop Watch Chip Only (7205) S19.95 CPU 60900- same as above EAT only has 128 bytes or RAM on board used won IR RAM 004,0 fisted below INS 0.2 VDC 05 per Cent digital 1011meler features ole Mmprola 3': pipit Pan Gen., 68 CPU BOaIO $259.95 II has a 4 (Tom DVM chip set LED display ORO operates a single 5V BK RAM BOAR() - Uses low power staid RAMS 5000 csce lane. 1 5 Amos RAM Timebclnd power Supply The unen Is provided complete with an Injection molded black 611, G

1116 VECTOR BOARD BUGBODK Ira - Introduces DART - recommended for RTTY Kit S29 95 - -. 01 Hole Spacing P Papero Price enthusiast 55.00 /hook --.Tr Pam N, L w I 2 up Assembled: $39.95 BUGBOOK III - Explores 8080 chip - Introduces Mark 80 Microcomputer /9mok .r 50 t rpr 515.00 CASE ONLY Unctudes hardware. mounting bracket and 5eze0S6.50 1 n:P::062 450 650 701 A 1 TIMER ... ::114.7 :X e5 7% 7:1 555 APPLICATIONS SOURCEBOOK WITH 'S9h l4 062 450 1.00 504 45: EXPERIMENTS - ovet 100 desrg techniques $6.95/book 151.6: P62 850 1:00 97, 826 rany '.I 1. ..n52( 1 4 E 50 I Introductory Otter - all 5 b oks (worth $43.95) I JE700 CLOCK SPECIAL 539.95 ab 4111 Incn.l' HEAT SINKS

OTAN r mon 01,9011e, Ieadnul und II. CONTINENTAL SPECIALTIES ATMs ili n.uk,mo 205-CB u rv.wl, ome' Hen Son cam, 8,.6 t all.l tor In s S .25 PHOTO BOARD 6 Other CS Prolo Boards PROTO CLIPS 291-.360 0,11111111 1111 Sr., l0 10 220 lonl.,ual. 6 nnwA. S .25 P8100 - 4.5" x 6" S 19.95 14 PIN 115 VAC $17.95 600.75A bl.rr. A,I,a,nn Amnnmrn 51.60 $15.95 $4.50 16" long X 4" wade) PB101 5.8" o 4.5" 29.95 16 PIN 4 75 HEXADECIMAL ENCODER 19 -KEY PAD PB102 - 7" x 4.5" 39 95 24 PIN 8 50 PB103 - 9" x 6" 59.95 1 O DESIGN MATES ABCDEF PB104 - 9.5" x 8'. 79.95 0M1 - Circuit Designer Relu'n Key PB203 - 9.75 x 654 x 23/4 75.00 54 95 PB203A - 9.75 o 614 x 24í 120.00 Optional Key 1 Period) DIGITAL CLOCK KIT 31/2 INCH DIGITS includes power supp'y1 DM2 - Function Generator - 4 DIGIT KIT 549.95 4 DIGIT ASSEMBLED 559.95 - Key 69 95 Logic Monitor 584.95 6 DIGIT KIT 569.95 6 DIGIT ASSEMBLED 579.95 DM3 - RC Bridge lo, OIL Ill Ill a, Culls 14 rue. $10.95 each 59.95 tins clock features big 3'7 high digits tot viewing m offices. auditoriums. etc. Each digit Is formed by 31 bright 0.2' LED's The clock operates from D type 115 price 117 VAC. has either 12 or 24 hr operation The 6 digit version Is 27" k OT PROTO STRIPS 0 -595 590 12 50 63 KEY KEYBOARD 01.598 bus strip 2X 315 "k 1'n and the 4 digit is 10 k 31.7' x l': KITS come complele with JEW O 47S 470 1000 all components. case and Iranslormer orb bus stub 1 25 Specify 12 or 24 Hour When Ordering 0 355 350 B 50 O 359 bus imp 2 00 111 O in ISO 4 75 $19.95 0 .125 120 3 75 0 -85 80 25 JE803 PROBE 1100165 16 LINE TO FOUR SIT PARALLEL KEYBOARD ENCODER 61 95 U IS 70 Do Ines LOaC PI1be,3 4u811 , ensole m hpupe snow., c^fa 'il'!IMM11g1I,'.. Ekperlmenlor 300 S 9 95 Ill Olt R111 CMOS q delves Inc PO", n Expeumentor 600 SIO 95 JOYSTICK needs to 0041110 OWN. oil of the normt umler I a These joysticks lealule our u .0.16.001 IO a scant 10 TA It uses MANS 55.00 Minimum Order U.S. Funds Only Spec Sheets 25p Send 35e Stamp tar 1977A Catalog lollow15 polenllo1neters. that vary re- - - to trod.* any 01 Ile Stoles by Calllornle Residents - Add 6% Sales Tax Outer Discount Available - Request Pricing mbph MI III OWI oIPUL5E1 P IM sistance proportional Io the Pate un dried non fnelWmey oases to 45 MHa $9.95 Per Kit angle of the slick Sturdy metal t.in I be used at MOS revels or 0..4 domain construction wits plastics om1e5un printed circuit board components 01161 at the mova-

ble Perlecl TOT eleCIromc 10101 James PL 5V 1A Supply tnls rs Dames ana lnsll umentallon ELECTRONICS a,1.19.0 ail gown 1100-1 15.4 lne cadi auw, L12309K rpuaator IC loi rova0 u 5141 AMPo1 Curren, at 5 45K Pots $6.95 1021 -A HOWARD AVE.. SAN CARLOS, CA. 94070 .J Its We In In aie mals eJs1 tor you by pltml': ,s n.. I - PHONE ORDERS WELCOME (4151 592 -8097 auandme *100K Pots $7.95 - - All Advertised Prices Good Thru April S9 Per Kit

www.americanradiohistory.com computer display, terminal

This display terminal has an integral controller, B/W cathode ray tube and keyboard. The system has a serial I/O interface for communication and an I/O interface for a printer

DISPLAY (P /N 4802 -1095 -501) FEATURES: 17" B/W CRT 41 lines of data 52 characters per line Characters are generated by a diode matrix "graphic" technique 21 special push- buttons wired for a program call up Brightness Control Self- contained power supply

KEYBOARD (P /N 4802 -1115 -501) FEATURES: Reed switch technology 54 data keys 28 special keys detachable with cable $180.00

LOGIC UNIT (P /N 4802 -1157 -502) FEATURES: External logic & power pack not shown. 1024 by 6 bit core memory "AS IS" Printer I/O interface 4 way cursor control, graphics display. Communication I/O interface The story: These are unused terminals made for airport ticketing & seat assignment. After several years of POWER: 115V, 50/60 Hz, 500 Watts storage they require tinkering to make operable. We have some hints printed such as cleaning PC fingers. One of WEIGHT: 210 lbs. (including logic unit, keyboard, our customers has this tied into his KIM -1, another has display and cables.) his running with his IMSAI. We have data on this. Should be useable on most common computers. A hell of a deal and all for a paltry $180.00. Don't be left out FOB LYNN MASS (you pay shipping) as many were on our past VIATRON deal. Sold "as is" Check with order please. all sales final. WITH COMPLETE DOCUMENTATION = cos= WIRE WRAP GUNS

C=...11.11 4.= Used wire wrap guns, released due Gl=r, CC2=, to factory closure. Various mfgrs, ,0.09,®,® .31211 atiXar some Ingersol Rand, electric or air. No collets. State choice. Cost over $100.00 each Here is a real deal in a PC module 6x5 sockets (30). List price over $50 each, most by AUGAT. Some pre -wired. Our price only $15.00 each. New, unused boxed, 14 or 16 pin, 5 x 6 sockets. $15.00 each or 2 for $25, state your choice 14 or 16 pin.

shown actual size IC Sockets, while they last ... 8 Pin 10/$1.00 SOLAR CELLS 14 Pin 10/51.25 Designed for the space program, these are highly 16 Pin 10/$1.50 the efficient high output cells. Used for powering 18 Pin 10/$1.75 silicon equipment, charging batteries. Made by Ion Physics 14 Pin IC connector 10/$1.25 Corp. Each with spec sheet. Size .394 x .788" 65 mA, .43 V $1.25 12/$12.00 Size .788 x .788" 125 mA, .43 V $1.60 12/$15.00

Please add shipping cost on above. Minimum order $10 FREE CATALOG SP-9 NOW READY P.O. Box 62, E. Lynn, Massachusetts 01904

www.americanradiohistory.com THE PROKO PTR -1I PAPER TAPE READER KIT $54 To use the PTR -II ASSEMBLED $64 Just connect to a standard parallel input port +5VDC STROBE LINE GROUND WHICH CAN BE EIGHT -TTL BUFFERED EITHER A PULSE DATA LINES OR A TTL LEVEL

TOP QUALITY $28

HEAVY 5VDC DUTY @ 22A POWER TRANSFORMER .18 VDC FOR 40V IMSAI / ALTAIR (Prom programming) NctrwwCs INCLUDE SHIPPING LIMITED QUANTITY 20 LBS the proko Check or money order residents only. Calif. 6% electronics shoppe The Proko Paper Tape Reader: A manually operated reader, reads 9 -level paper . All orders postpaid 439 marsh st. tape into on The Min. U.S. Ste any parallel input port. Just supply a light source, grab the tape and pull! order. Prices sublc'ct to san luis obispo, ca. 93401 ch,any,. nohc,. 805/544 -5441

KITS BY Lei MUSIC l JUST IN: 64 x 16 VIDEO BOARD Altair plug compatible display 2102AL -4 - FULL SPEED MEMORY (500ns) 4Kx8 Static Memories 32 x 16 or 64 x 16 switch selectable. Composite and MB -1 MK -8 board, 1 usec 2102 or eq. PC Board $22 parallel video ports, upper and lower case with Nearly 1/3 less power consumption software. * (NOT FOR S-100 BUSS) Kit $179.95 of even a 21 L02A PC board S35 MB -2 Altair 8800 or IMSAI compatible Switched address SP -1 Synthesizer board. Computer controied wave * 2.00 EACH 32 FOR 1.80 EACH * and wait cycles. PC Board $25 forms 9 octaves 1 vrms '4% distortion includes high level MB -4 Improved MB -2 designed for 8K "piggy- back" music language. KIT $250. 82S06 2.00 82S126 3.50 74C200 5.50 without cutting traces. PC Board $30 82S07 2.00 825129 3.50 Altair comparable mother board. Room for 15 connec- 8573 4.50 Kit 4K .5 usec $129.95 Kit 8K .5 usec $199 82S11 2.00 825130 3.95 8574 5.50 tors 11" x 111/2' (w /o connectors)....,..$45 MB -3 82S12 2.00 825131 3.95 8575 4.50 1702A's Eroms, Altair 8800 & Imsai 8080 compat- With 15 connectors $110.00 82517 2.00 74S206 2.10 8576 4.50 ible Switched address & wait cycles. 2K may be ex- Altair extender board (w /o connectors) $9.50 82S23 2.50 74S412 4.00 8577 3.50 panded to 4K. Kit less Proms $65 2K Kit $145 82S123 3.00 74S301 3.50 8578 4.00 4K Kit $225 With w/w connector $13.50 100 Pin spec WW or Soldertail both fit IMSAI or SSM MB -6 PC 7400 .16 7473 .35 74164 1.10 Bd 535 Mother Bd $5.00 ea 10/$44 7401 .16 7474 .35 74165 1.10 MB- 6A8Kx8 Switched address and wait assignments 7402 .21 7475 .50 74166 1.25 MODEMS $85.00 Memory protection is switchable for 256, 512, 1K, 2K, 4K 7403 .16 7476 .30 74170 2.10 1702A EROM $10.00 1404 .18 7480 .50 74173 1.50 and 8K. 91L02A .5 usec rams, Altair 8800 & IMSAI 'programming send hex list 5.00 7405 .24 7483 .70 74174 1.95 compatible. With battery power option AY5.1013 UART $6.95 7406 .20 7485 .90 74175 .95 Kit $250 Assembled & tested...... $290 2513 prime spec. upper or 7407 .29 7486 .40 74176 .90 LO Boards lower case 11.00 7408 .25 7489 2.00 74177 .90 LO -2 1/0 for 8800, 2 ports, committed pads for 3 more, 8080A prime CPU 25.00 7409 .25 7490 .45 74179 .90 8212 prime latch buffer 4.00 7410 74180 other pads for EROMS UART, etc. .18 7491 .75 .90 8224 prime clock gen 5.00 7411 .30 7492 .50 74181 2.50 Kit $47.50 PC Board only $25 8228 prime sys controller 8.90 7413 .45 7493 .50 74182 .95 7414 70 7494 .80 74184 1.95 7416 .35 7495 .75 74185 2.20 MM1402A 1.90 2501B $1.25 1101 1.25 74LS00 .40 74L00 .25 74L78 .90 7417 .35 7496 .90 74190 1.15 MM1404A 1.90 2503V 2.00 1103 1.25 74LS01 .50 74L01 .25 74L85 1.40 7420 .20 74100 1.00 74191 1.25 MM5006A 1.50 2504V 2.00 2101 4.50 74LS02 .40 74L02 .25 74L86 .75 7423 .37 74107 .40 74192 .90 MM5013 2.50 2505K 2.00 2111-1 4.50 74LS03 .40 74L03 .25 74L89 3.50 74193 7425 .30 74109 .90 .90 MM5015A 1.50 2507V 1.25 2112 4.50 74LSO4 .45 74L04 .30 74L90 1.50 7426 .30 74121 .40 74194 1.25 MM5016 1.50 2509A 2.00 2602 1.60 74LS05 .45 74L05 .40 74L91 1.50 7427 .35 74122 .50 74195 .75 MM5017 1.90 2510A 2.00 4002-1 7.50 74LS10 .40 74L06 .30 74L93 1.70 7430 .25 74123 .70 74196 1.25 MM5025 2.50 2511A 2.80 4002-2 7.50 74LS11 .50 74L08 74L95 7432 .30 74125 .60 74197 .90 .40 1.70 MM5026 2517V MM5260 1.00 7437 .27 74126 .60 74198 1.75 2.50 1.25 74LS12 .55 74L09 .40 74L98 2.80 MM5261 1.00 7438 .27 74132 1.00 74199 1.75 MM5027 2.80 25186 1.50 74LS20 .40 74L10 .30 74L123 1.50 7440 .15 74141 1.15 74200 4.95 MM5053 1.50 2519B 2.80 MM5262 1.00 74LS22 .45 74L20 .35 74L154 2.00 7441 85 74145 1.15 74251 1.75 MM5054 1.90 2521V 1.50 7489 2.00 74LS27 .45 74L26 .40 74L164 2.50 7442 .60 74147 2.35 74284 4.95 MM5055 1.90 2522V 2.00 74200 4.95 74LS30 .40 74L30 .40 74L165 2.50 7443 .75 74148 2.00 74285 4.95 MM5056 2.80 2525V 2.80 74S89 3.50 74LS42 1.50- 74L32 .45 74L192 1.25 7444 .75 74150 1.00 74365 .90 MM5057 2.80 2527V 2.80 74C89 3.50 74LS55 .40 74L42 1.50 74L193 1.20 7445 .75 74151 .80 .75 74367 MM5058 3.50 2528V 2.80 74L89 350 74LS73 .65 74L51 .35 MC4044 2.25 7446 .80 74153 .90 74368 .90 MM5320 5.95 2529V 2.80 8223 2..50 74LS74 .65 74L54 .45 N8264 3.50 7447 .70 74154 1.00 MH0025 2.50 MM5554 1.90 25328 2.80 2.4576 MHZ 74LS76 .65 74L55 .35 N8263 3.50 7448 .80 74155 1.00 MH0026 2.95 MM5555 2.50 2533V 2.80 Crystal 8.95 74LS151 1.55 2.50 7450 .25 74156 1.00 95H90 9.95 74L71 .30 N8826 MM5556 2.50 2.55 7451 .25 74157 1.00 2102-1 1.65 91L02APC 74LS174 2.20 74L73 .55 DM8131 2.50 7453 25 74160 1.25 32 50.00 32 each 2.40 74LS175 1.95 74L74 .55 8737 2.50 7454 .20 74161 1.00 64 96.00 64 each 2.25 74LS192 2.85 74L75 1.20 8T10 2.00 7460 .20 74162 1.50 1488 1.50 7470 .45 74163 1.00 1489 1.50 For large orders send money order or cash- 7472 .40 please iers check to avoid delays in waiting for checks to clear.

90 Day Guarantee on SSM Products. Kits MB -2, MB -3 MIKOS Check or money order only. Calif. resident 6 %tax. i2K OR 4K), MB -4. MB -6, 10-2 video board and mother 419 Portofino Dr. All orders postpaid in U.S. All devices tested prior to board with connectors may be combined for a discount of sale. Money back 30 day guarantee. Sorry we can San Carlos, Ca. 94070 not accept returned IC's that have been soldered to 10% in quantities of 10 or more. This supercedes the flier $10 min. order. Prices subject to change without of 13 Sept. 1976. Please send for xistor, IC & kit Hut notice.

Thinly disguised affiliates of KO Electronics and Surplus, S.L.O., CA 93401

www.americanradiohistory.com s. D. SALES CO. P.O. BOX 28810 -4 DALLAS, TEXAS 75228

JUMBO LED CAR CLOCK THE HOTTEST SELLING KIT WE EVER PRODUCED! You requested it! Our first D.C. operated clock kit. Professionally engineered from scratch. Not a makeshift kluge as sold by others. Features: <) $16.95 A. Bowmar inch CLOC Iw Jumbo -.5 LED array. ID ., B. MOSTEK - 50250 - Super Clock Chip. \EO PNNO :At KIT Ct C. On board precision crystal time base. 000 Sp`TSc MERS D. 12 or 24 Hr. Real Time Format. K)T Cvl' WRONG Alarm Option - $1.50 E. Perfect for cars, boats, vans, etc. AC XFMR - $1.50 F. P.C. Board and all parts (less case) included.

1702A 2K EPROM UP YOUR COMPUTER! THIS MONTH'S SPECIALS We tell Ilke It is. We it could have said 21 L02 -1 1K LOW POWER 500 NS AMD - 8080A $14.95 these were factory new, but here Is the straight scoop. We bought a load of STATIC RAM Time is of the essence! Z -80 CPU 49 95 new computer gear that contained And so Is power. Not only are our 82S129 1K PROM 2.50 a quantity of 1702 As in sockets. We RAM's faster than a speeding bullet carefully removed the parts verified but they are now very low power. their quality, and are offering them We are pleased to offer prime new 60 HZ CRYSTAL TIME BASE on one heck of a deal. First come, 21L02 -1 low power and super fast first served. Satisfaction guaranteed! RAM's. Allows you to STRETCH S.D. SALES EXCLUSIVE! U.V. Eraseable. $6.95 ea. 4/$25 your power supply farther and at the same time keep the wait for $5.95 ea. 21$O 00 $12.95 KIT FEATURES: S.D. SALES EXCLUSIVE A. 60HZ output with accuracy comparable to a digi- $12.95 MOS 6 DIGIT UP -DOWN COUNTER $12.95 tal watch. 40 PIN DIP. Everything you ever wanted in a counter chip. B. Directly interfaces with all MOS clock chips. Features: Direct LED segment drive, single power supply (12 VDC TYPE.), six decades up /down pre -loadable C. Super low power consumption (1.5 MA typ.) counter, separate pre -loadable compare register with compare out - D. Uses latest MOS 17 stage divider IC. put, BCD and seven segment outputs, Internal scan oscilla- E. Eliminates forever the problem of AC line glitches. tor, CMOS compatible, leading zero blanking. 1MHZ. count Input frequency. Very limited F. Perfect for cars, boats, campers, or even for port- quantity! WITH DATA SHEET able clocks at ham field days. 7400 -19c 7411 -29c 7451 -19c 7490 -65c 74153 -75c G. Small size; can be used in existing enclosures. 74L500 -49c 7413 -50c 7453 -19c 74LS90 -95c 74154 -1.00 Kit includes Crystal, Driver IC, PC board, plus all necessary 7402 -19c 7416 -69c 7473 -39c 7492 -75c 74157 -75c 74LS02- 49c7420 -19c 7474 -35c 7493 -69c 74161 -95c parts and specs. At last count - over 20,000 sold! 7404 -19c 7430 -19c 74L574 -59c 7495 -75c 74164 -1.10 74L04 -29c 7432 -34c 7475 -69c 7496 -89c 74165 -1.10 74504 -44c 7437 -39c 7476 -35c 74121 -38c 74174 -95c 1000 MFD Slide Switch 74L504 -49c 7438 -39c 7480 -49c 74123 -65c 74181 -2.50 Assortment 7406 -29c 7440 -19c 7483 -95c 74132 -1.70 74191 -1.25 Filter Caps 7408 -19c 7447 -85c 7485 -95c 745138 -1.95 74192 -1.25 Rated 35 Our best seller. iiiUpright 7410 -19c 7448 -85c 7486 -45c 74141 -75c 74193 -1.00 style Includes mini- TTL INTEGRATED CIRCUITS 74195 with PC leads. ature and Stan- RESISTOR -69c Most popular dard sizes; sin- ASSORTMENT Disc Cap value for hobby- gle and multi - y4W 5% & 10% fists. Compare Assortment at position units. PC leads. A good P.C. LEAD PC leads. up to $1.19 ea. All new first At from franchise mix of values. DIODES HEAVY DUTY least 10 different name brand. Try values. type electronic one package and 200/52. 1N4148/1N914 Full Wave Bridge Includes parts stores. S.D. you'll reorder 100 /$2.00 25 AMP 50 PIV .001, .01, .05, Special 4/$1. 1N4002 -1A. $1.25 plus other stan- more! Special LUIDJI 100 PIV 40/$1. dard values. 12/$1.00 60/51.00

SIX DIGIT ALARM CLOCK KIT $ KIT 9.95 We made a fantastic kit even better. Redesigned to take advantage of the P.C. Board - 3.00 latest advances in I.C. clock technology. Features: Litronix Dual t/z" AC XFMR - 1.50 displays, Mostek 50250 super clock chip, single I.C. segment driver, SCR Do not confuse with Non -Alarm digit drivers. Greatly simplified construction. More reliable and easier to kits sold by our competition! build. Kit includes all necessary parts (except case). P.C.B. or XFMR Eliminate the hassle - avoid the 5314! optional.p NEW! WITH JUMBO LED READOUTS! COMPUTER POWER SUPPLY Motorola SCR A very fortunate purchase. One of the best industrial quality REG- 2N4443. 8 AMP 400 PIV. ULATED supplies we have seen. High performance, small size. P.C. Leads 31$1. Input is 120 VAC 60 HZ. Has the following regulated outputs: -5VDC @800MA; -15VDC @ 1.25 AMP; -25VDC @ 180 MA. FAIRCHILD - TBA 641 Sold at a fraction of original cost. Do yourself a favor and order 4W. ^/ Audio power Amp. Just NOW. We expect a quick sellout. out! In special heat sink 4.V DIP. One super audio IC. NEXT MONTH: $1.50 with data f`_ II'".' 4 S.D. will have music for your ears. Watch our ads. FND -359 -Led Readout .4 IN. Common Cathode. For your (msai or Altair 8080 Computer: High effeciency. Has FND - V/\' Z -80 CPU Kit - $149. 4K Low Power Ram Kit - $89.95 70 PIN \ OUT. 59c OUR CATALOG Special Thanks to: Call your Bankamericard or Dennis, Fred, Abe, Bill, Sam, is chocked full of rare parts Terms: Money back guarantee. Master Charge order in on our Hal, Tom, Alex, John, Ely, bargains, deals, RAM or CPU No COD. Texas residents add continental United States and kits, plus much more. Yours Larry 5% sales tax. Add 5% of order toll free Watts: FREE! for postage & handling. Or- ders under $10. add 75c. 1- 800 -527 -3460 S.D. SALES CO. PRICES SHOWN SUBJECT Foreign orders: US funds Texas Residents Call Collect: P. O. BOX 288100 TO CHANGE WITHOUT only! -0022 NOTICE. 214/271 DaIIaS, Texas 75228

ORDERS OVER $15.00 - CHOOSE $1.00 FREE MERCHANDISE www.americanradiohistory.com SOLID STATE What more SALES Features could INTEGRATED CIRCUITS you ask for ? HARDWARE

P.C. SOCKETS SILICON POWER RECTIFIERS

ZEN ERS

TRIACS SCRS Wegjot it. LIGHT EMITTING DIODES PRINTED CIRCUIT BOARD TANTULUM CAPACITORS Full Wave Bridges 2708-PROM ...... S55.00 2522 STATIC SHIFTRE6 $1.95 4.1/2 "x6.1 /2" SINGLE SIDED EPDXY .22UF 35V 5,51.00 4.7UF 35V 4/51.0 PR V 2A 6A 25A 2518HEX 32 BIT SR 53.50 BOARD 1/16" thick. unetcherl .47UF 35V 5/S1.00 6.BUF 35V 3/51.00 200 .75 1.25 2.00 $50 ea. 5/$2.20 .68UF 35V 5/S1.00 22UF 35V .40 2102 -1 1024 BT RAM $1.80 5 400 .95 1.50 3.00 1UF 35V 5 /S1.00 33UF 35V S .40 52804K DYNAMIC RAM . . $10.50 7 WATT L LASER DIODE $8.95 000 1.20 1.75 4.00 D-65 IR 2.2UF 20V 5/S1 00 30UF 6V 5/51.00 5202A UV PROM $10.50 POWER MM5203 UV PROM $10.50 2N 3820 P FET S .45 3.3UF 35V 4 /51.00 1000F 35V $ .50 SANKEN AUDIO AMPS S Si 1010 G 10 WATTS S 7.90 1702A UV PROM $10.75 2N 5457 N FET S .45 I50UF 15V .50 Si 1020 G 20 WATTS $15.95 5204 -4K PROM ... $18.95 TIS 43 UJT ...... S .35 M7001 ALARM CLOCK CHIP.... `' 75 Si 1050 G 50 WATTS $27.95 MINIATURE MULTI -TURN TRIM POTS ER 900 TRIGGER DIODES .. 4/ $1.00 2N 6028 PROG. UJT S .65 100, 500. 2K. 10K. 100K, 200K, 1 Meg. NATIONAL MOS DEVICES CCD 110 LINEAR 256 %I BITSELF 8 PIN DIP SOCKETS S .24 5.75 each . 3/52.00 MM1402- 1.75 MM5057- 2.25 SCANNING CHARGED COUPLED 14 PIN r/ 30 WIRE MULTI -TURN TRIM POTS Similar to Bourns DIP SOCKETS S .25 MM1403- 1.75 MM5058- 2.75 DEVICE $99.00 16 PIN WRAP WIRE 3010 style 3/16'x5/8 "x1.1 /4 "; 50. 100. DIP SOCKETS S .28 MM1404- 1.75 MM5060- 2.75 x SINGLE CCD 201 - 100 100 CHARGE 1K, 10K, 50K ohms 18 PIN DIP SOCKETS S .30 MM5013- 2.50 MM5061- 2.50 COUPLED DEVICE S135.00 24 PIN DIP SOCKETS S .40 STRAND 51.50 ea. . . 3/54.00 MM5016- 2.50 MM5555- 4.75 100 FT. LIGHT ACTIVATED SCR's 40 PIN DIP SOCKETS S .60 MM5017- 2.70 MM5556- 4.75 LINEAR CIRCUITS VERIPAX PC 51.40 LM307 - Op. Amp...... 5 .30 TO.18. 200V IA S 1.75 BOARD MM5055- 2.25 MM5210- 1.95 This board is a 1/16" single sided paper epoxy LM 309K 5V 1A REGULATOR S .95 MM5056- 2.25 MM5260- 1.75 TRANSISTOR SPECIALS board, 4'/, "x67," DRILLED and ETCHED 723 - 40 * 40VV REGULATOR . . S .50 2N3585 NPN Si 10-66 S .95 which will hold 21 single 14 301/748-Hi Per. Op. Amp S .31 up to pin IC's TTL IC SERIES 2N3772 NPN Si T0.3 S 1.60 or 8, 16. or LSI DIP IC's with busses for 3201 5,12.15, or 24V NEG REG . 51.25 7400- .15 7442- .52 74126 40 2N456A PNP GE S .75 power supply connector. $4.00 709C Op. Amts. 5.31 7401- .15 7445- .70 74151- .70 2N4908 PNP St TO-3 S 1.00 MV YELLOW-GREEN 741A or 741C OP AMP. S .31 5691 7402- .15 7446- .70 74153- .65 2N6056 NPN Sr 10.3 Darlington S 1.70 710 COMPARATOR 5 .35 BIPOLAR LED $1 25 7403- .15 7447- .70 74154 - 1.10 2N5086 PNP Si TO -92 4/S 1.00 FP 100 Pet. PHOTO TRANS S .50 7404- .20 7448- .70 74155- .70 CA 3047 Hi Op. Amp...... $ .95 2N4898 PNP TO-66 S .60 RED, YELLOW, GREEN OR 340T 5. 6, 8, 12, 15, 18, 24V POS 2N404 PNP GE TO -5 5/5 1.00 7405- .20 7450- .20 74157- .70 AMBER . . 51.10 LARGE LED's ea. S .20 7406- .25 7472- .33 74161- .85 REG. TO -220 2N3919 NPN Si TO -3 RF 5 1.50 MOLEX PINS 100/51.00 101 OPER. AMP. HI PERFORM 5 75 MPSA 13 NPN Si TO-92 3/S 1.00 7407- .25 7473- .35 74164- .95 1000/57.50 LM 308 Oper. Amp., Low Power . S .95 NPN 7408- .25 7474- .35 74165 -1.05 2N3767 Si TO 66 5 .70 10 WATT ZENERS 3.9, 4.7, 5.6, 8.2, 747 - DUAL 741 S .65 2N2222 NPN Si TO -18 5/S 1.00 7409- .21 7475- .49 74173- 1.40 18. 22, 100, 150 or 200V ... ea. $ .60 7410- .15 7476- .35 74174- .95 556 - DUAL TIMER $1.00 2N3055 NPN Si TO-3 S .80 PRECISION AMP 51 70 1 WATT ZENERS 4.7, 5.6. 10. 12, 15, 537 - OP. 2N3904 NPN Si TO-92 5/S 1.00 7411- .20 7480- .35 74175- .92 18 OR 22V ea. LM 3900 - QUAD OP. AMP S .49 2N3906 PNP Si 10-92 5/5 1.00 S .25 7412- .20 7483- .70 74176- .75 MC6860 MODEM CHIP 74177- .79 LM 324 - OUAD 741 $1.50 2N5296 NPN Si TO -22o 5 .50 $13.00 7413- .45 7485- .88 7414- .70 7486- 74180 .70 560 - PHASE LOCK LOOP . . $2.00 2N6109 PNP Si 10220 S .55 Silicon Power Rectifiers .30 7416- .25 7489- 1.85 74181 -2.10 561 - PHASE LOCK LOOP . . . . $2.00 2N3638 PNP Si TO-5 5/5 1.00 PRV 1A _ 3A 12A SOA 125A 7417- ,25 7490- .45 74190- 1.20 565 - PHASE LOCK LOOP 51.25 2N651 7 NPN TO-92 Sr 3/5 1.00 100 .06 .14 .30 .80 3.70 566 FUNCTION GEN $1.65 (DIODE CLAMPED) 7420- .20 7491- .70 74191- 1.20 CIMOS 200 .07 .20 .35 1 .15 4.25 7425 -- .28 7492- .50 74192- .85 567 - TONE DECODER $1.50 74CO2- .22 4015- .95 4035- 1.10 400 .09 .25 .50 1.40 6.50 7426- .26 7493- .45 74193- .85 LM 1310N FM STEREO DEMOD. 52.75 4042 .78 74C10- .22 4016- .40 600_ _11 .30 .70 1.80 8.50 7427- .30 7494- .70 74194- .85 8038 IC VOLTAGE C ONT. OSC. 53.90 1.50 4047 -2.00 LM 370 AGC SOUS LCH AMP. . 74C193 4017 -1.05 800 .15 .36 .90 2.30 10.50 7430- .20 7495- .70 74195- .75 - S1.15 4001- .22 4018- 1.00 4049-- .40 555 - 2ps -2 HR. TIMER S .45 1000 .20 .45 1.10 2.75 12.50 7432- .25 7496- .70 74196- .88 4002- .22 4019- .25 4050- .40 7437- .25 74107- .32 74257- 1.25 553 QUAD TIMER 52.50 4006- 1.20 4020- 1.05 4055-- 1.50 SILICON SOLAR CELLS 7438- .25 74121- .38 74279- .90 FCD 810 OPTO -ISOL ATOR S .80 4007- .22 4022- .95 4066- .80 7440- .16 74123- .65 75324- 1.75 1458 DUAL OP AMP 5 .60 4009- .42 4023- .22 4071- .22 2'/4" diameter 7441- .85 74125- .40 75491- .65 LM 380 - 2W AUDIO AMP. . S .95 4010- .42 4024- .75 4076- .70 75492- .65 LM 377 - 2W Stereo Audio Amp. . $2.50 4011- .22 4027- .40 4081- .22 .4V at 500 ma. ... $4.00 ea., 61$22.50 LM 381 - STEREO PREAMP. . . $1.50 4012- .22 4028- .88 4520-1.15 MINIATURE DIP SWITCHES LM 382 - DUAL AU DIO PREAMP $1.50 REGULATED CTS -206 Four 4013- .40 4029- 1.10 MODULAR -4 SPST switches LM311 -HI PER. CO MPARATOR S .90 4030- .22 POWER SUPPLIES in one minidip package. . . 51.75 LM 319 - Dual Hi Speed Comp. $1.25 '- 15 VDC AT 100ma CTS -206 -8 Eight SPST switches in a 16 LM 339 -GUAD CO MPARATOR $1.50 MCA81 OPTICAL LIMIT SWITCH. $1.50 115VAC INPUT ...... 527.95 pin DIP package $1.95 TRIACS SCR'S 5VDC AT IA. 115VAC INPUT . . . $24.95' LED READOUTS 12 VDC AT .5 AMP $24.95 AY- 5- 1013.A3OK ser. /par., par. /ser., uni- PRV lA 10A 25A 1.5A 6A 35A FND C.C. 51.75 500..5" IN 4148 . . . 11N9141 15/51.00 versal UART. 56.95 100 .40 .70 1.30 .40 .50 1.20 HP 7740 -.3" C C 51.40 MAN-73" C.A 51.25 Send 25i for our catalog featuring 4LCU MINIATURE TOGGLE SWITCHES 200 .70 1.10 1.75 .60 .70 1.60 NS 33 -3 dal. array S1 35 Transistors and Rectifiers MTA 106 SPDT SI 20 400 1.10 1.60 2, 1.00 1.20 2.20 DL 747 $2.50 145 Hampshire St., Cambridge. Mass. MTA 206 DPOT SI 70 600 1.70 2.30 3.60 1.50 3.00

Terms: FOB Cambridge, Mess. 5)SOLID STATE SALES WE SHIP OVER 95% Send Check or Money Order. OF OUR ORDERS THE P.O. 74B Include Postage, Minimum DAY WE RECEIVE THEM Order 55.00, COD'S $20.00 ' SOMERVILLEBOX , MASS. 02143 TEL. (617) 547.4005 www.americanradiohistory.com AL[",.^, 0.05% of Reatlnq I Count

rya, Voltage Ra,ye, 1.999 V a 1 199.9 mV Up to 750c...smmh Z., 1000 M Wpm Auto Ptu.voV anti Auto Ze,o 5.y1. Pasphye Voltage Rele.e,.n, SIo.tla.V B Sen CMOS Outputs Otyes Om Low Pow., hl Schottky Load too -s On CI ,I, System Clock, n, EIe,nal Clock Low Powe, Con moron B O mW tyOUI ík ' 5 0 V W,ue Supply Ba. qe e q,'45V Io 80V MC14433 SINGLE CHIP 3'.DIGIT A/D cjjtal'J Single chip combines linear and CMOS digital to bring you the simplest yet DVM approach. Requiring only 4 external passive parts, this subsystem gives you: Auto polarity, auto 5oYG zero, single voltage reference, 8 mW operation, overronge, I'm one year old underrange signals, 25 conversions per second and .OS %= this month gain' on two - the folks at Tri -Tek will be bringing 1 count accuracy! 100 uV resolution. 24 Pin DIP. you full gnawed values MCI 4433P with specs S19.55 in electronic parts and the latest in books 61 and data. et/ They've been doits it for six years now ASR -33 , COS -MACS KEYBOARD BACK These are BRAND NEW keyboards from one of the notions largest switch and keyboard manufacturers - CDPI802 COSMAC IS BACK IN STOCK I11111I I I not surplus. A special arrangement with the maker lt The famous and very popular 1802 is here again after a allows us to bring you these quality keyboards at long dry spell. This is the little B bit CMOS micro- less than cost. Available in O.E.M. any quantity, processor which sold out on our first offering. you con design them into equipment your and be Special AMP'L ANNY birthday price of $24.95 for the sure continued of source. Individual keys can be month of APRIL only!! easily replaced if damaged - you won't wear them CDPI802 529.95 out II CDPI852 . Parallel adapter $15.95 MODEL 2129007 KB $74.95 1 CDPI821 SCD $24.62 C DPI 8225CD $25.80 v, ..15. s I I x CDP1824CD 513.35 .(

Y..e ''''1111'' N 11 ii .I rv'1 . 0111 . COMBINATION LENS AND i'tr r MOUNTING DEVICE FOR ` T .r . . W ...... MM 13'4 LED W ...... 1 REQUIRES KOK...... E/ NO TOOLS SNAP CLIPLITE

KEYBOARD ENCODER MM74C922 74C923 CMOS key encoders provide all the necessary logic to fully encode an array of SPST switches. On chip oscillator for scan or use with external clock source. Out- put is binary and is low power TTL compatible. Keybounce elimination with single capacitor. Memory holds last key INSERT LED depressed. Operates on 3 to 15 volts. 2 -key rollover. AVAILABLE IN TRANSPARENT RED .GREEN AMBER CLEAR & YELLOW MM.74C922N 16 key encoder $6.35 DATA BOOKS BY NATIONAL SEMICONDUCTOR '.LIPLITE 74C923N 20 key keyboard $6.50 etc DIGITAL. Covers TTL, DTI, Tri- State, $3.95 Combination lens and mounting device for T 1 -3/4 LED. Specs for both chips 60c LINEAR. Covers amplifiers, pre -amps, op- amps $4.25 The CLIPLITE combines the benefits of the present LED LINEAR APPLICATIONS VOLUME I. Dozens of display panel mounting methods and eliminates their def- MM5865 UNIVERSAL TIMER I.C. application notes and technical briefs covering the iciencies.Requires no special tools and installs in 6 seconds A truly universal timer can be used for a stopwatch, kit- use of op -amps, regulators, phase locked loops and in .250" hole. Simple two -step installation. Just snap timer, event timer /counter, rally timer- chen timer, oven audio amps 53.25 CLIPLITE, insert LED. Available in transparent red, green, two counters, internal comparators, on ----. 7 functions, LINEAR APPLICATIONS VOLUME II. Takes up where amber, clear and yellow. Specify colors, any mix. chip oscillator. Memory for rally with total elapsed time. I the latest linear devices. Volume left you --All 5 /51.00, I0/S1.90, 20/53.50, 50/57.50 '6A)1(.63.1. Can be cascaded - --selectable resolution- -count up or down Along with Vol I you hove a great source of app- - -- selectable modulo for time or event count. Operate or lication data on the most widely used devices os well 30V DIAC. Tiny glass diode for triggering SCR's and 7 to volts at about 7mA. 20 as new types just appearing $3.25 triacs. Improve your firing circuit for more reliable and MM5865N 58.75 CMOS Gates, Flip Flops, registers, etc $3.00 repectoble operations. At a fraction of the O.E.M. Specs and applications VOLTAGE REGULATORS. A must for anyone making price ll DIA -0030 10/$1 a power supply. Complete theory including transform- regulators etc 53.00 ers, filters, heat sinks, MINIATURE POWER SUPPLY MIL RANGE 5V REGULATOR. MEMORY. MOS and Bipolar memories, RAMS Info on 5V, .25A, P,C. mounting module supplies logic o better performance from your 5V supply? ant little ROM$ PROMS and decoder /encoders $3.95 voltage from 105- 125VAC input, 50- 400HZ. Ultra - from cancellation brings you trans- LM140K in TO -3 contract INTERFACE. Covers peripheral drivers, level stable and noise free with external trim capability. a port at the price of plastic regulotor. superior lators, line driver /receivers, memory and clock drivers, Mode by PMC. (Model MM -5811 $15.95 LM140t' S1.95 sense amps, display driver and opto- couplers $3.95 SPECIAL FUNCTIONS DATA BOOK, Contains detailed information for specifying and applying special LINEAR CONTROL DATA BOOK LM1889 TV VIDEO MODULATOR amplifiers, buffers, clock drivers, analog switches and T.I. linear products data and applications. Price includes The LM1889 is designed to interface audio, color difference, D /A -A /D converter products 53.25 shipping charge, U.S. only 54.25 and luminance signals to the antenna terminals of a TV re- AUDIO HANDBOOK Contains detailed discussions, Outside U.S., add postage for 2 lbs. ceiver. It consists of o sound subcarrier oscillator, chromo including complete design particulars, covering many subcorrier oscillator, quadrature chromo modulators, and R.F. areas of audio with real world design examples $3.25 oscillators and modulators for two low -VHF channels. SPECIAL NEW BOOK FROM NATIONAL The LM1889 allows video information from VTR's, games, DATA BOOKSHELF. Buy oll ten of the National Dota MOS LSI. Giant data book filles with spec and apps test equipment, or similar sources to be displayed on block books at one time and save $5.10111 $30.00 on large scale MOS circuits from National Semiconductor and white or color TV receivers. All books shipped ppd in US only. Foreign orders Corporation.Price includes shipping in U.S. only...54.25 LM1889 with 16 pages of dota 59.95, data only, 51.00 please odd shipping for 1.5 lbs per book) Outside U.S., add postage for 2 lbs.

We pay surface shipping on all orders over $10 US, $15 foreign in US funds. inc. Please add extra for first class or air mail. Excess will be refunded. Orders -tEk, $10, Si handling. Please add 50c insurance. Master charge and tRi under add 6522 fTORLh 43R0 avenue. Bonk America cards welcome, ($20 minimum). Telephone orders may be placed GLéT1Ò \EE, ARIZOTIdI 85301 IOAM to 5:30PM daily, Mon thru Fri. Call 602- 931 -4528. Check render flyers with new and phone 602 - 931-69.19 service card or send stamp for our latest packed surplus electronic components.

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232 Abbott Electronics 155 157 Electronic Warehouse 165 230 Pan Delta 159 75 Advanced Microcomputer Products 163 56 E &L Instruments 121 63 Parasitic 131, 133, 139 168 Aldelco 129 102 Eltron 166 239 PCS 129 173 Anderson Jacobson 131 241 Expandor 151 PerCom Data 32 142 Associated Electronics 147 9 Godbout 167 194 Peripheral Vision 39 " Audio Amateur 148 HAL Communications 120 105 Personal Computer Corp 157 225 Bay Area Timeshare 155 218 Hayden Publications 86 " Personal Computing Show 76 4 BITS Inc 134, 136, 138, 145 226 Homestead Technical Corp 151 Polymorphic Systems 57 149 Bits and Bytes 157 109 iCOM 114 213 Prime Radix 75 217 BPI 73 12 IMSAI 7 24 Processor Technology 5, 27, 53 BYTE back issues 150 60 Interface Age 119 219 RHS Marketing 98, 99 " BYTE index 157 204 International Data Systems 84 234 Rotundra Cybernetics 151 240 Capital Equipment Brokers 161 215 Jade Company 168 26 Scelbi 51 126 Cheap Inc 151 15 James 169, 170 73 Scientific Research 28, 29 127 Comptek 143 130 JGM 129 27 SD Sales 173 140 Computalker 157 229 Libau Inc 159 236 SEALS 91 216 Computer Components 81 158 Lillipute 159 169 Smoke Signal Broadcasting 97 161 Computer Corner 151 209 Logic Design 155 59 Solid State Sales 174 143 Computer Enterprises 143 90 Logical Services 150 29 Southwest Tech CI I " Computer Faire 68, 69 18 Meshna 171 99 STM Systems 85 83 Computer Mart NY, LI 157 182 Micro GRAPHICS 129 164 Sunny Computer Stores 129 156 Computer Place 155 196 Micronics 155 96 Synchro -Sound Enterprises 88, 89 141 Computer Room 115 119 Midwestern Scientific Inst 122 205 Szerlip 150 208 Computer Shack 127 57 Mikos 172 121 Tarbell 137 237 Computer Shop (NH) 157 112 MiniTerm 21 82 Technical Design Labs 93 138 Computer Warehouse 164 " MITS CIV, 58, 59 136 Technical Systems Consultants 135 6 Continental Specialties 118 71 mpi 141 192 Tec Mar 149 202 CRC Engineering 38 233 M Systems 151 Trenton Computer Festival 144 87 Creative Computing 112, 113 171 Mullen 139 32 Tri Tek 175 41 Cromemco 1, 2 22 National Multiplex 83 193 US Robotics 159 178 Cybercom 31 NCC 152, 153 228 VAMP Inc 159 125 DEC 33 " NCR 87 221 Vector Electronics 116 185 DAJEN Electronics 133 155 North Star Computers 117 137 Vector Graphic 23, 123, 160 78 Digital Group 55 64 Oliver Audio Engineering 155 224 Wyle Computer Products 149 170 ECD CIII 198 Omni 135 154 Worldwide Electronics 142 211 Economy Terminal 159 40 OSI 11 220 Ximedia 125 47 Electronic Control Technology 129 147 OK Tool 77 222 Xybex 137

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130M6- BYTE's Oagoiag Moaitoí Box BOMB Exploded

We put BYTE's Ongoing Monitor Box on On BOMB Card, a postal card starting with the January issue Article No. ARTICLE PAGE in order to encourage responses. Never did we 1 Butterfield: KIM Goes to the Moon 8 expect the BOMBslide that resulted.

2 McNatt: A Guide to Baudot Machines: Part 1 12 Peter Travisano and Gregory Spitzfaden, 3 Ciarcia: Having a "Private Affair" with Your Computer 18 who shared the staggering job of totalling 4 Rosner: A Review of Tom Pittman's Tiny BASIC 34 the voluminous January responses, have 5 Helmers: Software Controlled 1200 bps Audio Tape Interface 40 emerged from the countinghouse to an- 6 Rosenbaum: Artificial Intelligence: What Is It? 50 nounce that David M Allen, who wrote 7 Emmerichs: Designing the "Tiny Assembler," Part 1 60 "Saturation Recording's Not All That 8 Gray: Establishing the CHU Dynasty 70 Hard," and Terry Dollhoff, author of 9 Barnes: Technology in Roman Military Arts, or Plexitus 78 Hash 10 Melton: Why Aren't There Any Altairs on Arcturus II? 94 "Making With Tables," were so close in 11 Salter: Navigation with Mini -O, Part 3 100 the balloting that each will receive $100 for 12 Baker: Microprocessor Update: 8008 110 the top award, instead of our usual first and 13 Price: Microcomputer Glossary 124 second place division of BOMB prizes.

176

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Micromind is an incredibly flexible, 32K byte expansion boards and a mapping complete and expandable, hardware/ option give Micromind expandable access software, general purpose computer to 64 Megabytes. Utilizing software- system. You won't outgrow it. controlled I/O channels, Micromind's Hardware includes an 80 key, software - advanced encoding techniques load data definable keyboard, I/O interface board, from ordinary tape recorders at 3200 6500A- series microprocessor (powerful bits per second. enough for advanced computing), a high - Micromind comes to you ready -to -use, detail graphics and character display factory assembled and fully tested. Among processor, power supply, rf modulator, microcomputers, it has the largest memory and connections for up to 4 tape recorders capacity and the fastest storage. You're plus TV or monitor. An interconnect bus looking at the work of the finest display processor on the market. You won't find a microcomputer with a more powerful CPU. powerful assembler, a debugger, a file You won't find a computer with a system, graphic routines, and peripheral more flexible keyboard. You won't handlers. We also include dynamic graphic find anything to games: Animated Spacewar and Life. touch it at ECD's standard Micromind $987.54. supplies 8K bytes of memory. Additional

So, quit the kluge scene and key into Micromind. You'll be a main frame per- former, with all the comforts of home. permits 15 additional microprocessors, We're not fooling ...this is the cat's µ! parallel processing and vastly increased computing power. ECD CORP. System software- including ECD's own 196 Broadway, Cambridge, Mass. 02139 notsoBASIC high level language, on (617) 661 -4400 advanced error -correcting tape cassettes - provides a word processing editor, a Ea) r 1 Name Address City /State Zip

Fantastic! Check enclosed: $987.54. Shipping paid by ECD D BankAmerica rd D Master Charge Mass. Resident add 5% Sales Tax Expiration Date Signature D Send me your brochure. b Actual unretouched photographs. www.americanradiohistory.com software flexibility as well. HITS software, including the innovative Altair BASIC language, allows the full potential of the Altair 8800b computer to be realized. 8K ALTAIR BASIC has facilities for variable length strings with LEFTS, RIGHTS, and MIDS functions, a concatenation operator, and VAL AND STR$ functions to convert between It Comes Naturally With strings and numbers. The AltairTM 8800b Extended ALTAIR BASIC allows integer, single choice of four different memory boards and and double precision variables, automatic The Altair 8800b from MITS: the second gen- many others. line numbering and renumbering, user - eration design of the microcomputer that defined string functions, PRINT USING for for- started it all. The mainframe that has the abil- Reli -ability: matted output and a powerful EDIT com- ities everyone is demanding from microcom- The unique design features of the Altair mand for editing program files during or after puters today: 8800b, which have set the standard for the entry. Extended statements and commands microcomputer industry, make it the most include IF THEN . ELSE. LIST and DELETE Expand- ability: reliable unit of its kind. The Altair 100 -pin bus, program lines, SWAP variables and Trace On The Altair 8800b power supply and one - the now -standard design used by many imi- and Off for debugging. piece, 18 -slot motherboard allow efficient tators, has been "standard" all along at MITS. and easy expandability for memory and I/O The unique Front Panel Interface Board on Disk ALTAIR BASIC has all the features of options. All Altair PC boards are designed to the Altair 8800b isolates and filters front panel Extended BASIC with the additional capa- give you maximum capability /lowest power noise before it can be transmitted to the bus. bility to maintain sequential and random usage possible per board. This means that The all -new CPU board utilizes the 8080A access disk files. Utilities are provided for for each slot used you get more features and microprocessor, Intel 8224 clock generator formatting disks and printing directories. the - require less power, than with any of "off and 8216 bus drivers. In all versions of ALTAIR BASIC you get the brand" Altair- bus -compatible boards. ease and efficiency of BASIC for the solution Whether you buy an entire system up front or Flex -ability: of real world problems. choose to expand gradually, it's easy to get Meeting the diversified demands of an ever - Package II, an assembly language develop- the configuration you need with the com- increasing microprocessor market requires ment system for the Altair 8800b, includes plete family of Altair peripheral equipment, tlexibUity: not just hardware flexibility but system monitor, text editor, assembler and including debug. floppy disk, line printer,, audio Afford- ability: cassette record Prices for the Altair 8800b start at interface, A/D $840.00 fora kif and $1100.00 for an converter, assembled unit (all documentation PROM program- included). mer, serial and For a complete listing of prices on parallel I/O boards, all Altair products and a free bro- wt.! chure, contact:

MITS, Inc. 2450 Alamo S.E. Albuquerque, N.M. 87106 (505) 243 -7821 (