ISSUE =2 OCTOBER 1975

$1.50 the small systems journal

* Build a GRAPHICS DISPLAY

* TELEVISION INTERFACE

* NOVAL ASSEMBLER

* KLUGE HARP: Music?

* LIFE Line: Game

. '":l i f nili\%r1mrn1mnrmlDJ.Wj_1,·~,nf

Computers- The VVorld's Greatest Toy! CT-1024 TERMINAL SYSTEM

When we designed the CT-1024 we of Fra me f unctions. These may be wa nt to co nnect it to the computer knew that there were many app lica­ operated by pushbutton sw itches, or with a para ll el interface system. A di­ t ions for an inexpensiv e TV display uncommitted keyswitches on you1· key­ rect para ll el interface allows for much term inal syst em. Even so, we have boa1·d. A lthough not esse ntia l to ter­ faster data transmission and reception been su rprise d at the many add itional minal operation, t hese features ca n be and is bas ica ll y a simpler device than a uses that have been suggested by our very helpful in some applications. se ri al interface sy ste m. Our paral lel customer in the last four months since CT-M MANUAL CURSOR CONTROL in terface circuit contains the necessary we introduced this kit. KIT...... $ 11 .50 ppd tristate buffers to driv'e either a separ­ ate t ransm itt and rece ive bus system, or The bas ic k it, consist ing of the charac­ a bidirectional da t a bus system. TTL t er generator, sync and timing circuits, If you plan to use your terminal w it h a log ic leve ls are sta nd a1·d on this inter­ cursor and 1024 byte memory gives telephone line modem, or any other face. Switch se lection of either fulI, or you ever ything you need to put a six­ system t hat requries a se 1·ial data out­ half duplex operation is provided. The teen line message on the sc ree n of any put; you w ill need our se 1·ial interface terminal may write directly to the TV monitor, or sta ndard set with a (UART) plug-in circuit. Thi s circuit scree n, or t he computer may "echo" video input jac k added to it. In put conv e1·ts t he ASC 11 code from a par­ the message and w 1·ite to t he screen. information to the CT-1024 may be all el to a ser ial form and adds "Start" any ASCII coded so urce having TTL and "Stop" bit s to each character. The CT-L PARALLEL INTERFACE log ic leve ls. Two pages of memory for standard trnnsmiss ion rnte for this KIT ...... $22.95 ppd a total of up to one t housand and circuit is 110 Baud, but optio nal rates twenty four characters may be stored of 150, 300, 600 and 1200 Baud may We w ould be happy to send you a com­ at a t ime. The CT-1024 automatica lly be obtained by add ing additional parts plete data package describing the CT- switches from page one to page t wo to the board. The output of t hi s cir­ 1024 and a achematic. If you want th is and back when you reach t he bottom cuit is an RS -232 type intedace and add itional information, circle our num­ of the scree n. A manual page se lector may be used to drive any type modem, ber shown be low on your reader info1·­ switch is also provided. The main board or co upl er system using t his sta ndard mation serv ice ca 1·d. The CT-1024 kit is 9Y2 x 12 inches . It ha s space pro­ interface. has complete assemb ly instructions vided to allow up to four accesso ry w it h parts location d iagrams and step­ CT-S SERIAL INTERFACE (UART) by-step wiring instructions. If you circuits to be plugged in. If you w ant a KIT...... $39.95 ppd display for advertising, a t eaching aid , wou ld li ke to check t he instruction or a communication system then our manual befo1·e you purchase t he kit, If you are us in g the CT-1024 as an 10 basi~ kit and a suitab le power supply please return the coupon w ith $ 1.00 is all you will need . (in put · output) device on your own an d we wi ll rush you t he manual and computer syste m, you w ill probably the add it ional data mentioned above. CT-1 TERMINAL SYSTEM with MEMORY KIT ...... $175.00 ppd Power supply kit to provide + 5 Volts @ MAIL THIS COUPON TODAY 2 .0 Amps and - 5 Volts, -12 Volts @ 100 M a. required by the CT-1 b asic display 0 Enclose d is$______0 or M ast er Charge#------­ system. CT-P POWER SUPPLY KIT...... $ 15.50 ppd 0 or BankAmericard # ______Card Expiration D ate ______A very nice conven ience featu1·e at a 0 CT-1024 Kit 0 CT-M Cursor Control Kit very reaso nable cost is our manual cur­ 0 CT-S Serial Interface Kit 0 CT-L Para llel Interface Kit sor control plug-i n circuit. The basic NAME ______kit all ows you to era se a frame and to ADDRESS______bring t he cursor to the upper left cor­ CITY______STATE _____ ZIP____ ner (home up) . By add ing this plug-in, you ca n get Up, Down, Left, Right, 0 $ 1.00 Enclosed sen d manual and data package Erase to End of Line and Erase to End Southwest T ec hnica l Products Corp., Box 32040, San Antonio, T exas 78284 In t:he Queue ~'111 #2 OCTOBER 1975

- ~ .._;;..· ~·: Foreground '·J: .

ADD A KLUGE HARP TO YOUR COMPUTER ...... 14 Fun and Games - Carl Helmers LIFE Line2 ...... 34 Software - Carl Helmers p. 14 A QUICK TEST OF KEYBOARDS ...... 43 Hardware - Walters ADD A STACK TO YOUR 8008 ....52 IE Hardware - Chamberlin IJ ITS EEe?EEa:!f·fl·HE 1-l A NOVAL ASSEMBLER FOR THE 8008 ...... 64

ENT Software - Peter Helmers IVE I' ;A "X"- 1 ASYNCHRONITIS ...... 68 LI VE CE LL p. 34 Hardware - Bancroft BUILD A GRAPHICS INTERFACE ...... 70 J . Hardware - Hogenson •+:) . I

Background ·, ~~· ' I .. • 1·· ·­ . , I" , :'•·)­ TELEVISION INTERFACE ...... 20 ["» Hardware - Lancaster p.52 MODULAR CONSTRUCTION ...... 46 Hardware - Walters BUCK ROGERS AND THE HOME COMPUTER ...... 58

Speculation - Gardner MICH Owtil.rT INtM,,ATIOH L AT REA~.-. M 1 Nucleus p. 58 Speaking of Computers ...... 5 BYT E ntaJ,!az ine is publis h ed month /)' b :v Gl"ee n P ublishing, Letters ...... 8 I nc., Pe t e ,.b ol"ough , New H a m ps hir e 03458. Clubs and Newsletters ...... 12 Su b scriptio n .-a l es are $ 1 2 fo ,. o ne vear wo,.l dwide. T w o years, $22. T h re e y e ars, $30. A Word From the Publisher ...... 61 Seco n d c l as s pos ta ge ~b;- app li ca ti o n pend in g a l Book Reviews ...... 82 Pe te rb orouf[h . New H amp shire =.=-J­ 03.J58 a nd a l add i ti o nal Bits and Pieces ...... 84 m a il i nl! o ffi ces . Ph o n e: 603-924-3873. E ntire co n te n ts Reader's Service ...... 96 cop ;v ri11ht 1 9 75 b :v G r een p. 70 Publishing, In c .. Peterbo r ough , N H 03 4 58. A ddress edito rial The BYTE Questionnaire ...... 96 corr esponde n ce t o E dit o r , B Y TE. Box 378. B e l mont MA 0 2 1 78.

Are you? send info to o an educator STA MP o a hobbyist HERE n an OEM ... QTY/ YR __ o looking for product to ZIP------­ sell.

What is your application .,, SPHERE CORP . 0 791 South 500 West a. CD Bountiful, Utah 84010 Q) n,.. I ~ "'

cut here cut here

Clip out and mail coupon or call (801) 292-8466

Before After KITS Sept. 30 Sept. 30

SYS 1 4[( By te computer with TV /.erminal, $ 650 .$ 860 keyboard, and ROM monitor

SYS 2 4[( By te computer with T V terminal, 750 999 keyboard, ROM ni onil.or, and audio cas sette interface.

SYS 3 20[( By te computer wi lit T V term.irwl, 1345 1765 keyboard, ROM monil.or, audio cass elle inte1face, and e:r l <> ndcd basic programming language.

NEW FEA TURES

PEN Light pen kit for CRT board 80 JOO

BAS I [(micro-basic prom set (a modified basic language lhat makes y our comput;er talk basic w1.t:hout loading from. cass e/;l e) 90 140

RAC 2 A ltractive plastic chassis with CRT display and acoustic coupler. 2 70 300

791 Soul.Ii 500 West. Bo11nli.fi1/, Utah 81.010 (80 I) 292-8466

4 Carl Helmers Functional Specifications • Editorial H The Home Brew Voder"

the "ship 's compu ter" giv e the 5 unu sed bits o f the status reports aurall y to make typical speech valu e word the ga me more exciting - could be used to control 5 perh aps coupling in a few additio nal bell s and whi stles. A whole line of home bell s and whi stles (literall y) in Th e sof twa re of t he co mp u ler experimen tat ion the fo rm of spec ial purpose a pplicatio n is in t wo can be started by the person sy n t h es ize rs of p h oton segme n ts. There is the who des igns -- and wri tes up to rp edo, phase r, transporter ma c hi ne- independcnt da ta as an article for BYTE - a speech elem en ts, say mo a nd oth er sound e ffects table which specifics the bas ic simp le and p1-act ical circui t to basic sound s, the data Trckkies know and love. phoneme in fo rmation - and genera te speec h output from req ui re ment is thus 3900 Then there is t he ul timate the rules fo r combin ati on ph oneme codes in a program. bytes we ll wi thi n the ap pli catio n - mak ing a higher in to understandable word s. The output problem in di gital memory budgets of many grade voice sy nthesizer whi ch Then there is the mac hin e­ s p eec h 1-eprcse nta li o n BYTE readers' syste ms. The can sin g, literally, so your d e pe nd e nt progra mm e d tec hniqu es is we ll within the thrupu t req ui red to outpu t mac hine can pl ay vocal "ta lk e r " rou ti nc whi ch range of a microcompu te r the vo ice bytes is also we ll music. accepts an "n-byte " charac ter sys te m a nd inexpensive wi thin a mi cra's capac ity ­ How ca n such audio string wi th phoneme codes digi t, tl lo analog conve rsion 1000 mi croseco nd s is J lot of peri pherals be brought into and sy nthesizes the phonemes m e l h o d s ( s u ch a s t he tim e to foo l around wit h. It's ex iste nce? One way is one by one fro m the data Motorola 6-bi t cl ch ea po even long enough fo r a through the encourage ment I t abl e by outputting the MC l406 DA Cs) . tortoise of a compu te r li ke ca n give by publi shin g ar ti cles se lecte d se ri es of 3-bi t codes Consid er, for in stance, a the 8008 to do enough bit on va rious approaches - the in real ti me. In a des ign bru le rorce tec hni que in diddlin g to p repare a design articles of 1·eaders article, " talk er" would be whi ch the voice in fo is command code for a 3-bit whi c h make BY TE an specified functio nally in a encoded as 3-b it (e ight level) DAC port. esse ntial publi cation fo r the hi gh level language along with quantiti es whi ch arc se nt out No w, w hat 's al I the h ome co mpu ter a global flo w chart, and the at a ra le of once eve ry purpose to the home voder7 experimenter. A seco nd way phoneme data in fo rm ati on millisecond for co nversion. Well , if you ca n't thin k or a i s for the vai- ious wo uld be spec ified as a ta bl e (Rate: 3000 bi ts per second.) use fo r it, I ' II suppl y a couple entrep reneu ria l readers in the in hex and/or octal codes. So A typ ica l vo ice "phoneme of suggestions. Wouldn 't it be audience to take a cue fro m here you have the idea - let's s tring " in t he micra's neat to pu t up a home th is Ii ttle essay and get see what BYTE rea ders can me mory would spec ify data security sys tem using your wo r k in g o n packaged come up wi th in the way of for may be 100 milli seconds. mi cro in whi ch the burglar products in the audi o outpu t arti cles on the subjec t. Thi s wou Id rcq uirc a total of gets scared ou t of hi s wits by line wh ich th e majority of mo data va lues or 300 bi ts, a t h re at iss ued in a rea ders wil I be able to put sto red in a packed bi t string compu te reezc voi ce while toge th er and program. (Oh yes, one parentheti cal for mat in 38 bytes plus one li ghts are fl as hing and other The esse ntial elements of note - the proof of the ove rh ead byte for string o min o u s t hin gs are t h e in ex pe ns iv e vo ice pu tting is in the speakin g. length . Ir one consid ers a happenin g? Or in the area of sy nthesize r are the famili ar Pro spective voder des igners reaso nable vocabulary of ga mes manship - when the ha rdware a nd software should se nd along a tape ga me program gets erro neous combin ati on: The hardware recording of their des ign in input, have your program part is the n-bit (3 will do) o pe ra ti o n prefe rably issue the tex t of the message DAC output port (and latch) speakin g the first two lines of "fou 11 " Or, getting less whi ch co nverts intern al codes Lewi s Ca rroll's p oe m exotic, simply make yourself into one of 8 vo ltage leve ls. "jabberw oc ky," the universal a ca lcul ator whi ch will The DAC in turn will drive an test string: ) literall y read out the answers activ e lo w pass fil ter (op to your problems as we ll as amp) and a po wer amplifier show th em o n an output for the speaker. If yo u ge t sc reen. Getting exo ti c aga in, fa ncy, a second DAC could suppose you make a Star be use d as a ga in control T rek ori ented space wa r output (with an appro pri ate game. You rea ll y should have 8-bit latch fo r storage) - and

5 A Need in Search of a Product

duplication stencils - the blu e in k smeary reproduction that was in vogue for high schools and grade schools Have you ever run a b efo re Xerox a nd its business, newsletter or club imit ato rs b ecame so which requires periodic widespread. A Sears version mailing of information? Have of this system, per their you ever tri ed to maintain a office products catalog, costs mai ling list? The purpose of from about $70 upwards. this short essay is to identify Similar units run up to the technology which can be an opportunity which exists range of about $200 to $300 asse mbled by any of BYTE's for the entrepreneurial and address master blanks for more experienced readers is a persons in BYTE's readership the "Elliott" system cost h ardw a r e/software system - the opportu nity to create about a dime each. This type consisting of the following and market a specialized of system has a higher degree items: mailing information system of auto mation (retyping of 1. Microprocessor (8-bit) using contemporary names is much less frequent) with 1024 bytes RAM, 2048 technology in the form of - but still involves a costly to 4096 bytes ROM program, microcomputers an d "use-only-0nce" part, the three se ri al ports, one 8-bit automatic sequence checking ine xpe nsive peripherals. Here stencil. parall e l output and one 8-bit to maintain a sorted sequence is wh at you have to compete parall e l input. on the files. aga inst in the general market Addressograph-Multigraph 2. Adding machine tape 6. Update/Merge program - the free market of all the The next step up in cost ­ ASCII printer accepts software for "batch" poss ible solutions to the a much more permanent parallel output and prints it changes to the file, in which a problems of mailing labels . system for large usage - is as characters on rolls of tape. previously prepared (and the Addressograph­ 3. ASCII input keyboard sequenced) update tape is Multipart Carbon Forms Multigraph type of system - parallel input of text and merged with an old tape to My old standby in the which uses metal plates commands. create a new output tape. m ai lin'g list area is the prepared in advance. These 4. Triple audio cassette 7 . Pr in t p r o gram multipart carbon form which systems have a much longer interface capable of two software to print the file is manufactured by Denniso n lasting and more expensive input operations and one either as an unconditional among others. These forms label maste r blank - and o utput operation dump of all labels, or a hold 33 names per sheet and minimal systems can be had simultaneously. selective dump such as "every come with four parts to in the $800 range and up. 5. Edit/Merge program ­ nth name" or "names with reduce typing and retyping of The system involved is software for editing of zips 07932 to 07860." names. They come with water essentially the same as the "curre nt label" records held 8. A Percy Wing Machine. base glue backing and are duplicator style systems ­ in RAM, using the keyboard This is a hand-operated gizmo perforated - but the main but more costly, due to fo r commands and te xt input, which costs about $100 and problem is typing. The 33 fa ncier equipment, some using the printer for output. is used to automatically apply name pe r sheet figure only a utomat ion of envelope All ow optional input from I abels from the roll of holds if you don't make any handIi ng and longer lasting one tape port, output to a printout - slicing each label typing errors! The degree of media. There is still no second tape port, with off the roll and automatically au to ma ti on of this system is automation of the typing and applying it with glue to the usu ally zero, unless you have related information handling. mailing piece. a power typewriter and are Here is where the new Put together a packaged usin g the carbon forms to computer systems will begin product based on these ideas, save output. Cost is also lo w to effectively compete. and it could most likely be - paid for in typing time of sold in the $1 500 to $2000 course - at about $2 to $3 The Hypothetical Small range, supplying a nice profit fo r a package of ten. No Computer Addressing System margin and a product which competition labor A "trivial" application of competes effectively with the intensive. the mic roprocesso r Addressograph- Mu I ti graph "systems," yet provides Spirit Duplicator Methods automatic features and a The next step up in the much more compact storage world of office automation is method (cassette tape) for a system involving spirit lists of moderate size.

6 __.. R GS ELECTRON ICS

DISCOUNTS: 10% OFF ORDERS OVER $25.00; 20% OFF ORDERS OVER $250.00.

SPECIAL ANOTHER POWER SUPPLY ... PS 25- 1 0 to 25v 1a lab type power supply w ith ad justabl e cu rrent 1-8008 $50 limiting; remote se nsing & remote programming for voltage & cu rren t. lnsturctions included. All parts except chassis. meter(s), p. c. board. 8-2102 Kit of parts with schematics. $ 14.95 P.C . boards avai lab le. No. 007 $3.00 ea .

2K RAM BOARD KIT. ALL PARTS INCL. SOCKETS

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8008 MICROCOMP. CHIP$30.95 2102 1 K STATIC RAM 3.00 5203 256x8 PROM 15.00 5204 512x8 PROM 25.00 008A MICROCOMPUTER KIT INFO ON ABOVE CHIPS IF 8008 CPU, 1024 x 8 memory; memory is expand­ ASKED FOR. abl E. Kit includes manual with schematic, program­ ming instructions and suggestions ; all I Cs and parts supplied except cabinet, fuses & hardware. Includes p. c. boards. $375.00 MANUAL ONLY, $25.00 (no discount on manual) ORDERS OF $50 OR MORE GET FREE BYTE 008A-K ASCII keyboard input kit . $135.00 SUBSCRIPTION IF ASKED FOR (CONTINENTAL U.S. 008A-C Audio cassette adapter kit. $100.00 ONLY). Det ails on computer, peripheral kits in our f lyer.

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7 other factors. The simplest solution to this problem .( approach, with the least either to you privately or for . ·:.; · ~·~ . amount of money and I he publication.} _.. ~~ ~. least amount of computer In order to program the technology ''learning'' ty pical three-space navigation experience is to simply go out pro blem, assuming well and buy one of the new det ermined static orbital HP-25 calculat01s. You'll find elements, the following items it quite capable of solutions are required: to a large number of 7. A computer with numerical analysis problems software for SIN, COS, TAN for engineering - although and A RCTA N trig functions unit sphere for o !mown it's adequate for extensive (you can get this set from an latitude, longitude and time. linear algebra and matrix data interface calculator chip}. This is the right ascension and calculation. My associate 2. Vec tor-matrix algebra declination of an optical "IT'S ALL IN THE Chris Bancroft has been using subroutines for three-space. telescope or equivalent terms EPHEMERIS . . . " the slightly more powerful Since you are ta/!?ing about for y our radio antenna. HP-65 for more than a year static orbits (no active Th e place to fool? for Dear Mr. Helmers, now to arrive at exact con trot altering parameters}, detailed in formation is an I have se nt in a an a I y tic a I (and very you don 't need much in the advanced undergraduate or subscripti on order for BYTE. predictive} solutions to nature of the more advanced graduate level boo!? on It seems to be what I'm engineering problems in error correcting algorithms. classical m ec hanic s , looking for. Already I have applied electronics - and the 3. A floating point spacecraft ncwigalion or been looking at surplu s ads HP-25 should be able to arithmetic paclwge to go astronomy if you want to for CPUs with an eye to perform similarly on many along with the computational find info on the calculations. making my own digital problems. But a pre-paclwged requirements of # I and #2. One possible source of computer though "simp le calculator may be "no fun" ­ This should probably include information, mentioned to minded" it would probably and certainly is not useful for data conversions to in teger m e by Bob Bal?er of have to be . anything other than and character string forms for Littleton, Mass., is a radio Among other things, I am calculation. Further, the convenience of programming. amateur organization called a ham and a consulting programming of a really 4. An orbital model which the Amateur Satellite engineer for EBASCO. What I complicated satellite position uses a given set of ephemeris Corporation - AMSA T, Box have in mind is to have algorithm (e.g ., adding in info1matio11 at some time "t" 27, Washington DC 20044. av a i Iable a programmable second and third order Bob tells me that their computer to solve fi lter perturbations of the earths newsl e tter frequently design problems (and gravitational potential} may mentions computational ante nn a/feed lin e impedance be beyond the range or a algorithms for the OSCAR prob Iems parametrically). simple hand calculator amateur radio satellite However as a first without multiple mental algorithms which could be question: Do you think it overlays. adapted to any satellite may be in the realm of a The problem of simple orbital elements. Another "non-computer expert" to ce l estia l mechanics poss ibl e source or make a home built computer computation is well within information is the HP-65 so lv e weather satellite orbits the range of a small home Users Club run by Richard and read out azimuth and microcomputer system which Nelson - in scanning through e levation information for contains perhaps 4k bytes {or his bacl? issues recently I saw tracking purposes7 I can feed equivalent} and the facility to several listings of names of in very accurate time do o ver!ay programming programs sounding information. I don't know using at least one audio suspiciously like what you yet how to get from "here" cassette drive. In order to do want, e.g., "Orbital Element to "there." this kind of ca/culalion, Determination" and the like. W. J. Byron however, I am making the (HP-65 Users Club, 2541 New York NY following assumption: you West Camden Pl., San ta Anu already have the ana!y lical CA 92704.} While by no solution to the problem in and calculates new satellite means a complete design , I the form of an algorithm position at time "t + 6.t" hope this information proves You have an interesting specification. (In case you later. (The "now" position.} useful to you. question. . . For the first don't, maybe a reader with a 5. An output model which . . . CARL portion, how to solve the bent for applied celestial uses various coordinate analytical equations of mechanics, coordinate transformations to turn the engineering, there is a range transformation problems and "now" po s ition in or solutions depending upon numerical integration might "geocentric coordinates" into your p111poses, budget and be so kind as to supply a an apparent position on the

8 EVOLUTION publishing operation I have I invite you or any reader NOT EROSION joined - and ii will be the who thinks he or she is element which makes the getting a bad deal on the reputation for the magazine magazine to write me Dear Mr. Helmers, as a source of ideas and fun. connection with the M. P. personally at any time. I I dm a subscriber to ECS . . . CARL Publishing Co. operation I won't promise to publish all magazine and was a li ttle was running in my spare time such letters - yours, Mr. uneasy to receive the until BYTE started - one of Southard, is published by distinction of being the first announcement of its "BILL ME" the first such items was a transformation into "BYTE". condition of the arrangement - but I will endeavor to answer each one personally. I hope this is an evo luti onary Dear Sir: I made with Green Publishing development, and not an tho t all ECS subscribers As to technical content, you can peruse the first issue, erosion into the murkiness of Yes, I' ll byte, but I think should be picked up by then make a judgment. I will total commercialism. I have I've been taken. I was a BYTE on a two issues for one endeavor to produce the best very much enjoyed and subscriber of ECS and was basis. Thus since your ECS possible magazine by benefited from ECS. told that subscri ption was subscription of $27 was selecting the best possible Thanks for the help, and okay for the charter BYTE fulfilled by mailings of 70 articles. I am not about to good lu ck rn your new publication; I guess that issues, the remaining two ECS ignor e the biggest venture. promise ... and ten bucks issues become four BYTE mu Iti processor systern of Duane L. Gustavus can also buy a year's issues. Adding to that your them all - the human race subscription. I've been bit inadvertent resubscription Denton TX . . . all the people in the (for more than the ten bucks} gives a total of 76 BYTES . . . readership of BYTE who will by others feeding off the OK, you say, "he promises be coming up with ideas for crumbs of micro machine 76 BYTES - will I get I think I can sympathize articles and submitting them data, so can't begrudge you them?" You can best evaluate with your uneasiness about will set the level of much of yours. that after you've gotten ECS Magazine's the material available for I am eternall y hopeful for BYTE #7 6. The aim of BYTE transformation into BYTE. publication. If you don't like BYTE, but not optimistic. I magazine is - as is the aim of Yes, it is indeed an my personal wort?, kindly have been a ham for a long the large corporation for evolu tionary transition, in give me the courtesy of several respects. First, ifyou time (23 years), and Mr. which you work - to turn a fool? in the first issue you will Green is not my favorite; als o reasonable profit in the long find a much larger and more I didn't think Mr. Helmer's run and provide enduring and varied editorial content than I ECS info was very good. I satisfying work for those was ever able to achieve in agree, however, that there connected with the the course of preparing my "sure is a need for a good enterprise. It can only do so self-published 24-page photo magazine," so hope BYTE by providing good service to offset magazine. Second, by can serve that need. Let's its customers - the readers providing a place for hope it's better than 73. and advertisers who patronize commerce - a free market ­ Pl ease bill me for the lousy the magazine. BYTE is very it serves as a unifying element sawbuck. much a market phenomenon, and cannot exist unless it in the whole sphere of the C. Southard WA~IOT computer hobby endeavor. Cedar Rapids IA maintains a readership of Throughout history, it is the intelligent and active persons market place which has such as yourself. If BYTE sustained the progress in I am printing your letter in were to consistently turn you ideas, and technology which BYTE for a reason, a matter off - as well as others on a stating why - I !mow that has brought the human race of principle if you will: I am large scale - we'd be heading the ECS Series articles I from crude wheels to $20 personally responsible for the into bankruptcy faster than a previously put out had many bus-oriented microcomputers. editorial content of BYTE Penn Central express train flaws. I have heard some good Third, there is the element of magazine, and have my should be running. and some bad evaluations of professionalism in format and reputation on the line as a the ECS Series and ECS execution. BYTE is being put result. I believe that after you Magazine items. t ogether by a fine have read your first issue of I will not however disown organization of craftspeople BYTE you will find it well anything I have done - and who lal?e pride in the work worth a $ 70 which you had tho t series of sel f-pub lish ed which results. Sure, the no reason to send in at this articles is my product with all magazine is commercial and time other than (perhaps) a its flaws and imperfections. If has advertisemen ts - but negative attitude and a you wish to exercise the then, don'/ you work for promotional circular which moneyback guarantee, let me yourself, some employer, or came your way as a result of know . .. and send back your other agency? This pride in one of our mailing lists. I copies to fulfill your part of the quality and value of work have a number of items of the exchange. extends throughout the unfinished business in . .. CARL

9 WHAT SINGLE ELECTRONIC MACHINE CAN BE USED TO PERFORM/CONTROL ALL THE FOLLOWING TYPES OF SERVICES?

Send morse code Control repeater stations Operate as a calculator Receive/send/buffer data between a wide variety of communication devices Monitor instruments Control machines Sort/compile data Test other devices Play games the SCELBl-88 MINI-COMPUTER CAN !

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10 MACHINE LANGUAGE PRC>GRAIVllVllNG I I fe>r the SOOS (ANos1M1LARM1cRocoMPUTERs)

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11 Notes from th e Garden State via the Goethels Bridge Clubs GP6ativ0 computh~fl ACSNJ 's secon d mee ting 11 ~• · •r• 1w:; •1 ~" was held at the Uni on Coun ty Tec hnical In sti tute on Jul y 18, 1975 . The meeting was Newsletters presided over by Bohd an in th e abse nc e o r Sol Libcs. Thirty hobbyists showe d up LA Update including 8 new me mbe rs. In defe rence to Ste phen Gray, Than ks to the efforts of founder of the origin al ACS, Derek McCo ll , I've rece ived a we are considerin g changing further update on the Los Creative Computing is the not satisfactoril y ad dress . In our name to the New Jersey Angeles club acti vi ties . . . a name of a magazin e which is particul ar, sc hool users, both Am ate ur Compu te r Group very ac ti ve bunch of people. edited and published by co ll ege a nd e lementa ry/ (NJACG) . Derek se nt me a copy of t he Davi d H. Ahl. The motto of second a ry, need more Roger Amidon gave a S o uth e rn C a li fo rni a the operation is "a non-profit class room activities, exercises, presentati on on the UART. Computer Society Interface magaz ine of edu cational and pro blems and ideas th an arc Ma rty Ni c ho ls he ld a - Volume 1, # 0 (do I detect recrea ti o nal co mputing." avail able in textbooks and disc uss ion on the di ffe rences an algo lm aniac at work? ) for Creati ve Computing is other magaz ines. Also th ere betwee n 8008 and 8080 August. The motto in the publi shed bi- monthl y, printed ought to be a di scussion of mi croprocessors. Andy Vi es hea d i n g I i n e reads "an in a saddle-stitc hed 8!/i by 11 the social as pect of the talked about his ex peri ences announce ment fo r compu ter fo rmat (s imil ar to BYT E) compu ter, its effect on jobs, wi th the construction and h o bby ists des igned to with 60 pages in a typical medical care, privacy and the operati on of TVT 1 and TVT connect people and id eas issue. Tile ed itorial content is li ke. Fur t herm ore, what 2. Way ne Ahl ers showed us . .. " - and it lives up to that heav il y o ri e nted towa rd about the user of non-DEC hi s octal keyboard built billing in its six pages of information useful in an computers7 Cl ea rl y to be around PEs 12- 7 4 low cost ty pewritten copy. educational context. Davi d responsive to these needs compu te r terminal. Li te ratu re The pe rso n wh o is Ahl was for merly the another ve hicle was needed. and oth er in fo rm ati on was handling the administrative E du ca ti o nal Mar ket in g Thus Creative Computing was disse min ated befo re and after detail s of SCCS fo r the ti me Manager at Di gital Eq uipment born . .. " the fo rm al mee tin g. being is Hal Las hlee, who can Cor p., where he was The various iss ues I have Late r that ni ght, a small be reac hed by phone at responsibl e fo r the creation see n t o d ate in c lude gro up vi site d Roge r Amidon's 1-2 13-682-3108, or by mail of DE C's EDU publication. n umerous pu zzles, BAS IC site . In addi tion to hi s 16k at PO Box 987, So uth To quote from his ed itorial in games, an d articles on Al tair, TIY and magnetic and Pasa dena CA . the March-April 1975 issue of co mp uters, co m p u ter paper tape periph erals, Roger The fo ll owing topics and Creative Computing: edu catio n and compu te r K2SMN also has a home brew conce rns we re draw n from " Over the years EDU careers. T o o rd er a RTTY contro ll er whi ch is the sugges ti on boxes of a fl ouri shed and grew in to a sub scription, se nd $8 fo r one affectionately named Spider. brief survey fo rm handed out 48- plu s p age magazin e. year o r $21 fo r three years to (I f I can ever get a pi cture of to members at the first However th ere we re certain Creative Computing, Box it, you 'II understand why.) meetin g of SCCS (and prin ted as p ects of ed u cat io nal 789- M, Mo r ristow n NJ The third meetin g or the in Volume 1 #0 of In terface): computin g whi ch EDU coul d 07960. . .. CARL NJ ACG will be held in - Members would like to September, no t Au gust, on see a co mpu terize d the third Friday , September clearin ghouse fo r compu ter 19, 1975, at the Middlesex hobby in fo rmati on. County Coll ege. For more - On e purpose of the ~ INTERFACE info rm ati on contact George orga ni za ti o n sho uld be Fisc her, 1-21 2-35 1-1751. mu t u a I assist a n c e w ith spec ific pro blems. - Hardware procurement by gro up purchase s. Oklahoma City Club - Standardi zation. In Oklahoma City OK, Bill - The club mi ght act as a bra in pool fo r small bu sin ess Co wden re ports th at he is needs. orga ni z ing a compu ter - Th e usual clu b type enthusiasts' club. Co ntact Bill activities of social meetin gs, at hi s home address, 2412 l ec tur es, se min a r s, SW 45th, Okl ahoma Ci ty OK 7311 9. wo rkshops, public service, etc.

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One of the most Simplify the music problem The next problem (si nee I interesting computer to one channel of melody, wasn't using th e Motorol a applications is that of and you can use a virtually ROM software) was to make electronic music. This is the bare CPU with a very simple a test program which could use of software/hardware peripheral to pl ay music.* be lo aded by hand. By systems to produce sequences The combination of the CPU combining a littl e of notes heard in a loud with this simple peripheral is imagin ation, my predilections speake r or record ed on what I call the "Kluge Harp" for computer music systems mag netic tape. The idea of - a quick and dirty electronic and an evenin g ge tting the generating music - if well music kluge. whole mess straightened out, done is of necess ity I invented this electronic th e Klu ge Harp resulted. complex. If I want to put my musi c kluge to answer a Whil e the program and favorite Mozart piano sonata specific pro blem: I had just schematic are specific to the into an electronic form, I'd gotten a new Motorola 6800 system I was usin g, the idea have to record a very large system's CPU, memory and can be appli ed to your own number of bits in order to control panel up and running. system just as well. completely specify the piece with all the arti stic effects of The Kluge Harp Hardware expressio n, dynamics, etc . .. The hardware of a Klu ge Th e m ag nitud e of the Harp is simplicity at its by TAIR owners: Write an problem can be intimidatin g. (*Al esse nce. The peripheral is Carl Helmers 8080 version of this program and But, neve r let a hard problem your machine can do more than driven off two "un-used" Editor, BYTE get in the way of fun! blink its Iights.I hi gh order address lin es (I used A1 4 and A 13), and consists of a set-reset flip flop . A program running in the computer alternate ly will Fig. 1. The Kluge Harp Circuit . .. minus computer. set and rese t the flip fl op by +5V refe rencin g one o r the other of two addresses. These Al4 OF COMPUTER addresses are chosen so that the address lin es in question will change state, actuat ing Al the set or reset side of the flip CLR SETLOC flop. A "note" at so me pitch SPEAKER consists of a delay loop in the

8 pr og r a m followed by instructions to change the I I Al3 OF COMPUTER I I state of th e flip flop. Since L J\N'\r J OPTIONAL th e sa me count is used fo r the Al RESISTOR two halv es o f a compl ete CLR RESETLOC (IOOfl) cycle of th e no te, thi s will produce a perfect sq uare wa ve . The actual music program orga ni zation is J bit

14 Q) ."1­ l'.) Backplane Interconnections I

f)

~· ­ lft.ltt;...... '""" • ,,_ .._, • ·- .."" - • !@,

.. CPU and Buffers (M6800) Speaker KLUGEHARP Peripheral

Control Panel Interface

The Kluge Harp peripheral and the KLUGEHARP program were concocted in order to test out a Motorola 6800 system 's operation. This photo shows a test bench mounting of the three main cards and control panel. The Kluge Harp peripheral, such as it is, is the single isolated wire wrap socket in the foreground, with wires dangling from connections on the CPU card.

m o re complex and is ove r and over aga in al I the indicated by th e length code column were determined described in detail below. lines of code down through ju st retrieved. The no te usin g the prime number 137 Fig. 1 illustrates the the "END" at the same ge neration is accompli shed by as an arbi trary starting point hardware as implemented in margin, found at line 17 . This delayi ng a number of time and calculating the integer my syste m. The 7437 circuit is the mai n loop use d to cycle units (CPU states) set by the closest to the resu It of the is use d to form the NAND through the SCORE stored at pitch code fo und at fo llowing fo rmula: gate flip flop. This flip flop in some poin t in memory as SCORE(NOTER) , then turn drives a parall el pairs of note se lection/length changin g the state of the {ln{137)+ n ln(2)/12) co mbin ation of the two data bytes . output flip fl op and repeating re maining 7437 gates, acting Lines 3 to 4 compu te the the process. Th e loop at lin es as a bu ffe r. The output of " nex t" pointer to th.:: SCORE 8-10 counts down the pitch this buffer is used to drive the - in crementing NOTER by 2. code and has a fi xed de lay Where e is the usu al speaker; an 8 Ohm 5" speaker Then LNGTH is set eq ual to mul ti plied by the pitch co de mathematic al number 2.717 produced more than adeq uate the second byte of the to give th e time for one half ... and the natural logarithm vo lume. (A 100 Ohm resistor c urr ent p a ir , SCO RE cycle of the des ire d of x (base e) is indicated by in se ri es wil l limit the volume (NOTER+l ). The length frequency. Lin es 11 to 15 ln( x). This is th e standard leve l Lo spare the ear drums.) codes are taken fr om Table I change the state of the Klu ge mathematical calculation of alo ng with note codes when Harp output device (Oto l , 1 the musical "well tempered" Ge nerating Music With you set up a SCORE, and to O) - re membering in the sca l e the 8-bit Program Loops represent a fixed interval of software locatio n IT what the approximation use d by the Fig. 2 illu strates the bas ic time fo r the note in qu es tion, previous state was. Kluge Harp is not perfect by conccp t of the one-c hann el measured as the number of any means, but comes close mu sic ge nera Lor, expressed in cyc les. Generating Codes enough for th e purposes of a procedure-ori ented language Linc 6 begi ns a note length Table I is a reference table this project. for compac tn ess. The main loop which ex tends to Ii ne of 21 notes "roughly" space d The length count columns pro gram loop beg ins at line 2 14. This "note len gt h" loop at equal in terva ls on the well are determined base d upon of th e li sting " DO repeats th e ge nera ti on of the tempe red scale. The integer t he asse mbly la ngu age FOREVER" means repeat note a number of times numbers in the "divide ratio" ge nerated code for this

15 Fig. 2. The KLUGEHARP program specified in a procedure-ori ented computer language.

1 KLUGEHARP: PROGRAM; 2 DO FOREVER; 3 NOTER = NOTER + 2; 4 IF NOTER = NOTE ND THEN NOTER = NOTESTART; 5 LNGTH = SCORE(NOTER+1); / * SECOND OF TWO BYTES */ 6 DO FOR I = LNGTH TO 1 BY -1; 7 PITCH = SCORE(NOTER); / * FIRST OF TWO BYTES */ 8 DO FOR J = PITCH TO 1 BY -1; 9 / * COUNT DOWN THE PITCH DELAY *I 10 END; 11 IT = IT + (-127); / * SWITCH SIGN BIT OF IT */ 12 IF IT OTHEN 13 SETLOC = O; / * SET FLIP FLOP WITH MEMORY REF */ 14 ELSE 15 RESETLOC = O; /*RESET FLIP FLOP WITH REF */ 16 END; 17 END; 18 CLOSE KLUGEHARP; Data assumed by KLUGEHARP: NOTER: 16-bit (two-byte) routine, so that for each Len = nth le ngth count. the pi tch count innermost address value. Initialize to pitc h, t h e corresponding time is the to tal number of loop. point to the address of the length count column will states for one " beat " of the pen is th e pi tch co un t for the first byte of SCORE. measure a nearly identical music (e.g., the sh ortest nth frequency. SCORE: An array of data in inte rval of t ime. The fo rmula note). Table I sho ws the divide memory containing the code is: oh is the overhead of the rat i o i n d ec im a l , a sequence of the music (see Len = time I (oh + dt# pe n) length counting loop. hexadecimal equivale nt no te Table II). Initialize with the whe re: dt is the number o f sta tes in p i t c h c od e, a nd seven music of your heart's desire or use the example of Table II. Table I. Klu ge Harp Sy nthesizer pitch/length sp ecifica tion codes (HEX ). NOTEND: 16-bit address value, the address of the last n divide hex note Note Length Codes (second byte of pair) byte of SCORE (must be an ratio code 1 2 4 6 8 16 32 even number). -10 77 4D 19 32 64 96 CB NOTESTART: 16-bit address -9 B1 51 1B 30 60 90 co value, the address of the first -B B6 56 17 2D 5A B7 B4 byte of SCORE (must be an -7 91 5B 16 2B 56 B1 AC even number). ·6 97 61 14 29 51 7A A2 F3 SETLOC: An unimplemented -5 102 66 13 27 4D 74 9A E7 address location which if -4 10B 6C 12 25 49 6E 92 DB referenced turns off one bit .3 115 73 11 23 43 6B BA CF among the high order address -2 122 7A 10 21 41 62 B2 C3 lines, bit 14 in the author's -1 129 B1 10 1 F 3E 5D 7C BA FB case . 0 137 B9 OF 1D 3A 57 74 AE EB RESETLOC : An 1 145 91 OE 1C 37 53 6E A5 DC unimplemented address 2 154 9A OD 1A 34 4E 6B 9C DO location which if referenced 3 163 A3 oc 19 31 4A 62 93 C4 turns off one bit among the 4 173 AD oc 1B 2F 47 5E BD BC high order address lines, bit 5 1B3 B7 OB 16 2C 42 5B B4 BO 13 in the author's case. 6 194 C2 OB 15 2A 3F 54 7E AB Data used but not initialized: 7 205 CD OA 14 2B 3C 50 7B AO LNG TH B 217 D9 09 13 25 3B 4A 6F 94 PITCH 9 230 E6 09 12 23 35 46 69 BC IT 10 244 F4 OB 11 21 32 42 63 B4 I, J

16 Fig. 3. Motorola 6800 Code for KLUGEHARP program.

Address Data Label Opcode Operand

FSOO FE KLUGE HARP: LO X NOTER F801 FA 3: F802 00 Add 2 to locat ion in score F803 08 IN X by incrementing and then F804 08 INX sav ing 16-bit new address F805 FF STX NOTER F806 FA F807 00 F808 SC 4: CPX #NOTEND compare aga inst immediate F809 FC NOTEND: (I ast address o f FBOA 80 SCORE plus 2 1 F80B 26 BNE Skip if not at end ... FSOC 03 *+3+2 FSOD CE LOX #NOTESTART FSOE FC NOTESTART: (first ad dress of otherwise recycle FSOF 00 score ... I F810 FF STX NOTER save in either case . .. F811 FA F812 00 F813 FE LOX NOTER This is superfluous! F814 FA F815 00 F816 E6 5: LDAB 1,X F817 01 F818 5A LENGTH : DECB F819 26 6 : BNE Skip if length remains .. . F81A 03 *+2+3 F81 B 7E JMP K LUGE HARP Restart piece F81C F8 F81 D 00 Data allocations for KLUGE­ F81E A6 7: LDAA O,X HARP: F81F 00 FAOO- FA01 Current F820 4A FLOOP: DECA i=821 26 8: BNE FLOOP pointer to SCORE, NOTER, F822 FD *+2-3 which should be initialized to F823 86 11 : LDAA #so FCOO before starting the F824 80 (-127) program. F825 BB A DDA IT = F826 FA FA02 IT an arbitrary F827 02 initialization will do. i=828 2B 12: BMI FA03-FFF7 = memory area F829 05 *+2+5 available for SCORE - the F82A 7F 13: CLR SETLOC example uses FCOO to FC7F F82B BO (address with b it 14 off . .. I F82C 00 and puts the relevant F82D 20 BRA initializations into locations F82E 03 * +2+3 F809-F80A (NOTEND) and F82F 7F 15: CLR RESETLOC F80E-F80F (NOTESTART). F830 DO (address with bit 13 off . .. I F831 00 NOTE: In the label column, F832 B7 STAA IT the numbers followed by colons F833 FA (e.g., "6:") are used to indicate F834 02 corresponding places in the high F835 7E 16: JMP LENGTH level language version of the F836 FS program of Fig. 2. F837 18 In the system for which this program was written, all active memory is found at addresses F800 to FFFF. Thus for all columns of hexadecimal pitches you 'I I get from these in terva l of t im e i s normal program activity, bits A 14 length codes weighted to 1, 2, codes depend upon the a pproximately 2000 CPU and A 13 at the back plane of the 4, 6, 8, 16 and 32 unit details of the algorithm in states o r abo ut 4 system are logical " 1 " . When the intervals of tim e. A note is your ow n particular mil Ii seconds. location SETLOC (8000) is computer and the clock 1·a te cleared, the high order address placed in the score by picking T h e h a n d a s s e m b I ed portion changes and bit A14 goes a note code, putting it in an of the computer. For the M6800 code for the to negative for a short time, even numbered byte, then 6800 system on which Klu ge KLUGEHARP program is setting the Kluge Harp flip flop. pl ac ing a length code from Harp was first imple mented, listed in F ig . 3. The When the location A 13 is cleared the same Ii ne of the table in the lowest note (code F4) is (DOOO) on an alternate cycle, mn emonics and notations address bit A 13 goes to logical 0 the odd numbered byte approximate ly 170 Hz with a have been taken from the for a short timer resetting the which follows it. The actual 500 kHz clock - and th e unit Mot oro l a M6800 Kluge Harp flip flop . ..

17 Table II. WOLFGANG: Set the content of SCORE in memory to the codes in this table - given for the addresses of the M6800 program version - and KLUGEHARP will play fo ur bars from th e classical period. 6800 Address Value 6800 Address Value

FCOO 9A34 FC40 5856 FC02 9A34 FC42 5856 FC04 9A34 FC44 5856 FC06 9A34 FC46 5856 FCOB 9A34 Note 1 FC48 5856 Note 8 FCOA 9A34 FC4A 5856 FCOC 9A34 FC4C 5856 FCOE 9A34 FC4E 5856

FC10 FC50 FC12 7A41]7A41 Note 2 FC52 6640]6640 Note 9 FC14 7A41 FC54 6640 FC16 7A41 FC56 6640

FC18 FC58 FC1A 6640]6640 Note 3 FC5A 4064]4064 Note 10 FC1C 6640 FC5C 4064 FC1E 6640 FC5E 4064

FC20 FC60 FC22 A331]A331 FC62 6640]6640 FC24 A331 Note 4 FC64 6640 Note 11 FC26 A331 FC66 6640 FC28 A331 FC2A A331 FC68 7343 - Note 12 FC6A 6640 - Note 13 NOTE : This program is FC2C 9A34 Note 5 FC6C 7343 - Note 14 simpleminded and not at all FC6E 7A41 - Note 15 optimized. As a challenge to FC2E 893A Note 6 FC70 7343 - Note 16 readers. figure out a way to make the notation more compact yet FC30 9A34 FC72 preserving the total length of each FC32 9A34 FC74 7A41 note. FC34 9A34 FC76 7M']7A41 FC78 7A41 Note 17 FC36 9A34 Note 7 FC38 9A34 FC7A 7A41 FC3A 9A34 FC7C 7A41 FC3C 9A34 FC7E 7A41 FC3E 9A34 FC80 (end pointer points here)

Fig. 4. Timing of the Kluge Harp Output Waveform. 6.t is the amount Microprocessor Programming of time spent in the inner loop, and is set by ch oice of pitch codes. 6.T Manual available from the is the length of the note, measured as a count of half-cycles at its man ufactu re r. frequency. Se e Table I for a consistent se t of length codes. While not the greatest t:. T ------­ mu sical instrument in the world, the Kluge Harp represents an interesting and challenging diversion. The program presented here is by 7437 no means the ultimate in PIN3 IN music systems - and can FIG.I serve as a basis for further ex p e rim e nt atio n a nd elaboration. Some challenges for readers : modify the Al4 LINE program to change t he frequency of the notes / without changing the SCORE CLR SETLOC INSTRUCTION data; write another (longer) EXEC TED music program which o nl y s p ecif i es the pi tc h Al3 LINE code/length information o nce - and represe nts the score as a series of one-byte indices / into the table of pitch CLR RESETLOC INSTRUCTION code/length information. EXECUTED

18 ALTAIR USERS!

Did you know... •That all our modules are 100% compatible with the Altair 8800 VDM-1 Video D isplay Module computer, NO modifications necessary I This module is the first real computer terminal display in kit •That our 4K RA Static Read/Write Memory module doesn't have form. Under software control the VDM·l displays sixteen 64 to lose it's data when you pull the plug! character lines to any standard video monitor. Characters are •That our 3P+S Input/Output module will fully interface two TV produced in a 7x9 dot matrix, with a full 128 character set, upper Typewriters with keyboards and a modem or teletype at the and lower case plus control characters. Data is accessed by the sa me time! VDM as a block from any 1 K segment within the 65K address •That we make the most powerful alphanumeric Video Display rang e of the 8800 computer. Multiple cursors are completely module anywhere! controlled by software and the display can begin anywhere on the •That our software is FREE, or close to it! screen !this is great for many video games). When the last line is •That all our modules are truly high quality, computer grade, but filled the display scrolls up a line. Powerful editing capabilities are that our prices are the lowest in the indust ry I provided with the FREE software package included in every •That we have already shipped hundreds of modules on time, and VDM ·l kit. Available in September '75. we will continue to deliver what we promise, FAST! SOFTWARE

Our Assembler, T ex t Editor and System Executive is being CHECK THE SPECS: shipped now. This software package gives you very powerful 4KRA Static Read/Write Memory Assembly Language capability in the Altair 8800. The Executive This 4096 word STATIC memory provid es faster, more reliabl e and Editor allow you to call programs by name !including and less expensive operation than any currently ava il ab le dynamic BASIC) and then add, delete, change, or list programs by line m emory system. The 4KRA permits Altair 8800 operation at number. The A sse mbler provides a formatted symbolic mnemonic abso lute top speed continuously. All RAM's !R andom Access listing as well as octal or binary object code from Assembly Memories) used in the 4KRA are 91 L02A's by Advanced Micro Language programs written using the Editor. The A ssemb ler also Devices, the best commercial memory IC on the market today. gives valuable error messages to help in debugging those inev itable 91 L02A's require typically 1/3 the power of standard 2102 or errors. The Assembler, Editor, Execu tive Package No. 1 w ill be 8101 type RAM's and each one is manufactured to military available in read only memory along with an expanded Executive specification Ml L STD-883 for ex tremely high reliability. Th ese and a powerful Interpretive Simulator by October or November memories can be operated from a battery backup supply in case of 1975. of power failure with very low standby power consumption. !Ask We are working on two BASIC Language packages which should for our technical bulletin TB-101 on power clown operation. ) In be ready by October. One will be a basic BASIC needing about short we have clone everyth ing we cou ld to mak e the best 4K BK of m emory as a minimum and the other will be an Extended memory module in the computer fi eld , and because we buy in version with additional string manipulation, matrix operations large quantity, we can make it for a verv rea so nable price. and double precision arithmetic capabilities requiring about 12K. Available now. Both these packages w ill be available in Read Only Memory for a reasonable price. 2KRO Erasable Reprogrammable Read Only Memory Module With this module th e Altair 8800 can use 1702A or 5203 type PRICE LIST Erasable Reprogrammab le ROM's. The 2KRO accepts up to eigh t Item Kit Assembled Delivery of these IC's for a capac ity of 2048 eig ht bit words. Once 2KRO EPROM module $ 50. $ 75. 2 weeks ARO programmed this module will hold its data indefinitely whether or not power is on. This feature is extremely useful wh8n 3P+S 1/0 module 125. 165. 3 weeks ARO developing so ftware . All necessary bus interfacing logic and 4KRA·2 RAM module regulated supplies are provided but NOT the EPROM IC's. Both w/2048 8-bit words 135. 185. 2 weeks ARO 1702A and 5203 PROM's are available from other advertisers in 4KRA·4 w/4096 B·bit this m agazine for well under $25. Available now. words of RAM 215. 280. 2 weeks ARO 3P+S Input/Output Module RAM only, AMO 91 L02A Just one 3P+S card will fulfill the Input/Output needs of most 500n sec low power 8/$40 2 weeks ARO 8800 users . There are two 8-bit parallel input and output ports MB· 1 Mother Board 35. 2 weeks ARO with full handshaking logic. There is also a ser ial 1/0 using a UART with both teletype current loop and EIA RS -232 standard VDM·1 Video Display module 160. 225. Sept. 29, '75 interfaces provided. T he ser ial data rate can be set under so ftware then 3 weeks ARO control between 35 and 9600 Baud. You can use your old model Send for our FREE f lyer for more complete specifications and 19 TTYI This module gives you all the electronics you need to for pricing on additional items. interface most perioheral devices with the Altair 8800, it's really the most useful and versatile 1/0 we've seen for any computer. TERMS: All items postpaid if full payment accompanies order. Available now. COD orders must include 25% deposit. MasterCharge gladly accepted, but please send us an order with your signature on it. MB-1 Mother Board DISCOUNTS: Orders over $375 may subtract 5%; orders over Don't worry any more about wiring hundreds of wires in your $600 may subtract 10%. Altair to expand the mainframe. Our single piece 1 /8-inch thick, rugged mother board can be installed as one single replacement for either three or four 88EC Expander cards, so you don't have to replace your already installed BBEC card if you don't want to. ~~hnology The MB·1 ha s very heavy power and ground busses and comes with a piece of flat ribbon cable for connection to the front panel Berkeley,Ca.94710 (415) 54s-0a51 board of the 8800. Available now. l Television

Anyone with a bunch of memory circuits, control logic and adding a video input and a a wire wrap gun can whip up a digital video generator with selector switch or else TTL output levels. The problem as I see it is to get that digital dedicating the set to exclusive video signal into a form that the TV set can digest. The care TV typewriter use. Direct and feeding of digital inputs to the TV set is the subject of video e liminates the bandwidth restrictions Don Lancaster's contribution to BYTE 2 - an excerpt from provided by the tuner, i-f his forthcoming book, to be TV Typewriter Cookbook, strip, and video detector published by Howard W. Sams, Indianapolis, Indiana. filter. Response can be .. . CARL further extended by removing or shorting the 4.5 MHz sound trap and by other modifications to provide us with longer line lengths and We can get between a TV certain exactly spelled out premium characters. No FCC typewriter and a television FCC regulations and that approval . is needed, and style display system either by system type approval is several sets or monitors are an rf modulator or a direct r eq uired . Th e second easily driven at once without video method. limitation is one of complicated distribution In the rf modulator bandwidth. The best you can problems. method, we build a possibly hope for is 3.5 MHz There are two Ii mitations miniature, low power, direct for black and white and only to the direct video technique. wired TV transmitter that 3 MHz for color, and many One is that the set has to be clips onto the antenna eco nomy sets will provide far modified to provide direct terminals of the TV set. Th is less. Thus, long character line video entry. A second, and has the big advantage of lengths, sharp characters, and far more severe, restriction, is letting you use any old TV premium (lots of dots} that many television sets are set and ending up with an character generators simply "hot chassis" or ac-dc sets essentially free displ ay that aren't compatible with with one side of their chassis can be used just about clip-on rf entry. connected to the power Ii ne. by anywhere. No set In the direct video These sets introduce a severe modifications are needed, and method, we enter the TV set Don Lancaster shock hazard and cannot be you have the additional immediately following its used as TV typewriter video advantage of automatic safety video detector but before entry displays unless some isolation and freedom from sync is picked off. A few isolation technique is used hot chassis shock problems. premium TV sets and all with them. If the TV set has a There are two major monitors already have a video power transformer, there is restrictions to the rf input directly available, but usually no hot chassis modulator method. The first these are still expensive and problem. Transistor television of these is that transmitters rare. Thus, you usually have sets and IC sets ·using no of this type must meet to modify your TV set, either vacuum tubes tend to have power transformers, as do older premium tube type sets. All others (around half the sets around today) do not. Fig. 1. Standard video interface levels. (Source impedance= 72 or 100 Ohms.) Direct Video Methods WHITE LEVEL ----- 2VOLTS With either interface DOT ­ (OPTIONAL approach, we usually start by GRAY) SYNC 1 getting the dot matrix data, TIP 1.ov blanking, cursor, and sync 0 .5 VOLTS BLACK LEVEL signals together into one ------SYNC LEVEL------­ composite video signal whose

20 Interface

form is usefu I to monitors miniature coax), the receiving Fig. 2. Analog switch combiner generates composite video. and TV sets. A good set of end of the cable need not be standards is shown in Fig. 1. terminated in a 72 or 100 lf+5 -5 The signal is de coupled and Ohm resistor. When H SYNC

always positive going. Sync terminated cable systems are JL+5 -5 tips are grounded and blacker in use for long line runs or CURSOR than black. The normal open multiple outputs, they should circuit black level is positive be arranged to deliver the u+5 -5 by one-half a volt, and the signal levels of Fig. 1 at their V SYNC white level is two volts output under termination. +5 n (WHITE) -' L-5 positive. In most TV camera Generally, terminated cable VIDEO DOTS systems, intermediate levels systems should be avoided as IK between the half volt black they need extra in the way of level and the two volt white drivers and supply power. Cl The exact width of the SMEARING 4066 (CMOS) level wil I be some shade of CAPACITOR ANALOG SWITCH gray, proportionately brighter horizontal and vertical sync (SEE TEXT) with increasing positive pulses isn 't usually too voltage. With most TV important, so long as the typewriter systems, only the shape and risetime of these 680 three states of zero volts pulses are independent of (sync), half a volt (black), position control settings and and two volts (white dot) power supply variations. One would be used . One possible exception to this is when

exception would be an you 're using a color receiver SYNC• OV additional one volt dot level and a color display. Here, the BLACK•0.4V for a dim but still visible horizontal sync pulse shou Id WHITE• l.5V portion of a message or a be held closely to 5.1 single word. microseconds, so the The usual video source receiver's color burst impedance is either 72 or 100 sampling does in fact Ohms. Regardless of how far intercept a valid color burst. very much improve the shabby, or washed out we travel with a composite More on this later. display legibility and character. By reducing the video output, some sort of contrast. Why? video bandwidth going into shielding is absolutely Intentional Smear Because we are interested the system, we can move the essential. Fig. 2 shows us a typical in getting the most legible dot matrix energy lower in For short runs from board composite video driver using character of the highest frequency, resulting in to board or inside equipment, a 4066 quad analog switch. It contrast we can. This is not cleaner characters of higher tightly twisted conductors gives us a 100 Ohm output necessarily the one having the contrast. should be OK, as should impedance and the proper sharpest dot rise and fall For most TV displays, properly guarded PC runs. signal levels. Capacitor Cl is times. Many things interact to intentional smearing will help Fully shielded cables should used to purposely reduce the determine the upper video the contrast, legibility, and be used for interconnections video rise and fall times. It is response of a TV display. overall appearance. The between the TVT and the called a smearing capacitor. These include the tuner ultimate limit to this occurs monitor or TV set, along with Why would we want to settings and the i-f response when the dots overlap and other long runs. As long as further reduce the bandwidth and alignment, the video become illegible . Th e the total cable capacitance is and response of a TV system detector response, video less than 500 pF or so (this is that's already hurting to peaking, the sound trap around 18 feet of RGl 78-U begin with? In the case of a setting, rf cable reflections, quality video monitor, we and a host of other responses. wouldn't. But if we're using Many of these stages are an ordinary run-of-the-mill underdamped and will ring if TV set, particularly one using fed too sharp a risetime rf entry, this capacitor can input, giving us a ghosted,

21 remove the ca rri er· and then routed to a video amplifi er made up of one o r· more tub es m transistors. At some point in the vid eo ampli fica ti on, the bl ack and whi te signa l is sp lit three ways . Fir st, a reduced bandwidth output routes sync pulses to the sy nc Fig. 3. Block diagram of typical Band W television. separ-ator stage to lock the set's hor·izonta l and vertical

ANTENNA sca nning to the video. A second bandpass output sharpl y fi lte red to 4.5 MH z extracts the FM sou nd sub carrier and routes thi s to a SO UND so und i-f ampli fier for further PROCESSOR SPEAK ER processing. The third output DIRECT VIDEO is video, which is strongly ENTERS HERE a mpli f ied a nd then capacitively coupled to the cathode of the picture tube. VIDEO 1-F "DEO ( ~V-1D-E-0~-~ TUNER AMPLIFIER The ga in of the video DETECTOR AMPLIFIER CRT 44 MHz amplifier se ts the contrast of the display, while the bias setting on the cathode of the picture tube (with respect to its grounded control grid) sets

POWER the di s p I a y brightness. SUPPLY Somewhere in the vid eo amplifier, further rejection of SWEEP the 4.5 MH z so und subcarrier CIR CU ITS is usuall y picked up to minimi ze picture interference. This is call ed a so und tra p. Sound traps can be a se ri es resonant circui t to grou nd, a parall el resonant o p t imum a m o un t of tru e of recent smal I sc reen , circuit in the video signal intentional smear is usuall y solid state portable TV sets. path, or simpl y part of the the value of capacitance that On the other hand , if you transformer that is picking is nee ded to just close the have a hot chass is type with off the sound for more inside of a "W" prese nte d to one side of the power line processi ng. the display. connected to the chassis, you The video detector output should avoid its use if at all is usuall y around 2 volts peak Adding a Video Input possible. If you must use this to peak and usuall y subtracts Vid eo inputs are easy to type of set, be abso lutely from a white level bias add to the average television certai n to use one of the setting. The stronger the set, provid ed you fo ll ow safety techniques outlin ed signal, the more negative the some reasonable cautions. late r in Fig. 8. swing, and the blacker the First and foremost, you must A block di ag ram of a picture. Sync tips are blacker h ave a n accu rate a nd typical TV set appears in Fig. than black, helping to blank complete sc hemat ic of the set 3. UHF or VHF signals the disp lay during retrace to be modi fied, preferably a pi cked up by the tun er are times. Sams Ph otofact or so mething downconverted in frequency simil ar. The first thing to to a video i-f frequency of 44 check is the power supply on MH z an d then fil te red and the set. If it has a power ampli fied . The output of the transformer and has the vid eo i-f is transformer c has s i s p rn p er- I y safety coupl ed to a vid eo detector, isolated from the power lin e, most often a smal I sign al it's a good choice fo r a TVT ge rm anium diode. The vid eo monitor. Thi s is particularly detector outpu t is filtered to

22 Fig. 4 shows us th e typical and thus higher gain to high video circuitry of a transistor frequency video signals. bl ack and white television. Note particularly the Our basic circuit consists of a biasing of the video driver. A diode detector, a unity gain bias network provides us ·with emitter follower, and a a stable source of 3 vol ts . In variable gain video output the absence of input video, stage that is capacitively this 3 volts sets the white coupled to the picture tube. level of the display, as well as The cathode bias sets the establishing proper bias for accepting a max imum of a 2 brightness, while the video both stages. As an increasing volt peak to peak signal. It gain sets the contrast. signal appears at the last also has the right polarity, for Amplified sign als for sy nc video output transformer, it a positive going bias level and so und are removed from is negatively rectified by the means a whiter picture. But, the collector of the video video detector, thus lowering an unmodified set is already driv er by way of a 4.5 MH z the 3 volts proportionately. biased to the white level, and resonant transformer for the The stronger the signal, the if we want to enter our own sound and a low pass filter bl acke r the picture. Sync will video, this bias must be for the sync. A parallel be the strongest of all, giving shifted to the black level. resonant trap set to 4.5 MH z us a blacker than black bias We have a choice in any eliminates sound interference. level of o nly one volt. TV of direct or ac coupling of Peaking coils o n eac h stage The base of our video our input vfdeo. Direct exte nd the bandwidth by driver has the right sensitivity coupling is almost always providing higher impedances we need for video entry, better as it eli111inates any

Fig. 4. Typical video circuitry of transistor B and W TV set.

+12V BRIGHTNESS IK ~ .001

+150V IOOK 4 .5MHz SOUND PICKOFF c:-SOUNC 6800 3V (WHITE) IV (SYNC) 5V VIDEO LAST VIDEO l· F XFMR DRIVER 620/LH (PEAKING)

+ 12V

4.5MHz l.5K 47 SOUND TRAP

(3V) " 470 BIAS SOURCE PICTURE TUBE I 200

CONTRAST

23 Fig. 5. Direct coupled video uses 1.2 volt offset of Darlington transis tor as bias.

+12

+12 EXISTING DETECTOR 8 BIAS NEW shading effects or any change CIRCUITRY of background level as 22K addition al characters are L added to the screen. Fig. 5 1.2V(SYNC) RF shows how we can direct 3.2V(WHITE) couple our video into a OV (SYNC) VIDEO 2V (WHITE) transistor black and white set. DARLINGTON We provide a video input, VIDEO TRANSISTOR INPUT PAIR IN914 usually a BNC or a phono IK MPSA65 jack, and route th is to a PNP ALTERNATE USING TRANSIS­ Da ri i ngton transistor or TOR AND DIODE transistor pair, borrowing around 5 mils from the set's +12 volt supply. This output is routed to the existing video driver stage th rough a SPOT switch that either picks the to pick up the same amount Ac or capacitively coupled 2 volt peak to peak video, the video input or the existing of offset, as shown in Fig. 5. video inputs should be sync tip voltage would be 1 video detector and bias If more or less offset is avoided. Fig. 6 shows a volt; the optimum bias is then network. needed, diodes or transistors typical circuit. The TV's 1.6 volts. Input video is The two base-emitter can be stacked up further to existing bias network is capacitively coupled by a diode drops in our Dar Ii ngton pick up the right amount of lowered in voltage by adding fa irl y large electrolytic transistor add up to a 1.2 volt offset. a new paral lel resistor to capacitor in parallel with a positive going offset; so, in The important thing is ground to give us a voltage good high frequency the absence of a video input that the video driver ends up that is 0.6 volts more positive capacitor. This provides for a or at the base of a sync tip, with the same leve l for white than the blacker than black minimum of screen shading the video driver is biased to a bias and for black bias in sync tip voltage. For instance, and sti ll coup les high blacker than black sync leve l either position of the switch. with a 3 volt wh ite leve l, and freq uency signals properly. A of 1.2 volts. With a white clamping diode constantly video input of 2 volts, the clamps the sync tips to their video driver gets biased to its bias value, with the 0.6 vo lt usual 3.2 volts of white level. drop of this diode being Thus, our input transistor taken out by the extra 0.6 provides just the amount of Fig. 6. Ac coupled video needs shift of bias to black level plus a clamping diode. volts provided for in the bias offset we need to match the network. This clamping diode white and black bias levels of automaticall y holds the sync our video driver. Note that tips to their proper value, the old bias network is on the EXISTING .01 * DETECTOR regard less of the number of other side of the switch and white dots in the picture. does nothing in the video EXISTING Additional bypassing of the RFL ,\' VIDEO position. bias network by a large VIDEO ~O,F,+ DRIVER Two other ways to offset INPUT VIDEO electroly tic may be needed our video input are to use for proper operation of the two ordinary transistors IN914 * clamping diode, as shown in connected in the Darlington CLAMP Fig. 6. Note that our bias configuration, or to use one network is used in both transistor and a series diode 250/LH switch positions - its level is shifted as needed for the direct video inpu t. I.SK (l.6V) 470 +12 Tube type sets present about the same interface 0 problems as the solid state + *470 versions do. Fig. 7 shows a 1005 VIDEn *New components. *170/L F typica l direct coupled tube interface. In the unmodified

24 Fig. 7. Direct coupled video added to tube type Band W television.

+140

PEAKING

-----SYNC 4 .7K

rSOUND

20K 10 DX 8 ------'v'h----o+ VIDEO-AMP FROM VIDEO LAST DETECTOR .I CRT i..;..'----•• CATHODE 130V I CONTRAST t~') \ \ \ \ I I J:'

-l(· VIDEO NEW CATHODE SELF-RIAS INPUT SHIFTS TO SYNC LE\IEL IN IK VIDEO POSITION

*New components.

circuit, the white leve l is ze ro minus two volts with respect power line connected to the volts and the sync tip black to the cathode. A white level chassis. Dependin g on which level is minus two volts. If we presents +2 volts to the grid, way the lin e cord is plugged can find a negative supply which equals ze ro volts grid in , there is a 50-50 chance of (scarce in tube type circuits), to cathode. the hot side of the powe r line we could offset our video in Should there already be a being connected direc tly to the negative direction by two self bi as network on the the chassis. volts to meet these bi as levels. cathode, it is increased in H ot chassis sets, Instead of this, it is usu ally value as needed to get the particularly older, power possible to self bi as the video black rather than white level hungry tube versions, should amplifier to a ca th ode voltage bias in the direct video mode. be avoided entirely for direct of +2 volts. This is done by video entry . If one abso lutely breaking the cathode to Hot Chassis Problems must be used, some of the ground connection and There is usually no shock suggestions of Fi g. 8 may ease adding a small res istor (50 to haza rd when we use clip-on rf the hazard. These include 100 Ohms) between cathode entry or when we use a direct u s in g an i so l atio n and ground to get a cathode video jack on a transformer­ transformer, husk y voltage of +2 volts. Once this powered TV. A very severe back-to-back filament value is found, a heavy shock hazard can exist if we transformers, three wire electrolytic bypass of 100 use direct video entry with a powe r systems, optical microfarads or more is pl aced TV set hav ing one side of the coupling of the video input, in parallel with the resistor. Switching then grounds the cathode in th e normal rf mode and makes it +2 volts in the video entry mode . In the direct vid eo mode, a sync tip gro unded input presents zero volts to the grid, which is se lf biased

25 and total package isolation. Fig. 8. Gett·ing Around a Hot Chassis Problem. Far and away the best rou 'te is simply never to attempt Hot thassis problems can be avoided entirely by direct video entry onto a hot . using ·only transformer-powered TV circuits or chassis TV. by using clip-on rf entry. If a hot chassis set Makirig the Conversion must be used, . here are some possible ways Fig. 9 sums up how we around the problem: modify a TV for direct video entry. Always have a 1. Add an isolation transformer. complete schematic on hand, A 110 volt to 110 volt isolation trans­ and use a transformer style former whose wattage exceeds that of the TV set if at all possible. Late models, small screen, medium set may be used. These are usually expen­ to high quality solid state sets sive, but a workable substitute can be made are often the best display by placing two large surplus filament trans­ choice. Avoid using junk sets, formers back to back. For instance, a pair particularly very old ones. of 24 volt, 4 Amp transformers can handle Direct coupling of video is far around 100 Watts of set. preferable to ac capacitor modulator, the tuner, video coupling. Either method has i-f strip, and the video 2. Use a three wire system with a solid ground. to maintain th.e black and detector filter. Direct video white .bias levels on the ·first entry should bring us to a 3 Three prong plug wiring, properly video amplifier stage. A shift MHz bandwidth for a color polarized, will force the hot chassis connec­ of the first stage quiescent set and perhaps 3.5 MHz for a tion to the cold side of the power line. Th is black and white model, unless bias from normally white to protection is useful only when three wire normally black is also a must. we are using an extremely bad set. The resu Itan t 6 to 7 plugs are used in properly wired outlets. A Use short, shielded leads severe shock hazard is reintroduced if a between the video inp~t jack million dot per second rate is user elects to use an adaptor or plugs the and tlie rest of the circuit. If adequate for short character a changeover switch is used, lines of 32, 40, and possibly system into an unknown or improperly keep it as close to the rest of 48 characters per line. But wired outlet. The three wire system shou Id the video circuitry as you the characters will smear and NOT be used if anyone but yourself is ever possibly can. be illegible if we try to use to use the system. longer line lengths and Extending Video and Display premium (lots of dots) 3. Optically couple the input video. Bandwidth character generators on an By using the direct video ordinary TV . Is there Light emitting diode-photocell pairs are input route, we eliminate any anything we can do to the set low in cost and can be used to optically bandwidth and response to extend the vid eo couple direct video, completely isolating restrictions of an rf bandwidth and display the video input from the hot chassis. Most response for these longer line of these optoelectronic couplers do not lengths? have enough bandwidth for direct video In the case of a color TV, the answer is probably no. use; the Litronix I L-100 is ohe exception. The video response of a color Probably the simplest route is to use two set is limited by an essential separate opto-isolators, one for video and delay line and an essential one for sync, and theri recombine the 3.58 MH z trap. Even if we signals inside the TV on the hot side of the were willing to totally circuit. separate the chrominance and luminance channels, we'd still 4. Use a totally packaged and sealed system. be faced with an absolute limit set by the number of If you are only interested in displaying holes per hori zontal Ii ne in messages and have no other input/output the shadow mask of the tube. devices, you can run the eribre circuit hot This explains why video color chassis, provided everything' 'is sealed inside displays are so expensive and one case and has no chassis-to-people so rare. Later on, we'll look access. Interface to teletypes, cassettes, at what's involved in adding color to the shorter line etc., cannot be done without additional lengths. isolation, and servicing the circuit presents With a black and white the same shock hazards that servicing a hot TV, there is often quite a bit chassis TV does.

26 we ca n do to prese nt lo ng lin es of characters, depending Fi g. 9. How to Add a Direct Video In put to a TV Set. on what set yo u start out wi th and how much you are willing to modify the se t. 1. Get an accurate and complete schematic of The best te st signal you the set - either from the manufacturer's ca n use fo r bandwidth ex tension is the dot matri x service data or a Photofact set. Do not try data you actuall y want to adding an input without this schematic! di spl ay, fo r the frequency response, time de lay, rin gin g, 2. Check the power supply to see if a power and overshoot all get into the transformer is used. If it is, there will be no act. Wh at we wa nt to end up shock hazard, and the set is probably a with is a combination th at good choice for direct video use. If the set gives us reasonably legible has one side of the power line connected to charac ters. the chassis, a severe shock hazard exists, A good osc ill oscope (15 and one of the techniques of Fig. 8 shou Id MH z or better bandwidth) is ve ry usefu l during bandwid th be used. Avoid the use of hot chassis sets. extension to show where the signal loses its response in the 3. Find the input to the first video amplifier circui t. At any time during stage. Find out what the white level and the modification process, sync level bias voltages are. The marked or th ere is usuall y one response quiescent voltage is usually the white level ; bottleneck. This, of course, is sync is usually 2 volts less. A transistor TV what should be attacked first. will typically have a +3 volt white level and Obviously t he better a TV a +1 volt sync level. A tube type TV will you start with, the easier wi ll typically have a zero volt white level and a be th e task. Tube ty pe gutl ess -2 volt sync level. wonders, particularly older ones, will be much more di ffic ult to work with than 4. Add a changeover switch using m1 nimu m with a modern, small screen, possible lead lengths. Add an input con­ qua li ty soli d state portable. nector, either a phono jack or the premium Seve ral of the things we BNC type connector. Use shielded lead for can do are watching the interconnections exceeding three inches in contro l setti ngs, getting rid of length. th e so und trap, minimizing cir cuit strays, optimi zing spot 5. Select a circuit that couples the video and size , controllin g peaki ng, and biases the first video amplifier stage so that shi ftin g to hi gher cu rrent the white and sync levels are preserved. For operati o n. Let's take a look at these in turn. transistor sets, the direct coupled circuits of Fig. 5 may be used. For tube sets, the circuit of Fig . 7 is recommended. Avoid the Co ntrol Settings use of ac coupled video inputs as they may Alway s run a data display introduce shading problems and changes of at t he lowest possible background as the screen is filled. contras t and using onl y as much brightness as you rea ll y 6. Check the operation. If problems with nee d. In many circu its, low contras t means a lower video contrast or sync tearing crop up, recheck amplifier ga in, and thu s less and adjust the white and sync input levels or· a ga in - b andw idth to match what the set uses during normal rt rcslric Li o n. operation. Note that the first video stage must be biased to the white level during rf operation and to the sync level for direct Eliminate th e Sound Trap video use. The white level is normally two The sound trap adds a volts more positive than the sync level. notch zit 4.5 MH z to the vi dco response. If it is eliminated or switched out of lhc circu it , J wider video brndw id th zi ut omat ica lly

27 Fig. 10. Removing the sound trap can extend video bandwidth. (a) Response (b) Parallel resonant trap ­ short or bypass.

h WITH SOUND VIDEO ~ OUTPUT ~F;~~UENCY L__lHOUT frequencies. Some ti mes you FREQUENCY can alter this second network CONTRAST to favor dot presentations. Fig. 11 shows a typical (d) Combined trap and peaking network and the pickoff ­ open or SOUND 1-F effects of too little or too (c) Series resonant trap ­ remove (series resonant); much peaking. Note that the open or remove. short or bypass (parallel resonant). stray capacitance also enters into the peaking, along with the video amplifier output capacitance and the picture tube's input capacitance. Generally, too little peaking wil I give you low contrast dots, while too much will give you sharp dots, but will run 1-F dots together and shift the SOUND]~4.5 MHz more continuous portions of the characters objectionably. Peaking is changed by in­ creasing or decreasing the results. Fig. 10 shows us the Additional Peaking low frequency signals double series inductor from its design response changes and the the amplitude of the higher Most TV sets have two value. several positions for this trap. peaking networks. The first frequency ones. The second Generally, series resonant of these is at the video of these goes to the collector Running Hot traps are opened and paral lei detector output and or plate of the video output Sometimes increasing the resonant traps are shorted or compensates for the vestigial stage and raises the circuit operating current of the video bypassed through suitable sideband transmission signal impedance and thus the output stage can increase the switching or outright that makes sync and other effective gain for very high system bandwidth - IF this elimination. The trap has to stage is in fact the limiting Fig. 11. Adjusting the peaking coil can extend video response. go back into the circuit if the response, IF the power set is ever again used for supply can handle the extra ordinary program reception. (af Circuit. + current, IF the stage isn't Sometimes simply backing already parked at its the slug on the trap all the PEAKING COIL gain-bandwidth peak, and IF way out will improve things the extra heat can be gotten enough to be u sefu I. COLLECTOR rid of without burning LOAD Minimizing Strays anything up . Usually, you can try adding a resistor three One of the limits of the VIDEO times the plate or collector video bandwidth is the stray OUTPUT OUTPUT, STRAY,8 load resistor in parallel, and capacitance both inside the INPUT see if it increases bandwidth CAPACITY video output stage and in the I by 1/3. Generally, the higher external circuitry. If the the current, the wider the contrast control is directly in bandwidth, but watch the signal path and if it has (b) Response. TOO MUCH long le ads going to it, it may L TOO LARGE be hurting the response. If you are using the TV set exclusively for data display, AMPLITUDE can you rearrange the control TOO LITTLE location and simplify and L TOO SMALL shorten the video output to picture tube interconnections? FREQUENCY

28 carefully any dissipation Fig. 14. Television Picture limits. Be sure to provide Carrier Frequencies. extra ventilation and Channel 2 ...... 55.25 MHz additional heatsinking, and Channel 3 ...... 61.25 MHz check the power supply for Channel 4 ...... 67 .25 MHz unhappiness as well. For Channel 5 ...... 77.25 MHz major changes in operating Channel 6 ...... 83.25 MHz current, the emitter resistors and other biasing components should also be 300Q. Carrier proportionately reduced in Fig. 13. Standard rf interface levels. Impedance frequency per Fig. 14. value. SYNC TIPS= Spot Size 100 % AMPLITUDE Even with excellent video ( 4mV RMS TYPICAL bandwidth, if you have an BLACK= out-of-focus, blooming, or 75% AMPUTUDE I/' 3 mV RMS TYPICAL changing spot size, it can completely mask character sharpness. Spot size ends up 0 Fig. 15. FCC Regulations on Class the ultimate limit to ~, WHITE= 10% OR 1 TV Devices. More complete LESS AMPLITUDE resolution, regardless of video .3mV RMS TYPICAL information appears in subpart H bandwidth. Ill of Part 15 and subpart F of Part 2 Once again, brightness and of the Federal Communications Commission Rules and Regula­ contrast settings wil I have a tions. It is available at many large profound effect, with too technical libraries. much of either blooming the spot. Most sets have a focus A Class 1 TV device generates jumper in which ground or a a video modulated rt carrier of a min1m1ze display washout with a 55.250 MHz carrier positive voltage is selected. standard television channel from ambient lighting. Fig. frequency, except in areas frequency. It is directly You can try intermediate 12 lists several sources of where a local commercial connected to the antenna values of voltage for material for contrast Channel 2 broadcast is terminals of the TV set. maximum sharpness. Extra The maximum rms rf voltage improvement. Much of this is intolerably strong. Circuit power supply filtering can must be less than 6 millivolts rather expensive, with pricing cost, filtering problems, and using a 300 Ohm output line. sometimes minimize hum and from $10 to $25 per square stability problems tend to The maximum rf voltage on noise modulation of the spot. foot being typical. Simply increase with increasing any frequency more than 3 MHz Anything that externally away from the operating channel adding a hood and channel number. must be more than 30 dB below raises display contrast will let positioning the display away The sync tips are the you run with a smaller beam the peak in-<:hannel output from room lighting will also strongest part of the signal, voltage. current and a sharper spot. help and is obviously much representing 100% An antenna disconnect switch Using circularly polarized cheaper. modulation, often something of at least 60 dB attenuation must be provided. filters, graticule masks, or around 4 millivolts rms across simple colored filters can No user adjustments are Direct Rf Entry a 300 Ohm line. The black permitted that would exceed any If we want the con­ level is 75% of the sync level, of the above specifications. venience of a "free" or about 3 millivolts for 4 Residual rf radiation from display, the freedom from case, leads and cabinet must be millivolt sync tips. White level less than 15 microvolts per meter. Fig. 12. Contrast Enhancing hot chassis problems, and is less than 10% of maximum. A Class 1 TV device must not Filter Materials. "use it anywhere" ability, Note that the signal is interfere with TV reception. direct rf entry is the obvious weakest when white and Type approval of the circuit is choice. Its two big limitations strongest when sync. This is required. A filing fee of $50 and Circularly polarized filters: an acceptance fee of $250 is are the need for FCC type the exact opposite of the involved. Polaroid Corp. approval, and a limited video video interface of Fig. 1. Cambridge MA 02139 bandwidth that in turn limits Rf modulators suitable for Anti-reflection filters: the number of characters per clip-on rf entry TV Panelgraphic Corp. line and the number of dots typewriter use are called Class 10 Henderson Dr. West Caldwell NJ 07006 per character. 1 TV Devices by the FCC. A Light control film: An rf interface standard is Class 1 TV device is supposed shown in Fig. 13. It consists to meet the rules and 3M Visual Products Div. 3M Center of an amplitude modulated regulations summarized in St. Paul MN 55101 carrier of one of the standard Fig. 15. Acrylic plexiglas filter sheets: television channel video Fig. 16 shows us a block Rohm and Haas frequencies of Fig. 14. diagram of the essential parts Philadelphia PA 19105 Channel 2 is most often used of a TV modulator. We start

29 Fig. 16. Block diagram of rf modulator.

FROM ANTENNA ,------, 55 250 MHz DIODE UPPER AN TENNA I I CRYSTAL MODULATOR SIDEBAND DISCONNECT 0 I OSCILLATOR 8 ATTENUATOR FILTER SWITCH I TO TV SET I I VIDEO I SLICER VIDEO I I INPUT L------~~~--J with a stable oscillator tuned to one of the Fig . 14 freq ue nci es. A crystal output. The phase of this osc ill ator is a good choice, bl ack and white video dot and low cost modules are rate is low enough in subcarrier (or its time delay) widely available. The outp ut frequency to be attractively is shifted with respect to displayed o n an 01·dinary of this oscil lator is then what the ph ase was color TV . Color may be used immediately after eac h amp litude modulated. This to emphasize portions of a horizontal sync pulse to can be done by changi ng the vestigial sideband signal that message, to attract attention, generate the various colors. bias current through a silicon stays inside the channel band as part of an electron ic game, Fig. 18 shows us the s ma ll s ign al diode. One limits. This same fi lter or as obvious added value to a differences between normal milli ampere of bias current elim in ates second harmonic graphics displ ay . Color color and black and white makes the diode show an ac effects and other spurious technique s work best on TV operation. Bl ack an d white an d rf impedance of 26 noise. The fi lter's output is typ ewriter systems having a base band video is so me 4 Ohms. Half a mil will look usually ro uted to an antenna horizontal frequency very MH z wide and has a narrow like 52 Ohms, and so on. The disconnect sw itch and the near 15,735 Hertz. 4.5 MHz sound su bcarrier. diode acts as a variable TV 's antenn a terminals . A All we basically have to do The video is amp litude resistance atte nu ator in the rf specia l switch is needed to is generate a subcarrier si ne modulated, while the sound is circuit, whose bias is set and provide enough isolation . wave to add to the vid eo narrow band frequency changed by the video circ uit. Some of the actual Since diode modulators circuitry involved is shown in are non-linear, we can't Fig. 17. The video sli cer simpl y apply a standard video consists of a pair of high gain, signal to them and get a sma ll sig nal NPN transistors, standard rf sign al out. A while the osci ll ator is a Fig. 17. Channel two oscillator, modulator, video slicer and attenuator. R sets output level. differential amp lifier circ uit commercial ly ava il abl e call ed a video slicer may be module . OX OSCILLATOR MODULE 8 use d to compensate for this Rf entry systems always EX CRYSTAL (INTERNATIONAL non-Iinearity. The video sli cer must be direct coupl ed to the CRYSTAL) OR EQUIV 7T · l/ 4in. DIA (NO SLUG) provides three distinct antenn a terminals of the set curren ts to the di ode and should never provide any DIRECT COUPLE OUTPUT modulator. One of these is more rf than is needed for a IN914 or 4 7pF alm ost zero for the white minimum snow-free picture. leve l, while the other two The y shou ld be perman en tly '""' FFO ~~T provide the black and sy nc tuned to a singl e TV cha nn el. levels. A contrast control that Under no ci rcu mstances sets the slic ing level lets you should an antenna or cab le adjust the sy nc tip height serv ice hookup remain con ne cted to the set during with respect to the black MPS6520 level. The video slicer. also TVT use, nor shou ld +5V 2N5129 minimi Les rf getti ng back into 2N4400 radiation rather th an a direc t ETC the video. An attenu ator to rf cab le connection ever be reduce the size of the used. VIDEO modulated signal usually IN PUT 470 follows the di ode modul ator. Color Techniques An upper side band filter We can add a fu II co lor removes most of th e lower capability to a TV typewriter 4 .7K sideband from the AM system fa irl y easi ly a nd modulated output, giving us a cheap ly - provided its usual -5V

30 Fig. 18. Differences between color and black and white spectra.

(a) Black and white - baseband video.

SO UNO SOUND I VIDEO i I I VIDEO i

DC 4 . 5 MHz 54 55. 25 59.75 60 MHz

(b) Black and white - Channel two rf.

(c) Color - baseband video.

LUMINANCE LUMINANCE modulated. This translates up I CHROMINANCE I CHROMINANCE to a 6 MH z rf channel with a vestigial lower sideband as shown in Fig . 18(b). II Z±St.. ,, l±Iit'"" 0 3. 58 4 .5 MHz 54 55.25 58.82 60 MHz To generate color, we add a new pilot or subcarrier at a (d) Color - Channel two rf. mag ic frequency of 3.579545 MH z - see Fig . 18(c). What ratios of electron beam was the video is now called currents on the picture tube's the luminance, and is the red, blue and green guns. sa me as the brightness in a same spectral space, with the 19. The burst is around 25% Meanwhile, the luminance bl ac k and white system. The one being where th e other of max imum amplitude, or channel gets amp'lified · as new subcarrier and its one isn 't, overlapping comb abo ut the peak to peak height brightness style video. It is modulation is called the style. of a sy nc pulse. delayed with a delay line to chrominanc e signal and The phase or relative del ay Th e TV set has been make up for the time delay determines what color gets of the chrominance signal trained at th e factory to sort involved in the narrower band displayed and how saturated with resp ect to a refe rence all this out. After video color processing channel. It is the color is to be. determines the instantaneous detection, the set splits out then filtered with two traps ­ Since the black and white color, while the amplitude of t he ch rominance channel the 4.5 MHz sound trap, and information is a sampled data this signal with respect to the with a bandpass amplifier and a new trap to get rid of any sys tem that is scanned at the luminance sets the saturation th e n sy nchronously remaining 3.58 MHz colm vertical and ho ri zontal rates, of the color. Low amplitudes demodulates it with respect subcarrier that's left. The there are lots of discrete holes generate wh ite or pastel to an internal 3.58 MHz luminance output sets the in the video spectrum that shades, while high amplitudes reference . The phase of this overall brightness by are n't u se d. The color of the chrom inance signal demodulation sets the color modulating the cathode? of subcarrier is designed to stuff produce saturated and deep and the amplitude se ts the all three color gun s itse lf into these holes (exactly colors . saturation by setting the simultaneously. in a NSTC color system, and At le ast ei ght cycles of a Just after each horizontal pretty much in a TVT reference or burst color phase sync pulse, the set looks for di spl ay). Both chrominance are transmitted immediate ly the reference burst and uses and lumin ance sign als use the fol lowing each hori zontal this reference in a phase sync pulse as a timing reference , as shown in Fig.

Fig. 19 Adding a color reference burst to the back porch of the horiz ontal sync pulses.

8 CYCLES (MIN) OF 3 .57945 MHz COLOR REFERENCE PHASE

BLACK BLACK

SYNC :1JI I I I '­ 5 .lµSEC L. - 5 .lµSEC ( BLACK 8 WHITE) (COLOR)

31 Fig. 20. Colors Are Generated by Delaying or Phase Shifting the Burst Frequency.

Approximate Approximate Color Phase Delay Burst 00 0 Yellow 15° 12 nanoseconds wa nt e d . Th e o utput Red 75° 58 nanoseconds chromi nance signal is RC filtered to make it somewhat Magenta 135° 105 nanoseconds sinusoidal. It's then cut down Blue 195° 151 nanoseconds in a mplitude to arou nd Cyan 255° 198 nanoseconds one-quarter th e maximu m Green 315° 244 nanoseconds vid eo white leve l and is capacitive ly coupl ed to the 100 Ohm video output of Fig. 2 or otherwise summed into the video o r rf mo dul ator circuitry. For detector circui t to keep its is, or ca n be trimmed to refe re nce phase position truly dramatic color effects, own 3.58 MH z reference spec ifi c colors by va rying th e (000) imm ediately befo re, the amplitude and delay of locked to the version being supply voltage. during and for a minimum of the chrominance sign al can be transmitted. The refe rence ph ase and a few mi croseconds after each changed in a more compl ex Fig . 20 shows us the ph ase the delaye d co lor outpu ts go horizontal sync pul se. This version of th e sa me circuit. angl es re lated to eac h co lor to a o ne -of-eight data gives the se t a chance to lock More information useful in with respect to the bu rst selector. The data se lector and hold onto the reference solving television interface ph ase. It also shows us the picks either the reference or a color burst. appears in the Television equivalent amount of delay selected color in res ponse to a The chromin ance output Engineering Handbool?, by we need for a given ph ase code prese nted digitall y to fro m the data selector should Donald Fink, and in various angle. Since we usu ally want the three select lin es. The be di sa bl ed for th e duration i ss u es of th e IEE E onl y a fe w di screte colors, it's logic that is driving th is of the sy nc pulses and any Transactions on Consumer far eas ier to digitally generate selector mu st return to th e tim e a white sc ree n di spl ay is Electronics. colors simpl y by del ayi ng the refe rence through gates or buffe rs , rather than using . compl ex a nd ex pe nsive analog phase shift methods. Fig. 21. Color su bcarrier generator. Hex bu ffer used as delay line. Use Strictly s peaki ng, we supply voltage variation on 4 050 to trim colors. should contro l both th e c hr o min ance ph ase and amplitude to be abl e to do 3·30pF 15pF both paste l and strongly satu 1·ated co lors. But simply ~ kee ping th e subcarri e r 22K amplitude at the valu e we 4049 use d for the burst - around (CMOS) osc. 25% of video amplitude - is fa r simpler and will usuall y get us useful results. A circuit to add color to a REF TV typewriter is shown in P HASE Fig . 21. A 3.579545 MH z WHITE cry stal osc ill ator driv es a 01234567 string of CMOS buffers that H SYNC inh 4512 (CMOS) INPUT o------• dis make up a digital delay lin e. ONE-OF· EIGHT a b c OUT SELECTOR Th e output delays caused by the propaga tion delay times CO L OR SELECT 33on in eac h buffer can be used as INPUTS 680pF

MUST RETUR N TO 000 ~~ SET TO (REFERENCE PHASE ) 2 .5 K / 25% OF PEAK DURING 6 AFTER H I WHITE LEVEL SYNC PULSE MJV\f\f\

.01 VI DEO COMBINER (IOOn LOAD)

32 The MODULAR MICROS shifts each digit left automatically as a from MARTIN RESEARCH new digit is entered! The value on the display is also entered into an internal CPU register, ready for the next opera­ Here's why the new MIKE 2 and MIKE 3 tion. Simply by pressing the write kev, are the best values in microcomputers to­ for example, the user loads 135 into day! memory.

8008 OR 8080 The MONITOR program also allows the user to step through memory, one loca­ Martin Research has solved the problem tion at a time (starting anywhere), to bothering many potential micro users check his programming. Plus, the Swap . ... whether to go with the economical Register Option allows use of the inter­ 8008 microprocessor, or step up to the rupt capabilities of the microprocessor: powerful 8080. Our carefully designed the MONITOR saves internal register bus structure allows either processor to status upon receipt of an interrupt re­ be used in the same system! quest; when the interrupt routine ends, the main program continues right where The MIKE 3 comes with an 8080 CPU it left off. board, complete with crystal-controlled system timing. The MIKE 2 is based on We invite the reader to compare the pro­ the 8008. To upgrade from an 8008 to grammability of the MIKE family of an 8080, the user unplugs the 8008 CPU microcomputers to others on the mar­ board and plugs in the 8080 CPU. Then ket. Notice that some are sold, as basic he unplugs the 8008 MONITOR PROM, units, without any memory capacity at and plugs in the 8080 MONITOR all. This means they si mply cannot be PROM, so that the system recognizes the programmed, until you purchase a mem­ 8080 in struction set. That's about it! ory board as an "accessory." Even then, adding RAM falls far short of a conve­ If t he user has invested in slow memory nient, permanent MONITOR program chips, compatible with the 8008 but too stored in PROM. Instead, you have to slow for the 8080 running at full speed, enter your frequently-used subroutines he will have to make the 8080 wait for by hand, each and every time you turn memory access-an optional feature on the power on. our boards. Better still, a 4K RAM board can be purchased from Martin Research EASY 1/0 INTERFACE with fast RAM chips, capable of 8080 speeds, at a cost no more that you might The MIKE family bus structure has been expect to pay for much slower devices. designed to permit easy addition of in­ put and output ports. A hardware inter­ In short, the MIKE 2 user can feel confi­ face to the system generally needs only dent in developing his 8008 system with two chips-one strobe decoder, and one expanded memory and other features, latching device (for output ports ) or knowing that hi s MIKE 2 can be up­ three-state driving device (for inputs). A graded to a MIKE 3-an 8080 system-in new 1/0 board can be plugged in any­ the future. where on the bus; in fact, all the boards in the micro could be swapped around in EASE OF PROGRAMMING any position, without affecting opera­ tion. 1/0 addresses are easy to modify by Instructions and data are entered simply reconnecting the leads to the strobe de­ by punching the 20-pad keyboard. Infor­ coder (full instructions are provided) ; mation, in convenient octal format, ap­ this is in marked contrast to the clumsy pears a utomatically on the seven­ input multiplexer approach sometimes segment di splay. This is a pleasant con­ used. trast to the cumbersome microcom­ puters which require the user to handle all information bit-by-bit, with a confus­ POWER & HOUSING ing array of twenty-odd toggle switches and over thirty red lights! The micros described to the left a re com­ plete except for a cabinet of your own A powerful MONITOR program is in­ design, and a power supply. The basic cluded with each microcomputer, stored micros require +5 V, 1.4 A, and -9 V, permanently in PROM memory. The 100 MA. The 4K RAM board requires MONITOR continuously scans the key­ 5 V, 1 A. A supply providing these volt­ board, programming the computer as ages, and ±12 V also, will be ready soon. keys are depressed. OPTIONS Say the user wishes to enter the number 135 (octal for an 8008 OUTPUT 16 in ­ A number of useful micro accessories are struction). He types 1, and the right­ scheduled for announcement. In addi­ hand three digits read 001. Then he tion, the MIKE 3 and MIKE 2 may be presses 3, and the digits say 013. Finally purchased in configurations ranging from he punches the 5, and the display reads unpopulated cards to complete systems. 135. Notice how the MONITOR program For details, phone, write, or check the (Continued in column 3.) reader service card. ine•

For the readers who are li sting of some speciali zed onl y ju st now beginning to se rvice routine or simple learn the programmin g of "gimmi ck" program (see the computers, an elementary Kluge Harp artic le in this acquaintance with so me issue), th e complexities and machine's language, a BAS IC subtleties of scale beg in to interpreter, or hi gh level enter in to the programming langu ages would tend to give art. For an applica ti on such th e impr ess i o n t h at as t h e L I F E p r o gram, pro g r a mmin g i s proceeding from the vague by fundamenta ll y simpl e. It is! n ot i o n "I wan t this Ca rl lfelmers To wri le a program which app li catio n" to a working fills a sin gle page of li sting ­ program can be done in l~' ditor , IJ YTE whatever the language or innumerable ways - many of machin e architecture involv ed whi ch wi ll work quite well. - is not a tremend ously This is th e first ambiguity of down is for the most part difficult task. Wh en it comes scale - where do you head as visible through the obscuring to more co mpl ex pro jects ­ you sta rt programmin g? water. Bu t the detail s of the say 1000 or more words of Unless you have a unique base of the pyramid - while hand or machine-ge nerated parallel processing mind, you you know they have to be code on your microcompu te r can't possibly concentrate on there in some form - are not - the problem is how to the whole problem of at all visible at th e start. The What Is This Process prese rv e t h e bli ssful programming at once. des ign process moves the Designing A Program? innoce nce of simplicity in the In ord er to make a big l og ica l "water leve l" face of the worldl y forces of app li catio n program work , surr o unding the pyramid comp lexity. you have to se lect " bits and lower and lower as you figure Wh en you begin to talk pieces " of the de sired resu It, out more and more of the a bout programs mo re figure out wh at they do and det a il co ntent of th e complex than a one page how th ey fit into the big progra m. asse mbl y or mac hine code picture, then program them one by one. Th ese Ii ttle Start at the Top ... pieces of the program - its In LIFE Lin e 1, "modules" - are like the m e ntioned two m a jor multiple layers of stone functions which compose a LIFE Line 1 (BYTE # I } presented !he general picture of blocks in a pyra mid. In fact, practical LI FE program ­ the LIFE program application ofyour computer. Thal picture defining wh at to do is very data entry and manipulation i11 chuk.1· the rules uf the game, me thods o f i11tera cti 11ely mu ch like the tip of so me is one, the LI FE evolution entering graphic data, maju r software compon enls in verbal Egyptian tyrant's tomb in the algorithm is th e second . description and some of !he h ardware requireme nts of Ill e spring fl ood . .. as the murky Together, these functions ga111 e. In this instal/111 e11/, the discussion lums to som e of the genera li ties recede, more and defin e the " progra m control" prugra m d esign fo r the LIFE applicatio n. The d iscussio n starts more of the structure of the layer of the LI FE pyramid. "at the top" (overall program flo w) an d w o rks d own to m o re p rogra m is defined and Fi g. 2 is a fl o w chart de taile d levels of design, con ce11trati11g upo n th e "evolutio n cl arified. Fig. 1 illu strate s the illu s trating the program algorithm " which gen era/es new pallern s ji·om o ld pa//ern.1" pyramid of abstractions at control algorithm which is As in the previo us LJ FI~ · Line, the gua/ of th e article series is th e start of a program des ign the top leve l of the program as much to explai11 and i11 slru cl as ii is to elabo ra te upo n this process. The to_p laye r is clear str ucture. Although the o ne particular syste 1n This article co 11 ce11/ra/e.1· 0 11 the - a LIFE program is the diagram - and the algorithm program design prucess as ii/us/rated hy a real LIFE example. desired goal. The nex t layer - are ex tremely si mpl e, they

34 Fig. 1. Defining what to do is like the tip of some Egyptian tyrant 's tomb in the spring flood .. . as the murky generalities recede more and more of the struc ture is defined and clarified . ..

DESIGN ~~~4

PROCESS

and "N" defi ned. If " N" is greater than ze ro, control flow s to the evo lution process - and "N" ge nerations of LIFE will be computed and d i s p Ia ye d a s th e y a re se rv e a very useful purpose in restart mec hani sms and a interactive commands an d the compl eted. After the " N" th e prog ram des ign proce ss: front panel console. sco pe di sp lay output. The ge ne rations have bee n Th is high level design has split The first mod ul e of the KEYBOARD INT E R­ compl eted, the scope di splay mosl of the programming LI FE a pplication to be PRETER eventually will and th e LIFE grid have the worl< into two moderately entered is the KEYBOARD receive a "GO" com mand or las t compl eted results. If the large segments, each of which INT ERPRETER, a set of an "END" com mand from program is not "DONE," is less complicated than the routin es which is used to the user - whereupon it will contro l flows back to th e whole program. This view of define the ini tial co nte nt of return to the main routine K E Y B 0 A R D I NT E R­ the probl em now gives us two the LI FE grid u sin g with the parameters " DONE" PRETER for modification of ma jor co mponents upon the data, clear ing th e scree n whi c h to conce n trate and starting ove r, or other attention once the top level operations. If the program is routi ne is co mplete d. The 'r " DONE" then the control START (J UMP OR flows back to th e syste ms progra m control algo ri thm of CALL ) FROM SYSTEM Fig. 2, elaborated in Fig. 3, is EXECUTIVE OR MONITOR, ETC. programs - or to a halt point. the "mortar" whi ch ce ments Thi s program control toge th er these two bloc ks of algo ri thm is elaborate d in fun ctio n. more ex plicit detail in Fig. 3. The LIFE program is entered by one of a number of methods. Fi g. 2 illustrates branch or jump possibilities EVOLVE rrom a sys tems program .. N '' ca ll ed a ''monitor, '' GENERAl lONS "exec utive" or "operating sys tem" - the preferred way onc e you ge t such a system Fig. 2. LIFE program flow of generated. If yo ur system control. run s "bare bones" with li ttle sys tem-res id ent software, you mi ght select the starting point RETURN TO MONllOR OR H A LT and activ ate the program ,­I through use of hardware

35 Fig. 3. The main control routine of LIFE specified in a procedure­ on lin es 5 to 8 are executed complete LI FE grid pattern oriented language . .. over and over agai n until into the "next" complete DONE is found to be equal to pattern. The rules of the logical 1 or "TRUE" when a Game of LI FE - the "facts l LIFE: test is made at the END of life" - must be appl ied to PROGRA~; statement of line 9. A "DO eac h location in the grid to DONE = FALSE; FOR" loop is used to compute the next value of DO UNTIL DONE = TRUE; sequence "N" calls to a that loc ation. Fig. 4 CALL KF.YBOARD_INTERPRETER ( N, DONE); subroutine called illustrates two potential DO FOR I = l TO N; GENERATION which does strategies for computing the CALL GENERATION; the actual work of computing next generation - methods of END; the next generation content scanning the grid to compute q END; and then displaying it o n the one location at a time. 10 RF.TURN; /•TO EXECUTIVE, MONITOR, OR J UST HALT•/ scope. The remainder of Fig. The first strategy, Fig. ll CLOSE LIFE; 3 summarizes the data and 4{a), is to employ alternate subroutines referenced by copies of a complete LI FE LIFE. grid of 64 by 64 points. If From this point, the LI FE generations are numbered Subroutines Referenced by LIFE: Line can ex tend in two consecutively, the generation KHYBOARD INTERPRETER ... This is the routine which directions. In order to have a algorithm would transform looks at the interactive keyboard and interprets user actions comp I e te LI FE program, copy A into a "next" copy in such as specifying initial patterns, modifying patterns, etc. N is both areas have to be B o n odd ge nerations, and defined by the GO command which causes return from this traversed the complete the cycle by subroutine to LIFE. K E Y B 0 A R D I NT E R­ transforming copy B into a GENERATION . .. This is the routine which is used to evolve P RE TE R and the "next" copy in the A grid on one generation of the life matrix and display the result. Since GENERATION even generations. Si nee each the entire matrix is kept in software by GENERA T!ON until routine ... but the grid requires 4096 bits ­ after a new matrix has been evolved, there will never be any partitioning has ni cely which can be packed into 512 partially updated patterns on the scope. separated the two problems. bytes - a total of 1024 bytes The simp ler and most is required for data storage if Data (8 bit bytes) used by LIFE at this level : se lf-c ontained of the two this method is used. The FALSE - the value "O''. segments i s the primary advantages of this TRUE - the value "1 ". GENERATION algorithm, so method are its "straight­ DONE - variable set by KEYBOARD INTERPRETER I' ll turn attention to it next. forward" nature and its after a user command (GO) to start execution. separation of o ld and new N - a variable set by user interaction in KEYBOARD _ Grid Scanning Strategies data at all times. INTERPRETER giving the number of generations to evolve. Th e GENERATION A seco nd strategy is I - a temporary loop index variable. subrou tines of the LIFE illustrated in Fig. 4{b), the program has as its design goal strategy of using alternate the transformation of one row-buffers with only one

Fig. 4. The LIFE evolution algorithm - matrix scanning techniques which preserve relevant old information while creating new infoimation in overlapping storage areas. Fig. 3 uses a "procedure­ A. oriented language" (see the OOD GENERATIONS box accompanying this article) to specify the program in a more explicit . .. the problem is how ADVANTAGES and compact form than is 1. STRAIGHTFORWARD. to preserve the blissful 2. ONLY "NEW" BITS possible with a flow chart. 64 )( 64 64 )( 64 ARE UPDATED IN innocence of simplicity Each line of the program as BITS"A" BITS "B'' AlTERNATE MATRIX. DISADVANTAGES in the face of the wordly specified in Fig. 3 could 1. TWO 512·BYTE R.A.M. forces of complexity. AREAS REQUIRED FOR potentially be compiled by an 64 x 64 LIFE GR ID. appropriate compiler - but for the purposes of most hom e computer systems, EVEN GENERAT IONS

generation of code from this B. model would be done by hand. The outer loop is MA IN GR IO ROW·BUFFEAS ADVANTAGES 1. ONE 512-BYTE LIFE performed by a "DO UNTIL" GR ID PLUS TWO B·BYTE BUFFERS. construct starting at line 4 64 x 64 64 BITS OLD DISADVANTAGES BITS 1. LESS " INTUITIVE."' and extending through line 9. 64 BITS CURRENT 2. MO"JEMENT OF DATA TAKES TIME. The program elements found 3. EXTRA CODE.

36 main grid copy. Two 64 bit rows mu st be main ta in ed ­ the last previous row and the An objective: Split the processi ng into moderately large current row - as 8 byte segments, each of which is less complicated than the program copies. These copies co ntai n in formation prior to updating taken as a whole. in the row by row scan down the ma trix . Th e main advantage is a saving of data the new. If this is not the defined as the set of X and Y areas (partially offset by case, a less desirab le output in limits on the extent of live more co mplicated software). which partially updated ce ll s in the grid . In Fig. 5, the The main disadvantages are patterns are seen wi ll be t he active area is the inner sq uare its less "i ntuitive" nature, the result. (Counting the CRT of 7 x 7 = 49 grid locations. extra time required to make refresh, the method of Fig. In computing the next data copies, and a sli ghtly 4(a) thus requi res three ful l ge neratio n, a box which is large r program. copies of the matrix one location wider in each of The choice between these information, and the method the four cardinal directions is two methods is primarily one of Fig. 4(b) requires two full t he ''zone of possible of the amou nt of storage to copies.) expansion" for the pattern. be devoted to data. The Active Area Optimization In Fig. 5, thi s zone is the tradeoff is in favor of the outer box of 9 by 9 locations. double matrix method when With the choice of a The comp utatior1 of "next very sma ll LI FE matrix sizes matrix scannin g strategy generation" values need on ly are considered. The extra 8 t he alternate row-b uffer be carried out for the 81 grid bytes required for a second method anoth e r locations bounded by the copy of an 8 by 8 grid of bits consideration in designing the outer limits of the zone of hardly comp are s to the ge neration algorithm is a programming cost of the computation t im e alternate row-b uffer strategy. optimization method. There When large matrices are is no real need to calcul ate a Fig. 5. Active area optimization - never compute more than the considered, however, the new value of every ce ll in a absolute minimum if speed is at a premium. memory requi rements of an mostly empty LIFE grid. If I ZONE extra copy of the data are on ly have one glid er with its OF POSSIBLE co n s id erable, but the corner at location (34, 27) of EXPANSION I I I I programming involved is no the gri d, why shou ld I l l J/"OF PATTERN I I ~ I IN NEXT more difficult. For example, compute any new ge neration ,- ~~ T GENERATION consi der the limit of an 8 bit information outsid e the area f I ­ ~~ • • indexing method - a 256 by which could possibly be r­ i= '-'­ • • 256 grid. This will require a .. y .. LIVE '-­ ..•• • affected by the present ..___ total of 8192 bytes for each CELL LIM ITS pattern's evolution? Agai n, -­ 1..­ ••• copy of the LI FE grid. Two the savi ngs in computation -­ • L_ .... I? g••• • copies of the LI FE grid ti me using active area -T I i,­ II I I I I would use up 16k bytes, or optimi zation depend up on LI 11111 I ·1 the size of the grid . If most I I I I I I I ~~~' one fourth of the ad dressing I space of a typ ica l patterns occupy the full grid, PRESENT I co nt emporary mi cro­ then very Ii ttle will be saved ACTIVE I I computer, and all of the - for the small 8 x 8 grid AREA '~"X"---+I addressin g space of an 8008 "straw man" u sed in LIVE CELL microcomputer! At the 64 x discussing scanning strategy, LIMITS 64 bit level, the tradeoff is there would also be no point mu ch ciose r to the break-even to active area optimization. point, but I ex pect to find at But with a hu ge 256 by 256 possible expansion. Thus in least 100 bytes saved as a grid , and an 8 by 8 active the case of the 64 by 64 result of using the row-buffer area, this optimi zation might matrix of LI FE points, this method. An assu mption mean the difference between optimization for the pattern which is also bei ng made a 15 minute compu tation and of Fig. 5 will limit the when the alternate row-buffer a 1 or 2 second computation . program to calcu lation of 81 method is used is that the of the next ge neration. new points versus the 4096 scope display or TV display Fig . 5 illustrates the points which would be you use for output will have concept of active area calculated if at least one ce ll its own refresh memory so o ptimizatio n in a LIFE was found at each of the that the "old" pattern can be progr a m. The current minimum (0) and max imum held during computation of generation's active area is (63) valu es of the X and Y

37 (Subsc rip ts, li ke in XPL and PL/M are take n to run 0 through the dimensio n minus The "facts of life" must be applied to each location in the grid 1 . ) NRMIN , NRM AX , to compute the next value - cell or no cell ­ of th at location. NCMI N, and NC MA X are used to kee p track of the new active area limits after thi s ge ne rati o n is computed; NROWMIN , NROWMA X, coordinates. This case yield s a along wit h notes on further NCOLMI N and NCOLMA X sav in gs of 98% of t he s ub ro u t in es a nd da ta are ori gin all y initia li zed by max imum ge neration to req ui re ments. Th e procedure the KEYBOARD INT ER­ genera tio n compu ting ti me. starts by ini tia li zin g the data PRETER and are updated by use d for the scan of the LIM IT CHECK after eac h The GENERATION matrix, in lines 3 through 15. ge neratio n is calcul ate d ­ Subroutine THIS and THAT are used to usin g the new active area Fi g. 6 illu strates the code alte rn ate ly reference the 0 limits. o f th e GENERATION and 1 copies of an 8 byte The actual scan of th e grid routine, spe cified in a data item call ed a 2 by 8 byte of LIFE, stored in the data procedure-o ri ented language, data area ca ll ed "TEMP". area ca ll ed LIFEB/TS, is

Fig. 6. Th e GEN ERATION ro utine specified in a procedure-orien ted language . . . T EM P of the previous row, and t he saved va lue in TEMP o f the l GENERA TTON: curren t row befo re updatin g. PR OCE DURE: L/!11/J T CH ECK . . . This is the rou tine used to ca lcula te the TH T ~ = 0 : /• INITIALIZE PO I NTERS TO TEMPORARY RQ\; •/ n e x t va lues of NROWMIN, NROWM AX , NC OLMI N, THAT = 1; I• COPY VAR I ABLE "TEMP" •I NCOLMAX using the curren t valu es of NRMIN , NRMAX, DO FOR I = 0 TO 7; NCMIN a nd NCMAX. 6 IF NROW MIN = 0 THEN DJSPL A Y . .. This routine tra nsfers th e LIFEB ITS data to the TEMP ( THAT,I) • LIFEBITS (6 J , I); dis p lay , o n whatever kin d of device you have. ELSE

a TF.MP (THAT , I ) = 0; Data ( 8 bit bytes) used by GENERATION at this level: 10 /• THIS ESTABLISHED 'tlRAP - AR OllND BOU NDARY CONDITION •/

11 END : X = TEMPORARY 1 2 NRMIN = oa; /• THF.N TNITIALIZE ACTIVE AREA LIMITS */ 1 = temporary index (not the same as the I in Fig. 3)

13 NRMAX = O; !COL = index for column scanning . . . 14 NC MIN = aa; JRO W =index for row scanning . . .

15 NCMAX = 0: NCMAX = current maximum column index of live cell s 16 RCJtl_LOOP : NCMIN = current minimum column index of live cell s 17 DO FOR I ROW • NROWMIN TO NROWMAX; /• SCAN ACTI VE ROWS ONLY •/ N R MA X =current maximum row index of live cell s lR DO FOR I = 0 TO 7 ; /• COPY TH I S ROW TO TE MPORARY * / NRMIN =cu rrent minimum row index of live cells 10 TEMP (THIS, I) - LIFEB I TS (IROW, I) ;

20 EN D; Data (8 bit bytes) used by GENERATION but shared with the 21 DO FOR ! CO L = NCOLMIN TO NCOLMAX; /• SCAN ACTIVE COLUMNS ONLY •/ whole program : 22 CALL FACTS_ OF_LIFE ( IROW, ! COL ); THIS = current line copy index into T EMP. 23 EN D; THAT = previous line copy index into TEMP . 24 X = THIS ; TEMP= 2 by 8 array of by tes con taini ng 2 64-b it rows. 25 THIS = THAT : NROWMIN =minimum row index of live cell s. 26 THAT = X; /• TH I S SWITCHES BUFFERS • / N R OWMAX =maximum row index of live cell s. 27 END : NCOLMIN =minimum column index of li ve cell s. 2A CAL L LIM I TCHECK : NCOLMA X =maximum column index of live cell s. 20 CALI. DI SPLAY : LIFEB/TS = 64 by 8 array o f bytes con ta ining 64 rows of J O CLOSE GE NERATIO N: 64 bits. Assumptions: Subroutines Referenced by GENERATION : l/FEBI TS, N R OWMI N, N R OWMAX, N COLMIN, t T O L VtR . . . This is the routine used to calcula te the next NCOLMAX are initialized in K EYBOA RD INTC" R PR tTER va lu e o f the ICOLth bit in the IROWth row of LI FEBITS for the first time prio r to entry - and retain old valu es across usi ng the current va lu e o f the next row, the saved va lue in multiple executions of GtN ER A TJON thereafter.

38 Fig. 7. Th e LIMITCHECK routine specified in a procedure-oriented language . ..

1 LIMITCHECK :

PROCEDURE:

/• CALCU LAT E NEXT ROW LIMITS •/ IF NRMIN - 1 < NROWMIN THEN NR O'llMIN = NRMIN - 1 : I F NRMAX+l > NROWMA X THEN NROWMAX = NRMAX+l:

I F NROWMAX ) 63 THEN NROWMAX = 63:

I F NROWM I N <0 THEN NROWMIN = 0 : /• CA LC ULA TE NE XT COLUMN LIMITS * / into the output display a IF NCMIN - 1 < NCOLMIN TH EN NCO LMIN = NCMIN - 1: device. The LIMITCHECK 10 IF NCMAX+l ) NCOLMA X TH EN NCOLMAX = NCMAX+l: routine simply performs 11 IF NC OLMA X ) 63 THEN NCOLMAX = 6 3 : comparisons and updating ­ 12 IF NCOLMIN <0 THEN NCOLMIN = O: Fig. 7 illustrates the high level L3 CLOSE LIMITC HEC K: language description of its logic. Subroutines Referenced by LIMITCHECK: No ne. Computing The Facts of Data (8 bit bytes) useq by LIMITCHECK but shared with the LIFE . . . whole program: Fig. 8 contains the N COLMA X, NCOLMJN, NROWMAX, NROWMJN information on implementing the Facts of LI FE in a NRMA X, NRMIN, NCMAX, NCMJN (s ee Fig. 6) progr a mmed set of Assumptions: instructions. The The· arithmetic of the comparisons in this routine is do ne computation is divided into Two copies of a 256 by using sign ed two's complement arithmetic - thus a negative two major parts. The first 256 grid would require number results if 0 - I is calculated .. . this is consistent with part is to determine the more memory than (for code genera ti on on most 8 bit micros. STATE of the bit being example) an 8008 can updated, where "STATE" is a address if you want to number from 0 to 8 as have programs along described in LI FE Line 1 last with your data. month. The second major step is to evolve the grid location using its current performed by the set of DO by FACTS OF LI FE. At value a nd the STATE. groups beginning with the end of the row loop, prior FACTS_ OF_ LI FE begins ROW_ LOOP at line 16. For to reiteration, the THIS and by performing left and each row of the matrix, THAT copies of temp are bottom bound a ry ROW_ LOOP first copies the switched by changing the wrap-around checks by row into TEMP as the THIS indices. What was THIS row adjusting indices. Lines 8 to copy (the THAT copy is left becomes THAT row with 18 determine the current over from initialization the respect to the next row to be STATE by referencing all 8 first time at lines 5 to 11, or computed. grid locations surrounding the from the previous After all the rows have location being computed at ROW LOOP iteration been computed, line 28 is (IROW, ICOL). In thereafter). Following the reached_ Line 28 calls determining the state, the copying operation, another subroutine LIMITCHECK to subroutines TGET and LGET DO FOR loop goes from compute the next NCOLMIN to NCOLMAX generation's active area applying the FACTS_ OF_ computation limits using the LI FE to each grid position in results of this generation. th e current (THIS) row as Line 29 then calls a module saved in TEMP. New data is named DISPLAY to copy the stored back into LI FE BITS results of GENERATION

Why should I compute any new generation information outside the area which could possibly be affected by the present pattern's evolution?

39 Fig. 8. The FACTS _ OF LIFE routine specified rn a procedure­ oriented language. FACTS OF LIFE does th e ac tu al calcula twn of the next value for the LIFEBITS locat10n at the IRowth row and ICOLth column· based upon the previous valu e of the B neighboring locations. (The state defined in LIFE Line 1, la st month. ) This routine implements the rules described in BYTE # 1, page 73 .

Subroutines Referenced by FACTS_ OF_LIFE: TG ET. This is a "function" subroutine which re turns an l FACTS_OF _ LIFE : 8 bit valu e (for exa mple in an accumulato r when you ge nerate PROCEDURE (mm·/ ' ICOL I ; code) of 0000000 I o r 00000000 depending upon wh eth er or • M = mow + l : not a referenced column in one of the two tempo rary line I F M >6) THF.N M = 0 ; /* BOTTOM BOUN DARY WRAP CONDITION * / copies in TEMP is l or 0 resp ectively. The first argument tell s N = ICOL - l ; which lin e of the two, and the sec ond argument tell s which 6 IF N ( 0 THEN N = 6) ; /• LEFT BOUNDARY WRAP CONDITION • / column (Oto 63) is to be retrieved. 7 DETERMINE_STATE : L GET . . . This is a "function" subroutine which re turns an STATE= TGET (THAT , N); 8 bit valu e similar to TGET, but taken instead fro m the bit Q STATE= STATE+ TGE T (TH I S , N) ; valu e a t a specified row/column location o f LIFEBITS. 10 STATE= STATE+ LGET (M, N) ; LPUT . .. This subroutine is used to set a new va lu e in to the

11 N = ICOL ; specified row/column location of LIFEBlTS. 12 STA TE= STATE + TGE T (THAT , N) ; NOTE: Th e routines LGET and LPUT will be referenced ji·om

1) STATE = STATE + LGET (M, N); the KEYBOARD INTERPRETER ro utme in th e course of manipulating data wh en setting up a life pa/tern . 14 N = ICOL + l; SETLIMJT ... This subroutine is used to check the cun-ent 15 IF N > 6) THEN N = O; /• RIGHT. BOUNDAllY WRAP CONDITION */ ac tive regio n limits when the result of the fa cts of li fe indicate 16 STATE = STATE + TGET (THAT , N); a liv e cell . 17 STATE= STATE+ TGET (THIS,N ) ;

l ~ STATE = STATE + LGET (M, N); Data (8 bit bytes) used by FACTS_OF_LIFE at this level : 1q EVOLVEIT: !R O W= Parame ter passed from GEN ER A TION. 20 NF.WCF.LL = O; / • DEFAULT EMPTY LOCATIO N UNLESS OTHERWI SE •/ /COL =Parameter passed from GEN ER A TION. 21 OLDCELL = TGET (THIS , ICOL ) ; M = temporary , row index. 22 IF OL DCELL = 1 Tll F.N DO; N =temp orary , column index. 2) IF STATE = 2 OR STATE = ) THEN NE'llCELL = 1; STA TE = count of "on" bits in neighborhood of !ROW, !COL. 24 END; OLDCELL =tempora ry copy of old cell at /ROW, / COL. 25 ELSE DO; NE WC ELL =new valu e for loca tion !ROW, / COL. 26 IF STATE = ) THE N NEWCEL L = 1 ; Data (8 bit bytes) used by FACTS_OF_ LIFE but shared with END; the whole program: CA LL LPIJT ( IR O'll, I COL, NE'.iCE LL ) ; 20 I F NEWCEL L = 1 THEN CA LL SETLIMIT (mow ' ICOL I ; THA T, THIS (s ee Fig. 6) JO CLOSE FACTS_OF_LIFE;

are used to reference bits in the positive cases of an "on" TEMP and LIFEBITS (live cell) value for the grid respectively, using location. A cell will be in the appropriate bit location grid location for the next indices. The values returned generation in only two cases: What was THIS row becomes THAT row with respect to the by these two "function If the old content of the next row to be computed. (What's in a name? A pointer of subroutines" are either 0 or 1 location was a live cell and course!) in all cases - thus counting the STATE is 2 or 3; or if the the number of "on" cells old content of the location is consists of adding up all the 0 (no cell) and the STATE is TGET or LGET references 3. A default of NEWCELL = required to examine 0 covers all the other cases if neighboring grid locations. these two do not hold. Line Once the STATE of the 28 stashes the new value grid location is determined, away in LIFEBITS with the Facts of LI FE are subroutine LPUT, and if the implemented by examining new value of the grid location

40 Fig. 9. The SETLIMIT routine specified in a procedure-oriented language.

1 SETLIMI T:

PROCE DURE I IROW, I CO L) ; I F IROlf ( NRM IN THEN NRM IN = IROW; I F IROW ) NR MAX THEN NRMAX = IROW;

I F ICOL ( NCMIN THEN NCMI N = I COL;

6 IF ICOL ) NCMAX THEN NCMAX = I COL;

7 CLOSE SETL I MI T;

Subroutines Referenced by SETLIMIT: No ne.

Data (8 bit bytes) used by SETLIMIT at this level: /ROW= parameter passed from FACTS_ OF_ LIFE. /COL = parameter passed from FACTS_ OF_ LIFE.

Data (8 bit bytes) used by SETLIMIT but shared with the Fig. 10. The Tree of LIFE. whole program:

N RMIN, NRMA X, NCMIN, NCMA X (see Fig. 6)

is a live cell, SETLIMIT is call ed (see Fig_ 9) in order to update the active area pointers NRMAX, NRMI N, NCMAX and NCMIN. Where Does the LIFE Application Stand? An alternative to the pyramid structure way of viewing programming program designs introduced at the beginning of this article is a "tree" notation showing the heirarchy of modules in • the application. The "Tree of • LIFE" is shown in Fig. 10 as •? it exists in materials printed to date. The next installment of LIFE Line will explore the left hand branch of the tree dia gram by a similar pr e sentation of a ~• K E Y B 0 A R D I NT E R­ • PRETE R algorithm. •?

SETLIMIT

41 LIFE Line 2 Addendum

Procedure-Oriented Computer may be called as a language , one statement Languages "subroutine" from a program typically represents several The examples of programs or another procedure. A machine instructions. In these accompanying two articles iri procedure may be called in a the high level language thi s issue ha.ve been "function" sense as well , in statement has a "semantic constructed in a which case a RETURN intent" - a definition of its procedure-oriented language. statement would be required operation - which can be This method of program to set a value. translated into the lower level representation is compact and machine language. In these complete. In principle, one Data examples several types of could write a compiler to For the purposes of these statements are employed ... automatically translate the examples, no "data programs written this way declarations" are put into the into machine codes for some programs to complicate the picture. Instead , each computer. By writing the "IF .. . THEN ... ELSE .. ." "assignment" - a statement example has a section programs in this manner, constructs are used for of the form "X = Y ;" is called following it which verbally more detail is provided than notation of decisions. The the assignme nt state me nt. Y describes each data name in a flow chart, and the first set of ellipses indicate a is "evaluated" and the result used. Only one "data type" is program is retained in a condition which is to be is moved into X when the considered at this point ­ machine independent form. tested . The second set of statement is executed. If X or integers - and these are The particular ellipses in the model is used Y have subscripts as in generally assumed to be 8 representation used here to stand for the "true part" ­ "TEMP(THIS , I)= bits. resembles several languages in a statement (or DO group) LIFEBITS(IROW,l) ;" then the "PL/ l" family of Arrays of integers are used which is to be executed if and the subscripts (such as computer languages, but is in several examples. An array only if the condition is true; "THIS,I" and "I ROW ,I" in not in tended for compilation is a group of bytes, starting at the third set of ellipses is the the example) are used to by any existing compiler. For the location of its address and "false part" - a statement reference the name as an extending through ascending readers familiar with such which is only executed if the array and pick particular memory addresses from the languages, you will find a condition is false. The word bytes. strong PL/I influence and a starting point. The purpose of ELSE and the whole false moderate XPL influence. In a an array is to reference part are often omitted if not future issue BYTE will be "elements" within the array needed. running articles on a language by "subscripts". For these s pe ci f ically designed for examples, the elements are microcomputer systems, referenced by the numbers 0 "DO groups" - a grouping of PL/M , which is an adaptation through " n-1" for an array several statements beginning of the XPL language for 8-bit dimension of length " n". If with a "DO" statement and machines. For the time being, UFEBITS is an array of 64 "CALL X" is a statement running through a this represe nta ti on is used by 8 bytes, then used to call a subroutine, in corresponding "END" is used with some notes to aid your UFEBITS(63,7) is the last its simplest form. A more to collect statements for a understanding. element of the last row of the complicated form is to say logical purpose. In "DO FOR array, and LI FEBITS(l,J) is CALL X(Z) where Z is a set I= 0 to 7;" this purpose is lo Programs and Procedures the byte at row I, column J of "arguments" to be passed execute the next few A program is a group of provided I and J are within to the routine. Another form statements through the Lines which extends from a the proper ranges. of subroutine call is the corresponding "END;" 8 PROGRAM statement to a "function reference" in an times with I ranging from 0 matching CLOSE statement. Statements assignment statement, where to 7 . "DO UNTIL It is intended as the "main A program or procedure the name of the subroutine is DONE=TRUE ;" is an routine" of an application. A consists of statements which used as a term in an example of a group whi ch is fJrucedure is a similar group specify what the computer arithmetic expression. repeated indefinitely until a of lines which extends from a should do. In a machine condition is met al the END. PROCEDURE statement to language , these would "DO FOREVER" is a handy its CLOSE statement. A correspond to the selected way of noting a group to be procedure may have operation codes of the repeated over and over with para111l'ters indicated in the computer which is being no end test, a practice often PROCEDURE statement, and programmed. For a high level frowned upon.

42 A QUICK Test of Keyboards

This indicator circuit can be used to advantage when analyzing keyboards using techniques described in BYTE # 1, " Deciphering the Mystery Keyboard," page 62.

After comp let ing the pattern at the same time. The ASCII, EBIDIC, or whatever assemb ly of a keyboard late so luti on was very simple, could be checked out quickly one night, I wanted to check inexpensive, and quickly with this system. all owed the bit pattern on the the keyboard out for proper Example operation. So I picked up my keyboard outp ut pins to be VOM and started looking at viewed as a bit pattern. Fig. 1 A keyboard which the voltage leve ls on the shows the system used. The generates ASCII coded output pins of th e keyboard, LEDs are lit or unlit characters has the "A" key since I do not have a CRT dep ending o n the key pressed pressed and held . The LED terminal or any other ASCII a nd held . Th e pattern bit pattern would look like device ava il able. Well, being a produced by the LEDs will this: software type, I kinda fe lt a display the bits of the 0-LED on, logic level high little frustrated since I am character generated by the I-LED off, logic level low generally used to being ab le key pressed on the keyboard. 0 Ill 110 ASCII character to see a ll the bits of a bit Keyboards which generate code for "A" bit r/J 123 456 1 000 OOI It should be pointed out that this test method will work without modific ation Fig. 1. Examining Keyboard Outputs with LED Indicators. A with diode encoded TTL-compatible output can drive the typical LED with about 10 key boards such as Southwest milliamperes in an active low state. Technical Products KBD-2 keyboard (which is the keyboard I assemb led and + 5V tested with the above method). However, some keyboards may generate an inv erted code which +5 shouldn't be a problem. Some KP key boards (surplus and perhaps new) with more GND sophisticated debounc ing 330!), techniques may not work KEYBOARD BO by AND with th is test method with out ENCODER 330!l. some additional components. Don R . Walters Bl For example, some keyboards 330!l. 3505 Edgewood Dr. B2 have a bus-ori ented tri-stalc A 1111 A rbor MI 48 104 MOS o utput without 83 330!l. sufficient drive to li ght the B4 330!l. diode lamps; you would need a buffer gate in this case, as 330!l. B5 well as an output data strobe. Other keyboards require an 86 active "read" operatio n in which a pulse is suppli ed to reset flip flops acknowledging CPU accepta nc e of data .

43 FLYER HYPE---WE SELL CAPACITORS, CLOCKS, RESISTORS, LINEARS, TTL, CMOS, MOS, KEYBOARDS, KITS, MUSICIAN'S KITS, SOCKETS, FETS, TRANSISTORS, TOOLS, HOBBYIST'S SPECIALS, READOUTS, MORE KITS, AND SPECIAL ITEMS. SEND A STAMP AND YOUR ADDRESS TO GET OUR NEW FLYER BILL GODBOUT ELECTRONICS LISTING ALL OUR STUFF. BOX 2355, OAKLAND AIRPORT, CA 94614 Vi;GTOR WIRi; REGULATED, SHORT-PROOF, THERMALLY LIMITED, HALF AN AMP CONT INUOUS OR 1 AMP INT ERM ITT ENT, SAVE YOUR - Pi;NGIL SELF THE HEADACHE OF DESIGNING YOUR OWN; USE ONE OF OURS, SPECIFY 5, 6, 8, OR 12 VOLTS. $7,95 + 2 LBS,

0 0 +l POUND SHIPPING 5204 4K EROM VECTOR Pl 73 WIRING PENC I L---A HAND HELD , UNDER 1 OZ . TOOL Q USED TO HELP GUIDE AND WRAP #36 INSULATED WIRE (FROM A 0 ---$24.50--­ SELF-CONTAINED BOBBIN) ONTO COMPONENT TERMINALS. MAKE CON­ NECTIONS BY SOLDER I NG; HEAT FROM THE I RON MELTS THE I NSULA­ 8008 8 BIT Tl ON, PERMITTING A GOOD SOLDER BOND . THIS IS A FAST WAY TO 0 MICROPROCES­ 0 WORK WI TH COMPONENTS AND VECTORBOARD. COMES WI TH TOOL, AN This is a flat, multiconductor wire, INSTALLED BOBBIN OF 250 FT. GREEN WIRE, AND AN EXTRA BOBBIN SOR 0 0 availabl e in multiples of 10 conduc­ OF RED WIRE AS WELL AS INSTRUCTIONS . • ..• • ...•....•... $9 . 50 ---$27.95--­ tors up to 100 conductors . Comes in ---AND TO GO WITH YOUR WIRE PENCIL--­ 0 O 20 ft. lengths only. Cost is 1¢ per VECTORBOARD---TYPE 169P84-062 , PRE-PUNCHED VECTORBOARD WITH Q 8 BIT CHIP conductor foot; for example , a 20 HOLES ON . 1" CENTERS (PERFECT FOR I Cs). 8!" X 17", 1/16" SET - 8008 + conductor cable 20 ft . l ong = $4. 00 THIC K EPOXY GLASS .. •.. • ....•.• •.. $8 . 95 + 1 lb. SPHG/BOARD. 0 8-2102s 0 oO 0 0 o Q 0 0 ---$42.50--­ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ° SEE taci114 ° 0 0 0 P84E fOI' O 0 A LEADING MFGR OF TOP QUALITY IC SOCK ETS. a COlllPlllEr llE,VS CG) = GOLD PLATED CONTACTS (T) = BRIGHT TIN PLATE 0 0 0 0 0 0 0 T 14 PIN 11 /$1.9 5 T 40 PIN 5/$2.95 0 0 G 14 PIN 10 /$ 1.95 LOW PROFILE SOCKETS1 G 16 PIN 10/$1.95 G 40 PIN 5/$2.95 0 CIH£AP ClOCll~ 0 0 0 Oo 0 0 0 0 0 0 0 0 0 0 0

0 0 0 0 0 0 0 ° 0 ~~~WW TERMS: ADD 50¢ TO HOBBYWRAP TOOL---WHY SOLDER YOUR PROTOTYPES? WIRE WRAPPED ORDERS UNDER $10. This kit has gone over very well. Comes CONNECTIONS PROTECT COMPONENTS FROM HEAT, ARE EASILY MODI­ less case and transformer, but includes FIED FOR CORRECTIONS OR CHANGES, MAKE CONNECTIONS THAT ARE ADD SHIPPING AS eve rything else. Parts mount on mother­ BETTER THAN SOLDER, AND CAN SPEED UP THE TIME REQUIRED FOR SHOWN, CAL RES ADD board; readout + lens mount on daughter­ ASSEMBLY OF COMPLEX DIGITAL PROJECTS . IF THE HIGH COST OF board, and the readout may be remoted . WRAPPING PUTS YOU OFF, LOOK AT OURS . . YOU GET THE TOOL (RE­ TAX. NO COD. The readout-board-lens combin·ation alone CHARGEABLE SO YOU DON'T HAVE TO DEAL WI TH TRAIL I NG CORDS IN has sold for $14.95 nationally . POSTPAID TIGHT PLACES), BIT, CHARGER, NI CADS, AND INSTRUCTIONS. ~~~~~

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45 becomes defective il ca n be removed, repaired or replaced Modular Construction , OR without hav ing to do a lot of unw1ring and rewiring or performi ng major surge ry on Why Not Do It Yourself? the system. Well, yo u might think, thaL is fine for comp ani es and Mod ul ar constructio n is peop le who can afford Lo buy nothin g new. In fact, the the modules from Lhe various Ask a computer person what "hardware" is and you'll often concept has been around for manu facturers. But I ca n't get the answer "gates, MSI, ROMs and microcomputers". Ask a very long time. Man y afford that, so my sys tem will an astronautical engineer what "hardware" is and you'll often compani es which make have to be put together as computers o r computer best I can. Well, guess what7 get the answer "boosters, fuel tanks and space shuttles .. . " syste ms use this method of You too can put your system Here in this article, Don Walters covers a few of the "nuts and construction for their together in a modul ar form bolts" of packaging hardware for electronics. Which concept products. For example, a {ass uming you h aven't of hardware you wish to use depends upon the point of view ­ company which makes an purchase d a kit which tends your focus of attention. . ..CARL indu stria l process control to limit your ability to go the computer system might buy modul ar rou te, or already has th e power supply, printed done it for you, such as is the ci rcuit board card cage, case with the many ex isti ng Fig. 1. Printed circuit card cage concept. Card cages can be fabricated physical system enclosu re, in expe n s iv e comp ute r along these lines. A short cut would be to strip and modify a cage CPU o r memory, or systems). obtained from a surplus dealer. peripherals from one or more Figs. 1, 2, 3 and 4 show POP · RIVET OR BOLT HOLES ot h er co mpanie s. The how easy it is to fabric ate company which makes the printed circuit board card - - IBin. OR AS REO'D - -1 ~ 1 I TD'CLEAR PC B OARD LENGTH indu stri al process control cages, cabinets, printed ~ )) ~ ~ comp u ter system then c ircuit boards, and eve n : SPACING-BRACE BAR ~ assemb les the parts together, modular power suppli es. writ es th e n ecessa ry True, it always looks good on software, and adds wh atever paper, but if you think out - I other spec ial hardware is the project and are a little 4 .5in. OR TO needed. The end product is careful and persistent, you CL EAR PC BOARD someth in g new, but is sti ll should be able to fabric ate HEIGHT made up out of all the the mo dul es of yo ur _ l subasse mblies {modules). But computer syste m at a fraction FRONT more importa ntl y, because of the cost that commercial ..,._- ---- 19 in.-----­ the syste m is made up of units would cost, plus your EDGE CONNECTORS CAN BE MOUNTED EITHER mod u Ies, if a mod ule system wil I have a good VERTICAL OR HORIZONTAL

Fig. 2. Cabinet Fabrication . Im agination , metal plates and angle stock are blended into a computer cabinet for your system.

ALUMINUM OR STEEL ANGLE STOCK THICKNESS AS NEEDED FOR ADEQUATE STRENGTH

( PANELS ARE ALUMINUM OR CANE METAL (PERFORATED ~!----- K"'~~======~------I ALUMINUM)

HEIGHT AS rEEDED l> v PANEL /)1111 H. Walters DEPTH ,'f.'j().'j f•,'£lp.1• /llllOd /Jr. AS NEEDED . I 1111 Irlwr /\// 1f.R I 0 1/. ~L_~__Sl:..I=:======::::::=:::======~ WIDTH AS NEEDED I I-- USUAL IS 19in. FOR A 19in. --­ MOUNTING HOLES ON PC BOARD CARD CAGE 2 . 25in. CEN TERS

46 pr· o fes s i o n a l-l ooki ng Fig. 3. Typical 22-pin printed circuit board stock (minus printed wiring). Note: Gold plating on contacts is appearance. highly recommended ; avoid surplus backplane sockets with any tarnish to interface vrith contact. The printed circuit board card cage of Fig. 1 is simple to fabricate from locall y available materials (hobby + ·­ shops, hardware stores, and .15 6 in. perhaps lumber yar·ds are a WIDTH AS NEEDED good source of materials) . 3.6 in _FOR 22 PIN FOR 22 PIN EDGE EDGE CO NNECTOR CONNECTOR {4.5 in . The side panels of the PC IS COMMON) CHANGE DIMENSION board card cage can be made AS NEEDED FOR DIFFERENT NUMBER from heavy gauge aluminum. OF PINS Aluminum door kick pan els available in most hardware stores are good sources for the aluminum of the side panels. Th e spacin g- brace bar TA PER FOR EASY IN - is, aga in , so methin g fo und in SERTION INTO EDGE - most hardware stores in the O CONNECTOR form of l o ng thin EDGE CO NNECTOR LENGTH AS NEEDED (a pproximately 1/16 inch FOIL PADS 1­ ----- 5_5 OR IOin. IS EASY ------' T O DEAL WITH thick) aluminum bars. The PC BOARD EDGE CO NNECTO R card cage asse mbl y can be (SIDE V IEW) fastened together with pop rivets or nuts and bolts (6-32 binder head machine screws are about the right size). Card guides can be made from this is to use an abras ive hea vy gauge cookie shee t}. It is hoped that this short channeled plastic strips, cleanser such as COMET, Placement of parts is not burst of ideas will motiv ate aluminum or ~ve n wood. Th e AJAX, etc., and a li ttle elbow critica l and there is enough others into trying their hand card guides can be faste ned in grease. Th en use the methodl ro om fo r wh atever nee ds to at building so me of the the ca rd cage wi th glu e or that best suits your nee ds for be in the power supply. There physical hardware of their drill ed and bolted in. PC lay in g out the fo il pattern is eve n enough room fo r a syste m (termin a l or board edge connecto rs can be and etching the bo ar·d. PC barrier te rminal strip. Barrier co mpu ter}. Th e id eas mounted on the back edge of board edge con nector foi l termin al str ip ? Yep, if you presented here can be realized the back spacing-brace bars in pads are not too hard to put use barTier te rmin al strips on wi th a little cas h, some work, a vertical position by drilling on a board, eve n if yo u use an powe r supplies, in your and perseve rance. So if you and tapping holes in the back etch resist pen to do it. Th ere computer, and fo r· co nnecting are building your computer e dg e of the b ack are a lso a couple of the r·ea l world to your or terminal from scratc h, spaci ng-brace bars. Edge comp ani es who se ll a r-ubb er· computer, t hen it is very easy partially fro m scratc h, or connectors could also be stamp for edge co nnector fo il to disconnect a wire(s} fro m from a kit, here are some moun te d hori zontally on a pads, IC pin pads, etc. the barri er· terminal strip with ideas which should be of piece of aluminum and th en Etching PC boards is not a sc rewd rive,·. interest to you. fastened to t he back difficult eith er. Try it ; after spacing-brace bars . all, practice may not make The ca bin et of Fig. 2 is perfect PC boards, but after a Fig. 4. Building a power supply as an assembly. anoth er item that can be while of trial and error· you'll ~,.--- BARRIER TERMINAL STRIP fa bricated easily . The ca bin et be mak ing usable PC boar·ds I I - BRACK ET ETC can be made from aluminum (see Fig. 3}. I or stee l angle stock. For small Fi g. 4 illustrates a co mp act : ­ ~ TRAN SFO RMER 9'. In ca bine t s, a luminum is modul ar power sup pl y layout PASS TRAN SISTOR(S) OR __...VO LTAGE REGULATOR {S) pro bably more des ir able since that ca n be eas il y fab r·icated. { LM309K ETC) it is lighter. However, stee l is The " U" shaped piece of more easi ly welded and aluminum shou ld be made would be better for lar-ge r from I/32 or l / 16 in ch I cab inets or r·elay rac k type aluminum (yep, go get an I encl osures . aluminum door kick panel or Printed circu it boar·ds are ( -- ­ D not that har·d to make. " '" 1 Rea lly! Th e big sec ret to GC Electronics Printed Circuit '----- "u" SHAPED ALUMINUM Handbook and several artic les OPEN ENDED BUT WITH {O R WITHOUT) METAL success is to th orn ughl y cle an ~MOUNTING HOLES OR STUDS which have appeared in recent SCREEN COVERING OPEN the co pp er sur face of the PC issues of Popular Electronics a nd ENDS AND TOP FOR V ENTILATION AND RFI board. Th e best way to do Radio-Electronics. PRE V ENTION

47

0 Enclosed is check for$ 0 Altair 8800 O Kit O Assembled O BankAmericard # O Options (list on separate sheet) 0 or Master Charge # ------include $8 for postage and handling 0 Credit Card Expiration Date _ ___ _ O Altair Documentation Special O Please send free Altair catalog INSIDE the Altair®Co111puter

1. Central Processing Unit (CPU) Board. Other A lta ir Optio ns include additional PRICES : This double-s ided board is the hea rt of the ex pander board s, computer terminals, Altair Computer kit wi th complete assembly A ltair 8800. It was designed around a audio -casse tte inte rfa ce board , line instru ctio ns $439.00 Assembled and tested Altair Computer $621.00 powerfu I, byte ori en ted, variable word printers , ASC II keyboa rd s, floppy d isc sys­ 1,024 word memo ry board ______S97.00 kit and length processor - a comp let e central tem, alpha-numeri c display and more. $139.00 assembled processing unit o n a single LSI chip using 2,046 word me mory board ______$14S .OO kit a nd $195.00 assembled n-channel, silicon ga te MOS technology. 5. All aluminum case and dress panel. The The CPU board also contains the A ltair 4,096 word me mory board $264.00 kit and Altair Computer has bee n des igned both System Clock- a standard TTL osc illator $336.00 assembled. for the hobbyist and for industri al use. It Fu ll Parall e l Interlace board $92.00 kit w ith a 2.000 MHz crysta l as the feedback comes in an all alu minum case comp lete a nd $114.00 assembled . element. Serial In terface board (RS232) $119 .00 kit and with sub-panel and dress panel. $136.00 assembled. 2. Power Supply. Th e A ltair Power Supply Serial In terface board (TTL or teletype) $124.00 provides two +8, a +16 and a - 16 volts. 6. It all adds up to one fantastic computer. kit and $146.00 assembled These voltages are unregu lated unti l they The A ltair is co mparable to mini-com­ Audio Cassette Record lnterface ___ $126.00 kit and $174.00 assembled reach the individual boards (CPU, Front puters costing 10-20 thousa nd dollars. It Panel, M emo ry, 1/ 0 , etc.). Each board has Expander Bo a rd (adds 4 slots lo 6600) _ __ $16.00 kit can be connected to 256 input/ output and $31 .00 assembled all t he necessary regu lation for its own devices and can d irectl y add ress up to operation. 65, 000 words o f memory. It has over 200 NOTE: A ltair Computers come with complete docu­ The A ltair Power Supp ly allows you to m achine instru c tions and a cyc le time of mentati o n and operating instructions. Alt air c us­ expand your computer by adding up to 16 2 microse conds. to mers receive so ftware and general co mputer boards inside the mai n case. Provisions for iniorm ation through free membership to the Altair You can order the A ltair Computer by User's Club. Software now avai lable includes a the addition of a cooling fan are part of simply filling out the coupon in this ad or res ident asse mbler. system monitor, text editor and th e A ltair design. BAS IC language. by call ing us at 505/265 -7553. Or you ca n· ask for free technical consultation or for 3. Expandability and custom designing. Th e one of our free A ltair System Ca talo gues. A l tair has been d esigned to be eas il y expanded and eas ily adapted to thousa nds M ITS/ 6328 Linn NE , A lbuquerque, NM, 87108 505 / 265-7553 o f applicat io ns. The basic A lta ir comes ,------, w ith one expander board capable of hold­ 1 MAIL THIS COUPON TODAY! I ing four ve rtical board s. Three add itional ex pander boards can be ad ded in si de the : fo r $ : main case. ~ ~~~ l~~~~~~: c~~;~ c~ 0 or Maste r Charge # I 0 Credit Ca rel Expirati o n Date I 4. Altair Options. Memory board s now "Creative Electronics" 0 Altai r Compute r 0 Kit 0 Assembled : available inc lude a 1024 word memory 0 01; ti o ns (list on separate sheet) I board, a 2048 word memory board, and a In c lude $6.00 for postage a nd handling. I 4096 word memory board. Interface boards Pri ces a nd specifi cati o ns subject to c ha nge 0 PLEASE SEND FREE ALTAIR SYSTEM CATALOGUE I I include a parallel board and 3 serial boards w itho ut no ti ce . Warranty : 90 d ays o n parts NAME______I (RS232 , TTL and Teletype). Note: Interface io r kit s a nd 90 d Lty s o n part s a nd labo r io r I I boards allow you to connect the A ltair asse mbled units. ADDRESS------­ Com puter to computer terminals, tele­ I typewri te rs, line printers, plotters and other j CITY STATE & ZIP___ i devices . j MITS/ 6328 Linn NE , Albuque rque. NM , 87106 I 505/265·7553 I L ------~ Permission Granted to Xerox

(or .~!\1. IH!l/. i lfi<'1·u or ulh<'nuis <' .fi1ni111il<'. l'O{J_v ur clufilirnl<')

BYTE SUBSCRIBERS WILL LEARN .. . Abo ut a ll of the new small sys tems co ming on the market ... whi ch are rea l and whi ch arc sti ll in developme nt stages ... there wil l be a sim ple se ri es of articles on co mputer languages ... revi ews of kits . . . in fo on surplu s bu ys and use d equipment ... circuits fo r bui lding your own equipment .. . di sc uss ions of sta nd ards . .. news of use r clubs and programs ava il able ... in fo on speciali ze d newsletters . . . ga mes and game groups .. . ga me programs ... co mputer art ... co mputer music .. . and if that doesn't cover it, all you have to do is write in and either say what else yo u wa nt or else start wri ting the articles yourself.

BYTERS SAVE ... With si ngle cop ies go ing for $1.50 (insa ne p1·icc), the $12 sub scription price begin s to look attrac tive. You won 't want to mi ss a copy (presumab ly), so fill in the coupon here and se nd it in qu ickly ... no cash needed, just se nd it in , we' ll put you into the subsc riptio n computer (wi th fin ge rs crossed) and se nd you the in vo ice. It's probably a busin ess expense, right7 If you dislike rippin g you r soon to be va lu able iss ue of BYTE to shreds by removin g a coupon, yo u are hereby given permi ss ion in perpetuity (un til subsc riptio n rates go up) to violate the copyright and make a copy of any one of the fo ur co up ons ... nea tn ess counts. Your fri end s may do li kewise, unless you are a lot less pe rsuas ive than we thin k you arc.

Th e Management

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51 Add a Stack to Your 8008

Besides hi gher speed, the memory. The stack pointer contents of the top location most significant improveme nt does n o t need to be are read into register A and offered by the 8080 is the in it ial ized and thu s the stack then all of the lowe r data in additi on of a ge neral purpose is always ready for use, or it the stack moves up one stack ca pability . Usi ng the can be completely ignored by location and the top location stack, the programmer may programs that don 't need it is lost. save registers u sed in without problems. An obvious application of sub ro utines and interrupt Pr ogramming the data the stack is in wnt1ng serv ic e routines and then later stack is quite simple. The subroutines that do their job restore them. Argu ments to output address associated without d estro yi ng any subroutines may also be with the stack is given the registers. A simple example is pushed onto the stack. In the symbo li c name STPSH for the exchange HL and DE 8080 the stack is kept in STack Pu SH and the input subroutine in Fig. 1. First main memory and addressed by means of a stack pointer regi ster. One inconven iencc of the 8080 stack is th at data may be pushed and popped Fig. 1. A subroutine to exchange onl y in byte pairs creating DE and HL register pairs using one stack location and no addi­ wasted space ii. onl y a si ngle tional registers. reg is tc r needs to be saved. Also, the stack pu intcr MUST XCDEHL OUT STPSH be set up <1 l th e beginning of SAVE A ON THE STACK a program before any LAH EXCHANGE HAND D LHD USING A subroutines arc ca ll ed and LOA kept valid at all times or very LAL EXCHANGE LANDE strange th in gs may hap pen. LLE Mu ch of the programming LEA convenience of the 8080 INP STPOP RESTORE A FROM STACK stack may be had on an 8008 RET AND RETURN system with the add iti on of about six ICs and the use of one input and one output address. The basic stack is 16 eleme nts deep which is address is giv en the name register A is pushed onto the ge n era ll y adequate fo r STPOP for STack POP. Wh en stack. Th en registers H and D In: register sav in g app li cations. an OUT STPSH is executed and L and E are exchanged IJul 0111111 berlin Addition of more chips and by the program, all of the using A. Fin all y the origin al The Comp11 ter 1-1obby ist substitution of 256 X 4 ex isti ng data (or garbage) in state of register A is restored RAM s for the 16 X 4 RAM s the stack is conceptually by po pping it off the stack J>() /fo.r :!% gives a 256 element capacity, pushed clown one location and the su broutine returns. C111T \C :! I.I I I ample for alm os t any use. In and the byte in register A is Because of the push-down c i th e r case t he a cl deel written into the top location nature of th e stack, one hardware provides both a wh ich was vacated. When an subroutin e that uses the stack stack poi nter and a ded icated IN P STPOP is executed, the may ca ll another sub ro utine

Reprinted by permission from Th e Computer Hobbyist, May 79 75.

52 Hal Chamberlin and his associates at Th e Computer Hobbyist put out excellent small systems technology ... designs include a high reliability audio cassette recording method, an inexpensive high resolution graphics display - and this article's stack design among others. Several of their more general purpose designs (e.g., tape interface, CRT display) are that uses it and so on without soon to be available in kit or assembled versions. This article loss of data as long as the describes a custom modification of an 8008 based system stack's capacity is not which you can add to an input/output port to achieve a stack exceeded. Th e only mechanism. The method is that old standby of minicomputer requireme nt is that all of the instruction set escape mechanisms - use 1/0 commands to data saved on the stack by a implement "new instructions." With a stack of sufficient size subroutine be popped back and suitable save/restore subroutines accessed by RST instruc­ This circuit brings the off before it returns. tions of the 8008, you can eliminate conflicts in register usage 8008 one step closer Fi g. 2 shows a completely between multiple levels of subroutines. The overhead penalty to the goal of a "real" general interrupt service routine that uses the data is a single RST or CAL instruction in the linkage code, the computer. stack to save al I registers and register save and restore routines, and the time required to the state of the conditions (C, execute the save/restore subroutines. Z, S, P). When entered, ... CARL registe r A is first pushed onto the stack. Then the remaining six regis ters are saved one at a Fig. 2. A general purpose register time by first loading them and condition code save routine. into A and then pushing A onto the stack. None of the instructions necessary to do GSAVE OUT STPSH SAVE A ON THE STACK this affect th e condition fl ags. LAB SAVE B Fin ally a chain of conditional OUT STPSH jumps is executed to create a LAC SAVE C "magic number" in A that OUT STPSH LAD SAVED reflects the state of the OUT STPSH conditions. After A is pushed LAE SAVE E onto the stack, the interrupt OUT STPSH may be serviced without LAH SAVE H restrictions on register usage. OUT STPSH In order to return to the LAL SAVEL inte rrupted program, first the OUT STPSH magic number is popped off LAI 0 CLEAR A and added to itself with an RAR PUT CARRY IN HIGH ORDER ADA instruction . Th e JTZ GSAV3 JUMP IF ZERO FLAG IS ON LBI 170B PUT INTO B THE BIT MASK TO number is such that the JTS GSAV1 TURN OFF THE ZERO FLAG AND proper conditions are set LBI 030B RESTORE THE SIGN FLAG when it is added to itself. GSAV1 JTP GSAV2 OR IN A 004B IF PARITY Nex t the six index registers ORI 004B INDICATOR IS OFF are popped off and restored GSAV2 ORB COMBINE BAND A in reverse order from which GSAV3 OUT STPSH SAVE MAGIC NUMBER ON STACK they were saved. Finally A is * REGISTER AND CONDITION RESTORE ROUTINE rest ore d a nd a RET GRSTR INP STPOP RESTORE MAGIC NUMBER FROM STACK instructio n is executed. This ADA ADD IT TO ITSELF TO RESTORE CONDITIONS method of complete status INP STPOP RESTORE L saving may be modified for LLA use by a debug program. INP STPOP RESTORE H Debug can be entered by a LHA console interrupt and the us er INP STPOP RESTORE E may examine things. Th en LEA INP STPOP RESTORED program executio n may be LOA resumed with no loss of data. INP STPOP RESTORE C These tw o programming LCA examples should serve to INP STPOP RESTORE B illustrate the use of the stack. LBA The stack is im plemcntcd INP STPOP RESTORE A with an up-d own counter and RET RETURN WITH STATUS RESTORED

53 Fig. 3. Logic Diagram of a 16 element data stack. NOTE: "X" refers to a source of logical one, usually a lk resistor to +5.

+5 +5 •) ,,

OUTPUT ISK ISK ADDRESS NANO IOONS WRITE IOONS PULSE WRITE DECODE NO.I DELA Y 'STPSH' --PULSE PUSH DECODE -I -~ WIDTH 390 D 7 A a + A a D .. __I_ c ~2 20 pF B c 6 74123 SO NS 74123 A 74193 INPUT B 2 a ~ a ~ ADDRESS NANO X­ B X-B X--ti LD DECODE N0. 2 R R I CLR 5 A,l..._ 'STPOP' UPCLK POP DECODE ­ x x 4 DNCLK SS- I SS -2 I STACK COUNTER

7400 ~ I NPUT BUS DRIVERS 3 12 WE 7 IND 6 IO IN C D Li i 6 INB 7 5 4 4 INA c lq .~ 74B9 6 .___I]. ADS B 7 14 .~ AD4 I CPU DATA 15 AD2 AJ5 L_-==i1401 r 5 I OU TPUT BU S ADI CE l 12 c--17401 4 CPU DATA INPUT BUS J.3 12 WE IND 3 Dl11 I ~01; 3 2 IO IN C " INB I 4 0 INA c 9 ~oi) 2 74B9 __@_ ADS s'J-­ 14 I AD4 5 ~ 15 AD 2 A I ADI 0 CE ! _ J~1, 2 STACK 'f MEM ORY <3=­

a random access re ad-write timing problem may arise in a addressin g the next lower memory. Rath er th an the system using the 8008-1 if element o n the stack. data moving when pushes and the output data is not valid Figs. 3 and 4 show the pops are executed, the for the sum of write pulse logic diagram and timing An obvious application up-down counter ac ts as a delay and write pulse width chart respective ly for a ·16 of the stack is in writing pointer to the top cle ment on (950 NS} required by the element data stack. A bus subroutines that do their th e stack and the pointer MOS RAM. (Timing given is type of 1/0 system (as job without destroying moves . The logic is set up so fo r th e 2101 RAM. Matters opposed to a "port" type) is are improved if 2101-1, any registers. that when an OUT STPSH is assu med. As shown, any decoded, the coun ter first 210 1-2, or 9101 RAM is system with either separate counts up one notch and use d.) There should be no data input and output busses afte r sufficient time for the problems with the bipolar or a bidirectional bus may be add ress to settle in th e RAM , RAM in the 16 eleme nt used. Some systems may use a write pulse is ge nerated to ve rsion . an output bu s with TRUE write th e data fr om A into When an INP STPOP is data and an input bus th e RAM . Th e wri te pulse recogni zed, the contents of requiring FALSE data. In this delay can be fair ly short (50 th e currently addressed case, the 7401 s may be NS or so) in th e ·16 element loca ti on are simpl y gated omitted and the TTL RAM stack but mu st be at least 200 onto the input bus. The outputs tied directly to the NS for th e slower MOS RAM counter counts down one input bus . The tw o use d 1n th e 256 cle ment notch at the end of the I NP single-shots, SS-1 and SS -2 , ver·sion. It is poss ibl e th at a in struct i o n th e r e b y are used to time the sequ ence

54 Fig. 4. Stack Timing Diagram. 2 101 RAM. If a 910 1 is used, the timin g may be speeded up consid erab ly . An 8101 may PUSH OUT PUT ADDRESS D(____,_V::::.A"'-'Ll""'-D____~><. VALID X!/j/(l/J///j/ji}!!ljZ An overa ll improvement of INPUT ENABLE 10 to 20% can be expected

POP DECODE on large programs such as asse mbl ers. Th e bi ggest STACK OU TPUT flll.ll.11.717Z{![]]})<. \IALIO XI!l7JZlllll.1111{I/J1.!lll.a. improvement however wi ll be STACK COUN TER N N-1 in cod ing time si nce register usage will not have to be carefull y planned in advance. Use the stack to pass of eve nts for a stack push. memory when either a push parameters to subroutines First, NANO gate number 1 or a pop is being executed when you don't have recognizes the coincidence of and disables it otherwi se. enough registers. the ST PSH device code on The logic necessa ry for a the add ress bus and an output 256 e le m ent stack is strobe pulse or its eqt:1iv alent. essentiall y the same as for the The gate outp ut triggers SS-1 16 element version. The which increments the stack major di ffe rences are that a pointer counter when its separate si ngle-shot should be 1K 475ns all orders shipped cycle is finished. An RC used to t im e the write de lay STATIC RAM SIGNETICS postpaid and network between the two and that a buffer is abso lutely $4. 25 for one 2602-1 insured. Mass sin gle-shots delays firing of necessary to drive the CP U $4.00 each for residents add 3% SS-2 until the counter has input bus. If the polarity of eight sales tax settled down and the RAMs the input bus is the sam e as $3.75 recognize the new address. that of the output bus or it is each for 32 The write enab le is co nn ected the sa me bu s, 8093 or74-125 WHY PAY FOR BEING SMALL? to SS-2 which all ows data on n o n i n v e rt i n g a n d q u ad Centi-Byte is a new sou 1·ce of memory components the CP U output bus to be tri-state buffers are and othe1· necessary items For the compute r ha1·dwarc written into the newly co nv e ni e n t to use . builder. Our fun ction is to be a voice to the addressed RAM location. Open-collector 7401 gates manufacturing companies rep resenting you, the The occurrence of an INP may be use d in stead if the modest volume consu mer of special purpose com­ ponents. Cen ti-Byte brings you th is specia l in tro­ STPOP is detected by NANO input bus is inverted. The ductory offer or rast memory ch ips, chips fast enough gate number 2. As long as the chip enables on the MOS to run an MC6800 or 8080 at maximum speed. These gate is satisfied, data from the RAMS should be ground ed so 2602­ -1' s are new devices purchased in quantit y and RAM is placed on the CPU that the chip is always Full y guaranteed to manuracturer's specifications. Centi-By le works by conce ntratin g your input bus. At the end of the enabl ed. The connection to purchasing power into quantity buys of new INP instruction when the the bu s drivers is left as it was components. Let us know what you need in th e way NANO ga te output goes back for the 16 element vers ion of specia li zed components and subsyste ms for future to a ONE, the counter however. Th e timings for the offeri ngs. With your pu1·c has ing power co nce ntrated dccrcmcn ts to add ress the write de lay and write pulse through us, together we wi ll lower the cost or home comp utin g. ncx t lower clement on the width single-shots can be set stack. A 7400 connected as to the m 1n1mum va lu es a n OR-NOT enab les the allowable for the stand ard

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57 Ah yes! It conjures up visions of an earli er day, many yea rs ago, when Mom, Pop and the kids sat arou nd The Shadow, that newfa ngled gadget, the radi o, and li stened to "The Sh adow" and " Bu ck Rogers." FI ash forward to the future, right now! Aga in, we see Mom, Pop and the kids Buck Rogers, sitting · around that new­ fangled gadget, the computer, bala ncing a c heckbook, converting a four se rvings recipe to seven, and pl ay in g tic-tac-toe. Not ve ry exciting and the things to do with a co mputer, you say? Well , you're right. Bu t let's see if we ca n do something to make it at least as exciting as old -time radi o. We me ntion e d t h ree Horne Computer a pplications for a home comp uter: 1} checkbook bal ancing A computer at hom e? Ask many present day computer 2) recipe converting systems people what they'd do with a home computer and 3) game playing by you'll get the old silent treatment in return. But all that For starters Mom and Pop indicates is a lack of imagination. A large part of the BYTE Richard Gardner shou Id have a program for philosophy is the discovery of applications areas through the co ll ecting and summarizing Box 134 imaginations and practical results of readers. Richard Gardner all their fin ancial data, on a 1-/arvard Square supplies us with a " Gee Whi z" articl e on potential app lications daily , monthly and yearly Camb ridge MA 02139 areas to get things in motion a bit. Richard has extensive (fo r your "friend" and min e, computer applications experience including one sti nt working the IRS) basis. A fa mily will for the Children's Museum in Boston, creati ng interactive be more secure by knowi ng computer oriented exhibits. Eventu ally, many of the systems the sta te of its fin ancial ideas Richard mentions in hi s article will appear as practical affa irs. You will want to plans and programs in the pages of BYTE - as developed and desc ribed by our readers . If you 'd like an interactive meeting of the minds on possible uses and ideas, Richard invites correspondence from readers. . .. CARL

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58 compute interest for di fferent energy use. Open and close Using a Symbol Table to purchase plans, and bal ance curtain s on windows to use Im prove the Food Table the check book. the su n's energy or keep it Mov in g on to a s u~j ect out. Most people in America close to my heart (just below, 2) Security. Whil e you're have a poor diet in spite of and a li ttle to the right) ­ at home or away, monitor the the fact that we have more food . Almost anyone can opening and closing of food of a better qua li ty and conv ert 4 to 7 serv in gs - just windows a n d d oors. va ri ety th an any other double it and feed the Automaticall y telep hone the country. So I consider the Since your co mputer won 't leftove rs to the dog, or give it po li ce with a recorded fo ll owing to be important be doing anything most of to a charitable organi zation message when you're go ne or LJSes for a home computer: the day ... (tax deductible, of course). at home. Monitor the use of 1) Selection of foods on a 'Ml at you rea ll y want to your swimming pool - sound seasonal bas is to reduce cost know is whether everyone got an alarm when the pool is in and improve qua lity. A This application, li ke others enough nutrients (vitamins, use and nobody's in the program for doing this would mentioned, would use the minerals, prote in , etc.) from I ifegua rd seat. Fir e run for a year and use a data teleph one system the what they ate today. Hin t: it monitoring equipment can be base fo r yo ur area (to take wo rld's largest compute r. I ca n be done. I know of two located in many places and advantage of local produce). can see it now. The kids get people who started a small sound an alarm long before A second data base wou ld be home from sc hool and ask, comp any to do it. you might smell or see program med for wid ely "What's for dinner, Ma Bell ?" On to fun and games ­ hundreds of game playing The Bottom Lin e Isn't programs have been written (I Always an End Statement invent e d o n e ca ll e d Or, how to profit from YOUGUESS) for al l sorts of your home computer: compu ters and languages. 1) Income manage ment, as You should have them all. It previou sly mentioned, but will win fr iends and influence with the help of anoth er neighbors, if you'll pardon computer. Seve ral computer the pun . companies th at do nothing I'd say that's at least as but figure taxes (for you exciting as old- time radi o. know who!) already ex ist. Good, but we can do much Eventually the y wi ll all ow better. Let's consider three you r computer to call th eir things: computer. Your computer 1) Today's computers are shovels in a year's data and very fast. The app li cations out pops a tax form with all we've mentioned might take the right numbers. You might one hour of CPU time per smoke. The fire department ava il able foods and when th ink it easier to do your own day, at the very most. So can be call ed automatica lly they are best and cheapest. programming, but remember what do we do with the other with a nother recorded 2) A me nu bu ildin g that you can't write every 23+ hours7 message. program to take adv antage of program you will want to use . 2) There are lots of These app li cations wi l I the above system but with In addition, these compan ies computers in the world, and make use of photocells, the intention of increasing have staffs that do nothing they can talk to each other. therami ns (motion sensing variety a nd max 1m1 z1n g but m ake program 3) Computers can hear, dev ices), heat sensors, contact nutrition . improvements and changes see, fee l, sme ll and touch. switches, smel ling devices 3) A shoppin g gu ide to required by the IRS . Wh at Keep these things in mind (lik e those used by the take adv antage of local food person in his or her ri ght as we consider what mi ght be Defe nse Departm ent in supp lies by indicatin g the mind cou ld poss ibly keep ca ll ed economic, personal and Vietnam to sme ll passing best one or two markets from track of a myriad of new educational applications for elephants and tigers). Eight which to purchase your food. ru les from the I RS 7 the home compu ter. bits might be used to This data base mi ght be 2) Pl ay the pon ies or the represe nt a temperature range maintai ned by some perso n in puppies7 An obvious use f0 1· Computerizing the Home of 256 degrees. 1 00 degrees your locality - and then your computer. Again, use a Since your computer would be adequate fo r most rente d on a per use basis. No data base compi led by some won't be doing anything most locations. One analog to se nse in eve ryone typin g in local cager beaver. Perhaps of the day why not put it to di gital converter could be today's pri ce for cumquats. you'd be charged a small fee work: used for other analog inputs, Perhaps the New Yori? Times for accessing the day's 1) Heating and air such as from a photocell. A will eventuall y computerize statistics. Perhaps you have a co nditio nin g control. digital to analog converter its cookbook, plus thousands data base or prngram to Optimi ze in creases and would generate vo ltages to be of other recipes, and all ow trade. decre ases in the in side used by motors and other the publi c to access this data 3) Then there's always th e temp c r a tu re to minimi ze mechanisms. base via a perso nal computer. world's biggest dai ly crap

59 used to play Sp ace War - the Grandpa of computer games' Your computer, a TV set, a few buttons and sw itches and, presto - Sp ace War! Or ping-pong, or driving down a road, flying and landing an air plane, landing on the moon, chess, checkers {you can play these games in Boston with the Children's Museum computer). 2) Toys that play with you - like robots. The Boston Children's Museum has a robot that was built for about $200. Mass production of a special chip and board will bring that cost down. Then the biggest cost will be the Meccano Set (I ike an erector set, only bette r) , which can be used to build almost any sort of mech anical device. and quality changes during stories, fina nci al page stories, How about a robot to do t he year: clothes, home or any story that contains a housework ? furnishings, gifts, trans­ keyword or so me 3) The ultimate fun, portatio n, eve n housi ng. com bin ation of keywords. though, is to write your own Some local person, or you, This would be done early in programs to do all these could create the necessary the morning an d read by you things! Kids, and adults, will game - the stock market. A commodity and price data at breakfast time. pl ay only so many games of company in Phil adelphi a will bases, then use or rent them. 2) Your local university or tic-tac-toe - then th ey want charge you $300 a year for a Remember! Th ere is a host hi gh school mi ght have a to know how it works. Help small numeric terminal and of areas for sma ll bu si ness com puter with courses th at them write their first BASIC 24 hour a day access to their activities using your home can be taken via a remote progr a m . .. a nd they're stock data base. You key in computer as a tool of the terminal. Many universiti es likely to be hooked for life! the number of a stock and trade. All it takes is already give some courses Eventu ally programming will out pops the high , lo w, imagination, a bit of digging usin g only this method. include a broader range of average, etc. Your computer into the wants and concerns 3) The Children's Museum input/out devices such as the cou Id make one call after of your neightbors, and the in Boston will eventually previo usly mentioned buttons eac h trading day, co ll ect the programming of yo ur a ll ow you to call their and switches, photocells, stock data you're interested computer. computer, via a terminal or microphones, etc. This will in, han g up, and then computer, and access a data lead to the applications just determi ne if you should buy, base of cultural, educational, Six Munce Ago I Couldn't discussed, and who knows sell or hold. Th e deci sion and social even ts in the Even Spell Computer what? mak ing could be done by Boston area. Your computer Programmmer . .. These are just some of the your program or one being might call theirs once a day possible applications for a rented from a stock market Computers are good for to learn what's new or learn home computer. All of them wi zard you know. keeping you in touch with about a particular type of might not be re aso nable or 4) I mentioned how a the world. For example: event. practical things to do but computer could be used to 1) The New Yori? Times they should set you to opt1m1ze the purch ase of has a computerized data base Computers As Toys thin king. food. Thi s principle app li es to of all its back issu es ­ Computers are probably As future issues of BYTE any commodity wh ose pri ce currentl y accessibl e to the the greatest toy ever unfold, the Gee Whi zze rs general public, fo r a fee. The invented. Here are some applications will le ad to cost will probably go down to exa mples of how you can practical articles on the the point where yo u might play arou nd with yours: software and spec ialized program your computer to 1) It has been ru mored p eri phera ls needed to query the Times data base that 50%, or more , of the implement some of these a nd retrieve front page computer time used at MIT is ideas.

60 from the Publisher . ..

E~TI staff are they real?

EDITOR Carl T. Helmers Jr . PUBLISHER Way ne Green We have a lot of bu zz display ge nerator and hand and were expectin g to MANAGING EDITOR words these days, and o ne rece iv ed one a few days later be ab le to setup a production Judith Havey phrase we hear a lot is about in the m a il . I was department very soon. The ASSOCIATE EDITORS companies bein g "real". disappointed not to have a system is based upon the Dan Fyl stra Bein g the publisher of BYTE, chance to talk with them at Motorola M6800 chip and Chris Ryland it see med to me that it would greate r length. features a PROM loader. CONTRIBUTING EDITORS They plan to have anoth er be worth while if I were to In Salt Lake I was met by Hal Chamberlin PROM with Basic in it, which make a trip to visit the major Doug Hancey of Sphere and Don Lancaster mi croco mputer syste ms would be quite a step ahead driv en o ut to their new plant ASSISTANT EDITORS companies and talk with fo r it wo uld free all of the in Bounti fu l, a suburb. It's a john C. Burnett them . . . possibly mak ing RAM memory fo r use and small building and I have a Susan G. Philbrick would permit in stant use of them more rea l to our fee lin g that they will qui ck ly Basic without the usual PRODUCTION MANAGER readers. be outgrowin g the faci lities My first stop was in load in g process. Lynn Panciera-Fraser ... I don't think they realize Denver - a short layover ART DEPARTMENT what a demand there is go in g I gather that Motorola has betwee n planes on my way to Nancy Estle to be for the ir system. been extremely helpful in Neal Kand el Salt Lake. I tried to locate supplying in formation and They had a prototype up Peri Mahoney the Di gital Group there, but support fo r the effort. This and running and it looked Bob Sawyer had no luck. Sorry about may have a lot to do with that. I know they are real good. There were a cou pie of PRINTING because I recently sent them glitches, of course, but they Biff Mahoney Continued on page 81 a check for their video see med to have these we ll in PHOTOGRAPHY Bill Heydolph Ed Crabtree TYPES ETTI NG Barbara J. Latti Marge McCarthy ADVERTISING Bill Edwards Nancy Cluff CIRCULATION Susan Chandler Dorothy Gibson Cheryl Hurd Pea rl Lahey Lorraine Morto n Judy Waterman INVENTORY CONTROL Marsh all Raymond DRAFTING Bill Morell o Sphere HQ in Bountiful, Utah, just outside of Salt Lake. That's Michael Wise, the president, in COMPTROLLER front. These are new offices for Sphere and the production will be set up in the back part of the building. Knud E. M. Kell er

61 '"H ..r:: ~ :!~:·.:~} f ~ i ' Jo.rr1;now ' -----~-- ...... • Association for Computing--- Machinery·------­ I Since 1947, AGM has served as the educational and I 1133 Avenue of the Americas, New York, N. Y. 10036 I ~oientifJc soci .e~for co.mputing prof.essionals-30,000 st~on!tl ana growin§: · . ,., ' · · . I would like to consider joining ACM. I I Please send more information: ., Name I I Position I I Address I I City . S!ate , Zip I ------8 Hit the deck in shorts and a tee shirt. Or your bikirii if you want. You're on a leisurely cruise to remote islands. With names like Martinique, Grenada, Guadeloupe. Those are the ones you've heard of. A big, beautiful sailing vessel glides from one breathtaking Caribbean jewel to another. And you're aboard, having the time of your life with an intimate group of lively, fun­ loving people. Singles and couples, too. There's good food , "grog;' and a few pleasant comforts ... but there's little resemblance to a stay at a fancy hotel, and you 'II be happy about that.

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Name

Address

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P.O. Box 120, Dept. 121 Miami Beach, Florida 33139 A NOVAL Assembler for the SOOS Microprocessor

To the hardwa re spec ia li st code had to be written out asse mbler which is ve ry easy who has ju st spe nt months byte by byte. Well, there had to adapt to the 8008. buildin g hi s own personal to be a better way. computer (well, in the case of What ls An Assembler? the 8008, his own perso nal A "No val" Concept Co mputers, being digital processor), hav ing to actually The so lu tio n adopted is mac hines, operate on a se ri es program the computer can be not unique except in its of numeric co des which an entirely new and unique impleme ntation: Us e a piece instru ct them to perform one expe ri ence. In the auth or's of software called a macro of a fi xe d set of operatio ns. case, writing an aud io cassette assem bl e r. One way to People, on the other hand , sto rage based operating accompli sh this is to write a find it easier to instru ct the system for the 8008 was fun. macro asse mbl er which can computer using sy mb ols At least it wa,s fun the first run on a minimal 8008 rather th an numeric codes. time that the program was system. However, desp ite For example with the 8008, hard asse mbled and the fir·st doubts about whether this is HL T (e.g., stop!) is eas ier to time that some uni que, eve n theoretically possible conceptualize and understand so phi stic ated and entirely with the 8008, writing a than just: 3773. Th e process ambiguous method of double macro assembler is like of transl ati ng symbols in to a /Jy indirect addressing had to be re-inventing the wheel (which numeric code is call ed an asse mbl y. The software that Peter fl. llclmers deve loped. Howeve r, when it in itself was a came time to rewrite the code " rev o I u t io nary" idea ...) . does this is ca ll ed an /fo x 6297 fo r the operating system, all just a bo u t every large, asse mbl er. Hi vc r Stalion of this had to be done aga in : me dium and sma ll scale In the simplest case, there lfoc/u>.~/, er NY J1/,(i27 Every byte of code had to be comp uter has a macro is a one to one corres­ assigned to its core location; asse mbler. Wouldn't it be nice po nde nc e betwee n the every labe l had to be defined; to adapt one to the 8008? It sy mb ols used by the human a nd every t im e double tu rn s out that the Data progra mmer and the numeric indirect addressi ng or the General Corp . N o va codes used by the compu ter. equivalent was required, the Minicompu ter has a macro Bas ically, in order to use the Nova mac ro asse mbl er to assemble programs using 8008 mnemonic s, all that has to be done is to redefine the asse mbler's sy mbol table so that the correct mapping I wonder how many readers have ac cess to one or more between 8008 sy mbols and minicomputer systems - or larger syste ms . It might be a numeric codes is achieved. question of how many readers have already been in the The sy mbol ta bl e fo r the "pond" of using computers in one form or another versus how DGC macro asse mbl er is many are just in the process of "div ing in" for the first time. ge nerally co ntain ed in a file For those readers who have access to a mini, the software named MAC.PS. Howeve r, development aspects of the home microcomputer can be Data General has made it very easy to redefin e any and /or simplified by use of "cross assembly" techniques. In this all of the symbols in the article Peter Helmers tells how he and Loren Woody MAC.PS fil e. This is done by implemented the NOVAL assembler while undergraduates at using two spec ial opera nds the University of Rochester. NOV AL is an 8008 cross­ that the mac ro asse mbl er assembler running on a Data General NOVA, based upon recognizes: .X PNG and extensions of the Data General Macro Assembler. .DUSR. The .X PNG operand . .. CARL (m.eaning "expunge") del etes

64 Fig. 1. The ·INTEL .PS File Listing.

TJTL Hllf.!. ItlTEL 8008 F' S MA(f'·O ( Tf' T:: t4(U) • RV:>-: - 1 ·. ·-i1::.(1 RCi:-.-;(1 :?. . C.•U SR AC.A=21C1 DIJS".F: AC.E:=.211 . VU£.F: AC.( = .21.? ' - 1 · ­ ·' '. - l ' · 4(•(1' •-i(1(1' (.oiJ:=.R ACCi =.21 3 •. - 1 •/ 4 0(1 all Nova symbols from the . [ i USFi: AC.E=.214 . [.•u£. F: AC.H= .21".:· CTZ symbol table. Th e .DUSR ( •IJSR ACL=2h'· !':·.2 C>U::'.R HCM=.2 1 7 (olJ:E.F' F:ET=i!IO;"' operand {m ea ning "define . DUSR HC•R= 2130 C•U:E.F: F'FC =1:io: • [.11JSR f1(!8= ,21)1 . [.•USF: F·ff·=(1 : : user symbol") can then be . (>IJ::.F: AC1C=.2(1.2 JF( co1_1::.F.· F:F'.:.=02} (.•USF: f1(1(.•=20: C•U:E.R F'FZ=t1:1:. 101!1 used to equate most of the . [itJSF: RC•E= .21) ...i " - 1 .i ­ .. • •, · 1 •. 400,•·•-iOO • [ol_ISR F:LC.=-Oi:'.12 (iUSF: R(•H=.20~· . -!>. '41)(1 C•U::.F: F:R(.=1?11.2 8008 mn e monics to (•U:::.F: RC•L=.2•).:. [•l_l'.::'.F' F':=: T6:-:(u)5 'x . DUSR HL•f'1"'".2 •Z17 .·MACRO ~TFF [ •l_l:E.F: F:::.T1 =a):l5 corresponding numeric codes. . [.•U::'.F: CF'A=.271!1 1 2 0 C•USF: F:ST .2 =0.2':• CiUSF: CP8=271 . C•USF~ F· '.::'. T2.= 0 25 Th e us e of these two . C•U::.R C.F'C=.272 . - 1 •.'-i(11) . C•USF~ F·::.T4 "" 04':· . C.•IJ£.F: (f'(•= .2l:'. :--: (.oUSI<: F':E, T 5=(1 ~5':1 • operands can be seen in the [;.LISP.. C f'E=.C.'7 4 ,ff::. . [11J::.F: F.:STt.=(165 . HACf.,0 . C•u::.I': (.f'H=.2 7 ".:· L !:: O lis ting of th e INT EL.PS file DUSI" F·:E.T7=-0;-"5 C.•U::'.R (.f'L= 2r"o; . ' - 1 ,.- \ . ~ - 1 ', '4l) 0H4~)1?i : • . (i lJ::.F' F'TC = •~14 ;:. . C•US".F.' Cf'M=.;:·:·7 .. -1 .. . '4(11) shown in Fig. 1. . c.. u::.F: F:TP=07J Ciu ·:;. F: C.•CE:"=0.11 C·USR F : TS=1~1t',S Du::.p (•((.=1)2 1 MAC.RO ~T F2 The .X PNG operand first . [>U-£.F· F·TZ=05:. • C-•US".R C•C L•=(C 1 .110 C'USF~ SE:A=2:c1 . DUSR C•C.E=1:>-i1 deletes the Nova mnemonics . (.•U-£.R ::.E:E:= .2: 1 . C'USR C•C.H = 1)~·l C.>USF: SE:C.= 2:?.2 . [.•USR C•CL=(1t;".1 from the MAC.PS symbol , [.ol_t;.F.· SE:D=::.t.:.J. CiUSR HL T =01)1) . C•USF~ S8E=22. 4 . MAC.f'·O ~T MP . DU:!'.F.: ItlC•=1?11!1 tabl e. Then afte r telling the . c.. usF: SBH=.2:'.:5 104 (.•U'.!.R 1w:=1Z• 20 . C.•u::.R SE: L =.22.r:: \ .-.1 ) - ( ( .:-·1 )/40~:!1 ) +4~30 > IN(i=i?:::C1 mac ro asse mbler that all DU'.!-R (1USR SE; f'1 =2J.7 ( '-'1 )t''401!i . C>USR J/j£:-1Z, -4121 (•USR ::.ut=t=.<.: .;::o IHH=1jr;'.(1 numbers are interpreted as . pusF: SUE:=2.2 .l ~TT C. IUL=t\o;.(I . c.·u::.F: . DUSR C.•U:E.R -;.uc.=222 140 LAB=?O'l octal numbers {by means of . DUSR [ .o USR ::.uc..=22: . DUSR u=ic.=:1).2 . c.. u::.F: ::.u £ =2~4 the . ROX and .RDXO CiUSR LAO=?.tiJ C.•US'. F~ S UH =.22~· . DU£.P LHE ::::;~q . C.•USR 9JL =.2.;;:t. ,JTp . DUSR LHH=:::.O':· operands), the line: . Ci US!<· SIJl·1 =227 1 7 0 (.•u:E.R LAL=:::o.:. 0 . CiUSF<· ;< F: A =;~c;. ~) \ :l l-( (\ ~ 1 ) ..­' 4(1i3 /:ti4(1('1 ) .DUSR ACA=2H'l . C.•USF: LAM =:\ ~!17 (i lJSF: \ -1 :•/ 4IZ,1) (.•USR LE:A= J. 10 DUSF: :-.-:F.:C.= 2:':"2 tells the asse mbl er to insert . DUSR LE: ( ,:P- J 1 (1 ( ! USF~ :-.-; F~ C .•=25 2 . MAC:F:O . (.•USF.' LE:C•= :\1: (.oi, ,ISF.· ;-: F~ E=.2 ':· 4 an entry in its symbol table . [ i USf<• LC.• E =J.1-i . [i lJSF~ X F: H= .25~ . [i USR LE:H=:; .l':· C.oi_ISi::' ;<:F:L=.251;" LE:L =:::1.:. that will cause the mnemonic C>USFi' t' •-•5F. . t ' L1 $F; :.;F.:M ,,, _:_;;­ DUS"-Fi· LE:M =: 1 7 C' USR F.:0=:1(1:1 ~TTZ ACA {e.g., add register A to . [.•USI'.· LC.H=J.21J1 [.•USR R1= :1£(;: 1 ':·0 . C>USR L (.E:=:.~ 1 C.•USR F~ 2= 11?i!';• •: - 1 .•- ( •: \ - 1 ) / 41?1\j ,> >t•4(u) \ register A with carry) to be . DUSE<: LCCi= :~ .2 1 . C ~ USR F~ :~ = 1C1 7 < "1 )/400 translated into the octal code . DUSR LCE =::'.,2 -i . uu::.R 1=: '4=·1 11 . DUSR LC.H= J..2 ":· . UUSR R5=:113. RC I 210 every time that the ACA . l) IJ-::".R LC. L =:<:t. C.•IJ::.p Rt.= 1 1 5 O.l.4 C1USR L CM=J. 27 Ci USR F~ 7 = ·! 17 \ - l ) - ( \ \ -·1 .•/ 4(11) ,•·•·4(1\) ) operand is enco untered in the DUSR LDA= JJ. 8 C•U::.R l·J10=:1.2:l (JUSR L C.. 8<-:!,1 C>USR l·J1 1 =123 H[•I 8008 source code file . Most . C>USF: LOC= 3-:.2 VUSF; l·U2=1.2e'· (n)4 DUSR L DE=1:JA [.•USR l·U3:c:1 27 ' - 1 J - (( • - 1 .•/ 4(1(1.' '1'•10(1 • . DUSR LDH= 3. 3.5 UUSR i·l14 =1::.1 of the other 8008 mnemonics . DUSR LCi L=3J.t; . OUSR l.J1 5:::z1 J:J. (F· I (.>USR L(1M=:~ 3 7 are done simil arly. . DUSR l•J16c:l35 07·1 . OUSR LEA= 3.~! 1) DUSR IJ 17~1J : 7 • -1_.- ..;., . -1 •/ 4(u;1,> :1...i(11j • LE8=3A:l Al th ough most of the . DUSR . DUSR IJ20=141 . DUSR LEC.=1.4 2 . CiUSR M2 1=143: LH I mn emonics used are standard . DUSR LED= 3'.43 . (iUSR lJ 22c::l1":· :::: L E: I . C~ IJ S R versions of Intel 8008 LHA=3e"0 ll"-:· .:: - '1.~·r:'· 01.:. . ou::.R LHB=J.51 UUSR i · l .27=1~·? <- 1 ,•-v • "1 ) . 40(1 r •A~:;o ) d oc um e nt a tion, the C.> USR LHC=1.5.2 DU~.R lJ :?-0=:161 . DUSR LHU=3 5J. . DUSR lJ 3: !==:lt.:?: L( I INx/OUTxx mnemonics were . OUSR LHE= 3.54 c.. usR lJJ.2=1r::!:0 02.;. . [lUSR LHL=J 5b C.•US".F~ IJJ:J.=167 .. " 1 ) - (< •. -1;. / 4(10 .•'t'4(1(1' changed to a Rx/Wxx format . C>USR L HM=J.57 . Ci u:=.R LLR= 3:1'!'·~ . C•USR 1·134==1 71 LC!J to avoid confusion with DU:=.R LLB= J. t.1 . C.•U:=.F: 1·1];5==1 7:!. o :? .:: . C > u:::.F~ LL C=;:, i;~ . DUSI<· l.JJ.'b=l 7 .:. '· - 'l ,. ­ ((( '-1,o. 41~10 ··•40(1 ' mn emonics for incrementing DUSR LLD=J.63 . CiUSR 1-1 3.7=177 . DUSR LLE=J.€.4 . MACRO CAL LEI registers {e.g., INA) . OUSR LLH=J.i£.5 1 e.; 04€. (:•USR LLl'\=3.67 .. -­1 .) ­ .. \ ( - ·1 ) ,•'400 .•=+'4(0);. ( - 1 ) - ', .; \ · 1 ....-'400 ) 11·4(1(1.• Some 8008 opcodes are DUSR LMA= J;70 '-1 ,o/4(1!) . DUSR LME:= }7:1 MA(F-:0 LHI more complicated than those . DUSR LMC.= 3.72 MACRO CFC ou:=.R UID=37}. 102 '. - :i ;. ­ .. ... -1 ) / 4 (10 •:tC .o=.2 -i~ 07t;". . OU'.::-R l·ff•E=.244 ..: -1.i-•, \ ' - 1 .. / 41?1(1 •:t:4 (1(1' instructi ons involving labels, (.'LISI'' l·l[!H=.24 ~· Mt1(F·O C•u ::.F: l·H•L=.240:. NC · I and all instructions involving C·USF· N[•M=2-i 7 , - .l· - ·· \ -1• .-' 4 ~11)·• · -i(11)• C•-i-i C•USF· l l OF'=:, 00 ' - l ' . '4(11) ' -1 ;. ­ <1.,· -.1 J/4(11) •t400' imm e di ate oper ands. The (•l_l::.1<· OF·A=.;:.·o;·.(1 C•US F· 1)F,·E: = .2t;".1 (FL MHCF·(I SE: I basic probl em is th at these [·U ~.i:;.: (•F'C =20:-.2 .i.12 1?1:?~ C•l.l"E·F· (rf< ( •=.C.·.;.: •, - .l ' - ' ' ,- - 1 •. 41::.(• ' t ·li)(I • \ -1° - ..: .. . -1 · / 4(1(1 • t 4(11:l 1 instructions have operands C•U9•· OF.·E=.2':'.~4 . - 1 '· 40(1 (•l_l"E.F' (1FH= 20:·':· ::.u1 which must be evaluated. C•U"E.R (1F·L=.2.;.o;·. (Ti: 1).24 . C•USF' ( 1F'M "',2>';·.:­ .l42 ' - 1 ' ' - 1 '· ' 4(H) > 1.41)1) • Howe ver these instructions C•USF' f:·HL= .:122 ' - 1 •-• ' • - 1 •. ...i(11) .•···-i(u) • can eas il y be accommodated (•l_l5F" F'AF''-(<2 ' - 1 •. '4(1(• Etl[•

65 b y using the ass embl e 1" s immediate statements (e.g., macro facility to perform th e for those opcodes which eva lu ation s. An exampl e of a require the use of the macro macro defi ned fm the CAL facility). opcode is the following: Assembler Output .MACRO CAL The asse mbl er output 106 shown in Fi g. 3 was obtain ed (t1 )-((( +ll by issuing the command line: /400)*400) macro facility is used in a simil ar manner to create an MAC WALKL.SR $LPT/L which asse mbl es the source (fl )/400 8-b it octal representation of the operand for an immediate file WALKL.SR using the type of opcode. For exampl e, 8008 defined symbol table, if S 1#$ is defi ned as above, an d provides a li stin g via the (Note th at the twas printed then: N:wa's line printer ($LPT) . as a A by th e line p1·i nter.) LLI Sl #$ The leftmost numbers li sted As an exampl e, when the is evalu ated: give the line number in the following lin e is encountered source file. The five digit in the 8008 source code: 066 oc tal number gives the CAL 51 #$ ; CALL SOME 002 address (or program counter) KRAZY ROUTINE value. Note that this is not in then the mac ro will ex pand Implementing the Noval the lntelese format using page this lin e into the following Assembler a nd address within page form: (although as stated before, 106 The implementation of the label operands are correctly ( S 1 #$ )-( ( (Sl #$)/400)*400) asse mbl er with the evaluated into I ntelese (51 #$)/400 8008-defined sy mbol table is format). The six di git octal Now, if Sl #$ is a label at very straightforward. The number gives the contents of location 001002 (n ote that first step is to type in the the give n address. The leading thi s is a true octal number as source file iNT EL.PS as it is three ze roes should be opposed to an "I nte lese" listed in Fig. 1. (Note that it ignored. Printed next on the octa l. number), the number is ass umed that th e user has line is the source statement 001002 is substituted for so me fa mili arity with the that was asse mbl ed into the Fig. 2. A sa mple program, WALKL - so urce input to the every occu rrence of (S 1#$) in Nova test editor and fil e code shown. In the case of assembler. the above expansion so that format.) Then just iss ue the opcodes with operands, the th e fo l lowin g ex pression fo ll owi ng command line: source lin e is printed, res uIts: MAC/S/N INTEL.PS fo ll o wed by the macro T ITL l·U:.U( L 106 Once this has beeri done, the ex pansion of the source lin e. H H ::".THF:T. l •IHU~ L S THF·T >-:RH 001 002-((001002/400)*400) assemb ler can be used wi th U•I ~{( LE I :, ~;:13 001002/400 8008 source files. l·JH U L LAE For the Record ... F'H L which is evaluated by the LE H Using the Assembler L H(• asse mbler using octal integer Once the user has tried F·t:O. L U•H arithmetic to: It is very simpl e to this system, he will no doubt l·l:H LHE 106 asse mble any source program. find unique features of the l·J 2,(1 The first step is to type the mac ro asse mbler which he L ( I 3 . 0~ 002 (•ELF1'T' LFtM LHf'I 002 source prog ram into a fil e can utilize to his benefit (see ( •( C .J F Z C·ELH',' Thu s the macro, despite the using the Nova text editor. the Data General Corp. Macro .Jf'IF' l·IHU L An example is shown in Fig. Assembler User's Manual, ~ IMF' + l fact that the asse mbler was Et ff • ::. H1F'T written for a 16-bit mac hine 2. The .TITL statement is order no . 0 9 3- 000081 ) . and keeps track of memo ry used to name the program if Ho we ver the fo l lowing locations in true octal format, desi red (the default na me is features are some of the mo st is capable of formatting the .MAIN) and appears at the useful. The starting ad dress label's address in the prop er top of all output pages from value can be defined by use Int elese paged format of the macro asse mbler. of th e .LOC psuedo-op. Also, L( ... ) and H( .. . ). The The bas ic format of any th e assembler s upp orts statement is: repet1t1 on and conditional label : opcode operand ops such as: .DO, .I FE, .IFG, comment .IFL, .IFN, .ENDC, .GOTO. Both th e label and the These opcodes can all ow co m m e n t a re o p ti o n al. eas ier ge neration of code. Howeve r, if they are used, the Also, there is no reason why associate d punctuation must further use of the macro be included. An operand is facilities can't be used to take only used for branch and care of the double indirect

66 Fig. 3. The Assembler output for WALKL. INTEL 1 K 2102 RAM (1601 l·JHLI L MH( F'(I PE\! ( 1.2 Factory prime, tested units. Factory selected for O:.:•:l 1?1 2 TITL l·fftUL much faster speed than units sold by others. 650 Ern S TF1F'T . l·JH U -L NS. These are static memories that are TTL ,;_:,,.; (H!I E11) 1;:1 (11210 2 5CI S T HF' T · >:PH compatible and operate off + 5 VDC. The real ~ ~ I :~ (.,::;: •)')0 B:l i'10(u:-i: .:. l1: ..£. workhorse of solid state memories because they 1) :.=< ( 11)1?!t1;; L• (•O : 7 7 · · : ;- ;- •/ 4 ( n) • • 401!1 .• H:O LEI : o:: are so easy to use. Perfect for memories because l ,;_ (1(1(\\!•4 @1) (1 : (1 ~ .. IJ _ • - •' • : 121 : •, ' •h ..11) • • +41) 1~ ,' they are so easy to use. Perfect for TV typewriters, l: 1 4 U(oj (•5 0002 1) 4 l·IHU L LHE mini-computers, etc. With specs. .l5 (1(1 ~11 ) .;. 1)1)1)1) .2.2 F·HL l t . ( •( •( n) -;- 0(10 ::? 40 L EH $3.95 ea. or 8 for $30 l ;- 1)(u)l •) 1)(11) ;: o: LHC.­ 1 ·:: 00011 (n) 0 0 ..2';; F'HL l :.;,, (:1)(•12 (11)0 2 2 1?1 L[•H 2 0 ( u) (•j : 1)(0) 1 6 2 L·l '.! 1 .::J 1) ( 11)1 4 (11) (lJ (1 .:..\ LHE SIGNETICS 1KP-ROM :.: ~ ( 11'1(•1 ':· ( 1(u) 1 •;'.1 L·l '.! 1) L(. I : O•~• 82S129. 256 x 4. Bipolar, much faster than MOS _::4 ( 1( •1)1.;. 1)1)1)1),2.£. 2'': (11)(11 :- 1)(1(1.'.: 1) 1) devices. 50NS. Tri-state outputs. TTL compatible.

LHl'I Field programmable, and features on chip address 2 :? 0 00.2 1 1.)(11:'.:• 2 (17 LHM ;:._;,, 1) (11)2 2 ( •(1(11)21 [•( ( decoding. Perfect for microprogramming appli­ - .JF: C• ELH'1' : ·J (11)(1 2: •!0?1 1~1 .l .lO 1 1 0 cations. 16 pin DIP. With spec. $2.95 ea. : :;: 0002 ..i (1(1(11?1:2 0 o. L•E LFt'1' '•-· • 1.. [•ELH'1' , _,.· 4 e11!1 ··•4•:o!I · : : 1)(1 1!1 ~':• \2l 1) 1)(H)t' • C•E LH '1' ·. '4(11; : -1 .JMF' l·JHU L :;-:; 1) (11),2.;. •)(1t):l i •4 1 1)4 :: r;·. ( 11)(1.2;"' (1(0) 1)!;1~. 8T97B : :-- 1J1:io : o ~) (.i)O f::o) By Signetics. - -:. ~ I MF ' + ·l 41!1 oi::u::i :: ·1 001).1'!14 1~ ..& Tri-State Hex Buffer 41 (1 (u)~.2 •)(o!i0 J~ f-oH' "7" · +:L ·-• ,_ . + :l •/ 4 00 1 ,. 4(11) • MOS and TTL Interface to Tri-State Logic. ~ ~· O•X<::: •) (11)•!10(• ~fa~ e. Oo ~ Ei,7, ,.:. ~·:1:.1~ ~~~;'"0' n;Eec/ f

000.2 MHLt L DO YOU NEED A LARGE COMMON ANODE r ·E L fi'•' 1:;1;0(•2 0 1 / .2 7 1- /3. ~ 1 / 3. '.: JF:; .;,10(11) :-4 l'l( 1 . ' J. O READOUT AT A FANTASTIC PRICE? •.IMF· 0i:h)lt11 MC 1 . ':? 4 l . · -~ u: I (11)(11 5.:. M( l / L :'. S.D. presents the MAN-64 by Monsanto - 40 inch U•I •!1(11) 1 .;.2 M( :l/ 1?1 7 LE I ( 11?11) 1 .;. .; MC l / :l(t character. All LED construction - not reflective S THF·T t:i1;(11) 1)0 Ell 1 . '04 l / 00:: l ."4 4 L·Jf1U L (11!11)oi'11)~. Ell 1 . '(1: 1,•' 04 1 / 14 i.··: i:: 1 / 37 bar type, fits 14 pin DIP. Brand new and factory prime. Left D.P. $1.59 ea. 6for $7.50 addressi ng problem, etc. use of a post-processor could MOTOROLA POWER DARLINGTON - $1.99 Another interesting feature of be to punch a paper tape of MJ3001 - NPN - 80 Volts - 10 Amps - HFE 6000 the macros is that they can be the o bject code which could typ. To-3 Case. Ideal for power supplies, etc. recursive. be loaded directly into the We include a free 723 regulator w/schematic for Further refinement of t hi s 8008 system if a paper ta pe power supply with purchase of the MJ3001 . You system, currently being reader was available. get the two key parts for a DC supply for only considered by the author, is $1.99. Regular catalog price for the MJ3001 is the u se of a Fortran Disavowal . . . $3.82. post-processor program which The fact that the 8008 can cou ld reformat the li sting execute some opcodes LARGE SIZE LED LAMPS with addresses in Intelese so doesn't make it a cor:iputer. Similar to MV5024. Prime factory tested units. We that they would be easier to This was fo und o ut the hard include plastic mounting clips which are very hard read. Also, there is a slight way - by building an 8008 to come by. "bug" when using PC relative system (it seems that while Special 4 for $1 addressing as was done on software people claim they line 39 of the progra m in Fig. could have surmised this from 48 HOUR SERVICE 3 (e.g., the j MP .+1 looking at the instruction set, You deserve, and will get prompt shipment. On statement). In this case, the hardware people have to orders not shipped in 48 HRS' a 20% cash refund low o rder byte of the jump build a working system will be sent. We do not sell junk. Money back address is eva lu ated to one before they learn .. . ). guarantee on every item. WE PAY POSTAGE. less than it sho uld be. A However, there are some uses Orders under $10 add 75c handling. No C.0 . D. post-processor co uld eas il y for an 8008 system. The Texas Res. add 5% tax. identify this case, and correct author is presently working it. (Until such time, this on an artic le by the title: problem can be avoided by " How To Make the 8008 using labels for all branches ­ Emulate a Compu ter." S. D. SALES CO. which is better programming [Look for it in a future P. 0. BOX 28810 DAWS, TEXAS 75221 practice anyway 1) Another issue of BYTE - CH.]

67 Asynchronitis sufferers - relief is here. h Christopher M. Bannoft CELDA T Design Aswciales Box 752 Asynckronitis Amherst NH 03031

Do you suffer from h oweve r, because the the leading edge of the gate asy nchronitis? A typical frequencies are not identical and trailing edge of the clock, sufferer has two systems, - as we see in Fig. 1, showing or vice versa, are nearly eac h with its own clock, and Cas e 1 effective simultaneous - out comes a these systems must communication, Case 2 - a short pulse, alias glitch. If Fig. 1. The Asynchronitis communicate. With a simple bit garbled, and Case 3 ­ Sufferer. There are cases where counters - or any similar the system #I clock and the AND gate their oops! Th e result in Case 3 devices - are used, this blip system #2 gating signal overlap communications suffe r, shows what happens when may only partially trigger perfectly (1 and 2) and other them, causing erratic or pesky cases (like 3) where a glitch erroneous results. develops. The chronic sufferer may be cured with a dose constructed from a 7400

CLOCK package, just a shade more complicated than the single

CASE { GATE NANO gate. As simple and inexpensive as it is, this I OUTPUT -----~ dosage guarantees that the gated clock pulses are always { GA TE _____r---­ 2 complete, eliminating those OUTPUT nasty short spikes which cause bad operation. This { GATE 3 /--.., ,---, cure also provides an output OUTPUT ____I~ 1 which rises and falls in I '-',I,.,....,.,,,..,...,.,...._-=-==""...,.,...., ' --\GLITCH AT TRAILING EDGE '-'\GLITCH AT TRAILING EDGE synchronization with the OF GATED CLOCK OF GATED CLOCK clock, no matter when the CLOCK (SYSTEM NO I) >----OUTPUT gate command occurs. (See Fig. 2.) Examining the timing diagram (Fig. 3}, we see how the cure works. Gates 1 and 2 GATE (Fig. 2) form a latch that (SYSTEM NO 2)

Fig. .2. How the cure looks. Materials: one 7400 package.

A F CLOCK 8 SYSTEM NO .I

B GATE SYSTEM NO . 2 PIN 14=VCC =+5V PIN 7= GND= OV ALIGNED OUTPUT GATE COMMAND GATED CLOCK OUT TO SYSTEM NO .I

88 Fig. 3. How the cure works. Case 1 shows the de ·glitcher without an active role due to fortuitous alignment. Case 2 shows how a glitch (cropping up at C) is ignored and replaced by a full clock pulse at output F (and a clock synchronized gate level at output E). All gates 7400.

A

holds the data in the off state 8 ______. when the gate goes high (logic level one) with the clock c high. At C, there is a possible CASE glitch out when the gate turns I 0 off (Fig. 1, Case 3) . However, Gates 3 and 4 form a latch to E____~ shield the output from glitches. The output at F, as F seen in Fig. 3, is reliably glitch-free. Because E, Fig. 2, B is gated in synchronization c with the clock, the output at CASE F is synchronous with the 2 0 clock input E ---~

F

USE OUR HARDWARE ASSEMBLERSW SAVE TIME AND FRUSTRATION WITH THESE CONVENIENT PRINTED CIRCUITS Q

4096-BYTE MEMORY MATRIX MACRO CARD Have you ever wanted to construct a memory matrix as part of a system?? The tedious part is the interconnection of all the address a nd data bus pins! The CDA-1 .1 memory matrix is a general purpose memory prototyping card for the 2102/2602/9102 pinout static RAM chips. This PC card is 8"x10" with 70 pin edge connector, gold plated for reliability . The memory matrix occupies about 60% of available area with all lines brought out to pads for wire-wrap pins and has pl ated-through holes. The other 40% has 24 16-pin socket positions and a general purpose area which can hold 12 16-pin sockets, or 4 24-pin sockets, or 2 40-pin sockets. Add a custom wired controller to interface this board's memory matri x to any computer, o r use the prewired matrix as the basis for a dedicated 4K by 8 memory in a custom system. Think of the time you save!! GENERAL PURPOSE PROTOTYPING CARD The CDA-2.1 general purpose 8"x10" prototyping card comes predrilled for use in construction of custom circuits. This board accommodates 16-pin sockets plus has a general area for 16-pin sockets or 24 or 40 pin sockets. The 70-pin edge connector is gold-plated for reliabil ity and the pins are brought to pads for wire-wrap post insertion. The soc ket side has a solid ground plane to minimize noise problems; busses on the wiring side allow short jumper connections for power and ground. A whole system may be constructed in modules with these boards. DIGITAL GRAPHIC DISPLAY OSCILLOSCOPE INTERFACE, CDA-3.1 James Hogenson (see the October issue of BYTE magazine) designed a 64x64 bit-matrix graphics display for oscilloscope. This design permits use of your scope as a display for ping-pong, LIFE, or other games with your system. The CDA 3.1 card provides all the printed wiring needed to assemble the graphics display device down to the TTL Z-axis output as described in October 1975 BYTE . To complete the display you merely add components to this double sided card with plated-through holes. For info: CIRCLE READERS' SERVICE NUMBER - or, send your order using the coupon below:

YES~ Please rush me the boards ordered below: FROM: \... ( __ )-;l. D 4096-BYTE MEMORY MATRIX PROTOTYPING NAME CARD at $49.95 ADDRESS D GENERAL PURPOSE PROTOTYPING CARD AT .; ~ \ _ If --\ $29.95 _\ . ;. . D DIGITAL OSCILLOSCOPE GRAPHIC DISPLAY CARD AT $29.95 , ""\

D 1've enclosed a check or money order for CELDAT DESIGN ASSOCIATES $ Foreign orders (except Canada) please P.O. BOX 752 add $2 postage per card. AMHERST, N.H. 03031 Please allow four weeks for delivery - you must be fully satisfied or your money will be cheerfully refunded.

69 Build an Osei Iloscope

Ever wonder how to make a computer draw pictures for output? One way is to use an oscilloscope - which many readers have on general principles for debugging the logic Many members of the circuitry. Jim Hogenson provides a practical circuit for large family of alphanumeric accomplishing that end in his "Oscilloscope Graphics Inter­ computer output devices may face" design. This graphics device was conceived by Jim as a be readily used in the home neat idea to add to the 8008-oriented computer system he was computer system_ But there are as yet few devices of a building for a high school science fair. He first mentioned it to graphic orientation which are me in a letter late last year. I suggested to him (or was it the economically acceptable in other way around?) that it might be appropriate to turn it into the home computer system. an article for the ECS Magazine I was publishing at the time. The osci I loscope graphic Aher a fair amount of time spent researching the various interface project prese nted options - plus one lengthy phone conversation with me - Jim here provides one unique, settled on the design shown in this article, which is reprinted inexpensiv e a nd here from its original publication in the last issue of ECS uncomplicated solution to Magazine. The interface is very simple, and can be adapted to the graphic output problem virtually any computer with a minimum of 8 parallel TTL in small scale systems. It output lines and a clock pulse line which is active when output turns a n essential test instrument - the oscilloscope data is stable. Arrangements have been made for a PC version - into a versatile output of this design (see the parts list, Fig. 6) so you won't have to device. wire wrap the thing like Jim did in his first version. The oscilloscope graphic .. . CARL interface is programmed and operated through a parallel 8-bit TTL compatible input. An image is represented by a &y pattern of dots which is ./111ncs 1-logcnsun organized according to the /fo x 29.5 computer's instructions. llalsl11d MN 56548 During the scan cycle, the digital dot pattern is converted to a n a log waveforms which reproduce Fig. 1. Oscilloscope graphics display block diagram. the image on an oscilloscope screen. The graphic interface stores the dot pattern within INPUT its own internal refresh memory. Therefore, once the pattern has been generated CONTROL COUNTER and loaded into the graphic CIRCUITRY interfac e memory, the computer is left free to execute other programs.

CHIP MEMORY ____, SELECT Principle of Operation CKTRY The raster begins its scan ,- -1 in the upper left-hand corner, : BLANK I x scanning left to right and I CKTRY : DAC down. The full raster contains L_+_-1 4096 dots, 64 rows of 64 dots each. The horizontal z VERTICAL HORIZONTAL OUTPUT OUTPUT OUTPUT scan is produced by a

70 Graphics Interface

Fig. 2. Oscilloscope graphics inter­ face instruction codes. steppin g ana log ramp wave. Op Code Each or the 64 steps in th e Binary Octal Mnemonic Explanation ramp produces one dot. The OOdddddd Odd ST X Set X vertical scan is simil ar. It is a 01dddddd 1dd ST Y Set Y s t e ppin g r a mp w a ve 10xxx000 2x0 DCY Control - Decrement Y co nsisting o r 64 steps. 10xxx001 2x1 TSF Control - Turn off sca n Howe ver, there is only one 10xxx010 2x2 ZON Control - Set Z on step in the vertical wave for 10xxx011 2x3 ZOF Control - Set Z off eac h complete hori zontal 10xxx100 2x4 ZNI Control - Set Z on with increment ramp wave. The result is 64 10xxx101 2x5 ZFI Control - Set Z off w ith increment vertica l ste ps with 64 10xxx 110 2x6 T SN Control - Turn on sca n hori zo ntal ste ps per vertical 10xxx111 2x 7 DCX Control - Decrement X step, or 64 rows of 64 dots 11 xxxxxx 3xx CNO No Op each. d = data x = null The timing of hori zontal and vertic al sweep waveforms ori gin ates in a 12-bit bi nary counte r, the operational center of the entire circu it. contro l is represe nted by a The six least significant bits sing le bit. It is thi s bit which or the coun ter are connec ted is sto red in the intern al t o a di g ital- to-ana log memory of the osc ill oscope decodes the 8-b it input word co nv e rte r ( DAC) whi ch graphic interface. There is and all o ws fo r comp letely co nverts the di gital binary one bi t in the memory fo r programmed operation. input to a voltage level each of the 40% dots in the output. Th e output of the raster. When di splay in g the Programming leas t signific ant DAC is the image, the 12-bit counter Th e pro g r a mmin g hori zontal ramp wave. The which produces the raster instruction fo rmat is shown six most significant bits are addresses the app rop ri ate in Fig. 2. Bits 7 and 6 of t he connected to a second DAC. dot status bit in the me mo ry input word are the hi gh-order Th is DAC produces the as that dot is prod uced on the in s truction code. It is vertica l r a mp wave. screen. The on-off dot status assumed that the address ing In cre me nting the 12-bit bit taken from the memory is of dots is done on the basis of data bn bits 0 through 5 of cou nler at a fr equency of converted to a Z-ax is signal X and Y coordinates. The X the input word is loaded into aro und 100 kHz res ults in a which co ntrols the intensity coordin ate is the 6 bits in the the least signi fi cant counter rJster on th e screen of the of the dot on the scree n. least significant or horizontal section as the X coordinate. osc ill oscope. The major porti on of the section of the 12-bit cou nter. Wh en the instruction code is The contrast in the pattern circuitry is taken up in the The Y coordin ate is the 6 bits se t at 01, the data on bits 0 or clots needed to represent a 12-bit counter, t he DACs, in th e most sign ificant or through 5 is loaded in to the pi cture is dependent upon the and the memory. Fig. 1 vertic al section of the mo st significant counter in te nsit y or each dot. From shows a block di agram of the coun ter. In programming section as the Y coordinate. thi s point, it is ass umed that a osc ill oscope graphic interface . from an 8-bit microcomputer in effeCt, the Y coordinate dot can be either on or off. The remaining circui try is the source, all 12 bits of t he will se lect a row of dots, An "on" dot will show up on contro l c ircuitry which counter cannot be set at while the X coordinate will th e scree n as J bright cl ot of once. Th e counter is set one se lect one dot in the se lec ted light. An "off" dot will be J half or 6 bits at a time. It is row. The coord in ates loaded dim cl o t or li ght. for this reason X and Y into the counter will address Wh en a parti cular dot is coordin ates are assumed in addressed by the cou nters, it progra mming. may be se t to eith er the "on" Wh en the in stru ction code or the "off" state. Th e o n- o ff (bits 7 and 6) is set at 00, the

71 the memory and se lec t the clock pulse is used to execu te des ired dot status bit for the instructio n. This clock progra mming. pulse is take n from the After l oa din g th e programming. Control code mi c r ocomputer o ut p ut coordinates of the d ot "1" will sto p the scan. in terface. The in structi on se lecte d for programming, the Control code "6" will res tart code is decoded by the 74 10 status of the do t (on or off) is the scan. Wh en the scan is o n, triple three-input NAND ga te se t usi ng the ZON, ZOF, ZFI the 12-bit coun ter will be and two inverters. The clock or ZNI control codes. Setting incre me nte d at a hi gh will decrement the stored Y puls e is enabled by the the in structio n code at 10 frequ e n cy a nd t h e coordinate. Control code "7" NAND gate t o the directs the control circuitry pr og r a mm e d im age is will not se t Z, but will appropriate counter sec ti o n, to decode the three least di s pl ayed o n the scope decrement the entire 12-bit or to the strobe input of the significant bits of the input screen. counter by one. This, in control code decoder. word for fu rther instructio n. Control code "2", " set Z effect, will decrement the Th e 1 2-bit counte r The three least significant bits on", will program a b right stored X coordinate. Since consists of two 6-bit counting arc called the "control code." dot to appear at the dot the X and Y counte r sectio ns sections. Each sectio n Since the 12-bit coun ter location presently stored in a r e cascad e d , Y will consists of two cascaded TTL mu st s t ore selected the counter. Control code auto maticall y be incremented 7 4 193 presettable binary coor din ates durin g "3", "set Z off", will or decremented once for counters. Bits 0 through 5 of progra mmin g, the raster scan program a dim dot or bl ank every 64 executions of an the data input are common to mu st be disabl ed before to appear at the dot location in crement or decreme nt X both sections of the counter. presently stored in the 12-bit control code. The set X in stru ction wi ll counter. Th e increment a nd pulse the lo ad inpu t o f the Co ntrol codes "4" and decrement control codes are least significan t o r ho ri zon tal "5" set Z in the same manner very useful in constructing section, while the set Y as control codes two and lines in an im age since lin es instructio n will pulse the load req uire repeated "set Z" input of the most signi ficant instru ctio ns, often on the o r ve rtical section of the sam e axis. An effective counter. A pulse o n the load metho d of clearing an im age input will cause the data on bits 0 through 5 to be loaded into the proper counter Fig. 3. Timing pulse input to the sectio n. interface. Th e 8 data Jin es must Four TIL counters mu st be s ta ble during this pulse. b e u se d to provide ind e p e nd e nt l oad in g capabilities for each 6-bit

----~ 1- ---PULSE WIDTH DETERMINED - ­ section. The counters within BY EXTERNAL CLOCK PULSE SOURCE MINIMUM 750 NS each sectio n are cascaded in the normal fas hi o n. The two DATA STO RED COUN TER INCREME NTED seetions are cascaded by connecting the upper data B output of the X counter section (IC 8, pin 2) through inverte r "a" of IC 2 to the count up input (IC 9, pin 5) from the screen is repeating a of the Y counter section. The ''set Z with increment" inverter is needed to provide control code in a pr o p e r synchroniza tion three. However, afte r setting progr a mme d l oo p. This in hi gh frequency countin g. Z, these instructio ns will metho d allows the option of Th e control code is incremen t the counter by o ne using either a li ght or dark decoded b~ a 74155 decoder thus advanci ng to the next image background. connected for 3 to 8 line dot location in the raster scan decoding. Bits 0 through 2 pattern. This will all ow Circuit Operation are decoded by the 74 155. programming of the ent ire Once the data word o n the The control code is enabled raster using onl y a repeated microco mpu ter p a r a l le i by the pulse coming from the "set Z" in struction . output in terface is stabl e, o ne 7410 instructio n decoder Control code "O " will not only wh en the instructi on set Z, but will decrement the code is set at 10 o n bits 7 and most significant or vertical 6. secti on of the counter onl y. Decoder Ii nes 1 and 6 arc In effect, contro l code "O" connected to an R/S flip fl op

72 Fig. 4. PC art work of the graphic inlerface, by Andrew Hay. (a) Component side.

- .. -- -­ .. ... f5 -• - c: -I 0 • 1: ­- 0,. M - I - 0 • -O> ­-~• N II Ii rl= - - -­ - -(X) -.....

73 Fig. 4. PC artwork of the graphic interface, by Andrew Hay. (b) Solder side.

• ..... 0 '° • 0 0

0

0 0

• • 0 0 • 0 0 ---oo o~------0---~--~ 0 0 0 0 oo--~~~~~~oo--~~~~~- o 0­

0

2 •

74 TO 8-BIT DATA INPUT TO C LOCK PULSE INPUT

Fig_ 5. A test circuit for manual SPOT operation. The set-reset flip flop TOGGLE of the 7400 circuit genera tes a debounced clock pulse which will perform the operation set into the toggle switches. If you haven 't got a computer up and running yet, th e manual in terface can be used in order to SPOT test out th e display. MOME NTARY

1/4 7400 TTL NANO 1/2 7400 TTL NANO

instruction format, Fig. 2, bit ORed. The resu lting pulse zero wi ll be bi nary zero for incre m e n ts the counter "set Z o n" in structions and acco rdin g to co ntro l incremented o n the trailing w hich provides t he scan binary one for "set Z off" commands. edge. Fi g. 3 shows the on/off co ntrol. The flip flop in structio ns. The backward The same clock pulse waveform timing. enables the system cl ock to appearance of thi s binary taken from the computer Output bi ts 0 through 9 o r provide the high frequency format wi ll be ove rl ooked output in terface is used to the 12-bi t co unter arc sq u a r e wave which whe n programming in octal write data into the memory connected to the address incr e m e nts t h e 12-bit notatio n_ and in creme nt the counter in inputs of the me mory. The counter. The hi gh frequency system control commands 4 and 5. me mory uses fo ur MM2102 Control codes 2 through 5 clock controlled by the R/S The data is written into t he type 1 k x 1 bit MOS RAMs define the "set Z" flip fl o p and decoder Ii nes 4 memory o n the leadin g edge (Random Access Memories). instructions which perform a and 5 are negative logic of the pulse. The counter is Bits 10 and 11 of the counter data write o peratio n. Decoder output are connected to the lines 2, 3, 4 and 5 are chip select circuitry which connected to a group of AND gates (IC Sa, b, c) functioning as a negative logic 0 R gate. Fig. 6. Parts list. The outpu t of this gate is the Read/Write control lin e for

the me mory. Wh en this line is C1 , C2 20 p F disc ca pac itor in the low state, the data C3, C5, C6-C11 .01 mF d isc capacitor present o n t he data input line C4 .0015 mF disc capac itor of the memory will be C12 25 m F electrolytic capacitor written into the memo ry locatio n presently stored in IC 1 7410 TTL triple 3-input NANO gate the 12-bit counter. IC 2 7404 TTL hex inverter The data inpu t of the IC 3, IC 4, IC 20 7400 TTL quad 2-input NANO gate me mo ry is connected directly IC 5 7408 TTL q uad 2-i nput AND gate lo bit 0 o f the 8-bit input IC 6 74155 TTL dual 2-to-4-line decoder IC7 - IC10 74193 TTL p resett ab le 4 -bit bi nary counter word. This bit is stored in the IC11-IC14 2102 NMOS 1024-bit static RAM me mo ry on ly when a set Z IC 15, IC 16 MC1406 Motorola 6-bit DAC command is executed. The IC 17, IC 18 741 Op amp Z-axis circuit configuration IC 19 NE555 Oscillator (timer IC) wi l I require a hi gh state pulse for a bla nk o r dim dot. As R1, R2 3 .3k Ohm resistor s h ow n in the binary R3, R4 5.6k Ohm resistor R5, R6 10k Ohm miniatu re potentiometer R7 1 k Ohm resistor (all resi stors Ya Watt, 10%) R8 2.2k Ohm resistor R9 7.5k Ohm miniature potentiometer

A printed circuit board using the masks of Fig. 4 is available for $29.95. Write to M . F. Bancroft, CELDAT Des ign Associates, Box 752, Amherst NH 03031 .

75 Fig. 7. Osc illoscope graphics interface circuit diagram. (a)

8· BIT DATA INPUT CLOCK PULSE INPUT 87 BO

------iG

I 15 3 13 C B A IC6 74155 6543210

COUNTER INCREMENT '------~F

connected to the Y may be employed. The PC coordinate DAC. The DACs pattern is designed for easy are Motorola MCl 406 !Cs. soldering. The components enables one memory chip at a The DA Cs operate on need be soldered on the time for addressing and data voltages of +5 and -5 to -15. bottom side only. input/output operations. The A current output is produced Remember that the chip select circuitry uses 2 by the DACs. The current memory ICs are MOS devices inverters and a TIL 7400 output is converted to a and should be handled as Quad two-input NAND gate. voltage output and amplified on the interface PC pattern is such. Static electricity will The data outputs of the by the 741 op amps. The TIL compatible only. Most easily puncture the thin MOS RAMs are OR-tied and output from the X coordinate scopes will need some type of transistor junctions. connected to an AND gate. amp is connected to the blanking circuitry to amplify Bypass capacitors should The data output is horizontal input of the scope. the TTL level pulses. The be connected between supply synchronized with the high (The scope should be set for design of the blanking voltages and ground. A frequency clock for better external horizontal sweep.) circuitry will be of the minimum of a 10 mF blanking performance. The The output from the Y amp builder's choice, allowing the electrolytic or tantalum output of this gate is is connected to the vertical builder to best suit his scope. capacitor should be used for connected to the Z-axis scope input. A suggested method which is all supply voltages. For the blanking circuitry. The Although the scope used simple and effective is the use +5 logic supply, one .01 m F blanking circuitry converts does not need de-coupled of the circuit shown in Fig. disc capacitor should be used the TTL level signal to a inputs, triggered sweep, or 13. for each 2 to 5 integrated sco pc comp a·t i ble signal high frequency response for circuits. The large which may be varied over a this project, a Z axis or Construction wide range of output voltages intensity input is required. This project may be lo best match the scope being The Z axis output provided wire wrapped, the PC artwork used. in Fig. 4 may be used to Bits 0 through 5 of the fabricate a double-sided 12-bit counter are connected printed circuit board, or the 10 the X coordinate DAC. printed circuit board product Bits 6 through 11 are mentioned in the parts list

76 elec tro lylics will filter out Fig. 7. Oscilloscope graphics interface circ uit dia gram .(b ) low frequency noise and voltage transients while the small disc capacitors will c filter ou t hi gh frequency ~ ., , I I R5 IOK noise which cou ld false ly B 12 3 10 A6 LSB trigger flip flop and cou nter 9 13 RI 3 .3K IC15 R3 circuits. B MCl406 5.6K 7 Set-up, Testing and Operation 6 4 The system requires a +5 I I volt, 400 mA power suppl y 3 2 and a dual polarity sup ply of - 9V (SEE fro m ±9 to ±15 volts at 10 TE XT ) mA. The wide range of analog supply vo ltages all ows use of existi ng power suppli es for the graphic interface. The clock pulse derived +5V + 5V R7 from the computer parallel IK II R6 1/0 interface should be active IOK in the low state. If a device operating with an active hi gh pulse is used, one of the free 6 gates of IC 20 may be used to 5 4 .....-l~---IAI MSB I------~ invert the clock pulse or IC Y>-

3 C/ S3 ,-- --1 I z AXIS I I BLANKIN G CIRCUITRY I B C/S 2 I (SEE TEXT) I I I L__1__ _, II C/ SI

13 SCOPE COMPATIBLE Z AXIS OUTPUT H IC POWER AND PIN CONNECTION CHART C6·11 +5V .01 µ F IC +5 GND +9 .9 N/C 1,2,3,4,5 14 7 6 16 8 9.4 7,9 16 8, 14 8, 10 16 8 , 14 6,7,9,10, 12, 13 11 ,12,13,14 10 9 2102 MEMORY ADDRESS PIN CONNECTIONS 15,16 11 2 3 17, 18 7 4 1,5,8 A-0 - pin 8 A· l ·- pin 4 A -2 ·· pin 5 A -3 ·· pin 6 19 4,8 1 A -4 ··pin 7 A -5 ·· pin 2 A-6 ·-pin 1 A -7 ··pin 16 20 14 7 1.2.3,8,9,10, 11, 12,13 A -8 -·pin 15 A -9 ·· pin 14

77 Fig . 8. CLEAR Program flo w chart. Ad justi ng the frequency may Slight gaps or ove 1fa ppi ng be necessary to obtain a bet ween some dots is caused stable raster. The frequency is b y non-lin eariti es in the START manu fact uring or the DAC s. LOOP adju ste d using R9, the 7.5k pot. The frequency of the If no ras ter at all ap pears, syste m clock should be first chec k ror a sq uare wave app rox im ate ly 100 kHz, but output at pin 3 of th e 555 is not critical. The onl y ti mer IC. Th en check fo r OUTPUT requirement is ap pea rance of sq uare wave outputs at each " TURN OFF SCAN" INSTRUCTION the raster. TTL 74193 counter. These If the raster is evenl y square wave s will be binary distribu ted over the screen, submultiples of the osc illator but is severely chopped up, frequency . If the counter is check the digital inpu ts to the operating, check all con­ DACs. Use the scope to check nectio ns to the DACs and op LOAD ITERATION the vertical and horizontal amp s. COUNT INTO REGISTERS ramp waves individuall y. If Applyin g powe r wi ll the wave is not an eve n ramp, produce a rand om pattern of two or more of the DAC on and off dots. Adjust the inputs may be reversed . Note amplitude of the Z axis sig nal that DAC input A 1 is the for best contrast. Sin ce most most significant bit while s cop es wil l have an OUTPUT " ZFI " input A6 is t he least ac-cou p I ed {or capacitor INSTRUCTION sign i f i ca nt bit. Reversed coupled) Z ax is inpu t, both inputs may a lso cause ampl itude and freq uency of incomplete raster formations. the signa l will affect

DECREMENT ITERATION COUNT

Fig. 10. To construct a line se g­ ment in the direction shown by the arrow, alternately execute the NO YES RETURN commands shown.

a. ZNI

b . ~ ZNI, STV(n+1 I Fig. 9. Listing of 8008 code for th e CLEAR program. c. ZON, STV(n+1)

START d . / ZON, OCX , STV(n+1 )

00/344 = 006 LAI ZON, DCX 00/345 = 201 (TSF) 00/346 121 OUT10 I. ZON , DC X, DCV 00/347 006 LAI 00/350 205 00/351 016 LB: g. "' ZON, DCV 00/352 377 t 00/353 026 LCI h. / ZNI , DCV 00/354 021 00/355 121 OUT10 00/356 = 011 DCB 00/357 150 JTZ 00/360 365 00/361 000 00/362 104 JMP 00/363 355 00/364 000 00/365 021 DCC 00/366 110 JFZ 00/367 355 00/370 000 00/371 377 HLT

78 performance. Charging the Fig. 11. CHECKERBOARD Test Pattern Program flow chart. capacitor within the scope with too much voltage at a START given frequency will cause the blank pulse to carry ove r into the next dot. This co uld cause more dots than desired TURN OFF SCAN, to be blanked out or dimmed. SET X & Y TO "O," After a satisfactory ras te1· CLEAR REGISTERS, is obtain ed, each in struction SET PARITY shou ld be executed to verify REGISTER. its operation. First, clear the screen. The flowchart for a simple CLEAR program is INVERT PARITY; shown in Fig. 8. The method SELECT "SET Z" outlined is to simp ly send out DEC LOOP INSTRUCTION a "set Z off with in crement" ACCORDING TO PARITY. instruction 4096 times. Fig. 9 shows the program li sting for an 8008 system. This example used the B and

C registers to keep track of NO the iteration count. The DOTLOOP INCREMENT "B" register contents are decremented once for each outpu t ZFI instruction. The OUTPUT SELECTED RETURN instruction may be SET "Z" substituted with a HALT if INSTRUCTION the CLEAR program is not to be used as a called subroutine. The CLEAR subroutine as listed in Fi g. 9 NO begins by turning off the scan XSECLOOP INCREMENT "C" (which must be done before any programming, as stated), but does not turn the scan back on after the interface memo1y is cleared. The course of operation is left to NO the programmer once CLEAR ROWLOOP INCREMENT "D" has been call ed. The chart in Fig. 10 may be used in testing the various control commands. The chart shows the commands to be used to cor1struct a Ii ne YSECLOOP NO ADD 040sto segment in the direction "D" REGISTER shown by the arrow. Lines moving in a downward dir2ction require that Y be reset with (n+l) for each dot programmed, "n" being the

INCREMENT " E" TURN ON SCAN EXTRA TIME TO INVERT PARITY AN EXTRA TIME .

HALT

79 Fig. 12. Lis ting of 80 08 code for prese nt Y coordin ate. Use the th e CHECKE RBOARD program. STX and ST Y instructions-to se lect a sta rtin g point. The dot whose coordin ates arc START 00/ 200 = 006 LAI 00/ 255 = 302 LAC X=OO, Y=OO will be in th e 00/201 = 201 (TSF) 00/ 256 = 024 SUI 00/202 = 121 OUT10 00/257 = 003 upper left corn er, the point 00/203 = 006 LAI 00/ 260 = 150 JTZ where the scan begin s its 00/204 = 000 (ST X ) 00/261 = 267 cycle. 00/205 = 121 OUT 10 00/262 = 000 The fl ow chart for a 00/206 = 006 LAI 00/263 = 020 INC CHECKERBOA RD TEST 00/207 = 100 (STY) 00/264 = 104 JMP 00/ 210 = 121 OUT10 00/265 = 221 PATTERN program is shown CLEAR 00/211 = 016 LBI 00/266 = 000 in Fi g. 11, with an 8008 REGISTERS 00/212 = 000 ROWLOOP 00/267 = 026 LCI li stin g in Fi g. 12. The pattern 00/213 = 321 LCB 00/270 = 000 pr o du ced will be 16 00/214 = 331 LOB 00/271 = 303 LAD 00/215 = 351 LHB 00/272 = 044 NOi alte rn atin g li ght and dark 00/216 = 361 LLB 00/273 = 037 squares. The 64 rows of dots 00/217 = 046 LEI 00/274 = 024 SUI are divided in to 4 groups of PARITY REG 00/220 = 000 00/275 = 017 16 rows each. Eac h row is DECLOOP 00/221 = 040 INE 00/276 = 150 JTZ 00/222 = 304 LAE 00/277 = 305 divided into 4 seg ments. The 00/223 = 044 NOi 00/300 = 000 segments are altern ately li ght 00/224 = 001 00/301 = 030 IND and dark. The 4 gro ups also 00/225 = 150 JTZ 00/302 = 104 JMP alte rnated to reve rse the 00/226 = 246 00/303 = 221 patte rn between eac h group . 001221 = ocio 00/304 = 000 00/230 = 066 LU YSECLOOP 00/305 = 303 LAD The set Z with incre ment 00/231 = 332 00/306 = 044 NOi in stru ctio ns is use d. The DOTLOOP 00/232 = 301 LAB 00/307 = 340 leas t significa nt bi t of the E 00/233 = 024 SUI 00/310 = 330 LOA register is used in DECLOOP 00/234 = 020 00/311 = 024 SUI 00/235 = 150 JTZ 00/312 = 140 to altern ate between "set Z 00/236 = 253 00/313 = 150 JTZ on" and "set Z off." To 00/237 = 000 00/314 = 326 obtain the complement of the 00/240 = 010 INB 00/315 = 000 entire patte rn on the scree n, 00/241 = 307 LAM 00/316 = 303 LAD place a 001 in location 00/242 = 121 OUT 10 00/317 = 004 ADI 00/243 = 104 JMP 00/320 = 040 00/220 inste ad of 000. 00/244 = 232 00/321 = 330 LOA 00/245 = 000 00/322 040 INE DECLOOPJMP 00/246 = 066 LU 00/323 104 JMP 00/247 = 333 00/324 221 00/250 = 104 JMP 00/325 000 00/251 = 232 END 00/326 006 LAI 00/252 = 000 00/327 206 (TSN) XSECLOOP 00/253 = 016 LBI 00/330 121 OUT10 00/254 = 000 00/331 377 HLT 00/332 204 (ZNI) 00/333 205 (ZFI)

TTL Z - A X IS Z AXIS DRIVE (TTL)

DRIVE FROM GRAPHICS INTERFACE 2 .2k

Fig. 13. A Z-axis drive circuit used to control blan king in the au th or's original version of the design . Th e transistors are 2N 5139s and th e dio des are silicon switching diodes such as the 1N91 4 part or its equivalent. Z AXIS OUTPUT

80 -:;_? , , -,,,---;;:

Mike is demonstrating the prototype Sphere system It is on Here's Mike with the Sphere system cabinet and keyboard. In three boards, a keyboard/character generator, CPU and production there will be several more control keys on the memory board. The output is being displayed on a small keyboard, including a numeric set of keys for fast number television screen. entry, cursor control, etc. from page 61 game program and let me sit mu ch more th an a rumor. interfacin g of memory and down and kill off th e entire Th e dates of release we ren't peripherals. some of the other 6800 based populati on of a mythi cal fi rm ed up ye t, but it was We' ll have a lot more in fo computer systems which are country in short order ... definitely comin g down the on ju st wh at MITS is doin g comin g out . .. more on th at a nd b eco me in st a ntl y pi ke. Ed said th at MITS and their plans in the near later. addicted to compu te r games . would give good support to future. Th e pl ans were to se t up a I p romptl y o rd ere d a both the Intel 8080 and Fro m New Mex ic o I Aew pro du cti on fa cility in th e complete Al ta ir 8800 with Motorola M6800 sys tems. to San Antoni o and a short back part of th e building and enough memory to handle Wi th both Sphere and MITS vi sit to Southwest Technical have the first kits avail able in Sta r Trek. I wante d it ri ght p ro ducing 6800 systems Pr o du cts, Da n Meyer October. This will ta ke so me now, bu t I had to get in line Motorola was doin g we ll and pro pri eto r. SWTP has long doing, but I wouldn 't be behind the oth er custo mers. their so lid backup of th eir bee n we ll kn own for th eir surpri sed if they co me close Next, in ta lkin g with Ed chip s was pay in g off. This exce ll ent hi-fi kits . Readers of for th ey a re a ve ry Roberts, the president of would also mean a bi g plus to Th e A udio A m ate ur determined group. MITS, I fo und that the use rs sin ce this wo uld a ll ow a (Peterb orough NH 03458) They have an in terest in g rum ors of a new M ITS system lot more s wa ppin g of set of peripherals in the based upon th e M6800 was programs and would simpli fy Continued on page 87 wo rk s, including so me medium cost fl opp y disk sys te ms, and a poss ible revolu tionary tape syste m. We'll try to bring you up to date on Sphere as thin gs prog ress.

MITS The Altair 8800 has been se lling well , as you probabl y kn ow, and they are bu sy kee ping up with it. They are also in production on all sorts o f interface and control boa rds, memory boards, etc . They also have a ve ry busy gro up o r coll ege-types workin g away at pro gram dev elo pme nt. Th ey are deliverin g Basi c now and are about ready to let lo ose Ex tend ed Bas ic. They put Bas ic into a system for me so I could see it work . . . th en Meanwhile, at MITS, over 5000 Altair 8800's have been shipped. Here is a view of part of the ran in a tape of a Hammurabi production line (during lunch when people were out).

81 two covers and me et at the expandi ng one's creative middl e. Computer Lib is a powers - a topic of intense genera l , "cultural" personal interest to the introduction to comp uters author. Som e useful for all those who believe that in trod uctory mate ri al on COMPUTER the y will "never understand" display terminals, fi lm outp ut what computers are all a bout. (and computer art), halftone It covers many topics: The image synthes is, and shading basic stored program concept, and smoothing objects is the "rock bottom" aspects of included here . The author computer architecture and then describes his far-out m ac hine l anguage, ide as for a n advanced minicomputers, big text-handling system wh ich computers, t im e-s hari ng, manipulates "hypertext," and programming languages {with a super graphi cs system which two exce ll e nt exampl es, is the ideal medium for TRAC * and APL), IBM and "fantics" {the art of getting the computer ind ustry, ideas a cross , both ''cybercrud," th e author's emotionall y and cognitive ly) own term for the practice of and "thinkertoys." These are putting thin gs over on people then combi ned in to the using computers {especia ll y, ultimate system, "Xanadu ," fore ing them to adapt to a wh ich, of course, is part of Computer Lib/D ream with rotating clay aga inst rigid, inflexible, poorly the "Xanadu network." Mac hin es by Theodor H. your fingers until it becomes thought out system), and Besides the material on Nelson . $ 7 postpaid from a pot. This is categoricall y even some comments on grap hi cs, thi s part of the Hugo's Book Service, Box false. Computers involve "The Hearts and Minds of book also features CAI and 2622, Chicago IL 60690; 70 im agination and creation at Computer Pe op le." PL ATO, inform at ion copies for $50 postpaid the high est leve l. Computers I found t hese last retrieva l, and art ificia l are an involvement you can comments especial l y intelligence. This is a marvelous, really get in to, regardless of poign a nt. "Computer Nelson is a genera li st, for delightful, one-of-a-kind your trip or you r karma . . . people," Nelson says, "are a the most part, and, li ke many book. Softbound in an 11" THERE FORE, welcome to mystery to others, who see ge nera li sts, his explanations by 14" format and fi ll ed with the computer world, the them as so m ew h at for thin gs are sometim es short pieces on many damndest and craziest th ing frightening, somewhat overly simp li stic. Re aders elements of computer lore, that has eve r happened. But ridicu lo us. Th eir concerns wit h a strong technical this is the Whole Earth we, the computer people, are seem so pec uliar, their hours background in certain areas Catalog of computer fandom. not crazy. It is you others so bi za rr e, their language so will wince at his As the a uthor says, a who are crazy to let us have incomp rehensible . . . We are exp lanations of DNA and computer fan is "someone all th is fun and power to li ke those li ttle people down RNA, the brain , artificia l who appreciates the options, o u rs e I v e s . C0 M P UT E RS amo ng the mushrooms, intelli gence (which Nelson is, fun, excitement, and fiend ish BELONG TO A LL sk itter ing around completely stra nge ly, down on), and fasc in ation of comp uters . .. MANKIND." pr eocc upied with "body electronics" (ESB and Somehow the id ea is abroad The two halves of the unfathomable concerns and a ll that, including that computer activities are book, Computer Lib an d seem ingly indifferent to "psy cha-acoustic dil don ics "). uncrea tive, as compared, say, Dream Machines, start at the normal humanity. In the And "practicall y-minded" moonlight (i .e., pretty late, engineering types, who are with snacks around the involved in the hard work of equipment) you may hear our actuall y building interactive music ." I' ll leave some of the computer systems, may more telling comments about sni cker at Nelson's grandiose computer people for you to plans. But ideas like these are rea d yourself. desperately needed, and The other half of the people who use computers book, Dream Machines, is would do well to read this prim aril y an introduction to book and share its visions. computer graphics, as a way We're publishing this revi ew of orga ni zing ideas and in th e hope th at so me of you out there will get the book, *TRAC is a registered service se ize upon its ideas and turn mark of Rockford Research, Inc., which means that we have to them into reality. How about BOOK p ri nt this acknowledgement it, lad ies and gentlemen 7 whenever we so much as mention HEVIEIV its name . - d.h.f.

82 into th e inrr-i caci es of pr ogr·a m d eve lo pm e nt , ro u t in es, and sharp ening p r ogra mmin g sk ill s . Tec hniques like maskin g, se tting up pointers and Practical Di gital El ec tro ni cs ­ devo ted to descriptions of the co unters, a n d c harac ter An Intro du cto ry Course, by vari ous logic fa mili es (27 strin gs are disc usse d in deta il Juris Blu /?is and Mark Baker. pages) and more to data with illu strati on by ac tu al Hewle tt-Paclw rd Co., 7507 communica ti ons (7 pages) M ac hin e L a n g u age so urce pr ogra m s. Other Page Mill Road, Palo Alto CA and memori es (13). Not to be Progra mmin g Fo r Th e chapters cover sorting and 943 0 4 . Tex t ( ord er mi ssed a re so me useful " 8 0 08" ( a nd simil ar ma the mat ica l o perati ons, # 0 5035-90 0 73, $8) and a pp endices o n numbering mi c roco mputers) by Nat input/output programmin g, wo rl?book ( o rde r # syste ms and codes, and a Wadsworth. See/bi Computer rea l time progra 11s and 05035-90003, $8) may be bri ef descriptio n of Boolean Co nsult ing, Inc., 7322 PROM consi dera ti ons. Th e obtained fr om th e company alge bra and Karn augh maps. Rear-Bost o n Post Road, ma th ema thi cal operati ons at the above address, or Sequenti al circ uits are not Mil fo rd CT 06460. 7975. chapter gives deta il ed source through a local HP sales introduced in this elementa ry $79.95. programs fo r fl oatin g point office. tex t. Perh aps the bes t review of arithm eti c opera ti ons whi ch Wh e th er thi s book is Mac hin e L a n g u age are direc tl y translata bl e in to This is a good up-to-d ate, suitabl e for you depends on Program m ing Fo r Th e mac hine code fo r use. This intro ductory tex t on di gital wh ether you are app roac hing "8008" is in the author's own alo ne is wo rth the pri ce of elec tro nics. It is most nota ble the topic more fro m an wo rd s. " By the tim e you have the book considering so me of fo r i ts treatme nt of ex perim enter's or hobb yis t 's co mp leted abso rbing and the pri ces quoted for simil ar ari thmeti c elements and other vi ewp oin t, or fro m a more un de rstandin g the conte nts of programs being offered. e le m e nt a r y t o pi cs in " se ri o u s" profess io nal thi s publication you should Fro m a di ffere nt poin t of co mpu te r d es ign, d ata enginee rin g viewpoin t. If you be we ll eq uipped to develop vie w, Mac hine Language communication codes, and are a h ob by ist, Do n progra ms of your own and Programm ing For The memo ri es. Lancaste r's TTL Coo!?boo!? thus be in a position to reap "8008" is a very unusual The text beg in s with an mi ght be more appropri ate eve n greate r benefits fro m book. The author takes a elementa ry desc ription of (see the rev iew in BYT E # 1 ). yo u r 8 0 08 b ase d su bjec t matter that has a ll the ga t es a nd flip f lo ps. If you are more "seriously" mi crocompu te r . . . " possi biliti es of being dull Co nsiderable attention is inclin ed, this mi ght be the The book begin s with a reading and bl end s it into a devoted to th e simple RS flip b ook fo r yo u . T h e deta il ed description of the book th at is enjoyabl e to fl op in ord er to make sure acco mp a ny in g laboratory CPU instruction set and fro m rea d. One gets the impress ion that the reader understands workbook is indepe ndent of that poin t o n th e reader is led that prog ramming is a new art exac tl y h o w this bas ic the text and is useful o nl y if fo rm wi th th e prec ise ness of memory element works. This you are also purchas in g HP 's sc ience, but the beauty of art. is fo ll owed by chapters on 503 5T Logic La b se tu p. Although the book is base d da ta communica ti ons and - d. h.f. upo n the 8008 machines , the logi c fa mili es. Then counters, materi al is prese nted in such a shift registe rs, and other way that it is a worthwhile combin ational circuits are in vest me nt fo r lea rning stud ie d; especially useful are m ac hin e l a n g u age the ex pl anati ons of pri o ri ty prog1·ammin g. encoders, which are use d to se lect a mo n g in te rrup ts Bill Fuller co min g fr o m pe ripheral 2377 Dalworth 157 devi ces a t tach e d t o a Grand Prairie TX 75050 co mput er, a nd p a rity ge nera to r/checkers, which are use d in data communica ti ons. Fin all y, th ere is an exce ll ent c h a pte r· o n a ri t hm e ti c eleme nts, and a short chap te r on memori es (R AMs and RO Ms). Whil e the in clu sion of materi al on memori es and data communica ti ons is an exce ll ent id ea, th e ac tu al cove rage of th ese topi cs is somewhat sparse . One wishes th at less space had been

83 INTEL 8008 TABLE OF OCTAL OP CODES AND "OLD" MNEMONICS (Note: the instruction mnemonics used are those of Key: "M" ­ mnemonic "OP" - op code "L" - length "S" ­ states the orig i 11 a I 8 0 0 8 "T" ­ time@ 500 kHz (us). documentation, rather than the later Intel mnemonics for this computer designed for M OP L s T M OP L s T "compatibility"(?) after the fact with the 8080. The early ACA 210 5 20 JFC 100 3 9/11 36/44 mnemonics are easier to map ACB 211 5 20 JFP 130 3 9/ 11 36/44 into op codes using mental ACC 212 5 20 JFS 120 3 9/11 36/44 gymnastics than the later set.) ACO 213 5 20 JFZ 110 3 9/11 36/44 ACE 214 5 20 JMP 104* 3 11 44 ACH 215 5 20 JTC 140 3 9/11 36/44 ACI 014 2 8 32 JTP 170 3 9/11 36/44 M OP L s T ACL 216 5 20 ACM 217 8 32 JTS 160 3 9/11 36/44 LHA 350 5 20 JTZ 150 3 9/11 36/44 LHB 351 5 20 ADA 200 5 20 LHC 352 5 20 ADB 201 5 20 LAB 301 5 20 LHD 353 1 5 20 ADC 202 5 20 LAC 302 5 20 LHE 354 1 5 20 ADD 203 5 20 LAD 303 5 20 LHI 056 2 8 32 ADE 204 5 20 LAE 304 5 20 LHL 356 5 20 ADH 205 1 5 20 LAH 305 1 5 20 LHM 357 8 32 ADI 004 2 8 32 LAI 006 2 8 32 AOL 206 5 20 LAL 306 5 20 LLA 360 5 20 ADM 207 8 32 LAM 307 8 32 LLB 361 5 20 LLC 362 5 20 CAL ·•· 106 3 11 44 LBA 310 5 20 LLD 363 5 20 CFC 102 3 9/11 36/44 LBC 312 5 20 LLE 364 5 20 CFP 132 3 9/11 36/44 LBD 313 5 20 LLH 365 5 20 CFS 122 3 9/11 36/44 LBE 314 5 20 LU 066 2 8 32 CFZ 112 3 9/11 36/44 LBH 315 5 20 LLM 367 8 32 CPA 270 5 20 LBI 016 2 8 32 CPB 271 5 20 LBL 316 5 20 LMA 370 7 28 CPC 272 5 20 LBM 317 8 32 LMB 371 7 28 CPD 273 5 20 LMC 372 7 28 CPE 274 5 20 LCA 320 5 20 LMD 373 7 28 CPH 275 5 20 LCB 321 5 20 LME 374 7 28 CPI 074 2 8 32 LCD 323 5 20 LMH 375 7 28 CPL 276 5 20 LCE 324 5 20 LMI 076 2 9 36 CPM 277 1 8 32 LCH 325 1 5 20 LML 376 7 28 CTC 142 3 9/11 36/44 LCI 026 2 8 32 CTP 172 3 9/11 36/44 LCL 326 5 20 NOA 240 5 20 CTS 162 3 9/11 36/44 LCM 327 8 32 NOB 241 5 20 CTZ 152 3 9/11 36/44 NOC 242 5 20 NOD 243 5 20 DCB 011 5 20 LOA 330 5 20 NOE 244 5 20 DCC 021 5 20 LOB 331 5 20 NOH 245 1 5 20 DCD 031 5 20 LDC 332 5 20 NOi 044 2 8 32 DCE 041 5 20 LOE 334 5 20 NOL 246 5 20 OCH 051 5 20 LOH 335 1 5 20 NDM 247 8 32 DCL 061 5 20 LOI 036 2 8 32 LDL 336 5 20 NOP * 300 5 20 HLT 000 x x LDM 337 8 32 001 x x ORA 260 5 20 377 x x LEA 340 5 20 ORB 261 5 20 LEB 341 5 20 ORC 262 5 20 INB 010 5 20 LEC 342 5 20 ORD 263 5 20 IN C 020 5 20 LED 343 5 20 ORE 264 5 20 IND 030 5 20 LEH 345 1 5 20 ORH 265 5 20 INE 040 5 20 LEI 046 2 8 32 ORI 064 5 20 INH 050 5 20 LEL 346 5 20 ORL 266 5 20 INL 060 5 20 LEM 347 8 32 ORM 267 8 32

Input - see separate list .. . Output - see separate Iist ... Alternatives for conditional instructions: short time if false branch, long time if true branch.

84 M OP L s T 8008 INPUT-OUTPUT LIST RAL 022 5 20 RAR 032 5 20 Mnem. Code Description* RET' 007 5 20 RFC 003 3/ 5 12/ 20 RFP 033 3/ 5 12/ 20 INO 101 RFS 023 3/5 12/ 20 RFZ 013 3/ 5 12/ 20 IN1 103 IN2 105 RLC 002 5 20 RRC 012 5 20 IN3 107 RSTO 005 5 20 IN4 111 RST1 015 5 20 RST2 025 5 20 IN5 113 RST3 035 5 20 ING 115 RST4 045 5 20 RST5 055 5 20 IN7 117 RST6 065 5 20 OUT10 121 RST7 075 5 20 RTC 043 3/5 12/20 OUT11 123 RTP 073 3/5 12/20 OUT12 125 RTS 063 3/5 12/20 RTZ 053 3/5 12/20 OUT13 127 OUT14 131 SBA 230 5 20 SBB 231 5 20 OUT15 133 SBC 232 5 20 OUT16 135 SBD 233 5 20 SBE 234 5 20 OUT17 137 SBH 235 5 20 OUT20 141 SBI 034 2 8 32 SBL 236 5 20 OUT21 143 SBM 237 8 32 OUT22 145

SUA 220 5 20 OUT23 147 SUB 221 5 20 OUT24 151 sue 222 5 20 SUD 223 5 20 OUT25 153 SUE 224 5 20 OUT26 155 SUH 225 1 5 20 SUI 024 2 8 32 OUT27 157 SUL 226 5 20 OUT30 161 SUM! 227 8 32 OUT31 163 XRA 250 5 20 OUT32 165 XRB 251 5 20 XRC 252 5 20 OUT33 167 XRD 253 5 20 OUT34 171 X RE 254 5 20 XRH 255 5 20 OUT35 173 XRI 054 5 20 OUT36 175 XRL 256 5 20 XRM 257 5 20 OUT37 177

* Instructions marked with asterisk are typical of several alternate op codes, same function.

Arithmetic/Logical Mnemonics: AC = add with carry input * The description column is left blank for your notes on the current assignments of devices. AD = add, no carry input SB = subtract, borrow input SU = subtract, no borrow input ND = logical product (AND) OR = logical sum (OR) XR = exclusive or (XOR) CP = compare

85 Fig. 1. A typical "mark sense card " used to input data to a distri butor's ALTAIR OWNERS programmer. CMR PRESENTS (a). Programming side - marks (b ). Instruction side - no tes on are made with a soft lead pencil use of the card. THE MEMORY YOU'VE BEEN to indicate which bits are to be WAITING FOR "programmed" - to "progra m 11 means to change state from the default sta te to the opposite state. INSTRUCTIONS Only those bits wh ich are to be 1. Use a soil (No. 2) penc il 10 l1ll 1n the 1oner b o• es BK xB DYNAMIC RAM 2. Mark only the b1I positions 10 be p1ogrammod Do nol wri!c on th e mnrg1n s. Use a pin k pearl ern ser to make changed (permanen tly !) are progrnm c hanges Erase completely J. For progr;1ms w11h more than 31. w ord addresses, use ON ONE PLUG-IN CARD FOR programmed by marks. add1t 1ona1cards w•lh consecut1ve wo•d add1csscs w rot - 1en 1n lh1; notes sccl•on Plec• n w 5. Fo• last tuinamund send 1n 1s crird an d your P 0 10 me ONLY 0 Hamllto n I Avri cl toc.:11t on al the bollOm ot ttus ca•d $599° * fbL MARK SENSE ORDERING INFORMATION

~ PROGRAM CARD 1. Yo111tomp1nyn1m11ndtddrt n •FACTORY ASSEMBLED AND TESTED WORD NOTES: , ' ' ' ' ". ' p ~ ~.. ''° - ---­·---­ •PLUGS INTO 8800 WITH NO MODI Fl CATIONS 2. Yo111PA/Buyer's name . lelepllone number ind u11n1ion ------­ - - - • PROTECT-UNPROTECT CIRCUITRY INCLUDED J. Your progr1mmen n1me . tdephone numlm and uten1ion

TO MATCH 8800 ~ ------....;·~----· - 4. Pu1 chueo1dernumber

•TWO 4k BLOCKS OF DYNAMIC R.A.M. "'" 5. M1nul1th1111 '1 p1r1numbt101dued •USER OR FACTORY ADDRESS PROGRAMMING --­·----· - 6. Ou1nlllyolud'lp1r1icularPllO Mp1agram (SPECIFY) - ' . . •EACH CMR-8080-8k is SHIPPED WITH AN EDGE­ - -· 1. o·uatedpriceperucllPllOM i [Ill BOARD CONNECTOR INCLUDED. .., 8. Ouoledprogr1mmingch119u r~•• ~,t------'-'---=~ - •EXPANDER BOARDS AVAILABLE (ADDS FOUR 9. Yl)ijrPllO Mldtnlillt1tlonnumbt1 "" SLOTS TO 8800) intel

TEN REASONS TO CHOOSE 1- ..-... -+-­ ~ro!.lt5 -3071 TORONTO 14 16 J 6 77· i432 1. 300ns ACCESS TIME ' 2. TWICE THE MEMORY DENSITY ~;; ~---.: '.. ~ ~ 3. LESS$$ PER K OF MEMORY ,-_­ :·: r ;m _ , _ _ • _ _!_ _ ·_' _ · :_ bi ts. For PROMs of large r 4. DESIGNED FOR THE 8800 \JJO I •; ! \ • 1 5. USES THE LATESTT.I. CHIPS ~::_ -L.- . . : _ : . ;--:) : sizes, mu Itipie cards are used ifMARK ON LY BITS TO BE PROGRAMMED 6. G-10 EPOXY BOARDS WITH SOFT LEAD PE NCIL - see the instructio ns on the ...... _ OVER FOR FULL INSTRUCTIONS 7. PLATED THROUGH HOLES. card repro du ce d in Fi g. 1. 8. GOLD PLATED CONNECTOR CONTACTS. The onl y hi tch with this 9. 8192 WORDS OF DYNAMIC RAM method in sofar as ind iv idu als Progra mming Read-Onl y­ 10. 90 DAY WARRANTY ON PARTS AND LABOR are conce rn ed is that the Memori es The Easy Way dis tr ibu to r's m a r ketin g I t is ofte n t im es operation is set up to deal *ORDERING NOTE: wi th companies on a regul ar FOR FACTORY PROGRAMMING. SPECIFY TWO 4k adva ntageous for you to MEMORY ADDRESS LOCATIONS FOR EACH CMR-8080-8k "freeze" a program into one bas is. Thus it mi ght be best to MEMORY CARD ORDERED. of several ty pes of fie ld make an arrange ment fo r one ------progra mm ab le rea d-onl y person in a local compu ter MAIL THIS COUPON TODAY me mories (PROM is the club to handle orders fo r D E N CLOS ED IS CHEC K O R M .0 . FOR $ ------­ abbrev iat io n) . There are PROM s by this method - so D C.0.D.'s A CCEPT ED W ITH 3 0 % DEPOSIT. T O T A L several varieties of read-onl y that the club could be li sted AM OU N T $ 3 0 % = ------­ VA. RESIDENTS A DD 4% memories avail able, with as the "comp any" makin g the e PLEASE SEND---CMR·8080-8k CARD(S ) ' AS diffe rent characte ri stics. The o rd er. Th e pri ce for DESCRI B ED ABO VE @ 599.00 EA. POSTPA ID programmin g is nomin al ­ •PLE A SE SE N D ___EX PAN DE R BO A R D(S) pu rp ose of this note is to (ADDS 4 SLO TS TO 8800) BOARD O N LY @ 1 5.00 E A. illu strate one way in whi ch perh aps $2-$3 per chip over POSTPAID TO : you can get these memori es the basic cost of the device. BYTE N A M E~------~ programm ed usi ng the (Sooner or late r, will serv ices of an app ro pri ate prin t an article on the various A DDR ESS~------types of fi eld programm able CIT Y______ST A TE & Z IP______di stributor. Illustrated in Fi g. 1 is the me th od of getting ROM dev ices and the kind of inpu t data to the distribu to r's ine x pe nsive programmers CMR COMPUTER MANUFACTURING co. progra mming mac hin es - a whic h can be built fo r home P. O. BO X 16 7 , 1921 DOGW OOD LANE VIENNA, VIRGINIA 2 21 8 0 " mark sense" card with use.) positions fo r 32 wo rds of 8 ... CARL

86 BLACK Model Railroad Switch MA IN Control Circuit SW ITCH

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74121 And at Southwest Technical Products this prototype CPU 4 6 board was getting its final wringing out before getting into production. Systems are expected to be available by 7 6 7 November! Motorola M6800 based . .. again! I I 1 0 from page 81 of what is comin g. There are MAIN LE0~/I ~I~IOING L;: TO IC 'S••--1--­ outfits talking about some 1 ·1 have been reading the SWTP slower syste ms ... probably 100 100 ads for so me time and seen 8008 based .. . which wi ll the rave reviews of the come in under $200 for the +5 +5 eq uipm ent. CPU .. . and maybe eve n one GROUND Dan has a good si zed plant fo r $100! and is doing a substanti al All of the firms . are TO SWITCH COIL-MAIN } SEPARATE + 12V SUPPLY 1 AMP, (UNREGULATED) business in audio kits. I went working hard to develop TO SWITCH COIL-SIDING USED FOR SWITCHES there to just say hell o and te ll accessories, memories and CONTROL-SHORT TO GROUND TO THROW SWITCH TO him how mu ch I en joyed programs. Look out 1976. MAIN LINE putting his television typewri ter kit toget her ... FLAKES [I) CONTROL-SHORT TO GROUND TO THROW SWITCH TO SIDING and to see what he might It just doesn't take any have up his sleeve fo r the time at all for the flakes to 0 LED TO +5 TO INDICATE SWITCH IN MAIN (THIS POINT rise. New as the computer LOW) future . To my amazeme nt he had an M6800 CP U up and hobby field may be, there are (2] LED TO +5 TO INDICATE SWITCH IN SIDING go in g, hooked to one of his already so me sharp operators in there taking adva ntage of 0 +5 VOLTS IN FOR ICs TVT units. Those Motorola boys sure do get around. The the unwary. I'm put in mind POINTS 4 AND 5 CAN BE PARALLEL TO MANUAL plans are to have systems of the "lifetime" guarantee MOMENTARY SWITCHES AND LOGIC SWITCHES-ANY offered by a chap se llin g ball PULSE (LOW) WILL WORK, HOLDING POWER ON ABOUT 'h ava il able in kit form by SECOND, 74121 WITH RESISTOR AND CAP CONTROL November . .. more support point pens in t he subway cars TIME. for 6800 systems ... more in New York. users, more programs. One f lake is se lling Reader Her ma n De that the switch is energized in This is an excit in g time in 1m1tatio n Southwest Tech Monstoy is busy working up a g iv e n direction of the microprocessor business circuit boards (the te levision app li cations for his 8008 movement. Th e 2N3766 with systems getti ng going typewriter circuit) . Good system in the area of model transistors used in this just about eve ry month. The luck if you fa ll fo r thi s one. railroad layout control. He circuit's output drive have a Sphere, MITS and SWTP SW Tec h is a substantia l fir m se nd s along this diagram of a rating of 20 Watts, so this systems are just the vanguard with a lo ng hi story of good model rai lro ad switc h control circuit should be able to dri ve products and serv ice to back so lenoids which take up to them up - I've built their TV ci rcuit which is used to drive PCC Update the so lenoid operated track about 1 Ampere at 12 volts. typewriter and it is spl endid. switc hes of a typical HO trai n Note that it may be necessary In conversation with Bob Said fl ake is gettin g ready to layout. The input (at the left to put protection diodes Albrecht at Peop le's put o ut imit at i o n of the drawing) can be a pair across the coils of the Co mputer Company, PO Box microprocessor boards of comp lementary TTL solenoid operated railroad 310, Menlo Park CA 94025, and kits. Undoubted ly he wi ll sig nals (e.g., the Q and Q switch if the coil is hi ghl y the fo llowin g upd ated give all of the sup port to hi s outputs of some flip flop) or inductive. For manual information was obtained as boards an d system that o ne from th e manual switch o perat io n, t he electrical BYTE # 2 goes to press: might expect from so meone indicated with dotted lin es at push-button switc h Sl can be PCC's publication will be operati ng out of a cellar. the left of the drawing. in parallel with computer chargi ng a flat subscription Watc h out! The oneshot 74 121 is used driv e. rate of $5 for six issues, with to co ntro l the length of time no specia l rates for students. .. . WAYNE GREEN JAMES ELECTRONICS DELTAt P. 0 . BOX 822 BE LMONT , CALI FORNIA 94 002 (415) 592·8097

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Satisfaction Guaranteed . $5.00 Min. O rd e r. U.S. Funds. Add $ 1.25 fo r Postage - Write for FREE 197 5S Ca talog Cal iforn ia Residents - Add 6 % Sales Tox BYTE FOR RESALE p id. ?!!e.~, PHONE ORDERS - (415) 592-8097

88 • We've got a bunch of these fantastic video display terminals . . . and we've got a little problem. We promised Sanders Associates that we would sell them as scrap. A couple of wires disconnected makes them scrap, right/ These VDTs should be great for SSTV, for a CW/ RTTY keyer terminal, an oscilloscope, weather satellite monitor, or even a computer terminal (which they were) . We've tested some of these and they seem to be near-perfect. You aren't likely to find a VDT system like this for less than ten times the price .. . so order several right away while we've got 'em.

ITEM A ASCII KEY BOARD This LS the ASCII encoded keyboard used wirh rh e SANDER 'S ASSOCIATES 720Sysfem Terminal. Plugs into rhe ITEM 8 : ENCLOSU RE AND BEZEL FOH 12 .. CRT fro 111 o f rl1 f" chassis moun1ing bdse. Makes a very This is 1/1e fros1in g o n the c,1k e. I HI compon en cs A profc.o,..,·io n,11 Video Readou1 Termina l combina1io 11 . fhm E fi l perfectly insid e i11is cnc/osu/'e. / 1 is These keybo

ITEM C · BASIC CHASSI S AND f.10U NTING BASE for 12" biq·sc1een CRT. Tube can be moun1ed ei rh er ITEM n· FO UR PC BOARDS CllOCK-FUL L OF vertic..11/ y or h ori£ontally by ro1 a cing fron1 pld1e 90 GOODI ES .,.wo DIA CO M errers. o ne I C- loaded degrees. Comes wir.h bdse. on·off sw. and in1ens11y logic board , a nd o ne mu/iipurpose bo.wd. \'le have corurol, four con1 rols for ve1i . •md h oriz. H,ts n o sd1e111.:i1ic da ra for 1hese boa1 ds .11 prese 11 1. \'le plen ty of room for mosl an)' elec1ronics n~ed for will suppl y .111 y dald w e obrain fo p m·ch,1se1-s as we your pel projecl . All subassem blies offered w ill get ii. Of course wh en we finally fiqure 0 111 what perfccr/ y fil in spaces provided . \'Illy rry ro cu1 the th ese bo,i/'ds .1re good for. ui e price will cl1anqe me1.1 / youl'scl f? Th is chassis will /el you <.·o n·

ITEM E: V ER 'l'ICll L AND HOH I ZONH\I. /lMPL / F/ f R Subu.ssem blies Good for d conSi' l"V.llivt· / SOW complemen rar y DC coupled ou 1pu r. F1L''f resp. beyond 2.0 MHz. P.-u·rs .1 /one wor1J1 m,rny rimes 1he low, low price of S6. 95 e.1 ., 01 l>o d1 fo1 $10.95 PPO

ITEM F CRT HIGH VOL 1'A GE POWER SUPPLY ­ ITEM G : LO\'/ VO L 1'ACE PO\'IEN SUPPLY A r1M/ Th i:: is a re,1 / supcl' CRT High Vol1 aqe Po wer bn 11 c used 10 supply ,11/ low vollages n eeded by f1 1e .'1up ply. providing inputs o f pl us 5.0 VDC, plus 16.0 V DC I O.OA : plus 5.0V DC @ more tha n 2.0A, .11/ .'J nd iJ d rive signal o f approx 8.4 kHz @ 1.0 vrms or regu lated. Mounts 0 11 1ll c re.;ir of 1he Basic C/1 ,1ssi:; mote. A ll inputs/ou1pu1s via plug/jotck cables rt nd (l rnm C ) Weighs approx '15 /bs .md will be shipped t• vcn has a socke t/cable assy for lhe CRT. A very wifll i 111 erconnec1io 11 d,1 1<1 for only - $ 19.95 FOB. fint• bu y ;11 only $ 14 .95 (incl. da ta) FOB

PACKAGE DEAL - For the really serious experimenter we'll make a very special offer - you can buy all of the sub-assemblies listed above plus a good 12" CRT, a muffin fan far cooling. We'll supply instructions far interconnection far all subassemblies so that you can, within minutes after receiving this once-in-a lifetime deal, put an X-Y display on the CRT. We'll also include a list of possible applications for those with short imaginations' Don't miss out on this real money-saving bu y; th e individual prices for the sub-asseml.JliP.s add up to $127.70. You can buy the entire package for a very low package price of - $79. 95 FOB.

On all postpaid orders, please ADD $1.50 to cover handling costs. Orders shipped same day in most cases. • -·llANMAMERICARD BJJ1rr 11n11J~{ eDJ}) Pil 1J1 0 6 KING RICHARD DRIVE , LONDONDERRY , N. H. 03053 603·04 - 4644

89 5% OFF ON ORDERS OVER $50.00 5314 CLOCK CHIP 10% OFF ON ORDERS OVER $1 00.00 OCTOBER 6 digit multiplexed 7 segment output, fast; slow sel, 24 PIN DIP ...... - $3.95 1 5% OFF ON ORDERS OVER $250.00 SPECIALS 5739 CALCULATOR CHIPS , 9 digit, 4 function, chain operation, 9 V battery operation, 16 sec turn-off 22 PIN DIP . . . . . $3.95 SCHOOL TIME SPECIAL TTL 7451 .17 74154 1.25 7400 $ .14 7453 .17 74155 1.07 POCKET CALCULATOR KIT MEMORIES Fully decoded RAM MOS 1024 bit dynamic 7401 .16 7454 .17 74156 1.07 5 function plus constant ­ 1103 16 PIN DIP ...... $1.49 7402 .15 7460 .17 74157 .99 addressable memory with 7403 .16 7464 .35 74156 1.79 individual recall - 8 digit 1702A 2046 bit static PROM electrically program­ 7404 .19 7465 .35 74160 1.39 display plus overflow - mable and e rasable, 24 PIN DIP $15.95 7405 .19 7470 .30 74161 1.25 battery saver - uses standard 7406 .35 7472 .30 741 62 1.49 or rechargeable balteries ­ all 2102-2 1024 bit N channel static RAM 16 PIN DIP 7407 .35 7473 .35 74163 1.39 necessary parts in ready to $3.95 7408 .16 7474 .35 74164 1.59 assemble form - instructions 7409 .19 7475 .57 74165 1.59 included 5261 Fully decoded RAM MOS 1024 bit dynamic 7410 .16 7476 .39 74166 1.49 16PINDIP ...... $1.79 7411 .25 7463 .79 74170 2.30 CALC KIT (WITH BATIERIES) . . . . . $12.95 7413 .55 7465 1.10 74173 1.49 ASSEMBLED (WITH BATIERIES) ... . $14.95 DTL 7416 .35 7466 .40 74174 1.62 BATIERIES ONLY (DISPOSABLE) SET .. . $ 2.00 7402 Quad 2 inpul NOR gate s .13 7417 .35 7489 2.46 74175 1.39 7420 Dual 4 input NANO gate .14 7420 .16 7490 .59 74176 .69 7446 BCD to 7 seg driver .79 7422 .26 7491 .97 74177 .64 8038 FUNCTION GENERATOR 7460 Dual 4 input expander .10 7423 .29 7492 .71 74160 .90 Voltage controlled oscillator- sine, square, trianglar 7493 4 bit binary counter .51 7425 .27 7493 .60 74161 2.96 output 16 PIN DIP ...... $3.95 74175 Quad D flip flop 1.25 7426 .26 7494 .94 74162 .79 7427 .29 7495 .79 74164 2.29 7430 .20 74% .79 74165 2.29 MEMORIES Data sheets on request 7432 .23 74100 1.30 74167 5.95 1101 256 bil RAM MOS I 1.50 With order add $.JO for items less than $1.00 ea. 7437 .35 74105 .44 741 90 1.35 1103 1024 bit RAM MOS 3.9S 7436 .35 741 07 .40 74191 1.35 2102 1024 bil sU1tic RAM 5.55 5203 2048 bit UV er;u PROM 17.95 744-0 .17 74121 .42 74192 1.25 S260 1024 bit RAM 2.49 7441 .96 74122 .45 74193 1.19 526 1 1024 bit RAM 2.69 300 Pos V Reg (super 723) TO·S I .71 7442 .77 74123 .65 74194 1.25 S262 2048 bit RAM S.9S 301 Hi Perf Op Amp mDIP TO-S .29 7443 .67 74125 .54 74195 .69 7489 64 bit ROM TTL 2.48 302 Volt follower TO.S .SJ 7444 .87 74126 .63 741% 1.25 8223 Programmable ROM 3.69 304 NqVRq TO.S .BO 74200 256 hit RAM tri-sl;a le S.90 7445 .69 74141 1.04 74197 .69 30S Pos V Reg TO.S .71 7446 .93 74145 1.04 74196 1.79 307 Op AMP (supe1 741) mDIP TO-S .26 308 Micro Pw1 Op Amp mOIP TO-S .89 7447 .69 74150 .97 74199 1.79 CALCULATOR & CLOCK CHIPS )O'JI( 5V IA regul.a tor T0.3 1.35 7446 1.04 74151 .79 74200 5.90 310 V Fo llower Op Amp mDIP 1.07 7450 .17 74153 .99 S001 12 DIG 4 funct fh: dee 13.45 311 Hi pe rf V Comp mDIP TO·S .9S 5002 S.me ~ 5001 es.c btry pwr 3.95 319 Hi Speed Du•l Co mp DIP 1. 13 SOOS 12 DIG 4 funct w/ mem 4.95 320 Neg Reg 5.2, 12, 15 T0.3 1.19 MMS725 8 DIG 4 funcl chain & d ee 1.98 322 Precision Time r DIP 1.70 LOW POWER TTL MM5736 18 pin 6 DIG 4 funct 4.45 Qu.11d Op Amp DIP 1.52 74LOO S .25 74 L51 I .29 7Sl90 Sl.49 324 MM5738 8 DIG S func t K & mem S.JS Qu.11d Comparalor DIP 1.58 74l02 .25 74 L55 .33 74l91 1.45 339 MM57J9 9 DIG 4 funel (blry sur) S.JS Mlk Pos V reg (5V, 6V, 8V, 74LO J .25 74 L71 .2S 74l93 1.fi9 MMSJ11 28 pin BCD 6 dig mux 4.45 12V, 15V, 18V, 24V) TQ.) 1.69 74 L04 .25 74L72 .39 74 l95 1.69 MMSJ12 24 pin 1 pps BCD 4 dig mux 3.9S 340T Pos n~g (SV, 6V, 74L06 .25 74L73 .49 74 l98 2.79 v av, MM511J 28 pin 1 pps BCD 6 dig mux 4.4S 12V, 15V, 18V, 24V) 1.49 74 L10 .25 74L74 .49 74 l1 64 2.79 T0·220 MMSJH 24 pin 6 dig mux 4.4S 372 AF· IF Strip d etecto r 74L20 .33 74l78 .79 74 l1 65 2.79 DIP 2.93 MMSJ16 40 pin Oii lum 4 d ig S.39 173 AM / FM/ SSB Slrip 74l30 .33 74L85 1.25 DIP .SJ 376 Reg m DIP 74L42 1.49 74l86 .69 PC6 V 2.42 377 2w Slereo amp DIP 1.1 6 LED's 380 2w Audio Amp DIP 1.13 HIGH SPEED TTL MV1Uts Re d TO 18 S .22 380-8 .6w Audio Amp mDIP 1.52 74HOO S .25 74H21 I .2s 74H55 S .25 MV50 Axi01 l le01 ds .18 381 Lo Noise Dua l p1e.oimp DIP 1.52 74H01 .25 74H22 .2S 74H60 .25 MVS020 Jumbo Vts. Red (Red Dome) .22 382 Lo Noise Dual preamp DIP .71 74H04 .25 7-4HJO .25 74H61 .25 Jumbo Vis. Red (Cle01 r Dome) .22 S50 Pree V Reg DIP .89 74H08 .25 74 H40 .2S 74 H62 .25 ME4 lnftOil re d difl. dome .54 SSS Time r mDIP .89 74 H10 .25 74 HSO .2S 74 H72 .39 MANl Red 7 seg..270" 2. 19 SS6A Du.al SSS Time r DIP 1.49 74H11 .25 74H52 .2S 74 H74 .39 MAN2 Red 0iilph0ii num .32" 4.39 S60 Phase Lodie d Loop DIP 2.48 74H20 .25 74H53 .2S 74H76 .49 MAN4 Red 7 seq. •190" 1.95 S62 Phase Lodied Loop DIP 2.48 MANS Gree n 7 seg•.270" 3.45 S6S Phase Lodie d Loop DIP TO.S 2.38 MAN6 .6" high solid seq . 4.25 S66 Function Ge n mDIP TO-S 2.25 8000 SERIES MAN7 Red 7 seq. .270" 1.19 S67 Tone Decod er mDIP 2.66 8091 s .53 8214 $1 .49 88 11 $ .S9 MAN8 Yellow 7 seq • •270" 3.45 709 Ope ra tion.al AMPL T0·5 or DIP .26 8092 .53 8220 1.49 8812 .89 MAN66 .6" high spued seq . 3.75 710 Hi Speed Volt Comp DI P .35 8095 1.25 8230 2. 19 8822 2.19 MCT2 Oplo· iso tr01 nsistor .6 1 711 Du.oi l Dilfere nce Compar DIP .26 8121 .80 8520 1.16 8830 2.19 723 V Reg DIP .62 81 23 1.43 8551 1.39 8831 2.19 739 Dual Hi Pe rl Op Amp DIP 1.07 8130 1.97 8552 2.19 8836 .25 MULTIPLE DISPLAVS 741 Comp Op AMP mDIPTO-S .32 8200 2.33 8554 2.19 8880 1.19 NSN33 3 digit .12" re d le d 12 pin 747 Du.oil 74 1 Op Amp DIP 0 1 TO·S .71 8210 2.79 8810 .69 8263 5.79 fits IC skl. Sl.79 748 Fre q Adj 741 mDIP .JS 8267 2.59 HP5082 5 digit .11 led magn. le ns 1304 FM Mulpx Stereo Demod DIP 1.07 com. c.oi th 3.49 1307 FM Mulpx Stereo De mod DIP FNA 37 9 digit 7 seg led RH dee cir. 1458 Dual Comp Op Amp mDIP "'.62 9000 SERIES m 01g n. le ns 4.95 1800 Stereo multiplexer DIP 2.48 9002 I .35 9309 I .79 9601 s .89 SP-425-09 9 digit .25" neon direct inter· LH 2111 Du.11 1 LM 211 V Comp DIP 1.70 930 1 1.03 9317 .79 9602 .79 b ee with MOS/ LSI, 180 VDC, 7 segl.79 3065 TV· FM Sound Syste m DI P .62 3075 FM De l·LMTR & SHIFT REGISTERS Audio preamp DIP .71 3900 Qu.oi d Amplifier DIP .35 MM5013 1024 bit accum. d ynamic mDIP Sl.75 7S24 Core M em Sense AMPL DIP .71 CMOS 4016A .56 4050A .S9 MMS01 6 500/ 512 bit dynam ic mDIP 1.59 8864 9 DIG Led C .oi lh Drvr DIP 2.25 4000A S .26 4017A 1.19 4066A .89 SLS·4025 D uOill 64 bit st.11tic DIP 1.39 75150 Dual Line Driver DIP 1.75 4001A .25 4020A 1.49 4068A .44 75451 DuOill Perephe ral Driver mDIP .35 4002A .25 4021A 1.39 4069A .44 ... DTL 75452 Dual Pe riphe r.al Drive r mOIP .35 4006A 1.35 4022A 1.10 4071A .26 75453 (JS l ) Dual Pe riph D1iver mDIP .JS 4007A .26 4023A .25 4072A .35 930 I .1 s 917 .15 949 .1S 75491 Quad Seq Dr iver for LED DIP .71 4008A 1.79 4024A .89 4073A .39 932 .15 944 .1S 962 .1S 75492 Hex Digit driver DIP .80 4009A .57 4025A .25 4075A .39 936 .15 946 .1S 963 .15 4010A .54 4027A .59 4078A .39 4011A .29 4028A .98 4081A .26 4012A .25 4030A .44 4082A .35 Satisfaction guaranteed. Shipment will be made via first class mail within 3 days from receipt of 4013A .45 40J5A 1.27 4528A 1.60 4014A 1.49 4042A 1.47 4585A 2. 10 order. Add $.50 to cover shipping and handling for orders under $25.00. Minimum order $5.00. 401 5A 1. 49 4049A .59 California resid ents add sales ta x. HCOO S .22 74C74 Sl.04 74C162 S2.93 74C02 .26 74C76 1.34 74C163 2.66 74C04 .44 74C107 1.13 74C164 2.66 INTERNATIONAL ELECTRONICS UNLIMITED 74C08 .68 74C1S1 2.61 74C173 2.61 P.O. BOX 1708/ MONTEREY, CA. 93940 USA 74C10 .35 74C154 3.15 74C19S 2.66 74C20 .35 74(157 1.76 80C9S 1.35 PHONE (408) 659-3171 74C42 1.61 74(160 2.48 80C97 1.13 7.4(73 1.04 74(161 2.93

90 COMPUTER EXPERIMENTER SUPPLIES FACTORY FRESH-PRIME QUALITY PERFORMANCE GUARANTEED

MICROPROCESSORS AND MEMORY 8008 ...... $ 35.00 ----Commercial Grade-up to 35 ° C . 8080 ...... 135.00 These units are factory 2102 ...... 3.50 fresh, full spec devices. 2102-2 ...... 4.50

COMPUTER GRADE REGULATED POWER SUPPLIES All units are short-circuit proof, fold back current limited and with over-voltage crowbar protection.

• j

MD-15 MD-5-1 MD-5-3 MD-5-6 ±15 Volt at 200MA +5 Volt at 1 Amp +5 Volt at 3 Amp +5 Volt at 6 Amp Dual Tracking $24.50 $34.50 $44.50 $30.00

MICRO COMPUTER SUPPLY TTL INTEGRATED CIRCUITS COMBINATIONS All devices are factory fresh, full spec units. For the 8008 7400 ...... 23 MD-08-+5 volt at 6 amp, -12, -9 at 200 7404 ...... 25 ma ...... $75.00 7442 ...... 60 For the 8080 7447 ...... 95 MD-80-+5 volt at 6 amp, ±12v at 200 ma .. . $75.00 7448 ...... 95 For the Fairchild F-8 7475 ...... 60 MD-8-+5 volt at6 amp, +12 vat 200 ma ... $65 .00 7490 ...... 60 For the M6800 7493 ...... 60 MD-5-+5 voltat6amp ...... $44.50 74125 ...... 55 74126 ...... 55 All units are short circuit proof, fold-back current 74192 ...... 1.10 limited and with over voltage crowbar protection. 74193 ...... 1.10

All Prices Subject to Change Without Notice s~ os t devices s ~· UARANTEE Minimum Order $10.00 p 'PPab/e Wi th; 'PP ed Within 2 Add $1. 00 to Cover Postage and Handling erformanc n 2 Weeks 4 hours If Send Check or Money Order (No C.O.D. ) To: t~¥,;hic0:f~~~t~Y:~t~:i,£:;~~~~i~:f~~~~~t N. J. Residents Add 5% Sales Tax ave n t anty ap . no cha sockets f o been SOid P1•es on/y t rg e. or You r inco . ered. You 0 Pa rts ming in spect· must use ion tests. MICRO DIGITAL CORP. BOX 413, EDISON, NJ 08817 • (201) 549-2699 7400N TTL JAMES FALL SPECIALS DIODES TT L/ L INEAR C LOCK & CA LC . CHIPS IC'S KITS 0 1g1 1 §~&~ l.1"1511 111 6 SJ .!15 Sfl/400N . 16 SNW:llN 21 SNJ1115 1N l 15 IN4001 50V fl 1 A111 11 151S1 00 1400 G ~ 1 t 7151 OD . 16 SN745 3N .27 StO.llSJN 1 35 1N4001 IDOV !o..1 1 Amii 15 SI.OD 1.:.:1 Otcu dr1 19 l.llJ5Jl211 4-0 1g1 1 3.95 Stll40 Hl Ml.15] 1Jlj 601g11 l!l!i .21 SN7454N 41 SNJ-1154~ 1 15 tri40D3 200V fl 1 Amp 15 SI .DD 7490 Counui 49 SN140]N 1'2\0;) 8 811L <1 1ch 99 Mt.153 1411 601gll J.!15 FUNCTION GENERATOR KIT . 16 SN7459A 25 SN14155N I 21 IN400~ 400V P 1 A"'p 15;51 00 SN1403N 1Ndl 48 Sw11ch111!J 2015\.00 7415.! Ouodr• 99 MM5Jl6N 6 D1g1t .\ l~1 rn 4.!15 21 SNMliON 22 SN74 156N 1 JO SN1404N - 14191 C11tmt r1 15 /,\1.\57Z5N 8 01g11 4 Fur11 1.!18 24 SN1470N .'15 SN/415/N 1 30 SNl40!JN TAANSISTO~S lMJOlli LMN llt 4/SIOO /,\M!'i73 6N 6 0 1g 11 ·4 f1m1 . l .!15 . lralt!l i!S f 111r . •15 SNM72N .39 SN74160N I 15 SN7406N LM 37Hl ll u ~ tlN I 1 19 MM5138 fj 8 0 1g 11 ·5 F11ru 4.!15 11 14ngl,autl .45 SN.7 H3N .45 SN/4 161N 145 2N2907APNP Sw1tth111 g 6/Sl .00 . . SN M01N 2N1122ANPNSwuclu11y 61$1.00 LMJO!l ll 5V Reg J0.5 79 26 Awg AIBBON CABLE 25 SN7474N 45 SN7'1 163N I 65 111uar ewavt! , SNl4011N W3904 NPNA11111 6/Sl.OD LMJO!IK 5V Hf~ TO ·l .99 I fl. t.ii nim um 1-9 h . 10 h . - 25 SN747 5N .80 SN74 1MN 1 65 . TlllJ05 . rv11. SN/4U!JN 2NJ90G PNP Am11 6/SLOO ~""""49i1 39Tt. 20 SN1<17GN .47 SN7'1165N 1 6!i OYNAM IC SHIFT REGI STER S AM IFM ca 11a1111i1~ SN/41UN 2N918 !llPI~ HF 6/Sl.00 8 Cuoll. .B!llt. .69 11 . StH4 11N JO SNNBON 50 SN74 16GN I 10 2N595 1 tU ftl 6/Sl.00 /,\ M5001 t MM504 11 MM510H 2 FOR HiC 011d. 1.>19 11 . 1. 1!1 t1. SN/4 12N •12 SN7'182N US SN74167N 5.SO C10681 l6 Am11 SCR 11s1.oa l.IM503ft Ml.150611 l.H,150 16H $ 1.00 37 Cuud. 1.4!111. 1.99 h . . . SN74 13N 85 SN748JN 1 15 SN74170N J. 00 SNM14N 70 SN7•185 N l 12 SN/4177N IS.OU POCKET CALCULATOR KIT SPECIAL $17 .95 SN141fiN 43 SN1481iN .45 SN7H/ JN 1 70 4' POWER SUPPLY CORDS . . ,, 51unt1 1on plusconmn1­ XR·2206KA SN/4 1/N 4J SN7118B N J.50 SN74174N I.% addrmable rn emo ryw1 Ctl Includes monnl11h1c lunwon genera101 IC, PC hoartl. and assemtilv SNMlllN 25 SN7·189N 3.00 SN741/5N 1.!l!:i Black SPECIAL md1~1du•l 1 cul1 - 8d1gi1 ~ ins••truc1 i1.1 11munua!. SN142UN SPECIAL $27.95 SN/•1 2\N · ;~ ~~~:;~~ 1 : ~~ ~~~~ : ~~~ ~~ S :EE 3/$1 .00 :~:i~~l;~~;ae~~l=r~~rbamrv ~ SfjN 23 N 1 Same as XR ·22 0flKA above and mclucles external compu11e111s SN742!>N ~~ ~~~~ii~~ . :~ ~~~: : :~~ ~ - ~~ l-.....:'-T-H_U_M_B_W_H_E_E_L_S_W_l_T_C_H_E_S___-l ~:~~:~:~ b~:,~::~e:~:~~ :~ lor PC hoanl. SN147 6N 1 11 11 TIMERS 2 s• Al $12.95 each SN/4'1 tl ~~ ~~~; :;: ~ :: ~:~: ::!: ~~ !~':! ":.'.!!!, sr!'~~ .°!'~!.... ~~~~:::i~':. ';. ~ : 5~ ~ S PE°Cj XA ·555CP Monuhth1c T1me1 SPECIAL $ .69 SN/419tl J2 SN74 96 N 91 SN74185N 120 • ' ,) ~ ,...,,.. - _...,_ - ,.-. OPTIONS ­ 1 1.55 SNNJUN 76 SN 14 100N 1.25 SNN187N 600 t.,.. ·;-t . . Jif.=::-:~~::"::~: ;5 115VAC Tnn1! 01mt1 4.9511ch XR ·320P P1 em1un T1me1 SN1 4J2N XR·556CP Oual·555 Timer 1. 85 ·;; ~~~: : ~~~ · ~; ~:~: : ~~~ : . ~ ~ 1• n . J"3 6 mh ~ N ·· Alkahnr Biueriu . 1.95 hn SNMJ7N XR ·2556CP Dual Tir11111g Cncm1 J.20 SN/.I JB N 40 SN"M 122N •19 SN74 192N 1.50 .394" DIAM . TRIMMER XR·2240CP P1og1ammable Coun1e11T1me1 SPECIAL 3.25 .2!i SN7412JN 1.05 SN74193N 1 40 IUIUIF l •ool OI _._ .,, 1111111 SN '/43~JA ·4 STANDARDRESISTANCEVAlUEI PHA SE LOCKED LOOPS SN1'140N 21 SN74 125N 60 SN/4 194 N 1.4!'! woou •OGO i.oon u:; XR·2 IO FS K Oemodulaior 5.20 SN"M •11N 1.10 SN74126N .Bl SN7 41 !1!i N 1 00 10:t( 100: 1GIC SN/441N 108 SNN 1J m J OO SN14196N U!i ~ XR ·215 H1y h F1equencv PLL G.60 ~ ".. ,..... SNNHN 1.0!'! SN7414 IN I 15 SN74 197N 1 00 ·-- XA·567C P Tone Decoder (mi ni DIP ) 1.95 SN7444N \ 10 SN74 142N 650 SN1<1198N 725 SPECIAL I """~" I ,I ..I , _. XR ·567CT Tune Decoder fTO ·Sl SPECIAL .99 SNM4!JN 1 10 SN7HlJN 1.00 SN74199N 2 25 :·:, ';:':'j ·; ": !~ .-;· ~ -. : · ~· i1 Model ST~~:; io ~ u 1.1 5 SN7HMN 1 00 SNl,17UON 7 OU l u f U ll' ... I H \ 0~ 1 0 STEREO DECODERS SNJ.141iN J.20 SN/.\4 7N .89 SN74 145N 1 15 SNl425 1N 2.!iO TRn I ··" I""" I XA · 13 10P PLL Smeo Decode1 SNl•M8 N .99 SN74148N 2.50 SN1428 1JN GOO XR ·l310EP PLL Stereo Decoder 3.20 SN/ •l!i UN 26 SN741!JON 1 10 SN74i'R5N Ii .OU - XA · 1800P 3.2 11 .,,;;@;~ 1 / 16 v~-~.:oR BOARD PLL Stereo Decoder Disco m11 fn1 Combined 20% 100 71l OO 's , ~ • t O l "' >l""'Si>o<"'I WAVEFORM GENERATORS RAO 74C10 N 65 .. XR·205 Wave!orm Generaio1 C04000 1~ Cl"l40111 15 CMOS XR ·2206CP Muno l1th1 c Fune11011 Gcncrnio r SPECIAL 4.49 CU•10U1 l~ C04aJO .65 XR ·2207CP Vollage -Contr olletl Dscilla tm 3.85 CU41106 150 CU40 J!i 1.85 OTHER EXAR IC'S CU404U 2.45 C04001 15 NEWPROTO BOARD·lOO XA ·l468CN Dual• ISV Tr ac kmg Aegulatm SPECIAL 2.95 Cll400!1 59 C0404 2 1.90 11!11~ :i~ !!$.~ 5.80 f. IJ 401 0 59 C040•l4 l.50 14C90N JOO llt rf!\a low cou . b1q lOIC ca11ac1 1y ~-- XR · l 488N Ou ad I me D11vt1 CU •l011 25 C0•1°'11i Ell /•IC !l!'IN 700 tu ud b o.i1dk1 1w 1lh.il11h ~ Q u ahty o l • r ... XR · l489AN Duatl l me Receive r 4 80 /4C IOIN 1 ]!J OT t h and thr bell ul 1he P1111 11 ill or 5.20 C04012 25 CIM047 2.15 So c ~. ~· WALL T.V. DIGITAL CLOCK XR·2208C P Qper a 11011 at Mu1! 1pher CIJ401 J H CU4°'19 .79 14C l51 1.90 B11;11dm1u . cump1eieduwn 1o tl1' '.f 12 o r 24 ~t uu r 115 v ac XA·22 11 CP FSK Demodulator/Tone Decoder 6.70 C04050 .79 74CI S4 J OO la51nu t. bul1 111 u1 mew lucludu .VIEWINGOISlAUCE­ f.0401ti !16 ~ . • 25 XA·226 1 Monolithic P1oportiona1Servo IC Sys1em CIJ40 11 1.3!1 !:04051 2.98 11 Wiln ur • J.. • I" : 1:114019 !15 C040SJ 2.98 ;:~ : ~ri ~ ;.~ ~ ~~v;:~ 1~,~~.~ : •; ; , : 1 2 ! ~:beb:,u:,; : '. ' · t:~ \ ~ -~·· w/4 ea. D1iver Transis101 3.79 1:04020 I J9 C0 4060 125 74C 1GI J2!i uuw 1 . nut ~. l1ol11 . .:t11dUlYUitmb ly Hr &Mm 6 ll iqh ._•. en.ion 115 CU406G US 74C1G J J OO 1nmuc11un\ Stcond\ 3" ll 1qh CU4023 25 C040G9 .45 74C 164 J 2!i COMPLETE KIT· ·· $17 95 Kil All Cu n111 8 Ca1e •• .• _ .• . $34.95 *Special Requested Items* CU40"1 150 C0407 1 .45 14c11J 1Go *Special • \'Nfdf.A\sem b•ed . • • - ··· · ·· S39.95 RC419~ Ou.ii li te ~ V R19 S5.9!'1 NBl97 SJ.DO 1533 S1.95 CU•1[)]5 15 CU4D81 .45 14CltlJ 2.15 RC~195 • 15V h ark Rtg 3.2!1 4014P 1 1S B1G3 5.95 l------'-..O::.~::..:..=-----_J'------1 1SIJ 1100 8761 1 15 f. []40 71 .69 14COON .J9 74C 19!i 21'.J F9J68 01co d11 3.95 DISPLAY LEDS DISCRETE LEDS LOll0/111 DV MCtu11S11 28.00 mB 1.00 a1aa 1 1 ~ C l HU~fl 1G5 14COm .!JS SOCS"/ l !iO FND70 Com. Ca 1h. .250 .69 CAJ130 Su 1111 CMOS Qp Amp 1.49 2524 350 8876 JUO 1:01\ 02!1 l.90 14CUl\N .75 is15 6.ao 11sao 1 . J~ MAN 1 Com. Ano. .270 SUl5 MV 10 lhd SIS1.00 MCM08l7 A/0 9.95 F33~1 FIFO 8 . 9~ 15'1 5.0U 74!11 5.0U LM 100l t 15.00 LM1 310N 2.95 MAN 2 5x7 Matr ix .300 39!1 MV 50 ll ~ d GISI.OD LM11Jlill 2.50 LINEAR LM 13!. IN 1 6!1 MA N 3 Corn . Cath. . 125 39 MV 5014 ft ~ d 5/Sl 00 LM111tl J 75 LMJ73N 3 2S LM14 14N I 75 MAN 4 Com . Ca 1h. .187 1.95 1.1v !1 07•1 G11:e11 415 1 00 ZENERS-DIODES-RECTI FIERS l.M 21'1i 7.00 LMJHN 4 00 LM14S8C li5 MAN 7 Com . Ano. .30 1.50 1.\V5014 Yell uw 4 SI.DO T't'PE VOL TS W PRICE TYPE VOLTS W PRIC E lM 3UOli .80 L/,\ JB ON 1 J9 Lf.11496N 95 OLJJ Com. Ca 1h. . 125 1.95 r.IV!iON 0• 11u4t 4 51 00 411 .00 IN400J 200P IV I AMP 10 ll.\JDlli Jl l.00 LMJBOCN 1 05 Lr.1 1551iV I B!i OL747 Com. Ano. .625 2.50 Mv50· Red 1•,· Lu d1 5/SI 00 IN74G J 3 400m IN4004 400P IV 1 AMP LM3U l f. fj J/ l.00 L1'.13BIN 1.19 LM]lllN J!l!i 1------'~------IN 751A 5 1 400m 4/ 1.00 10 61100 L/.I JO]lt 75 LMJ87.N 119 Lt.1290 1N 2 95 IC SOLOERTAIL - LO W PRO FI LE ITINI SOCK ET S IN752 5 6 400111 4/ 1.00 1NJ600 50 200m IN4148 75 IOrn 15 fl 00 U.1 30411 1.00 NE!iOIK 8.00 Lt.13065N 69 2S49 50 100 1 2' 25-49 ~o 100 1N75J 6.2 400m 4/1 .00 1 7~ 17/ 100 I MJO!ill .95 NE!i lOA G.00 Lr.1J900N !i'.J IN154 6.8 400111 4/ 1.00 IN4 \54 35 10111 .16 15 24pon J8 .37 NE!JJ lll 3.00 LM 3!.105N 60 811111 S17 s IN9 65B IS 400111 4/ 1.00 IN473 4 5.6 1w 28 l M3 07CN .JS 14 p1n .19 18 28pm 45 ,. LM30811 1.00 NE!'i 3G T G.00 LM55!i6N 1.8!i 20 ·" lNS2l2 S.6 500n1 .28 IN 47J5 6.2 lw 16pm .17 .23 21 J6111n .60 _,, .58 LMJ08CN 1.00 NE54Ul GOO MC!iS!i8V 1 00 "' "' IN5234 6.2 SOOm 28 IN47J6 68 lw 1811 111 79 .28 11 40pon G3 .62 .6 1 IN4738 82 lw 28 LM 3091 i 1.10 NE550N 79 LM751!iN 90 IN52J!i 6.8 SOOm .28 " 22pin .36 .Jl JG 28 IN4742 11 lw \MJ09K 1.25 N£5!i J 1 ~O LM7518N 2 20 IN52 36 1.5 500m SOLO ERTA IL STAND ARD (TI NI IN 456 25 40m 6/1.00 1N4744 l!i lw "28 W 3 10CN 1 IS f~E5!i!iV 75 LM75 34N '} 20 IN458 150 1m 611.00 IN\18J 50PIV 35 AMP LMJllH 90 NE56SH 1.25 LMl 5J!iN I 2S 14 p1n S30 28 26 2811 111 s 99 90 IN48SA 180 10m 511.00 IN\ 184 IOOPIV J5 AMP 170 LMJ1 1N 90 NE565N 1.95 80388 •19~ J I 19 J611u1 139 1.16 11' "" 16pm 33 "' IN\ 186 100 PllJ J!i AMP 180 LM 3 18CN 150 NE566C N 1.95 LM/ 5450 •19 ,,, 39 37 4011111 159 l 4 I 38 100 15 24 }0 18 FREE Wi th each $75 order of Microp rocessor cu rn1rnnents. 33 29 .:n 100 50 J5 JO 78 .OR1x!. 1000 16 5!> 50 45 770 l(j 13 II Iii Sl 2.00 ge t a one vear ~ubm1 p1 ion to BYTE th e mayaw1e 101 ?!!~ ~, " 2200"' 16 70 G2 55 410 15 31 18 76 ~ alut co mpute! PHREAKS FREE FREE FREE PHONE ORDERS - (415) 592-8097 .J COMPUTER-DATA INPUT KEYBOARDS TRANSFORMERS Co mputer projects need power supplies. Finding the right power transformer can be a problem. W e have one of the largest and most diversified stocks of power transformers in the country. Below w e li st some representative items in our inventory . Our catalog, free on request lists many more. 36 V.@ 1.0 A . ct, & 6.3 V@ 200 ma. 3 lbs. 89313 3 .50 2/ 6.00 70 V.@ 1.5 A . ct, & 6 .3 V @ 500 ma. 6 lb. 89314 6.50 2/ 12 .00 90 V.@ 2 .0 A . ct, & 6.3 V@ 1.5 A. SY, lb. 89315 9.95 2/19.00 50 v . ~ @ 1 .5 A. ct, & 6.3V @500 ma. 6 lb. 89316 6 .50 2/12.00 26 V . @ 1 .0 A. c t. &6.3 V .@ 500 ma. 3 lb. 89318 3.75 2/7.00 38 V. @ 1 .5 A . ct. & 6 .0 V .@ 500 ma. 2 lb. 89319 6.95 2/ 13.00 350 V. @ 35 ma. ct. & 6.3 V .@ 2 .7 A 2 lb. 89321 3 .50 2 / 6 .00 85283 70 V. @ 1.5 A. ct. & 6.3 V@ 1.5 A. 7Lb. 89322 6 .75 2 / 13.00 35 V .@ 6.0 C t . & 10 V.@ 10.0 A. 6.0 Lb. B9906 8.95 ea. 64 or 32 V .@ 8 .0 A . ct. & 18 V .@ 8 .0 A ct. 10 lb. B9905 11.95 VOLT AGE REGULATOR BOARDS

85199

ASCII encoded keyboard. In its own enclosu re. Originaly used in SANDERS ASSOCIATES 720 Terminal System. In like new .I / ./ condition. U sefu l I for any project requiring an ASC ii encoded keyboard. 50 Alpha Numeric keys plus 11 computer symbols STOCK NO.B5283 keyboard $35.00 2/65.00 85169 is a board containing 3 15 volt high current regulators with 0.1% regulation. 2 of the regulators are rated @ 3 Amps., MICRO-SWITCH (Honeywell) 8 bit binary coded board. 56 keys, and the other @ 6.0 amps. The current in each regulator may alpha - meric and computer symbols Built in TTL decoder. New be doubled with the regulation going to 0.5%.All 3 regulators in factory cartons. A beautiful keyboard. are short circuit proof, and 2 have electronic crowbar protect­ STOCK NO. B5199 Microswitch keyboard. $ 45.00 2/80 .00 ion. Brand new, in factory boxes. STQCK N0. 85169 $11.95 ea. 2/21.00 KEYTOPS & SWITCHES 89013 is a triple regulator with + 12 volt regulation @ 200 TO MAKE YOUR OWN KEYBOARD ma. and the third regulator is a tracking regulator, providing regulation from 0 to 5 volta @ .5 A. STOCR NO.B9013 $5.95 ea. 2/10.00

£bt:1 re~ulators above come withcircuit diagrams. OPERATIONAL AMPLIFIERS W e have a large selection of KEYTOPS and SWITCHES. made by (OP -AMPS) RAYTHEON CO. The keytops come in black. grey and white. with contrasting legends. The switches mate with the tops. and are TYPE DESCR IPTION CASE STOCK PRICE magnetic reed switches. The following combinations are available: 709 Hi Performance T0-5 B4301 .50 5/ 2 .00 54 key typewriter set, keys only, black K9276 2.95 Dual 709 DIP B5301 1.00 6/ 5 .00 54 key typewriter set, keys only, grey K9278 2.95 4709 .65 5/'.l .00 54 key TTY set, no symbols white K9279 2.95 741 Hi Performance DIP B4316 54 key TTY set, with symbols white K9282 2 .95 747 Dual 741 DIP B4317 1.25 5 i b 00 741 Hi Performa nee Mini DIP B4345 .65 5/3 .00 54 key set, keys & switches black K9288 30.00 747CT Du al 741 T0-5 B3 111 1.25 5/ ti. 00 54 key set, keys & switches grey K9290 30.00 1458 Dual 741 Mini DIPB3112 1 .25 5/5.00 54 TTY set, no symbols keys & Sw. White K9291 30.00 LM101A Gen , Purpose T0-5 B4503 .50 5/ 2 .0 0 54 TTY set, with symbols, keys & Sw. whiteK9291 30. 00 SELF SCAN PANEL DISPLAY 11 Key Numeric set. Keys only Black K9283 1.50 11 Key Numeric set, Keys only Grey K9284 1.50 11 Key Numeric set, Keys only Wh ite K9295 1.50 12 Key numeric set, Keys only white K9286 1.50 ID Burroughs 11 Key Num.set, keys & switches Black K9293 7.00 11 Key Num. set, keys & switches Grey K9294 7.00 11 Key Num. set, keys & switchesWhite K9295 7 .00 12 Key Num. set, keys & switcheswhite K9296 7.50 1 Blank key 1 Y, keys wide :;;;,.·.;;;i ..ii:Jf5i/:7fi flicl:1 BURROUGHS SEL F white K9297 A 3/.2 5 _,. • ·-''·· SCAN display, des­ Blank key 2 keys wide wh ite K9297 B 3/.25 igned for numeric app­ K9297 A with switch white K9298A 3/ 2 .00 /""""'-.,. lication , requiring up to K9297B with switch white K9298B 3 / 2 . 00 MODEL SSD 1000-0010 . 16 char~cters of numeric 1nformat1on. Display 1s made 1------t up of neon dot matrix. Each c haracter is defined by a positive MINIATURE 7 SEGMENT READOUT logic 4 bit code. Display operates in a scanning mode. scanning from lef t to right, one column at a time. Electronics is in inter Miniature 7 segment LED readout (EXITON XMN 101). ior of bezel, and consists of LSI chip and integrated circuits. Displays all numbers and 9 letters. O.D. 5/16" x ll/4" Current distributor price is $135.00 . LIMITED QUANTITY Display is .12 ".SPECIAL FOR THIS ISSUE ON Y STOCK N0.5180 with data $49.5 0 2/90.00 STOCI-< N0.85173 with data sheet .50 ea . 5/2.00

Please include sufficient Send for the latest edition of ocr <:atalog. Loaded with postage. Excess refunded electronic and computer MINIMUM ORDER $5.00 har •~ains . ~ 7-St{-~~~ ~:;out Dale Trimmer 25K Trimmer PRINTED CIRCUIT BOARD TYPE Three digits with right-hand decimal EACH $. 20 10 FOR $1 . 50 Plugs into DIP sockets -12 t urn trimpots whi ch plug Si milar to (LITRONIX) DL337 into a DIP socket Magnified di git approximately .l" -5K and 200K Rectifiers Cathode for each digit -!411 x 1411 x ~ It I~ ~ ~ VARO FULL-WAVE BRIDGE Segme nts are parallel far multiple -4 leads spaced . 3" x . 2" operation Each $1 .00 10 for $8.95 ~ VS647 2A 600V $1.10 5-lD MA per segment MRSIO Rectifier 50V IA s . 10 EACH Sl .75 4 (12 DIGITS) $6.001 1000 MHz Counter 11C05 Fairchild ! GHz Divide By Four Special 811: Hex Inverter RCA Numitron -DC to 1000 MHz operation TTL DIP He x Inverter; pin interchangeable with SN - AC dr DC coup l ed EACH...... $ 5.00 7404 . Parts are brand new and branded Signetics -Vo l tage compensa ted and marked "Bil." - TTL or ECL power supp ly SPEC !AL : 5 FOR $20. 00 EACH .1 6" -50 ohm drive output DATA 10 FOR 1. 50 DR2010 -Lead compatib le with Pl essy SP613 SHEET 100 FOR 14 .00 - True and comp l ement ECL outputs SUPPLIED 1000 FOR 11 0.00 - 14 pin DIP MOS MEMORY 2102-2 -Data and appli cation notes 1 AMP RECTIFIER Each $49.95 1024 Bit Ful ly Decoded Static MOS EACH S . 15 Ra nd om Access Memory LED's 1N4007 ! KV PRV SA LE 10 for $1.00 -fast access 650ns -fully TTL compat ible MV 50 Red Emitting -n channel si li con gate 10-4 MA @ 2V =--- ­ - s ingle 5 volt supp ly -tri-state output cJ -:-_- ·­ MAN 4 7-Segment , 0-9 plus letters . ,, . ~ Right-hand decimal point. Snaps i n 14­ -1024 by 1 bit MV5024 Red TO -IB $ .35 ii' i - chip enable input pin DIP socket or Molex. IC voltage re­ -no clocks or refres hin o Hig h Dome Ci~ 10 FOR $2. 95 .,..·•1'-!'-' -'·:" quirements. Ide a 1 for desk or pocket required c· • cal culators! <; :...,,.. · ~ Brand New Factory Parts MVlOB Visi ble Red $ . 30 EACH $1. 20 10 OR MORE $1.00 EACH 16 PIN DIP Each $5.00 5-7 MA@ 2V 10 FOR $2.50 1------t a for S34.95 '------l CD-2 Counter Kit Power Supply SPECIAL! CMOS This kit provides a highly sophisticated display CD4001 .45 CD4023 $ .45 section module for clocks, counters, or other nu ­ 723 DI P variabl e regulator chip l-40V, CD4002 .45 74C20 .65 mer i cal di splay needs . The unit is .8" wide and +or - output @150 MA lOA with exter­ CD401 1 .45 74Cl60 3.25 4 3/8" long . A single 5-volt power source powers nal pass transistor--with diagrams for CD4012 .45 both the !Cs and the display tube . It can attain many appl ications . 1------t typical cou nt rates of up to 30 MHz and also has EAC H $1.QO 10 FOR $8 . 95 3-Amp Power Silicon Rectifiers a lamp test, causi ng all 7 segments to l ight. Kit includes a 2-sided (with plated thru holes) fiber­ MARKED EPOXY AXIAL PACKAGE glass printed c i r cu it board, a 7490, a 7475, a 5001 Calculator 7447, a DR2010 RCA Numitron display tube, complete PRV PR ICE PRV PR ICE 40-Pin ca lculator chi p will add, sub ­ i nstructions, and enough ~OLEX pins for the !Cs . . . 100 ...... $. 10 B00 ...... $.30 tract, multipl y, and divide . 12-digi t NOTE: boa rds can be su~plied in a singl e panel of display and calculate. Chai n cal cu la­ 200 ...... 15 1000 ...... 40 up to 10 digits (with a 11 interconnects) ; there­ tions . True credit balance sign out­ 400 ...... 18 1200 ...... 50 f o re , whe n ordering, pl ease specify whether you put. Automatic over-flow indication. 600 ...... 23 1500 ...... 65 want them in si ngle panels or in one mu 1tip1 e Fi xed dec imal point at 1, 2. 3, or 4.1------4 digit board. Not specifying will result in shi p- Lea ding zero suppression. Complete DIODE ARRAY 10-1N914 silicon pi ng delay . ;; data supplied with chip . s i gnal diodes in o n e package . 20 COMPLETE KIT ONLY $10. 95 ~ $2. 49 CHI P AND DATA ...... ON LY 1eads spa ced . l"; no common co nne c­ FULLY-ASSEMBLED ·•• .;;__----·-,_, . ,.. J DATA ON LY (Refu ndab l e) .. . $1. 00 tions. UNIT $15 . 00 ,°_ ·~·:~~~ . '{475, : .'7}_~~ : ' 5002 LOW POWER CHIP AND DATA $12.95 EA CH. .. . . $. 29 10 FOR $2 .50 Boards supplied separately@ $2 .50 per digit. High Quality PCB Mounting IC Sockets 7400 . 20 74H5 I .25 LIN EARS 74HOO . 30 7453 .20 8- PIN, 14-Pi n, 16-Pin and 24-Pin PCB 7401 .20 7454 .20 mounti ng ONLY--no wire wrap sockets . 74L54 NE555 Precision timer...... 90 74HO I .25 .25 NE560 74L55 . 25 Phase lock loop DIP ...... 2.9 5 7402 .25 NE561 Phase lock loop DIP ...... 3 . 00 7403 .25 7460 . 16 74L7 I . 25 NE565 Phase lock loop ...... 2. 95 7404 . 25 NE 56 6 Function generator T0-5 ...... • ...... 3. 50 74H04 . 30 7472 . 40 74L72 .60 NE567 Tone decoder T0-5 ...... •... . . , 3. 50 7405 .30 709 Popular Op Amp DIP ...... 40 7406 .40 7473 . 35 74L73 .75 710 Voltage comparator DIP...... 60 7408 . 30 711 Dual comparator DIP...... 45 74H08 . 30 74 74 .45 74H74 .75 723 Precision voltage regulator DIP .. . .•. 1. 00 7410 .20 741 Op amp T0-5 /MINI DIP ...... 45 7413 ,75 74 75 .80 7417 ,40 7476 . 55 fill IC ' s a rc ne w a nd fully tes t e d. Leads 748 Op Amp T0-5...... SU 7420 .20 74L7 8 .70 a re plate d w1 t h qo ld o r solde r. Orde r s CA3018 2 Isolat ed transistors and a Darling­ f o r SS . 00 o r mo r e wil l be sh1pped pr epa id 7480 . 50 74L20 .30 ton-connected transistor pai r ...... 1. 00 i\dd $ . :.:. f o r handling and posta ge f o r 74H20 .30 7483 .70 sm.J l l e r o r ders ; r es i dent s o f Cali forn i a add s a les t ax. IC o rde rs are s hipped 74H22 . 30 7489 3. 00 7490 1.00 CA3045 5 NPN transistor array, ...... 1.00 w1 t h1n 2 wo rkdays--ki ts are shippe d with­ 74 30 .20 LMIOO Positive DC regulator T0-5 ...... 1.00 1n 10 d a y s o f rcccn p l o f o rder . S l0.00 74H30 .30 7492 .65 m1n1mum on C .O.O . ' s . LM105 Voltage regulator ...... 1.25 7493 I. 00 74L30 .30 LM302 Op Amp voltage follower T0-5 ...... 1.25 Mail Orders to : Phone 7440 .20 7495 . 65 P.O. Box 41727 LM308 Op Amp T0- 5...... 2. DO 74H40 . 30 74 L95 I. 00 LM309H 5V 200 MA power supply T0-5 ...... 1. 00 Sacrame Ato, CA (9 1 6) 334- 21 6l 7442 1.00 74 107 . 3 5 95841 74145 I. 25 LM 309K 5V IA power supply module T0-3 ...... 1 . 00 744 7 I. 50 LM 31 l Comparator Mini ...... 1 . 7 5 7450 .20 74 180 1.00 LM370 AGC amplifier ...... 1 . 75 BRB'r'LOn 74 H50 . 30 74193 I. 50 7451 .20 74195 . 65 LM 380 2-Watt Audio Amp ...... I . 75 ELECTROnlCS LM1595 4-Quadrant multiplier...... l . 70 Mone y b~ck guarantee MC1536T Op Amp ...... 1. 35 on a ll goods: 7400 Series DIP

94 KEYBOARD WITH ENCODER Late model keyboard used on computer terminal. Mounted in modern designed wood grained case dust enclosure for desk top use. Utilizes magnetic reed relay bounceless keyswitches. The encoder board mounted within. Fine biz for Morse Code Generator, TV typewriter, computer terminals, etc. Ship wgt. 7 lbs. # SP-153-L ...... $35.00

GENERAL PURPOSE POWER SUPPLY A well designed transistorized regulated power supply with many uses. Each voltage adjustable by a pot. Each voltage fused. 115 volts AC 60 cycle input. Output (minus) 12 volts at 3 amp, 12 volts (pl us) at 1/3 amp, 6 volts at 1 amp .. . three output voltages. Many uses ... as battery charger, op amp, 5 volt logic supply, operate your car radio or tape player, CB set, in the house, etc. A commercially built regulated supply for far less than the price of a kit. Ship wgt. 10 lb #SP-152-L ...... $12.50, 5/$50.00

MEMORY SYSTEM $125.00 New memory system by Honeywell, small ... measures only 9x4x 1 inches. 1024 core memory, 1024 words with 8,9, 10 bits/word. Random access, with all logic, register, timing, control, core select and sense functions in one package. New, booklet of schematics and data. Looks like a good beginning for a mini-computer. Limited supply on hand. Ship wgt 3 lbs. # SP-79 ...... $125.00

CORE MEMORY This one by RCA, sandwich board construction with diode matrix. Fairly small measures approx. 5 x 7 inches. The memory is on one plane 32 x 32 x 9 (9216). Edge connector simplifies use. They are brand new and we have some data provided by one of our customers which we will photo copy and include. #SP-80 ...... $25.00

CORE MEMORY Another brand new memory, ultra small. Measures only 4 x 4 inches with format on one plane of 32 x 32 x 16 (16,384). Only about 35 units of this on hand. #SP-81 ...... $20.00

FREE CA TA LOG Please add shipping cost on abo ve. MESHNA PO Bx 62 E. Lynn Mass. 01904

95 reader I THE service To get further information on the produc1S advertised in this issue of BYTE merely tear, rip, or snip out t his advert iser index, fill out t he da ta at the bottom of the p age, mark the appropriate boxes, and send the works to BY TE, Peterborough NH 03458. Readers get extra Brownie Points for send ing for information E'1TI since th is encourages advertisers to keep using BYTE - which in turn brings you a bigger BYTE.

ADVERTISER INDEX QUESTIONNAIRE

0 ACM 62 BYTE is dedicated to the needs of its readership. ri A. P. Pro du cts 13 In order to better gauge matters of editorial policy 0 Baby lon 94 and content, as well as to give our advertisers some 0 Celdal 69 "hard facts", we publish this questionnaire. In this month's list are a few questions of editorial 0 CMR 86 interest: IJ Continental Specialties Cll I 0 Delta 93 What is your primary interest in personal com­ puting? 0 Delta T 88 IJ Godbout 44, 45 0 Hickok 56, 57 0 ln t'I Elec . Unlimited 90 IJ James 88, 92 Would you suggest a game or two you'd like to see IJ Martin Research 33 described in BYTE? 0 Mes hna 95 IJ Micro Di gital 91 IJ MITS CIV,48, 49, 50 IJ Processor Techn ology 19 ri RGS 7 0 Scelbi 10, 11 How did you hear about BYTE? 0 S. D. Sales 67 0 Signetics 55 0 Southwest Cl I 0 Sphere 2, 3, 4 0 Suntronix 89 What did you like best about the first two BYTEs? 0 Windjammer 63 Messages for the editor:

Reader's Service What did you like least about the first two BYTEs? BYTE OCTOBER 1975 Green Publishing Inc. Peterborough NH 03458 BYTE acquired vi a D Subscription Please print or tvpe. IJ Newsstand IJ Stolen Are you a member of a computer club or society? Name

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96 Power for the Professional! New Proto Boards PB-203 and PB-203A A complete m1ni­ with built-in breadboard budget 1995 kit with full IC capacity regulated Add $1.50 shipping/handlln g short-proof The PB-100 is a low cost, big 10 IC capacity power supplies! breadboard kit, complete down to the last nut, bolt and screw. Includes 2 QT-35S Sockets; 1 QT-358 Ready-to-use. Just plug in and start Bus Strip; 2 5-way binding posts ; 4 rubber feet ; building! 2 extra floating 5-way binding screws and easy assembly instructions. 4.50" posts for external signals (PB-203 only). Completely se lf-contained w ith power switch, indicator lamp and power (114.3mm) wide x 6.00" (152.4mm) long x 1.35" fuse. 24 14-pin DIP capacity. All metal construction ... (34.3mm) high. Order your PB-100 kit! Start building no chipping or cracking as with plastic cases. Two-tone and testing now! quality case makes both PB-203 and PB-203A aesthetically, as well as technically attrac tive.

PB-203 PB-203A • 3 OT-59S Socke ts • 3 OT-59S Sockets • 4 OT-59B Bus St rips • 4 OT-59B Bus St rips • 1 OT-47B Bu s Strip • 1 OT-47B Bu s Strip Trace signals or troubleshoot • Fu se • Power Switch • Fu se • Power Sw itch • Power-On Light • Power-On Li ght fast. Inject signals or wire • 9.75"L x 6.6"W x 3.25"H • 9.75 " l x 6.6"W x 3.25"H unused circuits into existing • Weight : 5 lbs. • Weig ht : 5 lbs. boards. Flexible plastic web' • 5V, 1 AMP reg ul ated power • 5V , 1 AMP reg ulated power construction eliminates supply supply (same as PB-203) springs and pivots. Plus, the • + 15V, Y2 AMP re gulated narrow throat is perfect for power supply • -15V, Y2 AMP regul ate d high density pc boards. powe r supply Order now! PC-14 14-pin Proto-Cllp : $4.50 ea . PC-16 16-pln Proto-Cllp : $4.75 ea. 75. 120. Add $1 .00 shipping and handling Add $2 .5 0 shipping/ handling Add $2.50 sh ipping/ handling

OUTPUT SPECIFICATIONS OUTPUT SPEC IFICATIONS Output Voltage 5V ± V. V Output Voltage 15V, internally Scope probes, Rtpple & Noise @ Y2 AMP adjustable t: test leads lock 10 millivolts Ripple & Noise @ V. AMP , onto unique Load Regulation Better than 1 % 10 millivolts toothed grips Load Regulation Better than 1 %

Continental Specialties Corp. LOGIC MONITOR brings ICs to life faster than a scope . .. safer than a voltmeter LM-1 95 84 each Add $2.50 shipping/ hand ling Self-contained, pocket size. No adjustments o r calibrations needed. Puts life into digital designs. Just clip to any DIP IC up to 16 p ins. NO POWER SUPPLY NEEDED! Simultaneously displays static and dynamic logic states of DTL, TTL, HTL or CMOS on 16 large high Intensity LEDs. Watch signals work through counters, shift registers, timers, adders, flip flops, decoders, entire systems. Concentrate on signal flow and input /output truth tables. Fo rget probe grounds, pin counting or sync polarity. Precision plastic guides and flexible plastic web- insure positive connections. Versatile. Fast. Accurate. Indispensable. Order yours today' urnrn rn~~rn~mfflrn~rn rnrn urn ~rnrnrn[[