HITS MOVING TO EXPANDED FACILITY
by David Bunnell tentatively scheduled for March, Altairs to Albuquerque for demonstra- 1976. All Altair owners will be in- tion purposes. Prizes worth several By the end of January, 1976, it vited to attend this convention. thousand dollars will be awarded to is hoped that MITS will be in its the best demonstrations in each of new facility near the Albuquerque While formal plans for this an undetermined number of catagories. Airport. Internal construction has convention have not been finalized, (We will be looking for unique ap- been in progress for several weeks $ an outline of this event calls for a plications as well as well-developed and plans call for moving the pro- weekend of seminars and demonstra- traditional applications.) duction department before Christmas. tions. The seminars will be con- Administrative departments will move ducted by MITS engineers and software writers and will cover a wide range during January. Since the new MITS plant is of topics of interest to Altair users. located close to the Albuquerque In connection with this move, Airport, it will be very convenient there will be a combined open-house, Hobby clubs and individual Al- for out-of-town Altair users to at- World Altair Computer Convention, tair owners are asked to bring their tend the convention. Hotel reserva- tions can be made at the Albuquerque Airport Marina Hotel across the street from the terminal building, FF7W Sponsors ACR Standards Meeting and from there to the factory it is just a short walk. Users and manufacturers of audio The rest of the meeting was cassette data recording hardware at- spent primarily on discussion of mod- tended a symposium sponsored by BYTE ulation techniques. Of the methods Once a definite time table has magazine in Kansas City, Missouri on presented, there were three main been established for the first WACC November 7th and 8th, 1975. The pur- groups. One was pulse modulation (World Altair Computer Convention), pose of the meeting was to investigate (The Computer Hobbyist. Tarbell), all Altair owners will receive a the various methods of recording data which has the advantage of high data schedule of events and a personal on audio tape and to make a recommen- density and data rate, but the disad- invitation. Attendance to the con- dation on the method that would meet vantage of more complex hardware. A vention will be free, and in addition the requirements of a low cost, reli- second type of modulation considered to prizes for the best demonstrations able system for interchange of tapes. was the HIT system (Processor Tech- MITS will provide door prizes and at nology, Popular Electronics). It was least one free luncheon. Those in attendance included decided to be too software dependent representatives of BYTE magazine, and possibly amplitude sensitive. The People who have suggestions for Popular Electronics, MITS, Processor last group of techniques discussed this conference are asked to address Technology, SWTP, Godbout, The Com- was frequency modulation, including their letters to: WACC/MITS puter Hobbyist, Pronetics, LGC and the 103 type (MITS, LGC) and the Lan- 2450 Alamo SE Sphere. caster method (SWTP, Pronetics). Albuquerque, NM Frequency modulation has the advantage 87106 The first portion of the meeting of somewhat simpler hardware, without Attention: was concerned with the minimum re- being software dependent. The meet- David Bunnell quirements of the cassette recorder. ing concluded with an agreement to in- It was found that speed tolerance was vestigate the Lancaster method as the With the help of the thousands the biggest variable, with speed var- possible modulation standard for hob- of Altair users, it is hoped that iance as large as +10% possible. byist and user interchange. (The Lan- this convention will become one of Minimum frequency response was set at caster method uses 2400Hz = logic 1, the most exciting computer conven- 500Hz to 3KHz +3db bandwidth, which and 1200Hz = logic 0 with the advan- tions in the industry and that it is easily attained by most low cost tage of being synchronous with UART will become an annual event. cassette recorders. Other parameters clock inputs.) such as start/stop time, remote con- trol and tape characteristics were discussed. It was agreed that the standard should include provision for remote start/stop of the tape recorder, and that low noise audio tape (not bargain pack tapes) should be used.
The next part of the meeting MoucmbgA/PeegmbM., ?975 concerned the bit format for record- ing data. The format decided upon was a UART style, 11-bit word to be OMITS, INC. 1975 recorded at 300 bits per second (300 ^o^omg. One. SZx baud). The 11-bit word consists of a start bit (logic 0), eight data bits, A PUBLICATION OF THE ALTAIR USERS GROUP and at least two stop bits (logic 1). PAGE TMO COMPUTER NOTES-NOVEMBER/DECEilSER. 1^75
ALTA^ MPT,
by David Bunnell
As I recall, the last issue of Creative Computing is published Computer Notes was the October issue by David H. Ahl, who in my opinion, and you got it around November 11. is the best writer in the "popular" Right? computing field. It is aimed pri- This issue of Computer Notes marily at the educational market. should logically be the November issue, however, if you get it before 19769 the December issue won't ar- Byte Magazine, which I reviewed rive until February. in September's C/N, is aimed at the hobby market. There have been re- Therefore, this issue of Compu- cent changes at Byte and I see these ter Notes is the Holiday Issue. changes as resulting in better edi- torial content. New Coding Form Nows that should make a lot of The Users Group Library has a sense. Both publications are excellent and since they have completely dif- new Coding Form for program submis- ferent editorial slants, I would sion that is much more efficient than However, doesn't that mean that our old form. A sample copy of the people who paid $30 to be members of recommend that the serious "computer freak" subscribe to both. new form is enclosed — it consists the Altair Users Group will get one of a cover sheet (to give pertinent less issue of Computer Notes before information about the program) plus their subscription runs out? No. Another magazine trying to make it on a national scale is Interface, an additional sheet of program list- ing space. Coding Forms are pur- Effective upon the arrival of which is published by the Southern California Computer Society. They chased from MITS in batches of 50. this issue, you automatically have a When you order the new Coding Forms, one-year subscription. Even if you have a long way to go if they want to compete effectively with Byte and please specify how many cover sheets subscribed back in July, your sub- you want included in that batch. scription now begins with the coming Creative Computing, but I understand their first issue is going like hot- (One cover sheet for each program to January issue (we've got our fingers be submitted.) If you still have crossed). cakes. This issue features the two Altair computers on the cover in a copies of the old form, feel free to stunning painting by Kim Behm (the use them up before ordering the new Hopefully, we will learn to be one. more punctual with this publication. artist who drew the "Created by Man" illustration). A list of articles Programs submitted to the Users I think you'll find our Holiday includes: "Toward the design of a Group Library become available to Issue well worth the wait. Included Micro-operating System," "Teleprinter other members much sooner when our are two four-page inserts from Byte Maintenance/Repair/Preventat ive coding form is used. The entry rules Magazine and Creative Computing. Maintenance," "Altair Switch Memory," for the Software Library are as fol- These inserts were prepared entirely "1+1=10?" and "Soup Up Your T.V. lows; your cooperation in following by the respective staffs, as was the Typewriter." these rules will be greatly appre- PCC insert in October's C/N, and I ciated. hope they give you an idea about what Enjoy this issue of Computer these two publications are about. Notes, and have a happy holiday. In order that programs can be reproduced for distribution to other Altair owners, they should The Amateur Computer Group be typewritten using a ribbon that of New Jersey produces fairly dark type. It is Sol Libes desirable that assembly language (201) 889-2000 (day) and machine language programs be 277-2063 (eve) submitted on official Coding Forms K^S George Fischer or copies of such forms. Coding (212) 351-1751 Forms are available from MITS at $2.00 per 50 to cover printing, 29 Palms California Area Group postage and handling. has changed the contact phone All entries should be on number and address to: 8 1/2" x 11" white paper. Tele- Sgt. Wesley Isgrigg type printouts and Xerox copies 74055 Casita Dr. are not acceptable. Atlanta Area Microcomputer 29 Palms, CA 92277 Hobbyist Club (714) 367-6996 C/N DeMvety Dates Jim Dunion, President I've had quite a few letters 421 Ridgecrest Rd. Homebrew Computer Club and calls regarding the delivery of Atlanta, GA 30307 Robert Reilling, Editor Computer Notes. Perhaps it will help (404) 373-8990 193 Thompson Square if I outline exactly how we mail Meetings are held the last Wed. Mountain View, CA 94043 Computer Notes to different areas: of each month, 7:30 p.m., at HP-65 Users Club I. Bulk Mail The Calhoun Co. % Richard J. Nelson 6000 Peach Tree Rd. A. Any address with a zip code 2541 W. Camden Place 1. United States Atlanta, GA Santa Ana, CA 92704 2. APO Computer Hobbyist Group of UCLA Computer Club 3. FP0 North Texas 3514 Boelter Hall Bill Fuller UCLA II. Third Class Mail (214) 641-2909 Los Angeles, CA 90024 A. Canada Neil Ferguson B. Mexico (817) 461-2867 San Diego Club Lannie Walker % Gary Mitchell Fhye - III. Air Overseas Mail (AO) (817) 244-1013 Box 35 A. Countries overseas Chula Vista, CA 92012 COMPUTER" NOTES-NOVEMBER/DECEMBER T M75 PAGE THREE c by H. Edward Roberts, President, MITS
This is a continuation of my if you have a system which contains very active internal program con- random ramblings concerning the small 6 or more MITS cards, we will provide cerning evaluation of all MPU's. computer industry, the Altair and you with a higher voltage transformer Since we have no ties with TC manu- MITS. If you have any comments on at no cost. Due to the heavy 5 volt facturers, our evaluations are any or all of these subjects, please current requirement of some of the essentially unbiased. Unfortunately, write me. 4K static memory cards (discussed non disclosure agreements prevent us in previous issue) you may run out from discussing some of the newer PROBLEMS: of voltage with as few as 4 cards in unannounced MPU's. The following is the system. The rectifier in the a list of the processors which we The 4K memory cards are still power supply is rated at 10 amp. have evaluated in detail. in a heavy back order situation,, The Which is 20% over the maximum current majority of the 4060-2 (4K RAM chips) required by a fully expanded Altair Intel 8008, 8080, 4004, 4040 we have received in the last few using MITS cards, i.e., .5 amp Motorola 6800 months have been diverted to replace average per card and 16 cards. The MOS Technology 6500 series higher voltage transformer should the 2604's which were shipped in National PACE, IMP 8 not be used in small systems, i.e^, August. There are now two shifts Fairchild F-8 operating in the Repair Department under 5 cards, because it places an unacceptably heavy thermal load on in order to eliminate this problem. In order to keep this evaluation the 7805's. If you have a new order for 4K mem=- short I have reduced our internal ories or if you have a 4K board at criteria to the following major MITS for repair, please bear with us Another point raised about the items: for the next few weeks. power supply is why didn't we use the lower cost single regulator for 1) Design Complexity of CPU - PHILOSOPHY: the whole system, i.e., not use card this is important only to the manu- regulation. There are two primary facturer and to the home brewer. There are a number of questions reasons: (a) the on card regulation significantly improves system noise raised each month concerning the 2) Hardware Flexibility - this immunity (b) and most important a Altair design philosophy. Therefore, is a measure of the flexibility of castrophic failure in a single regu- starting with this issue I will the system to interface to other lator system could destroy literally specifically discuss the most common hardware. ones. thousands of dollars worth of components. 3) Memory Efficiency - a 1) FRONT PANEL READY: The measure of how efficiently the front panel ready provides an active 3) CARDS: There are two com- system uses memory particularly pullup to the system ready line. ments raised concerning the DC cards important from a cost standpoint. Therefore, in the run mode if a bus used in the Altair. Some cards in card pulls the ready line low it the earlier Altairs did not have gold 4) Power of Instruction Set - must fight the front panel pullup, fingers, of course all Altair cards all measure of software power must this is an intentional design and produced recently have gold fingers. be done on the basis of relatively does not create any problems. (In- Contrary to popular opinion the gold large software packages, small or cidentally, a check of the Signetic has more esthetic value than practi- singular routines tell nothing data manual on the 8797 will show cal value. If you have an early about system power. that this is an acceptable condi- Altair board which doesn't have gold tion.) Nevertheless, if you are fingers, effective immediately you concerned about this, move the PRDY have a 5 year warranty on the 5) Overall System Speed - this line to the XRDY line on the system fingers. is a measure of both hardware and bus wiring from the front panel. software speed. That is, move the wire from pin 72 A valid criticism that was made to pin 3 coming from the front panel 6) Availability of Software - concerning early Altairs was related a measure of which systems have the harness. The XRDY was designed into to the 1/16" thick motherboard. the system to allow for a simplified largest amount of manufacturer While this motherboard didn't create supplied software. DMA which is no longer used by MITS. an electrical problem, it wasn"t One mod which has been suggested is rigid enough to support the card 7) Reliability of Primary move the PRDY line on each card to guides properly, in a word it was Vendor and Number of Second Sources - pin 3 on the card, don"t do it. sloppy. Of course, all the later this will give an indication of the This will cause major conflicts in Altairs have 1/8" motherboards. If availability of new software and the system if additional peripherals you have an early Altair and if you compatible hardware. are added. Some of them are looking are willing to remove the edge for a PRDY from other system cards. connectors from your mother card, If you are using a non-Altair card let me know and we will send you a 8) Overall System Speed - that uses the ready line, make sure new 1/8" card free! this is really the best single it is connected to PRDY and not XRDY. measure of system performance, For that matter, don't use any modi- but is only applicable when re- Next month I will discuss other lated to large real-world soft- fication in your system if it doesn't commonly asked questions or criticism, appear in Computer Notes or another ware packages, we use BASIC as a MITS publication. comparison. The following is a PROCESSOR COMPARISON: thumbnail chart. 2) POWER SUPPLY: There have I have been asked by a number been a number of questions raised of people the results of our MPU concerning the power supply used in (microprocessor unit) evaluations. the Altair. The basic Altair is We have probably had more experience shipped with a transformer which in designing general purpose MPU is rated at 8V and 8 amp. It turns hardware and software than any other out that in practice if the current group in the world. Therefore, our load exceeds 3-4 amps (6-8 Altair evaluations may be useful and hope- cards) the unregulated bus voltage fully interesting to anyone involved drops to the point where local regu- with small computers. I'm sure it lation by the 7805 is marginal. But goes without saying that we have a PAGE FOUR COMPUTER NOTES-NOVEMBER/DECEMBERi 117S 800 8 F- 8 808 0 PAC E 680 0 Ed Roberts^ 650 0 tn M M M 13 n Complexity 13 m O o m o Flexibility 13 o M M M 13 Memory Efficiency continued O 13 13 o M 13 Power of Instruction 13 13 13 o M O Avail, of Software 13 13 O o M O Efficiency of Software Hj 13 O o m 13 Speed There are several things that n O M M M Reliability of Vendor are apparent from the evaluation. m n Tj O m O Suitability as a G.P. The 24 bit byte oriented processors Processor are in general superior to the 16 bit processor (PACE, the IMP 16 is E Excellent not even in contention). The "old" Good 8008 is almost as good a processor C F Fair from a general standpoint than some of the newer processors, of course, P Poor it is significantly slower. The 8080 is still the most powerful criticism is very gratifying in the baud rate. Of course, the display single chip LSI processor available sense that it indicates that our has upper and lower case capability, but the 6800 is certainly good typical customer is more than so* black on white and white on black competition. As a matter of fact phisticated enough to establish the and any of the other things you in simple minimal systems the 6800 attacks on MITS and the Altair would expect in a terminal of this is preferred due to the simplicity for what they are. Therefore, in quality. The cost of this system of interfacing, it is the logical the future we will address these will be significantly greater than choice for someone who is planning sort of comments only in response the T-V typewriter type of display, to homebrew a small system. If you to letters you send us and in the but the capability will be much are interested in a more detailed general design philosophy section greater. report on our evaluation, let me of this column. know and we will write a full and Our internal scheduling calls complete article on the subject. NEW PRODUCTS: for shipments to begin in February, but you know how that goes. Never- CLUBS: As I indicated last month as theless, we will not accept orders a general rule we will not release on this product yet, but if you The majority of the computer information on new products until would like to reserve a unit pending clubs that exist today are a result they are production ready. But firm pricing and delivery schedules, of the catalyst provided by the there have been some inquiries write a letter to Barbara Sims and MITS road show. We are very inter- concerning the -2 and -II designa- she will assign you a slot in ested in continuing to provide what- tion on some of the newer cards production. ever assistance we can to clubs. At produced by MITS. Cards designated the present time our typical custo- in this way are designed to be mer is relatively sophisticated in compatible with the until now PUBLICATIONS: terms of general electronics techno- unannounced Altair II. Let me just logy and/or software, but the vast say the Altair II will be at least We have mentioned the Computer majority of the potential customers as revolutionary as the original Hobbyist in previous issues of in this hobby are not sophisticated. Altair was when it was introduceds Computer Notes, but I feel that it These new people are certainly All -II cards have downward compati- is such a valuable publication for needed by MITS and other manufac- bility with the Altair 8800 systems, the serious hobbyist it should be turers and their volume will bene- non-11 cards probably won't inter- considered required reading. You fit either directly or indirectly face with the Altair II. can obtain a subscription by writing everyone in the hobby. A large Another product which has got- to the following address: percentage of the education and ten a good bit of unintentional assistance getting these new groups publicity is the MITS CRT graphics The Computer Hobbyist up and running will have to come terminal. This is a product that Post Office Box 295 from the clubs, there is no other has been under active development Gary, North Carolina 27511 place. Our present efforts with for more than two years. Because the van only scratch the surface, of the great amount of interest in Please send any comments or incidentally the present van show this product let me break my own suggestions to me directly at MITS. is a basic technical presentation rule and give you some preliminary and not a sales pitch. We are data. HighesjL regards, actively working on a number of different courses which may prove useful to many of the clubs. In the alpha display mode it will present 80 characters per line, 24 lines per page. Up to 32 pages Any club which would like to can theoretically be stored within have a technical group from MITS the machine. There are two graphic come to their meeting, please let modes, in the low resolution mode me know and we will be there. If there are 256 x 256 elements. Any David B. Porter Jim Gerow you would like an equipment demon- number of graphics pages and alpha 528 Carr Ave. 2525 McCue #243 stration and/or sales pitch we have pages may be interlaced and dis- Rockville, MD 20850 Houston, TX 77027 representatives and dealers scat- played under real time software Peter Jarvis tered all over the country who would control. The brightness of each 10545 Ashworth N. love to have the opportunity to frame in an interlace mode may be Seattle, WA 98133 attend your meetings. controlled. Control logic allows Jerry K. Kozelsky the system to be used with a stan- 5711 Sarvis Ave. Suite 502 PARANOIA: dard color monitor if desired, i.e., Riverdale, MD 20840 full color graphics and alpha Jack J. Keith I have received a number of numerics are possible. 3435 Mansfield Rd. letters from readers of this publi- Falls Church, VA 22041 cation concerning our counter attack The data transfer rate between Olin A. Williams, Jr. of the armchair experts and others. display and CPU is at main frame 2871 Tony Dr. The majority of those letters have speeds, that is it should be possi- Lawrenceville, GA 30245 been critical in the sense that they ble to update the display at James T. Mattley seem to say we are wasting time approximately 100 K byte rate, 6417 Fernhurst Ave. attacking these characters. This this is equivalent to a 1,100,000 Parma Heights, OH 44130 COMPUTER NOTES-NOVEMBER/DECEMBERi 1^75 PACE FIVE
The only difference in AO and C/N Subscriptions invoices Air Mail is that the flap is taped rather than sealed for inspection For some reason many of our Our invoicing has been changed purposes. It is impossible for MITS customers think that the return of to a new system which has caused a to take special requests for air their warranty card initiates the small amount of confusion to some mail due to the large amount of mail- subscription to Computer Notes. This customer's. When you receive equip- ing we handle at one time. In the is not true; your subscription begins ment from MITS, you will have a pack- past, Computer Notes has usually been in the month we ship your 8800 or 680 ing slip enclosed called our MITS mailed around the 20th of the month. to you. Those customers with a com- order. A few days later you will re- After the first of the year, we will puter printout invoice are immediately ceive a MITS invoice for this equip- try to start mailing a little earlier on the mailing list. Those customers ment. Please note on the invoice how in the month. If for some reason you who receive a white (7" x 8 1/2") in- your order was paid for. If you are not receiving your newsletter voice are put on our mailing list have prepaid the order, this invoice within approximately three weeks from when their Altair is shipped. The is for your records only. If your the date it is mailed, then perhaps same is true with time payment cus- company is on a net 30 basis, the you should check with me. tomers. If you purchased from one invoice is for payment. Hopefully of our representatives or retail this will clear up the confusion. stores, then we add your name to our Change of Address mailing list when we receive word When a school or company pur- from them. chases the Altair, the sold-to ad- dress is used for our monthly mail- Ctassified Ads ings. If this is the case with you, Ordinarily, your membership in and you would like to change the the Users Group will end in a year's A classified ads section is be- monthly mailing address to come di- time (.in the same month you ordered ing introduced to our newsletter this rectly to the user, drop me a post your equipment). However, since month. Anyone who would like to ad- card with the purchasing name, 8800 there have been delays in getting vertise equipment for sale or trade, order number and new address included. Computer Notes out on a regular basis, or has a want ad to place, should I will see that the mailing label is no subscription will end until January send a postcard to my attention with changed. If you mail or call in a 1977. This means if your ordered an all the necessary information. change of address, please note that Altair this year, your membership is you are an Altair owner or user. good through December of next year. The following 4 pages of Computer /Vofes are reprints of 8 pages games and puzzles!) This 72-page bi-monthly magazine is also from Creaf/Ve Compuf/ng, "the magazine of recreational and crammed full of other good stuff of interest to Altair users. educational computing." Each issue of Creaf/'ye Compof/ng carries 4 Subscriptions are only $8 per year and a)l subscribers will receive a or 5 games in BASIC, most of which will run without modification $5.95 computer art book free as part of their subscription. in Altair BASIC. (The Jan-Feb 1976 issue is entirely devoted to CDMPLEHT COMPUTER CHTfULQEJE We welcome entries from readers for COMPUTERS BOOKLET 3 )F)P BOOKLETS the "Compleat Computer Catalogue" on A 94-page booklet for 40 cents? Why, Three booklets have been produced any item related, even distantly, to it's even difficult to get 94 sheets of between 1971 and '74 by various working computers. Please include the name of blank paper for 40 cents. And yet here is groups of the International Federation the item, a brief evaluative description, one of the best basic descriptive books on for Information Processing. price, and complete source data. If it is an computer hardware. It covers the birth of Computer MMcahon /or 7eac/:ew in item you obtained over one year ago, computers from the abacus and Babbage yecowdarj' gc/iooAs - /In OMfHne Guide is please check with the source to make sure up to the present day, the anatomy of a for those who are planning courses for it is still available at the quoted price. computer including simplified explana- the training of teachers. It gives sug- Send contributions to "The Compleat tions of some very sophisticated hard- gestions for the content of courses Computer Catalogue," Create CompMf- ware, and finally some speculation about although the information is of a very i'ng, P.O. Box 789-M, Morristown, NJ what's coming in the way of applications general nature. Includes 3 brief but 07960. and large networks. The booklet simply excellent pages on methodology. 75^. titled Compiler.: is written by William CciwpMfer F^Mca^'o?! /or TeacTierg ;'n Corliss and published by the AEC, sorry .Secondary ^cAoo^ - /li'nM and 0&/ec- ERDA. This one is a must. 40^ each, even fi'fM in Teacher Training. Booklet shows BOOKS AND less in quantity. (Many other booklets are how society and education is changing also available from ERDA; we recom- and discusses the role of the computer in BOOKLETS mend three: TWeoperafor.! modern education. Lists brief outlines for and Layers. Send $1.60 for all four.) seven courses. 75^. TOWARD UNDERSTANDtNG THE U.S. Energy Research and Develop- 77ie Mye o/ CowpMfer in Teac/dng SOOAL tMPACT OF COMPUTERS ment Administration, Technical Informa- and Learning. Describes ways of using the This very comprehensive 136-page tion Center, P.O. Box 62, Oak Ridge, TN computer in education, the rationale and book by Roy Amara is the distillation of 37830.. benefits. Discusses the necessary factors the thoughts of 60 participants in four for a successful program — key people, workshops held by the Institute for the instructional material development, facil- Future. The principal message is that a ities, and hardware acquisition. Depth of real urgency exists to systematically coverage is sparse (booklet has only 16 understand how computers affect the pages of text). $1.50. decisions we make, the goods and services AFIPS Press, 210 Summit Ave., we produce, and the world we perceive. Montvale, NJ 07645. Specific topics discussed in-depth in- clude: 1. Computer modeling and simula- tion as an aid to decision making, 2. Computers and financial processes, 3. Computer perceptions, attitudes, literacy, 4. Computers and individual access. A fifth could be added, "where do we go from here?" $10 to institutions, $7.50 to POPULAHON AND FOOD individuals and schools. There are two interrelated and indis- Institute for the Future, ATTN: Judy putable facts which many people have Flathman, 2740 Sand Hill Road, Menlo failed to comprehend: 1) world food Park, CA 94025. production cannot keep pace with world population growth (not even with com- SMALL PRESS MATER)ALS puter planning, miracle fertilizers, or Fdcen^ri'e, //ai'/cM Afagazi'ne, Tzaddi- COMPUTERS !N EDUCATtON plankton harvests from the ocean) and Mm, Femi'nMf ,4rf VoMrna/, /''i'cf/on, T^oar, This ambitious little booklet (48 pp 2) "family planning" or new contracep- Cri'My, R/Me Pig, /I/go/, A/aj'Ae, and text, 14 pp appendices) boldly attempts tives cannot and will not, in the Que.!; are just 11 of the approximately to cover in three parts: How Computers foreseeable future, check population 1800(!) little magazines and small presses Work, Administrative Uses of Computers, growth. People are clearly looking for a listed and described in the 1975-76 and Educational Uses of Computers. miracle solution since the alternative, of International Directory of Little Maga- Indeed in the reading time of one hour, a course, is triage. Every person in the zines and Small Presses. If you want a person will get from this booklet a clear, world, has an obligation to learn more different view of the world, sometimes concise and amazingly complete view of about this situation which can only be strange, sometimes ecstatic, but always the computer in education. Last known described as a crisis. Send for a copy of refreshing, get this directory and send for price $1.00. the "Declaration on Population and sample copies of 10 or 20 little Computer Services, Province of Mani- Food" and a subscription to "The Other magazines. Directory $5.95 plus 50^ toba Dept. of Education, 103 Water Ave., Side." Both free. postage. Winnipeg, MB, R3C OJ2, Canada. The Environmental Fund, 1302 Eight- Dustbooks, P.O. Box 1056, Paradise, eenth St., N.W., Washington, DC 20036. CA 95969. cpcative comparing MBRARY Four sets of books covering major topics in Probtem Solving With The Computer- Ted Sage computer literacy. Teaches problemsolving,chart flowing.and computer programming (in BASIC) in the ]0) BASiC Computer Games- Have Ah) context of the traditional junior/senior high An anthology of games mid simulations- irom X school curriculum precalculus math. 244 pp. $4.95 t- Acey-Deucey to Yahtzee. ait in the BASK' < Problems For Computer Solution- Gruen language. Contains a complete tisting and sam- 2 berger & Jaffray pkmnoteacligamciplusadescriptive write- A collection of 92 probtems in engineering, M up.Laigef'Oimat.25bpp. $7.50 t/s UJ K business, social science and mathematics.
Name. Street. City_ $0.75 Q Payment enclosed Postage and handling State. Zip D Bill me ($1.00 charge) Total
/3/70f/?er newgfa^e /row Create Cowpuf/ng. ..
by David Ah) LUNAR, a)so known as ROCKET, APOLLO, LEM, etc. is, next to STAR TREK and SPACE WAR, the most poputar computer game, it is certainty the most poputar on smalier machines, (i remember a miiestone of sorts when i managed to compress LUNAR to run on 4K PDP-8 BAStC whiie retaining fu)) instructions and tanding messages. ) used every singie character avaiiabte.) The version of LUNAR presented here was originatiy written in FOCAL by Jim Storer, a student at Lexington (Mass.) High Schoo) in the mid 60 s. Whiie everyone ctaims to be the origina) program author of LUNAR, t'm reasonabiy sure that Jim predates the others and therefore qualifies as the origina), origina) author. ) converted the MAPPING THE MOON program to BASIC in earty 1970. )t's a straight-forward This photograph pictures Mare Crisium, the large "flat" area near version without side stabitization rockets or other goodies the eastern edge of the moon as seen from Earth. In the foreground but, nevertheless, is quite a chaDenge to )and successfutty. is'the mountainous terrain that forms the southern rim of Mare Crisium. Visible near the horizon, 285 miles across the mare, is its northern rim. Prominent at above right in the mare is the PLAYtNG THE GAME 24-mile-wide crater Picard. Photo was made from Apollo 10, the last Your mission is to achieve a soft tanding of your LEM flight before the lunar landing. (Photo Kodak) on the moon. You separate from the command ship 200 mites above the surface of the moon and, every 10 seconds, set the burn rate of your retro rockets to stow your craft. SAMPLE RUN EUNNH You may free fat) (0 )bs./sec.) or burn at any rate between LUMRR LRNMNG StHULRTtON 8 Ibs./sec. and 200 tbs./sec. Since ignition occurs at 8 tbs./sec., burn rates between 1 and 7 tbs./sec. may not be used. A negative burn rate automaticatty aborts your CONTROL CRLUNG LUNHR MODULE YOU HKY SET THE FUEL RRTE (K) TO ZERO OR BUY YRLUE mission. BETWEEN 8 HMD 299 LBS PER SECOND R NEGRTtVE FUEL There are three poputar ways to tand: RRTE HtLLRBORT THE MtSStON. 1. Constant burn rate att the way down. YOU HRVE 16999 LBS OF FUEL 2. Free fatt for a white, then maximum burn rate tapering ESTmHTED FREE FRLLrNRHCTTtHEtS 129 SECONDS off as you get dose. CKPSULEMEtOHTtS 22,598 LBS FtRSTRRDRR CHECK COHtNG UP 3. Graduatty increase burn rate to a maximum, then taper 6E6tNLHN0tNG PROCEDURE off as you get ciose. Recall from physics that Newton found the force of TtHE(SECS) HEtGHT(MI) VELOCtTY(MPH) FUEL(LBS) FUELRI 9 129 MM 16989 K? 8 attraction (gravity) between two bodies varies directty with 19 199 95 3636 16899 K? 8 the mass of the bodies and inversety with the square of the 29 99 8 3672 16999 K? 8 39 89. 55 2798 16999 K? 8 distance between their centers. This may hetp you tand 49 79 2 3744 16999 K? e 59 48. 75 3789 16B08 K? e successfutty. Then again, it may not. ,46 58.2 2816 16999 K? 8 79 47. 55 2852 16899 K? 298 89 37.3636 2476.42 14899 K? 288 COMPUTER NOTES 99 28 262! 2972 94 12999 K? 288 199 29.3232 2637 46 19999 K? 203 Convert the program to your version of BAS)C. lie 13.644 2164.97 MM K? 269 Multipte statements on one tine are.separated by a coton 129 8.33572 1649.14 MM K? 289 136 4.52958 1981.92 4999 K? 189 (:). Everything etse is standard. 149 2. 2887 522.398 2288 K? 90 159 122786 238 772 1399 K? 49 Some computers produce an error catcutating the 169 .718389 127.493 999 K? 28 expansions (Statements 910 and 920) when you get ctose 179 .418989 88.5788 799 K? 22 1B9 .237646 41.1695 489 K? 14 to the moon and the numbers get very smat). tf yours does, 199 .147722 23.5114 348 K? 10 299 85962ZE-1 29.9169 240 K? it) substitute the expanded form. Here it is for Statement 910: 219 317394E-1 18 9912 149 K? 12 ON THE MOON RT 21B.451SECS. [MPRCT VELOCITY OF 8.98172 M P H. FUEL LEFT 33.5879 LBS. -Q* (1+Q* (1 /2+0* (1 /3+Q* (1 /4+Q/5)))) VERY GOOD LRNDtNG. NOT PERFECT YET. You should be abte to figure out the other one yoursetf. Would you tike us to print the other versions of TRYR6R!N<1F0RYES. 9F0RN0)?9 LUNAR in Creaf/ye Compuh'ny? tf so, write and tet me CONTROL OUT know-DHA. READY PROGRAM LS8T3MG LtSTNH 1 REN *** HRtTTEN BY JtH STORER. LEXtNGTON HS Puzzles and 2 REM *** CONVERTED FROM FOCRL TO BRStC BY DRVtD RHL. DtGtTRL 19 PRtNT -LUNRR LRNDtNG StNULRTtON" PRtNT 29 PRtNT F'RtNT PRtNT "CONTROL CRLUNG LUNRR MODULE.. -PRtNT - 35PRtNT*Y0U NRV SET THE FUEL RRTE (K> TO ZERO OR WW VRLUE" 49F'R[NT*BETREEN e RND Z99 LBS PER SECOND. R NEGRTtVE FUCL* Problems For Fun 59 PRtNT "RRTE MtLLRBORT THE MtSStON.":PR[NT 39PRINT-Y0U HRYE 13999 LBS OF FUEL. " 79PRtNT'ESTtMRTED FREE FRLL tHRBCT TtHE [S 1^0 SECONDS." 49F'RiNT't:HPSULE NEtGHT [S 32-599 LBS." ^ The number 153 = 13 + 53 + 33 Find a)! other 99 RRtNT.PRtNT "FIRST RRDRR CHECK CONING W 199 F'EtNT 'BEGIN LRNDtNG PROCEDURE* PRINT PRINT 3-digit numbers that have the same property. How liapRtNT'TIHEfSECS)','HEIGHTfMI!"-'VELOCITYCHPW)*,"FUEL(LBS)","FUEL RRTE* 129 LET L-9:LET R-1Z8LET Y-1:LET H-32599:LET N-13599 about 4-digit numbers? To the 4th? Bill Morrison Sudbury, Mass. 239[FKC9G0TOS99 235tFK-3G3T0 319 zsi139) PRtN:F Ttt<-za 'NOeT cPOSSIBLE",,,,"K*.o To 3ie '
339 LET S-T:tF GO TO 350 359LET[9*l:G0TO999 338tFIt-9G0T0 719 379tFV<-9G0T0 339 375 tFJ<9G0T0 319 339 LET t9-l:G0TO399 419F'RtNT"FUEL0UTFiT",'L;"SECS." 429 LET S=<-VtSOR C. 6. 4 2o 5 17 8 a & 54 92. G 3 1 49 7 .. 4 Appotlo 14 Launch Contro) Center, Cape Kennedy, Florida ^ Send us your favorite puzzies for this cotumn!! fi O 13 cr creative conapntiBg m -j m BACK tSSUES COMiNG SOON n MOV DEC 1974 - CHARTER ISSUE (Out of print) JAN FEB 1976 - GAMES AND PUZZLES t Re-inventing the Wheel — A collection of commonly-used CREAT!VE COMPUUNG SUBSCFUPTtON FORM Pubtished bi-monthty — 6 issues per year TMTM W ^ it ^^ i 1. Qt/a^!. f/pe Term Pr/ce fac/? 2. /Vew or 3. 5/7///!p Institutional 1-Year S15.00 D New Q Payment enclosed Institutional 3-Year $40.00 D Renewal D Please bill me ($1.00 billing charge $8.00 Q Gift will be added except on institution- it TMs w^i^e Individual 1-Year Individual 3Year $21.00 al and bulk subscriptions. Student 1-Year $6.00 4. /Varne /) Student 3-Year $16.00 Bulk (10 24 copies) 1-Year $7.00 Name Title/Dept. Bulk (25-49 copies) 1Year $600 Bulk (50 99 copies) 1-Year $5.00 School or Company ' SHnnw ^ Bulk (100+ copies) 1-Year $4.00 13 Street Address Sample Copy $1.00 -t^LW ILI. yct-^^y MCAtTMY, 0?i.T.y Tsey -ye ay fet- Foreign Postage $1.50 per year City State Zip CAS AT IV Ef , Dept m tumult ^yg^i-gM . Return form to: CREATIVE COMPUTtNG, P.O. Box 789 M. Morristown, New Jersey 07960 PAGE TEN COMPUTER NOTES-NOVEMBER/DECEMBERi M75 introduction to Flow Charting eomtribrnted by Thomas D. Thomas Salem, Oregon Part 1 Last September - 15, I paid $30 for membership on your Altair Users Problem Definition: Sue has 6 times as many apples as Joe. Fred has half as Association - see MITS order 6768. many apples as Sue. Joe has 4 fewer apples than Fred. How many apples has Mary, if she has 5 more than Sue? A few days after this date, I received the August issue of Compu- ter Notes. Having been for over 15 years in the D/P industry, where the 1. Define the number of apples that Sue has, in rather staid styles of the IBM and S = 6J terms of the number that Joe has, from the ACM publications set the standard problem definition. modes of communication, I found your lively and informal news letter full . ! 2. Define the number of apples that Fred has in of inspiration and human touches. F 2F = S relation to Sue, from the problem definition. Perhaps someday you will be re- T—' membered not so much for your in-ex- F = 3J 3. Define a relationship between Fred and Joe, pensive hardware, but for having from steps 1 and 2 above. helped in the "humanization" of the J " computer industry. F = J+4 4. Define the relationship between Fred and Joe, from the problem definition. CongratulationsI Keep up the good work. ! 3J = J+4 5. Substitution for simultaneous solution of steps 3 and 4 above. Mario F. Maffioli Ponce, Puerto Rico 00731 L—J" j = 6. Joe has 2 apples, from step 5. Dear Mr. Bunnell: I see in Computer Notes for October 7. Sue has 12 apples, from steps 1 and 6 above. that there are many quotes from PCC if.. for September. On pages 12 and 13 of the same issue of PCC there were some other comments of considerable s+sj 8. Relationship of Mary to Sue, from problem definition. interest to Altair owners. Specifically: 1. Conditioning of the reset switch ! M = 17 ! 9. From steps 7 and 8. as per diagram shown. 2. Modification of the dynamic boards. 3. C-7 no greater than 4700 pF. Fart 2 Under "Arrowhead Tips" the final value is given at 0.01 uF. Discussion: 4. Rewiring the PRDY to pin 3 of We are ready to ask ourselves, why flowchart at all? From the previous the bus. example, we see that Flowcharting forces us to clarify our thinking, by translating our solutions into a step-by-step procedure. Secondly, we have Would you please give me your com- stated the problem, and its solution, in a language that is more universal ments on these suggested modifica- than most programming languages. tions. Dr. George L. Haller We see then, that Flowcharting: Naples, FL 1. Helps us to formulate our solutions 2. Helps us to communicate our solutions to others. Dear Dr. Haller: None of the modifications mentioned As an example, let us communicate the solution to a data processing job in the PCC article are required, and to our employee, the programmer. some will even damage your machine. First, we define the problem: But specifically to answer your A. Define the input information (data deck). questions: B. Define the output information (report). C. Define the tools (language, computer, etc.). 1. Bounce in the reset switch can cause an undefined condition in the Second, we communicate the general form of the solution in the form of status latch, and this can result in the solution's flowchart: a loss of data in the 4K memory boards. At this time there is only one solution to this problem: don't use reset once the machine is loaded INPUT DATA PROGRAM (normally the case anyway). The (SORT) modification proposed in PCC was tested internally and the only effect it had on our machines was to sup- press the operation of the reset ( switch totally. If that's the goal, SORTED RPG PROGRAM . REPORT PAGE a simpler mod would be to remove the DATA ! \ reset switch. In addition to the fact that it didn't work in the majority of the machines in which it was tested, it will permanently dam- Notice that the problem*s solution is immediately clear, from the above age the reset switch due to high flowchart, and that the programmer should have no difficulty in understanding surge currents during the capacitor what is wanted by his supervisor. That is, the input data is to be sorted discharge. Never discharge a capa- and printed in report form, by two different programs. This simplistic flow- citor with a mechanical contact with- chart may seem to add little to the understanding of the problem statement. out using some sort of current limit- However, look again at page 1, and compare the problem statement to the flow- ing protection. chart, to see that the flowchart may often tremendously clarify a problem statement. COMPUTER NOTES-NOVEMBER/DECEMBER-, M75 PAGE FIFTEEN Build this "Record and Play Switching Unit" for your Aitair ACR contributed by Craig Pearce How many times have you run Also, the box contains a built- nal component placement. The your output bootstrap program to re- in, 1-watt amplifier module for mon- switches and speaker do displace cord material onto tape, only to find itoring of signal on playback (and some area inside and many times have that the cable in the back was con- during record, if the tape recorder I found a homebrew project does not nected to the 'Tape Play In' jack? allows this), plus a seven-segment fit together because of this problem. If you're like me, probably about as LED display to indicate the mode. many times as I've left the plug in (An "S" for Store—or record—and Another point to remember is 'Record Out' when I wanted to read a a "P" for Playback. The reason for always use a NON-SHORTING type switch. program into the core. the term 'store' now becomes obvious, This prevents the in and out lines on since an R (for record) looks more the ACR Modem from getting shorted I immediately saw I was in a like an "A" on a seven-segment dis- together. (A non-shorting switch is losing battle with what I call my play. ) said to "break before make," or dis- "memory" (I think my brain's refresh connect one lead before connecting circuitry has gone bad), so, I The builder can use any enclo- the other. In contrast, a shorting, quickly roughed out and threw together sure and any 6-volt DC source that or "make before break" type switch a handy, simple switch box, then he wishes. The parts used by this will intentionally short adjacent tacked on a few conveniences to make author are listed in a table to fol- contacts as it is moved from one the unit a. little easier to use. low. position to the next.) With the "RPSU" both the record- For those who wish to assemble out and play-in jacks on the back of Construction is quite straight- the unit like the author's, a com- the ALTAIR are connected to this unit forward. The various parts to be plete set of drawings accompanies at the same time. Coming from the mounted on the front panel should be this article, (see next page) unit are two cables that connect to laid out first and then the holes the recorder's microphone input jack drilled. A series of holes, or one Hopefully, your leads will no and the line output jack. A two- large one with a grill cloth, should longer be misconnected when using the position rotary switch is used to be made for the speaker. One ACR-Modem. Unless, of course, you select between the record (called IMPORTANT NOTE: Always check to see forget to throw the switch. 'store' for reasons explained later) component placement on the front and play modes. panel does not interfere with inter- —-see page*! 3 for parts list — to/M/75 f\LINR/f\CR "RECORD,Pw WW MOMSTOR ^ LER M0&& DUPW 1. Bf h. PE4ECE. O ^LLCABLR smELtiED ^ PAGE TWELVE COMPUTER NOTES-NOVEMBER/DECEMBERi 1^75 5 t .... 5." e 4 ! PHCiNE tAtMt psiMt E— J** n ei /I" 5&K - VOLUME ? lo^tc r G) r H LEb SCALE: 1" FRONT PANEL R6sisr(y,s (FRONT) ON ORKrrL^. HOT TOO MUCH HEW/ f\LTM!^ RECORDER S P TOP V!EW Sfhi REC. PLAY UNE OUT tM iNYEmGR ViEW-COMPON^T LAYOUT (USE S^EbED CASLE OM fSLL ^UOtO SS^WL COMNECDo^s) MtNt-J^K t^STALL^HoSU— i.e. SOCKET USE CONSTRUCTlOhi AME.4-PERT BOARD mMUTt^ . CASE WTS (J WUMM FI^O TWAT THE MECH OP THE MIMt-PHOME- H "00 SHORT TO FVT T.HR&mn THE THtC^ESS OF THE CUCiL WfSLL . !M THIS CASE FOLLOW THE -L"ro3. SFACERS (4) 'lEMLARQEOPEHiNt; TO ^LLOW TO THRU. S) U^E FLAT ^fs^E^ (sslPcLiED OS,) OTHER EMB, FILE ELAT TQ MOiJMT LEG. DRtLL HOLE^ iM TDP -r -WQSJNTWt * QF COVER FOR LE^S. LE^S DRtLL OPt=N!WS FtT SOCKET MOUMF \ TO ^OP KMOE SUPPPqE, FOR LEAM iM F)LE t OF SS P.FT M^MMm. ON UNWBC..ut^ . O;F COVER. u vnyELHTMEisC EHR FLRT HEAD t u MOT^'. UMkJsED SwtTCK K) PREVEMT 5W!TCH FROM SUPRMC,,DR!LL HOLE TERMS^H FM POLE 4 i.C. SOCKET FOR tAOUMHMQ SHOWN se USER FOR ^EQ'JfJO- (SOCKET Sf-:C,^..E6,MfAMS LIST HM IM<^COMMECT!om 'ETME1 /kM SHORT&'O TOCier^FR. COMPUTER NOTES-NOVEMBER/DECEMBERi 1^75 PAGE THIRTEEN Flow Charting Part 3 Definition of symbols commonly used by programmers. ^ ENTRY Entry to a program or subroutine Onpage connector (go to) Note that connecting lines that point DOWN or to the RIGHT need Move data, no arrowheads to indicate direc- computations, etc. tion. Connecting lines that point UP or to the LEFT should label (entry) have arrowheads indicating di- (P— rection of flow. General input 6 Offpage connector (go to some output label found on some other page) Exit from program of subroutine, eg. go to supervisor —continued from page 6 PARTS LIST for RPSU 1 Seven-segment LED display chip (Calectro -975 or equiv) 1 IC socket (for display) /s. tt #F2-998 tt tt tt 1 Audio amp module __ - ( #J4- -590 tt 2 220 ohm, 1/2 or 1/4 w 10% resistors ( %B1--376 " 1 1 5QK ohm trimmer pot (for volumn adj.) ( tt #B1--645 tt \ 1 Two-inch speaker ( tt #S2--202 tt \ 1 SPST light duty switch (0N-0FF) ( tt #E2--130 ) 1 2-position rotary switch with tt 3 or > poles: NON-SHORTING ( %E2--167 ) PANEL MOUNTING JACKS: 2 Mini-phone type (Calectro #F2-845 or equiv) 1 RCA Phono type ( " #F2-806 " ) 1 Standard phone jack ( " #F2-848 " ) 1 Case (Calectro #H4-729) CABLES: (Bought or made) 2 witb ^le, mini-phone plugs on eigher end JL with RCA type phono plugs on either end* 1 with std. male phone plug on either end** 1 6V (4 cell) C-battery holder (Calectro #D3-064 or equiv) MISCELLANEOUS: Shielded cable, C-cells, hook-up wire, mounting hardware, perf board and solder *one end should have plug to fit the out jack on your tape recorder ?'*one end should fit the microphone in jack on your tape recorder PAGE FOURTEEN COMPUTER NOTES-NOVEHBER/DECEtlBERn Power !ess !C Test C!ip circuit by John Errico written by Robert Baiter fTl his test dip operates iike the size of the LED display. simple and parts layout is not JL the expensive, The basic IC clip is a critical. Use a small piece of commerciatly available clips standard item available from 0.1" grid perforated board selling for $85 or more AP Products Inc., Box 110-Z, bolted to each side of the !C without requiring batteries or Painesville OH 44077. The clip to mount components external power. All types of 16-pin clip is part number on. Try to keep the overall ICs may be tested (TTL, 923700 (TC-16) and sells for physical size of the boards as DTL, MOS, etc.) and LEDs $5.75 each. small as possible to make the are used to indicate the logic The diode arrays are finished test clip easier to state of each pin being tested. 14-pin dip packages and were handle. The LEDs should be The heart of the test clip is chosen to make the test clip mounted along the top edge a Texas instruments TID125 more compact. To cut down of the perforated boards so diode array which costs about the cost, 16 general purpose they are visible from above $3.75. Two diode arrays are silicon diodes may be used in the clip when it is attached to used to determine the pin place of each diode array tC. an IC. ! would suggest with the highest voltage (Vcc) The transistors used to drive wrapping a small piece of boards to connect the Vcc properly. With the test clip and the pin with the lowest the LEDs may be any NPN dark tape or using a short and ground outputs of the installed on an IC package the voltage (ground). These pins transistor capable of handling piece of dark tubing around diode arrays together. These LEDs will indicate the logic are then used to power the the LED current. Any small each LED to improve wires should be stranded to level of each pin: LEDs on the test clip itself, size LED may be used; visibility of the finished LED withstand the movement of thus taking power from the however, the 1k resistance display. One of the TID125 opening and closing the test ON = Logic 1 (H)GH) or Vcc iC on the board and value may have to be diode arrays is mounted on clip when in use. pin eliminating the need for an changed. Choose a value each piece of perforated Using the test clip is the OFF = Logic 0 (LOW) or external or separate supply. which gives about 2 mA board along with the simplest part of alt. Just clip ground pin The circuit is straight forward current through the LED; this associated resistors and it over the desired IC. Don't and may be expanded to should give sufficient transistors, positioned worry about how to position On 14-pin ICs disregard the make a 24- or 40-pin test clip. brightness without loading wherever convenient. the test clip on the IC; pin 1 two pins not attached. The larger test clip, however, down the circuit supply. Remember to run two wires may be at either end and the Who said building an IC may be difficult to use due to Construction is very between the two perforated test clip will still work test probe is hard? " TIDI25 DtCCE ARRAY ONE LED DRIVER CIRCUIT REQUIRED FOR EACH PIN Uj K S- to cc ALL RESISTORS = I/8 WATT TOGETHER a ALL GND PINS TOGETHER -t: E F/t7. 7. fower/e^ /C C//p. 6* GND K § TIDI25 DIODE ARRAY COMPUTER NOTES-NOVEMBER/DECEMBER-, M75 PAGE FIFTEEN my vise grips on about half the ICs (this is with a 10" x 14" board). I adjust the vise grips so ) can grip a 14 pin IC Recyding without the vise grips locking and then light the torch. The flame on my Benzo-matic torch with the narrow tip is Used )C$ about an inch long. Beginning with the lowest !C I can reach, t heat it with 6y the torch by sweeping the Car/ torch over its pins (you obviously heat the non-component side). The surplus market is by hot, bubbling, liquid flux. Especially when using a torch saturated with used printed 2. The clean board is with a narrow flame it is circuit boards from early passed over a small fountain necessary to move the flame computer systems which of solder, so that the board over the pins. One complete offer a very inexpensive per just touches it. sweep should be done once or chip source of ICs. Used 3. After cooling, the board twice a second. After a boards typically contain is immersed in FREON gas to second or so, the IC should 50-200 chips of small scale or remove any remaining flux. be gripped, and rocking medium scale integration, As you can see, the board tension away from the board usually with many simpie two is subjected to high applied. It helps to rock the Sweep the Mow torch over the IC's pins-one complete sweep input gates and four bit data temperatures during the IC, especially if corner pins once or twice a second. registers. Common part soldering phase, which takes have been bent over to hold A certain amount of care accidentally grossly numbers include 7400, 7402, around 5-10 seconds. the IC in place during is necessary when gripping overheated one, so that when 7404, 7408, 74126, 74174, The blow torch method of assembly. The IC should very the ICs. Too much pressure ! gripped it in vise grips, the 74175, etc. Through careful !C removal duplicates rapidly become loose, and in may crack them. Too little chip was bent in a curve. The shopping, ) have found conditions during board another couple of seconds pressure will let the pliers plastic case must have boards with large numbers of soldering by heating all pins should come free of the slip, costing time to softened significantly. After multiplexors such as 74151, simultaneously; removing the board. 74153, and even scratch pad reposition them and marring allowing it to cool several !C is a single step. When the IC is removed, the cases. minutes to the point where I registers - 7489. After When attempting to could handle it by hand, ) removing chips from the Equipment Needed quickly drop it on the bench boards and eliminating any and move the torch and pliers remove the larger ICs such as plugged it into a circuit, non-functional units, cost per To use this technique, you to the IC above the one 74181s and 74154s, which expecting it to have failed chip is from 3 to 8 cents, will need: removed. Heating the lower come in 24 pin D!Ps, I have totally. !t worked, although ! resulting in an overall cost of /i fwr/7. Non-oxygenated IC pre-warms the board trouble gripping them, so I didn't check out its ac about one fourth to one propane and acetylene gas has above, making the next remove them as a two step characteristics. Out of general tenth of the individual chip been used. removal easier. Also, the process. First, I place an awl paranoiac distrust for a device cost through other surplus C/om/M or OUTPUT WRITE- FOR THIS LATCH + 5V A blinking light peripheral is an inexpen- 7475'S - + 5V=PIN5 I A sive, entertaining addition to your computer GND-PIN 12 I 220& !8) t LED(8) system. The use of multiple indicator lamps OA —ws, under computer control to produce moving OB patterns can lead to many hours of creative OC programming and pleasant amusement. QO Playing with blinking lights is nothing w- t 7475 BUS RECEIVERS QUAD LATCH new to people working with computers.. (USE TYPICAL ICS Early systems, to say nothing of science OF YOUR COMPUTER COMPUTER SYSTEM) fiction movie caricatures, tended to have DATA BUS monstrous front panels with rov? after row of indicator tamps. These tamps were used to reveat various machine states. As computers OA became more sophisticated, the need for OB many of these indicators diminished, but the OC fascination of making the indicator lamps' Q0 dance and gyrate in interesting patterns has t 7475 remained. QUAO LATCH As a simple example of moving lights, ir TO OTHER consider a single 8 bit byte of memory in OUTPUT LATCHES your computer, which might be called BUNK. Assume that you have also con- Figure i; The basic "straightforward" approach to display iamps. One latch is assigned to each of several output ports of the structed an 8 bit output data latch which computer. The output port decoding ioyic will determine when the iatch is addressed for output. The result of decoding is a WRITE signal which latches the data presented at the bus receivers. The sample program of figure 2 assumes two such display drives eight LEDs as shown in figure 1. When registers, in principle the idea can be extended to many registers in groups of eight, limited only by the computer's input output a certain program is started, BLINK might addressing capability and the available power for lighting LEDs. Jn this circuit, TTL fanout limitations on the bus receivers would be initialized as follows: limit expansion to a total of JO latches. The LEDs can be mounted on a separate display panel with connections by means of dual 0 0 0 0 1 0 0 0 in line header plugs and sockets. A neutral tinted glass or plastic cover plate and an attractive wooden frame are good finishing touches for the visible portion of the project. Suppose this value is sent to the display,, which is set up so that a 1 bit lights an LED, then the display will look like this: Figure 2: The CATERPILLAR program listing. Opcodes and addresses are specified in The key element in creating an ittusion of octal notation for the 8005 CPU. Comments at the right are designed to help convert the motion is time, tf the program starts out program to other machines. with data as shown above, waits a short time, then executes a left rotate instruction, address octal code label op. operand commentary a new pattern will be obtained. The new 010/000 250 START XRA clear carry and A; binary value 0001 0000 can be sent to the 010/001 036 377 LDI 11111111B first caterpillar word; display: 010/003 046 000 LEI 00000000B second caterpillar word; 010/005 304 MARCH LAE right byte to A; In the simplest of ail motion programs, 010/006 022 RAL shift left into carry; 010/007 340 LEA then saved for next time; these three steps are repeated in an endless 010/010 303 LAD left byte to A; loop: 010/011 022 RAL shift left into carry; 1. Rotate BLINK teft one bit position. 010/012 330 LDA then saved for next time; 2. Send BLINK to the display. * note that RAL shifts old carry into A each time, 3. Wait n milliseconds. * thus the above accomplishes shift from E's high * order bit into D's low order bit via carry...; 4. Go to step 1. 010/013 177 OUT 37 write into left lamps; With a program executing these four 010/014 304 LAE fetch right value; steps, the pattern of lit indicators will be 010/015 175 OUT 36 write into right lamps; seen moving to the left, disappearing on the 010/016 026 300 LCI 192D set delay loop constant; 010/020 307 DELAY LAM use left in the same step at which it reappears on 010/021 307 LAM several the right. By changing the program delay 010/022 307 LAM longish (step 3), the speed of the pattern's apparent 010/023 307 LAM instructions motion can be changed. 010/024 307 LAM to Figure 1 shows two quad latches which 010/025 307 LAM stretch 010/026 307 LAM out are used to drive 8 indicator lamps. The 220 010/027 307 LAM the O resistors are typical values for LEDs as 010/030 307 LAM loop indicators. This value allows reasonable 010/031 307 LAM (a BYTE in time saves nine); brightness with most LEDs. The comple- 010/032 021 DCC decrement delay count; ment outputs of the 7475 ICs used as latches 010/033 110 020 010 JFZ DELAY if non zero then repeat delay 010/036 104 005 010 JMP MARCH back for another step; produce a lit LED for each 1 bit received. * note that during the operations at addresses 010/013 When you purchase LEDs for a blinking light * to 010/036 the carry bit value set by the last RAL display, make sure they are all the same, as * is retained unchanged, so that the RAL at 010/006 the display will not look as attractive if * will shift the old high order bit of the left register lamps of different types are mixed. * (D) into the low order bit of the right register (E); Now, suppose you use four latches for 16 This program uses only the interna! CPU registers for its data, and assumes that 8008 bits of data and 16 LEDs. How do you output ports 36 and 37 are assigned to latched 8 bit displays so that a visible pattern can program an 8 bit computer to do the shifting be seen. COMPUTER NOTES-NOVEMBER/DECEMBERi 1^75 PAGE SEVENTEEN light pattern function for 16 bits? The basic a very reasonable display of 64 LEDs will set way in which this is accomplished is to shift you back only $24 and the time it takes to the bits through the carry flag of your put it together. machine. Using a bit of imagination, the extension Figure 2 illustrates a program which does of the program can lead to interesting a 16 bit shift in an 8008 microcomputer, patterns running around non-linear configur- and sends the data to the output ports ations such as those illustrated in figure 3. reached by the OUT36 and OUT37 instruc- Variations in the patterns result in displays * tions (octal 175 and 177, respectively). The of light. Beyond the scope of this short result is a moving display of 16 lights. A article are more complicated programs using band of several bits is always marching right the same display peripheral: Programs in to left around the display at a steady rate. which the tight patterns do more interesting Figure 3; Creativity in the arrangement of the lamps of your blinking iight peripheral can make But, why let the imagination end at a things than simply chasing around the race- the show more impressive and interesting. A; The traditional biinkingiight display, a la control track at uniform speeds. panel, is a straight iine of sixteen lamps in a row using two output latches. B; Tradition is nice, mere 16 bit display? The use of IO ports can but how about a bit of circular thinking, using thirty two lamps in a circle with four output be extended without too much cost (given Try building a simple 16 jbit blinking light latches. C.' Don't rule out the bouncing ball effect either. Here we make a parabola shape using limitations on power supplies, of course). display version first, then'-go on to bigger sixteen lamps, one at the focus, with two output latches. D: With enough lamps, we can make a The cost of two 7475s, eight resistors, and and better things. Then see if you don't spiral show with one or more arms. Here are forty lamps using five output latches. E: There are eight LEDs is about $3 (using BYTE's agree that there's more to BLINKing lights an infinite number of patterns to be made. Jn this case, infinity consists of sixty four lamps using 8 output latches. advertising pages as a source of prices). Thus than meets the eye! * Reprinted from Magazine, January 1976. If you are reading Compt/fer /VofM, have included projects such as: imaginative uses. BYTE also publishes specula chances are you either have an Attair or LiFE Line — a series on the design of a tive articles from time to time on applications hardware/software system to enable which are in advance of the present technology, will shortly purchase one. You've heard a your computer to play the game of as well as articles on the application and use of lot about the small computer scene, but LIFE. the computers now available. There are many where can you get more information? Oscilloscope Graphics — an article in ways you can use your imagination fortified by The answer is BYTE, the smatl systems October 1975 BYTE describes a 64 by hardware and software skills to achieve unique journal. 64 grid oscilloscope graphics display, and systems. Your computer is what you make of a second project article in January 1975 it, and BYTE provides you with the timely BYTE describes how to add a light pen inputs of imaginative ideas which will help you attachment. adapt your computer to personal purposes. BYTE features: Electronic Music — an article in October iT TAKES ALL KINDS & Comprehensive theoretical and practical 1975 BYTE describes how you can Use of this new technology makes for information on the design and use of small scale program a microcomputer system to synergistic bedfellows. Where else but among computer systems. play music using a simple NAND gate small systems users would you find a common & information on the fast breaking develop- flip flop for output directly to a loud bond between: The astronomer who uses his ments in integrated circuit technology and the speaker. The result is called the KLUGE computer to point his telescope and the ama- impact on small computer systems HARP. teur radio operator who uses his system to ^ Examples of imagination and creativity Test Equipment — December 1975 BYTE control an automated station; the modei rail- applied to the computer systems craft for included a short project article on a road buff who controls switch solenoids and personal use 16-pin logic test clip which can be throttle settings sharing cammon problems with Information on how to make your brand X fabricated for about $20 in component the electronic music enthusiast who wants to computer talk in ASCII to the brand Y com- parts cost. press the keys of his piano under program puter owned by your next door neighbor Blinking Lights - January 1975 BYTE control. Then there is the model airplane ^ Names and addresses of the computer clubs contains an article on the fundamentals hobbyist who has a real time control problem and societies which are forming in every major of blinking lights as an action peripheral, in the programming of his on-board computer city of the country including the design of the CATER- with miniature avionics and command com- ^Advertisements of parts and components PILLAR program. munications hardware. The hobbyist who wants which will help you to build and use Golf Handicapping — January 1975 BYTE to automate kitchen chores and the teacher customized peripherals with your system contains a short article on the use of a who wants to computerize homework grading typical home microcomputer for pro- and test scoring are reading (and writing about INFORMATION gramming of golf handicap calculations. their solutions in BYTE). It takes all kinds and Information science is one formal way of IMAGINATION you meet a great many interesting people and referring to the big picture of computer tech- A key element of the whole small scale ideas through the pages of BYTE. nology. Computers are about information computing scene is the imagination and excite- processing, and BYTE is full of information on ment of putting these machines to use for tNTERACTION the persona! use of computers. BYTE is packed people on a one to one basis. No longer is the BYTE is an interactive magazine. Many of from front to back with articles of interest to computer a mysterious oracle in the bowels of the articles on applications and theory are you, the personal computer user. the giant organization. No longer will you have submitted by readers of the magazine. BYTE Technology information. BYTE contains to wait for hours and hours of turn-around for has a lively letters column which serves as a general background articles on the technology a small calculation — you can afford to devote a means of communication from readers, with of computing and computer machines. You'll whole computer to such creative and imagina- occasional reactions and extended exchanges. find articles on assemblers, articles on high level tive tasks as playing games unheard of a few BYTE seeks to improve the quality and inter- languages, articles on the design of programs short years ago, or teaching your kids mathe- changeability of products for the personal and hardware which are oriented toward the matical and logical principles which will help computing field through such actions as the intelligent layman rather than the professional them advance to the technology of tomorrow. recent audio cassette standards symposium engineer. A key element in using these machines is sponsored by the magazine and attended by Advertising information. BYTE brings you imagination, and BYTE supplies a large dose of most manufacturers and many users. the benefits of a central mail order marketplace for the products you need. Manufacturers and distributors of components, systems and Subscriptions to BYTE are $12 for one year, $22 for two years, and $30 for three years. Fill peripherals all display their wares in BYTE, the out the coupon below and start enjoying BYTE. only magazine specifically tailored to your needs as a personal computing user and their Name . desire to make the products available. Educational information. When buying com- Address. plicated and expensive electronic equipment, you need to know a tot. BYTE provides you City .State. .Zip. with information on what to look for in computer products, reviews of typical products, 1 year 2 years 3 years and tutorial articles on the fundamentals you should know before buying. O Check enclosed o Bill me Bill CMC QBAC Project information. One of the most exciting aspects of our small scale computing No field is the ability to put together hardware and Exp. Date software systems projects: Sophisticated and unusual toys or practical systems for home use. 70 MAIN STREET Hardware, software and applications project PETERBOROUGH NH 03458 articles are a major part of BYTE. Past BYTEs EVTE PAGE EIGHTEEN COMPUTER NOTES-NOVEMBER/DECEMBERi 3.175 sult. Can be changed for different by Bill Gates size numbers without much difficulty. #1030752 Another fourteen programs were Dumps a program with page headings, Author: John Trautschold added to the library this months and an address field and the octal con- Length: 16 bytes I think a lot of Altair users will tents of the address. Columns are Title: VLCT load program find them useful. provided to fill in labels, instruc- Allows entry of a load address and tion mnemonics and comments. program data in octal from a VLCT Jim Gerow, whose FORTRAN cross- #1121751 keyboard. The entered data is dis- assembler #521751 has been the most Author: Gary Tack played for verification. Documented requested program in the library., Length: 152 bytes with high 8-bits of start address as has sent in a FORTRAN simulator for Title: Random Magic Squares "XXX" so the program can easily be the 8800 (#1123751) which is the win- Generates 3 numbers which are used located at the start of any memory ning major program this month. When to make a magic square (a 3x3 grid page (a block of 256 consecutive mem- a file is assembled by the cross- in which the sums of the numbers in ory locations, the first location of assembler there is an option to out- each row, column and diagonal are which has an address divisible by put the assembled code as a file equal). All "magic squares" can be 256 [decimal]). that the simulator can read and exe- generated since 3 numbers character- cute. The simulator allows the user #1030751 ize a magic square. Each group of 3 to set breakpoints, dump the regis- Author: Lee Eastburn numbers generates a distinct magic ters , dump memory contents, change Length: LOAD section-71 bytes square. Stores magic square infor- the registers and change memory con- DUMP section-96 bytes mation in memory. Doesn't do any tents. Title: ASCII Octal Loader and Dumper input/output. The DUMP section outputs the contents The second place major program #1117751 of a block of memory in ASCII octal is S. Armstrong's tape labeling pro- Author: George Rompot (3 characters ["0" - "7"] for each gram (#117751). This program is Length: 41 bytes byte). Twenty bytes are printed on very useful for users who have lots Title: GET - a "Lifeline" subroutine each line of output. The LOAD sec- of paper tapes. A well-documented subroutine to per- tion loads a tape of the same format, form the functions of the TGET and ignoring all characters except "0" The third place major program LGET subroutines specified in the through "7." The start and end lo- is Jerry Ford's JAMON (#117752). lifeline article in Byte magazine. cations are specified by changing Commands are provided which make it (October 1975, pp. 34-41) Includes LXIs in the programs themselves. unnecessary to use the front panel test routine. #1021751 switches. Author: Jack Coats Jr. #1117752 Length: 46 bytes Author: George Rompot The winning subroutine is Title: A Dual-Tasker Length: 25 bytes George Rompot's GET routine (#1117751). An Interrupt level routine to switch Title: CHECK This program is especially notable between two tasks. Context is saved A well-documented subroutine to cal- for its good documentation. Unlike on the stack and the stack pointer culate a 16-bit sum of an area of Mr. Rompot, most Altair users haven't is saved in memory. programmed for very long. A hard- core specified in the calling param- learned lesson about programming is eters. Optionally checks the com- #1027751 that good documentation is not just puted checksum with a checksum pro- Author: Jack Coats an aesthetic, but is indispensable. vided in the calling sequence. A Length: 43 bytes It forces a programmer to be aware testing program is included. Title: Time of Day routine Using the real-time-clock interrupts of what subroutines he has embedded #117751 in his program, what calling se- this program keeps track of the hours, Author: S.Armstrong minutes, seconds and hundredths of quences should be used and explains Length: 124 instruction bytes (not the assumptions and techniques used seconds that elapse. The data is including embedded NOPS) stored in binary coded decimal. in each section of code. 342 data bytes Title: Punch tape label #1027752 Punches paper tape labels by using 5 Author: Roger J. Walker The second place subroutine is tape frames to make a block letter. Length: 53 bytes Jack Coats' BCD multiply routine Can "print" any alphabetic, numeric, Title: TVTDR-1/0 handler for TVT-11 (#113751). BCD multiplication is or common delimeter. Additional TVTDR is designed to overcome a de- more complicated than binary multi- characters can easily be added. ficiency in the TVT-11 that prevents plication. For people who like num- "Prints" an entire line at once with it from blanking to the end of the bers with hundreds of digits and separating blanks. line when a carriage return is output. understand BCD (or want to), this The appropriate number of spaces are routine can be set up for up to 512 #117752 output instead of a carriage return. digits per number without much Author: Jerry Ford Instruction for interfacing to Altair trouble. Length: 318 bytes Basic are given. Title: JAMON - a teletype monitor Software Library This monitor allows examining (dump- #1123751 ing) of memory blocks, depositing Author: Jim Gerow #1020751 into memory blocks and jumping to a Length: 33 pages specified address. All inputs and Author: Gerhald Hansel Title: A FORTRAN simulator for the outputs are in octal. Subroutines Length: 46 lines of Basic 8080 for character input, character out- Title: Addition problems A FORTRAN program to take as input put, octal input and octal output Produces a group of math addition the code generated by Mr. Gerow's are included. problems and answers. Written to Cross Assembler (#521751) and simu- use PRINT USING, a feature of Ex- #113751 late the Altair's execution of the tended Basic, to format its output. Author: Jack Coats code. Extremely useful for debugging. Length: 83 bytes A manual is included with the source #1020752 Title: BCD multiplication subroutine listing. A list of changes to be Author: Lee Eastburn Currently set up to multiply two 8- made to cross assemblers received Length: 290 locations digit numbers in memory and give a before December 1, 1975 to allow them Title: Print program 16-digit number in memory for a re- to work with the simulator are given. COMPUTER NOTES-NOVEMBER/DECEMBER-, M75 PAGE FIFTEEN The Status of BAS by Bill Gates Some of the more persistent and Beware of using a loop variable, Besides the changes already expert users of Basic have noted a first in an outer loop that never mentioned, 8K BASIC 3.2 will have few bugs in some of the versions of completes and then in an inner loop. two other enhancements: Altair Basic. Example: 1) Numbers less than .1 and greater SPR (Software Performance Report) #1- 10 FOR 1 = 1 to 10 than or equal to .01 will print as CSAVE sees only three zeros. 20 IF Y(I) = 7 THEN 40 .0XXXXXX (trailing zeros suppressed) Symptoms: Some CSAVEd files will 30 NEXT 1: PRINT "ERROR":STOP instead of X.XXXXXE-2. not CLOAD. Happens infrequently. 40 FOR J = 1 to 13 Found by Bill Gates and later noted 50 FOR 1 = 1 to 5 2) Cassette versions will allow by Steve Grumette and J. Scott Wil- for verification that a CSAVEd file liams. is recorded properly. Giving the Present in: 3.0 and 3.1 cassette of 60 NEXT 1 command CLOAD? Checksum: go block 170 start character lower 8 bits of address to jump to high 8 bits Jeffrey G. Clark P.O. Box 2422 Springfield, MA 01101 The data block for locations 0 through 376 is the last data block on the tape so the bootstrap loader doesn't have to be keyed in again when checksum Orville F. Hamm errors occur, unless the checksum error is on the final data block. 4751 Louisiana Ave. St. Louis, M0 63111 BOOT STRAP LOADER Charles Can KL7HRP start at location zero SR Box 80688 Fairbanks, AK 99701 0/ LXI H, number of bytes in the checksum loader Craig Brockmeier page number of the checksum loader 4715 SE Adams #922C Bartlesville, OK 74003 Set [H,L] to point to the last location (918) 333-5608 in the checksum loader + 1. Capt. James K. Bostick LXI SP,STKADR Set ESP] so returns come back to this 3/ 12307 S. 33rd St. location. After each return [SP] is reset. Omaha, NE 68123 (402) 292-2466 (home) See if there is a character, and loop 6/ IN 294-5932 (work) RAR if not. RC Robert A. Van Winkle WB6HKA 288 Woodbridge Ave. IN Read a character and see if it's leader. 12/ 1 Yuba City, CA 95991 L (Lead character = number of bytes in the CMP (916) 673-1523 RZ checksum loader) James T. Mattley 16/ L Store the data in the next lower location, DCR 6417 Fernhurst Ave. and loop unless all bytes have been read. MOV M,A Parma Heights, OH 44130 RNZ Craig Pearce 21/ PCH Start the checksum loader at its beginning. 2529 S. Home Ave. Berwyn, IL 60402 22/ STKADR: D¥ LOPADR The stack pointer points here, so this William T. Shaw gives the address returns branch to. 3F Hogarth Circle Cockeysville, MD 21030 This bootstrap loader has several advantages: Steve Patchen Univ. of Washington 1) Leader is allowed. 1334 N. 122nd 2) Only 20 bytes need to be keyed in. Seattle, WA 98133 3) It automatically starts the checksum loader, so only one tape needs to be entered. Douglas Ingraham 4) It can run from Read Only Memory. Box 523 5) It starts at a convenient location (zero). SD School of Mines 6) It is easily relocated by changing the addresses at Rapid City, SD 57701 locations 4 and 22. 7) To load different checksum loaders, only location 2 Timothy Radde needs to be changed. 17 Harding St. Pittsfield, MA 01201 I've written a bootloader that only takes 13 bytes of keyed-in data, but anything smaller than 20 bytes isn't easy to use. Mark Rothstein Next Month: Signed and unsigned arithmetic 15401 Pegg Court Multiprecision arithmetic Bowie, MD 20716 (In a previous issue, there was an error in printing Mark's ad- 3. The proposed change to 0-7 will dress. He lives in decrease the timing margins and Bowie, Maryland—not should not be made. Missouri) 4. A complete discussion of the Daniel Duncan ready line appears in Ed Roberts Box 3388 2. The modification proposed for Pasadena, CA 91103 the 4K memory card converts the pro- column in this issue. tect input circuit from a toggle in- put to a type D flip flop. It won't hurt anything, but all it eliminates Donald D. Henson is the need to occasionally press If you hear of some mod or change 1676 Ala Moana Blvd. protect more than once. A better to the system, please write or call Apt. 307 design for the protect flip flop in us before you install it. Any modi- Honolulu, HI 96815 the 4K memory card.would have been a fication that we believe is useful, type D circuit. However, it is reliable and doesn't damage the sys- hardly a major issue, and the cure tem will appear in this publication. is worse than the problem. — DB ^ PAGE TMENTY-TMO COMPUTER NOTES-NOVEMBER/DECEMBERn 1175 The following is a list of Altair dealers. Most Altair kits should be I/O Programs for the ACR in stock at these outlet stores. Input/Output programs for the 88-ACR Arrowhead Computer Co. By Tom Durston (The Computer Store) 11656 W. Pico Blvd. Los Angeles, CA 90064 One request we've been getting frequently is for simple machine language Lois & Dick Heiser programs to write and read data on tape through the 88-ACR. Listed below is a (213) 478-3168 program to write and a program to read using the 88-ACR. These programs have Byte'Tronics been used in our engineering department to store lengthy test routines, and 5604 Kingston Pike can be used for any type of data. Knoxville, TN 37919 Bruce Seals WRITE PROGRAM - 38 bytes (615) 588-8971 Writing data on tape through the 88-ACR is accomplished by first specify- The Computer Center ing the start address of data and the end address of data. Then a test byte 3330 Piedmont Road (000 in this program) is written, followed by data output. The last portion Atlanta, GA 30305 of the program tests to see if the program has transmitted the last byte of Jim Dunion, Rich Stafford data. If it has, the program jumps to the last positions in memory, and is Steven Mann, Ron Roberts observed by a change in the address lights on the front panel. If the program (404) 231-1691 hasn't outputted the last data byte, the H & L registers are incremented by 1 Computer Kits and the program outputs the next byte. This program is placed in the upper 1044 University Ave. portion of 4K memory with a starting address of 017,000. The location may be Berkeley, CA 94710 changed, but be sure to change all jump addresses accordingly. After record- Pete Roberts ing data that includes program information, write down the start and end ad- (415) 845-5300 dress on the tape cartridge along with the name and test byte of the program for identification. Computers S Stuff 1092 S. State St. When recording data at the beginning of a cassette tape, record at least Orem, UT 84057 15 seconds of steady tone before running the write program (to get past the Eric 5 Debra Stewart plastic leader and wrinkles in the beginning of the tape). Also, if recording (801) 224-2066 more than one batch of data, leave at least 5 seconds of steady tone between Gateway Electronics batches. This program is written for 88-ACR addresses of 6 & 7. 2839 W. 44th Ave. Denver, CO 80211 George Mensik (303) 458-5444 88-ACR WRITE PROGRAM Gateway Electronics 8123-25 Page Blvd. St. Louis, MO 63130 TAG MNEMONIC ADDRESS OCTAL CODE EXPLANATION Alfred L. Elkins (Lou) Stuart Bartfield LXI 017,000 041 Load immediate H&L register pair (314) 427-6116 1 XXX Lo starting address of Marsh Data Systems 2 XXX Hi data to be written Suite 120, 1805 N. Westshare LXI 3 001 Load immediate B&C register pair of Tampa, FL 33607 4 XXX Lo end address Don Marsh 5 XXX Hi data to be written (813) 872-7334 MVI 6 076 Move immediate to accumulator 7 000 Test byte to be written at beginning Microsystems OUT 017,010 323 Output data from accumulator 6605A Backlick Rd. 11 007 Data channel # of 88-ACR Springfield, VA 22150 TEST IN 12 333 Input data to accumulator (Washington DC area) 13 006 Status channel # of 88-ACR Russell Banks RLC 14 007 Rotate accumulator left, test for D7 true (703) 569-1110 JC 15 332 Jump if carry (D7 not true) 16 012 To "TEST" CTI Data Systems 17 017 3450 East Spring St. MOV 017,020 176 Mov! e contents of memory specified by H&L Long Beach, CA 90806 register to accumulator Fred Whitney OUT 21 323 Output data from accumulator (213) 426-7375 22 007 Data channel # of 88-ACR MOV 23 175 Move contents of L register to accumulator Byte Shop CMP 24 271 Compare accumulator vs B register 1063 El Camino Real JNZ 25 302 Jump if not zero (L ^ B) 26 040 Mountain View, CA 94043 To "NEXT" Boyd W. Wilson, Paul Terrill 27 017 MOV 017,030 174 Mov! e contents of H register to accumulator CMP 31 270 Compare accumulator vs C register Ridgway East, Inc. JNZ 32 302 Jump if not zero (H # C) 33 040 161 Bell St. To "NEXT" Chagrin Falls, OH 44022 34 017 (Cleveland) JMP 35 303 Jum! p (if L = B and H = C) 36 375 Ray Wassum, Jack Stevens To "END" 37 017 NEXT INX 017,040 043 Incremen! t register pair H&L The Computer, Inc. JMP 1 303 Jump 2 012 P0 Box 2621 To "TEST" Framingham Center, MA 01701 3 017 Richard F. Brown END JMP 017,375 303 Jump (loop to self) 375 (617) 877-6984 376 To 377 017 ! "END" COMPUTER NOTES-NOVEHBER/DECEHBERi 1^75 PAGE TUENTY-THREE ! () Programs !or the ACR Notebook READ PROGRAM - 48 bytes 4K PROTECT As in the write program, start and end addresses of incoming data are Hitting the protect switch will specified first. Next, the program looks for the test byte (000 in this pro- occasionally not protect the 4K dyna- gram). Once the test byte is detected, the program inputs data and stores it mic memory board. This problem is al- in memory as specified by the H & L registers. The next portion of the pro- leviated by removing pin 10 of IC"T" gram tests to see if the end memory address has been filled. If it has, the from +5V and jumpering it to ground program jumps to the last positions in memory, and is observed by a change in instead. Ground is available the address lights on the front panel. If it is not the end, then the program on pin 11 of IC"T". increments H S L by 1 and jumps back to input another data byte. This program is placed in the upper portion of 4K of memory with a starting address of 017,000. The location may be changed, but be sure to change all jump addresses SIOB S ACR OWNERS accordingly. When reading data back in, the tape and program should be started a few seconds before the start of data. Before inserting IC"G" on the SIOB, TTL interface, check for a copper land between pins 2 and 3. If there is one, remove it, or you will get the follow- 88-ACR READ PROGRAM ing symptoms: you cannot enter a 1 (HI LEVEL) in bits 2, 3, 4, or 7 (of 0-7) TAG MNEMONIC ADDRESS OCTAL CODE EXPLANATION except at the memory address which cor- responds to the address of the I/O board. LXI 017,000 041 Load immediate H6L register pair contributed by Edwin F. Hanpton 1 XXX Lo starting address of 2 XXX Hi data to be read MISPRINT LXI 3 001 Load immediate BSC register pair 4 XXX Lo end address of October 1975 Computer Notes, page 5 XXX Hi data to be read 9: USING SERIAL BOARDS TSTBT IN 6 333 Input data to accumulator Echo Program Step 17 7 006 Status channel # of 88-ACR reads 012 RRC 017,010 017 Rotate accumulator right (test D0 true) should read 013 JC 11 332 Jump if carry (D0 not true) Interrupt Program Step 11 12 006 To "TSTBT" reads 011 13 017 should read 010 IN 14 333 Input data to accumulator 15 007 Data channel # of 88-ACR CPI 16 376 Compare immediate with test byte vs accumulator 17 000 Test byte Seminar Tours JNZ 017,020 302 Jump if not zero (test byte#input byte) Schedules for the next MITS- 21 006 MOBILE tours are now being planned. 22 017 To "TSTBT" Exact dates cannot be announced, as TEST IN 23 333 Input data to accumulator we do not yet have confirmation of 24 006 Status channel # of 88-ACR the availability of meeting rooms at RRC 25 017 Rotate accumulator right (test D0 true) all locations. JC 26 332 Jump if carry (D0 not true) 27 023 The tentative itinerary for the To "TEST" 017,030 017 last three weeks of February includes DATA IN 31 333 Input data to accumulator stops in Lubbock, Ft. Worth, Dallas, 32 007 Data channel # of 88-ACR Houston, Corpus Christi, San Antonio, MOV 33 167 Move contents of accumulator to memory Austin, Odessa, and El Paso—all in address specified by H&L registers that huge state of Texas. Also Tuc- MOV 34 175 Move contents of L register to accumulator son and Phoenix, Arizona. CMP 35 271 Compare accumulator vs B register JNZ 36 302 Jump if not zero (L ^ B) 37 051 To "NEXT" From mid-March to mid-April we 017,040 017 plan to be on the west coast—includ- MOV 41 174 Move contents of H register to accumulator ing San Diego, Los Angeles areas, CMP 42 270 Compare accumulator vs C register Fresno, San Francisco Bay area, Sa- JNZ 43 302 Jump if not zero (H / C) cramento, Portland, and Seattle. 44 051 45 017 To "NEXT" JMP 46 303 Jump (if L = B and H = C) 47 375 The general format of these lec- 017,050 017 To "END" tures will continue to aim at bring- NEXT INX 51 043 Increment HSL register pair ing information of interest to indivi- JMP 52 303 Jump duals with varying levels of experience. 53 023 To "TEST" 54 017 Upgrading plans for our seminars END JMP 017,375 303 Jump (loop to self) includes: more material in the course 376 375 manual, more emphasis on I/O devices, 377 017 To "END" more equipment demonstrations includ- ing several new MITS products. PAGE TMENTY-FOUR COMPUTER NOTES-NOVEriBER/DECEMBERi 1175 .more notes on ACR er Motor Controi WANTED: Name & address for owner of Another request for the 88-ACR has been for start/stop motor control for 8800 serial number 222755K. Infor- DC motor tape recorders with the subminiature phone jack marked "REMOTE." A mation was missing from warranty card simple way to do this is to utilize an unused flip-flop normally intended for mailed from Dayton, Ohio. the interrupt function on the 88-SIOB board. Since the interrupt circuit is usually not used in the 88-ACR mode, it is possible to connect the output of WANTED: Name & address for owner of one of the flip-flops to an unused driver of an 8T97, using it as a relay 8800 serial number 221128A. Infor- driver. mation was missing from warranty card mailed from Los Angeles. The circuit shown below uses control channel bit D0 to turn the motor on and off. Consult page 3 of the 88-SIOB manual and the 88-SIOB schematic for WANTED: Software developer with IBM detailed information on this circuit. equipment who will convert EBDICT to ASCII on a one shot basis. Contact Jim Leek, Bakersfield Audio, 2801 F MOL&R Y COMM6CTOH. Street, Bakersfield, CA 93301 ^ Ya TAPe RECORDER WANTED: FORTRAN to run on the Intel 8080 CPU based systems. Anyone with JACK , OR perron information on this please contact RE^V - OM/bfT C^gCUtT. Jack 0. Coats, Jr., El Paso Computer gVDC Cotu Group, 213 Argonaut #27, El Paso, TX 79912 FOR SALE OR TRADE: Techtronics 4602 video hard copy unit. Produces The other half of IC B may be used for another control function in the 8 1/2x11 prints from standard video same manner. IC U has 3 other spare drivers that may be used. (i.e. video terminal). Contact Mark Bunker/2703 S. 71st PI./Kansas City, We suggest the relay be mounted externally to prevent recorder supply KS 66106 913-375-1138 voltages from interfering with the Altair 8800. FOR SALE: 10 CPS EIS impact printing For the machine language Read/Write programs, adding the following in- terminal. Standard RS-232C data in structions will allow use of the start/stop feature. and out. Close equivalent of TTY model 33KSR. Good shape. $230 FOB To turn the motor circuit on, place these instructions before the begin- Denver. M. Smith/4355 S. High St./ ning of the Write and Read programs. Englewood, CO 80110 Octal Is anyone working on inventory con- Location Code Mnemonic/Description trol S bookkeeping packages in BASIC (extended)? If so, please contact 016,374 076 MVI move immediate to accum. Eugene Zander/0'Keefe Supply Co./ 375 001 Turn on motor 613 Williamson St./Madison, WI 53703 376 323 Output data from accum. 377 006 Control channel We are working on computer aided in- struction packages and executive NOTE: For Write program, single step through these 4 instructions, programs to operate under same. Es- wait appropriate time (5-15 seconds), then hit RUN. pecially interested in graphics dis- play terminal systems. If you're interested or have info, please call: Sgt. Wesley Isgrigg or Sgt. To turn the motor off, place these instructions before the jump to self Stanley Herr/74055 Casita Dr./29 loop at "END." Also change data in location 017,376 to 371. Palms, CA 92277 (714) 367-6996 Octal "Handy Dandy" paper tape winder. Location Code Mnemonic/Description Uses 4 D batteries (not included). $15.00 plus $1.00 postage & handling. 017,371 076 MVI Bill Roch, 5133 Catalon Ave., Wood- 372 000 turn motor off land Hills, CA 91364 373 323 Output 374 006 Control channel Chicago Users Group % Robert Swartz 195 Ivy Lane NOTE: The flip-flops Ba and Bb do not have power on clear. It Highland Park, IL 60035 may be necessary to single step the motor off circuit to clear these flip-flops. Southeast Minnesota Amateur Computer Club (SEMACC) For use with Altair 8K BASIC, use: 2122 NW 17 Ave. OUT 6,1 - to turn motor on Rochester, MN 55901 CLOAD or CSAVE OUT 6,0 - to turn motor off Oklahoma City Club 2412 SW 45th Keep in mind that if writing, you must turn the motor on Oklahoma City, OK 73119 5-15 seconds before outputting data. Texas Computer Club % L.G. Walker RtlBox272 Aledo„ TX 76008