Homebrew Computer Club - Stacks are the Stanford
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1. HOW I BUILT MY FIRST COMPUTER FOOLS RUSH IN WHERE ENGINEERS FEAR TO TREAD By Norman Walters A course Introduction to Computing taken during the fall of 1975 was my first exposure to the wonderful world of computers By mid term the itch to have my own was beginning to be felt The itch faded considerably when the prices of the computer kits on the market was considered After much thought I decided one could be built at home at a price my wife would not be able to use as grounds for divorce Naturally the fact that the largest project previously tackled was a digital clock did not cool my optimism a whit Ten months later my home brew computer is built and the cost was much smaller than if a commercial kit had been purchased but the time and effort expended have been tremendous During the construction of GEORGE every cost cutting trick possible was employed Naturally the mother board was built from scrap cut offs bought at the club and 80 pin connectors were cut to form 100 pin connectors Every friend I had plus some who had not realized that we were even on speaking terms was presented with a list of parts needed and a strong hint given If you have any of these parts just lying around you might be able to force me to take them off your hands if the price is right I haunted all the surplus e2. 2269 9988 AAAG 0014 2022 0220 2020 2032 0040 92240 20002 2258 2223 00260 00064 0070 0020 0080 TRAIN XRA A ONCE UPON 4 TIME 0021 D3 C8 4290 OUT dCEH IN A CURIOUS LITTLE BAAI 21 4 01 4100 LX HsSHED PLACE THERE WAS 736 01 00 98 2112 LXI 27243 oA TINY TRAIN 00029 55 23 0120 EMPTY MVI M 20H ese AND STAYED IN A 2228 23 01352 INX H ee TINY SHED AAAC AB 0142 DCX 8 THAT WAS ALL EMPTY 2289 AF 2154 XRA 000 AB 2162 XRA B 022 09 02 2170 JNZ EMPTY 0012 21 F7 02 2180 LXI H CLOUD FOR A HUGE 0015 11 00 07 2190 LXI D 0018 06 DE 2220 B 14 B AZIA CD 50 ag 221 CALL 58401 001211 28 02 9220 LXI 0945 L 2020 BSE 3257 1 12 1 8022 CD 50 23 2240 CALL 5 01 0 0625 11 32 23 0250 LXI 0943 W 2 06 09 2260 MVI 9 002 CD 50 22 276 CALL 5801 2090 11 34 AB 2227 LXI 5952 0050 06 04 02940 MVI B 4 L 00352 CD 52 BA 0500 CALL SM01 0 00355 11 38 00 93510 LXI 59 U 2258 06 22 4320 2 D 005 CD 50 721 0530 CALL 5 01 0030 11 3C 022 0547 LXI 60 0 0047 06 21 0552 MVI Boel F 7842 CD 58 gA 0566 CALL S401 2045 11 OA A372 LXI De62 5 0048 06 Bl 0580 MVI B 1 M 024A CD 50 BB 6397 CALL 5 01 0 ABAD C3 59 00 2420 JMP ENGIN K 0050 BAIA E 0050 19 0428 5 01 DAD D 0051 36 GF 9450 5402 MVI MsSMOKE e COUGH 0055 25 0440 H 006 05 0450 DCR B e COUG
3. 9 2027 92171 2 749 1 1A 1 1 9 so 8010422722 7792217 8 9 20421 92102 7 23 06 212012357 110200 11 273510111721406077205 4520125732205 22501 14 22 021112025 021587213022301 213 24721115 12 52371 12 21 0111201103230100 01652700213 0 801 222 6402 26301 8 25501 9 562 00211417507 2246 9216 72982424192 40 420453 5919502206591 1201 1226720672 19197263 CeCe LE TEC ET SEER CCC REET CONC Cee EAA aso ve 11 HCC Newsletter Vol 2 Issue 11 12 December 10 1976 TABLE CONTENTS Random Data Robert Reiling One Man s System Charlie Pack Wisconsin Area Computer Society Robert Getting The Most Out Of Tiny BASIC Tom PICMG easels e Inexpensive Graphics Workshop About Reconnecting the IMSAI Power Transformer Dave Kinkade How I Built My First Computer Norman Waltersa san ios Tiny BASIC Or How My Family Came To Love My Computer Ray Boaz Bulletin Board oves e rer ESTO Stand Alone Adapter For VDM 1 Lee Felsensiein Gordon French s Choo Choo Train HOMEBREW COMPUTER CLUB NEWSLETTER P O Box 626 Mountain View CA 94042 HCC Newsletter Vol 2 Issue 11 12
4. 1160 ACFB C2 FA GA 1170 JAFE C9 1189 JAFFE 1192 GAFF 21 01 CC 1220 810409 og De 1214 0174 7E 1220 ALAS 28 1230 2126 77 1242 0107 25 1252 198 1262 01239 7C 1274 ALAA BY 1240 2128 C2 04 AY 1290 ALAE C9 1520 ALAF 131A 010 21 ee 1320 0112 7E 1533 2115 22 1540 0114 FF AE 1550 2116 12 21 1560 0119 23 1570 ALIA 7E 1350 2118 FE 11 139 11D C2 31 1470 0190 11 7E 14 1410 7123 14 0 8123 06 07 1430 2125 72 1440 7196 a5 1450 0197 52 Al 1460 ALPA 23 147 AL2R 7 1434 012 23 1494 a12D 25 1520 2125 C2 25 0 1517 2151 1520 4151 FE 14 1530 0153 3C 2 1540 71 5 11 2D 15 1557 139 23 AL 1562 2 13 1570 ALIE 47 AY 1580 7141411 SF 12 1590 144 C3 92 Al 1620 0447 FR 12 1610 0149 C2 1A e 1620 ALAC 11 ap 11 1650 0144 63 23 Fi 1640 2152 165 0152 01 08 1660 HCC Newsletter Vol 2 Issue 11 12 December 10 1976 TRAVL 03 STROK COAL TURN HISS FOUND AXLE AXL AXL2 NXTI NXT NXT3 WORK LXI PUSH CALL CALL ncx XRA XRA LXI MVI MOV DCX MOV INX INX MOV JNZ RET LXI MOV INX CPI JN INX MOV CPI JNZ LXI MVI MOV DCR J INX MOV INX DCR JNZ CPI JNZ LXI JMP CPI JN LXI JMP CPI JNZ LXI JM LXI 10 64 13 TRIP 13 MILES ONCE MAKE FORWARD TURN VHEELS MAKE CHUFF MOTION TROK URN 13 NO DO NEXT TRIP MILES YET B S CLICK
5. ST 11 1 Homebrew Computer Club Robert Reiling Editor O Post Office Box 626 Mountain View CA 94042 O Joel Miller Staff Writer Typesetting graphics and editorial services donated by Laurel Publications 17235 Laurel Rd Los Gatos CA 95030 408 353 3609 n a a RANDOM DATA f By Robert Reiling MEETING Nov 12 1976 Acapacity crowd was on hand estimated at over 450 people for this meet ing Anderson Jacobson had their terminals and promised provided an informative talk about the Selectric machine as used in their terminals Particular ly interesting was the discussion of the way that the type ball is positioned to print a character Also the differences in the I O unit as compared to the office unit were listed I O Selectric is a heavy duty machine developed for computer use and workloads The office Selectric does not have the heavy duty features M amp R Enterprises demonstrated the Astral 2000 with the special version of BASIC which has been spe cifically designed to operate in the Astral system The Astral is available in fully assembled turn key condi tion as a partially assembled kithe kit saves lot of money and is easy to put togeth r since the majority of the electronics ar preassembted burned in and tested Marty Spergel and other representitives from M amp R discussed these and other features of this compu ter system If you missed the meeting you ma
6. 55 0 7 TRI KBD 8 gt E 1 TRO RI 40 17 25 2 001 gt 9 NEG STE 25 N i lt j f zd 1 2 xr 3 7 83 sy ong 2Nn2907 559 WIN CTT AAVA 2 GERD AA 1 xD cy nt 3 a co MET ors 5 56 o qp CAD 27 rn AE L Sy Le 2N2222 E x disi E oai 14759 lt CH AI X i 1 Ea tw gt 4 47 ip COT ree Gain NOTES UNLESS OTHERWISE SPEC f ALL RESISTOAS IN 5 5 4 Z ALL CAPACITORS MICROCARADS 3 ALL O ODES 1 4148 OR 154914 33K 756 KHZ 33 Ic 28 C23 1C 24 FERATE ra ie BH PRU CRAS 2 e 5 3 3 911 5 lt PRE BLANK 015 SCHEMATIC VDM t STAND ALONE ADAPTER 24 1775 FED 4 43 L FELSENSTEIN HCC Newsletter Vol 2 Issue 11 12 December 10 1976 9990909906000906000000900900000000000000000000000 GORDON FRENCH S CH90 2MOO TRAIN OR IDLE FANTASIES ON YOM SCREEN 0000000000
7. December 10 1976 p cLAss HOMEBREW COMPUTER CLUB MEETINGS Where amp When The Homebrew Computer Club meets a 7 p m at the Stanford Linear Accelerator Center Auditorium Dates scheduled for the remainder of this year are December 10 and 22 The date and location are subject to change If a change does occur every effort will be made to provide ad vance notice in the Newsletter 1 0 909 L BAKER DPT OF BIO SCIENCE STANFORD UNIVERSITY STANFORD CA 94305 12
8. ODOMETER A B CHOU Hs CC4IH MOVE DOWN THE TRACK CsADAH H H H C ENOUGH COAL COAL NO PUT MORE ON ADD MORE COAL HsSCCAZGH TURN WHEELS Ahem H 6 FIND COWCGTCHER HISS LOOK AGAIN H A M 11H WHAT QUARTER TURN D 147E amp H NEXT QUARTER TURN 5 7 DO 4 AXLES Msn WHEELS MOVED HIRE B LAST WHEEL WORK I VE BEEN WORKIN eee H THE RAILROAD es Mok SIDE RODS MOVED HERE H es ALL THE LIVE ee 3 ee LONG ecece 2 14H QUARTER TURN NXT D9132DH AXL1 13H QUARTER TURN NXT3 Ds125FH AXL 1 12H QUARTER TURN 5 12 3 AXL1 35400 1155 gn 1672 OIL DCX 0186 NR AC 1620 IN 0 DID CONDUCTOR ALISH FG 4A 1697 ANI RDA eeFLAG US DOWN MLSA C2 63 Al 1700 QUIT QUITTIN TIME 2155 AF 1716 NOs THEN HIGHPALL ALSE 1722 XRA AISE C2 55 9 1752 JN OIL NO 52 5 PLEASE a152 C9 174C RaT A163 01750 0163 176 PYT JUMP WHEREVER YOU NEED TO RETURN IN THE NEXT 216 C3 60 EA 1770 QUIT JMP AL33 ee YOUR RETURN LINK HERE AISE 17RA 0166 1790 RDA EAU 40H PUT YOUR DATA READY HERE 0166 1800 RIY EQU 8 0166 IRIA 5 0 FAU EFH SMOKE 2166 21 10 1822 CABI DU 122114 CAB DESCRIPTION 7163 10 50 1830 C482 DV 5018 2164 7E 22 1840 CARS DW 2 7 MISC 28 1957 2011 A A23H BOILER DESCRIPTION ALGE 15 267 R
9. assignment statement Another way to speed up program execution de pends on the fact that constant numbers are converted to binary each time they are used while variables are fetched and used directly with no conversion If you use the same constant over and over and you do not otherwise use all the variables assigning that number to one of the spare variables will make the program both shorter and faster You can even make the assign ment in an unnumbered line the variables keep their values until explicitly changed Debugging Very few programs run perfectly the first time When your program doesn t seem to run right there are several steps you can take to find the problem First of all try to break it up into its component parts Use the GOTO command and the END state ment to test each part separately if you can Add extra PRINT statements along the way to print out the vari ables you are using sometimes the variables do not have the values in them that we expected Also the PRINT statements will give you an idea as to the flow of execution For example in testing the sort of pro gram above lines 500 700 I inserted the following extra PRINT statements 525 PR x 545 PR 555 PR This gave me an idea where in the sort algorithm I was so I could follow the exchanges the 5 where each line represented one pass through the main loop Endless loops become more obvious this way If you have not used all the sequ
10. D 32EH BOI 5 0 36 012 36 BOIS ee SHEN 365H SHED 367H 014 SHED 369H BOIS ee SHED 36BH BOIS SMED 36DH FRA 5 SHED 3A2H FRA2 SHED 3A2H SHED 3SAAH SHED 3A6H FRAZ ee SASH FRA4 FRAS SHED 3ACH B 21H 6 A TINY LOCOMOTIVE WITH A LITTLE SMOKESTAK Hs SHED 325H AND A LITTLE BELL eeAND A TINY DOME AND A CAB WITH WINDOWS SO THAT YOU COULD SEE INTO JHER amp THE ENGINEER AND THE FIREMAN SAT IT HAD BEAUTIFUL POLISHED BRASS BOILER WITH THE NUMBER 39 ON THE SIDE OF THE CAB BUT YOU COULDN T SEE EITHER THE ENGINEER OR FIREMAN THE LITTLE ENGINE ALSO HAD A COWCATCHER AND LOTS OF FUNNY WHEELS AND THE THINGS THAT CONNECTED AND TWO VERY TINY WHEELS AT THE VERY VERY BACK ALTOGETHER IT LOOK QUITE LONELY ANO YET IT APPEARED VERY FUNNY JUST SITTING HsSHED SDEH THERE ON THE oe RAILS B ee WITH NOTHING AT ALL H ee EVER A ee TO DO B WELL RAILS ee LET S RUN IT JUST FOR FUN HeoRRY GET TRAIN OUT OF SHED e MOVE IT FROM SHED H SHED LIGHT FIRE H MoA eeMOUE IT H 2DGH END OF YARD FIRE NOs MAKE MORE STEAM TRAVL GO TAKE TRIP HOSTLE NO ROUND TRIPS JUST DO AGAIN HCC Newsletter Vol 2 Issue 11 12 December 10 1976 AARD 10280 AGED 01 42 1790 AGFA C5 1120 IAFL CD FF AA 111 CD AF 71 1127 CFT7 1137 2 5 on 1140 00 9 1152
11. H 0055 c2 51 02 2460 JNZ SMO2 aa5m cS 0470 COMING OF STACK OF HCC Newsletter Vol 2 Issue 11 12 December 10 1976 8 8659 0059 gase ASSE 0061 0065 7066 2063 0063 026 2071 007 2277 QATA 2275 2087 0082 BARE 00289 DARC agar 0292 2095 0098 BASB 099 AFAL 20 7 AAAD ABBA ASRS 2086 0289 8 AARF AAC2 eacs 00 8 A8CB AACD AACK GACF AADA 2021 0204 607 aapa aepR AADC AADD PADE AADF 9056 AAEN AAKD AGRA AAT 21 36 21 26 21 55 PA 22 2A 22 2A 25 24 2A 22 gt CB eo 2 DB FD D4 AG 01 22 aa 0480 0490 ENGINE LXI 6526 2510 25202 2550 0540 0552 2560 2570 2580 2590 9620 2610 2620 2632 2640 2652 2660 2677 esae 2692 27022 2712 0720 0752 27498 arse 2762 2770 0780 2790 252 2810 2620 0830 2840 2850 2860 ag7e 0830 28902 2922 2912 0922 2930 0940 0958 09624 2972 RAILS HOSTL FIRE MVI LXI MVI LXI MVI LHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD SHLD SHLD LHLD SHLD LHLD SHLD LHLD SHLD LXI LXI MVI INX INX XRA XRA JNZ LXI XCHG LXI MOV INX XCHG MOV INX MOV XCHG CPI JNZ CALL JMP 9 HsSHED 322H Me 16H M9 7H H SHED 327H Me GEH SHED 32AH CAB2 ee SHED 52 SHE
12. If the previous line was terminated by a CR the cursor disappears until backed over the CR The circuit may be constructed using wire wrap or solder layout is not critical except that proper supply bypassing techniques must be used for the TTL ICs Capacitors 0 14F should be connected between the 5 V and GDN pins of these ICs to prevent supply cur rent pulses The two boards may be interconnected with ribbon cables and DIP headers which plug into the IC sockets indicated on the drawing THE FOLLOWING MODIFICATIONS TO THE VDM ARE NECESSARY Cut trace on solder side from pin 4 of IC 17 Cut trace from pin 13 of IC 10 on component side Connect a jumper from pin 6 of IC 17 to pin 13 of IC 10 Connect a jumper from pin 7 of IC 31 to pin 4 of IC 17 Connect a jumper from pin 3 of IC 31 to pin 7 of IC 13 Connect a jumper from pin 8 of IC 15 to pin 9 of IC 31 Connect a jumper from pin 3 of IC 41 to pin 15 of IC 31 Remove ICs 18 23 24 28 29 31 32 33 34 35 37 38 39 and 40 9 If not yet installed resistors R27 through R32 and R41 through R48 may be omitted from assembly O OY O JO DB N N HCC Newsletter Vol 2 Issue 11 12 December 10 1976 Cv lt V h h 2N2907 p vo up 1 b WLS2 ETD 25 lpr ONE STOP 3e SBS 558753 Sere DART 1 KBD 1 20 TR 602B8 27 AY S4013 RAZ KBD 2 3 55 1 3 23 4 20 TRS 8 5 i RRS 28553
13. OI 19938 2179 BA 1870 BOTS DW RAGAH 0172 SB IERA ROIA DW SAAHA 0174 39 39 1290 3015 DU 3933H N 7176 5D 29 1922 BAIG DW 050 bx 2178 26 2A 1910 225 8 FRAME DESCRIPTION PITA 11 5D 192 FRA Du 217 11 20 1932 FRAZ DW 22118 2178 6F 2 1947 FRAA DW 206FH T 0180 6F 20 135 FRAS DY 2A6FH 2 19 19 1962 TIES 191 5 DESCRIPTION 0184 QA 1970 SHED NOP THIS IS SHED AREA 0185 990 CLOUD EaU t 0172H BEGINNING OF CLOUD 2145 1997 ALSS 2AAR 21 5 21 40101020085620030 9 1 7 21127004766050 21 201 00 50001128220262 500011252000609 050621135 0604 025063 1 2724200271128 00622 0 50021120040601 0580001135200601 052 0 394 14204500590919366 235065 096 00 921 6043616214 92 3262721 04366 7 1 2 6 0129 004 2 6 22042 6 24122 5742 6 09 1 9249220122 70 24 720122590422 8 2 2 2122 0242 74215 0 14 0296723762125F1642A7 R012224052A7AP1222605222305222A752A77 CO 195 14023627222005247701290z0 2A82010230050 IDFFF2162052519231 ARS lAa20 Dh00C0A0A 4C2057 22 02 CCER 2 15401 TE 3588772 3ATCESRFED2C20360CDEDCZEB1 1400 4 2090174072714201 5
14. TEM By Charlie Pack My background is in programming including 10 years of experience mostly on large scale IBM systems I ve used IBM 1401 Autocoder 360 Assembler PL 1 and COBOL for many varied applications includ ing some of my own personal accounting and inven tory chores In 1973 I went to work for an electronics HCC Newsletter Vol 2 Issue 11 12 December 10 1976 firm which manufactures intelligent terminals using the then new Intel 8008 Although I didn t program the 8008 it soon became apparent to me that micropro cessors were good for a lot more than just formatting data on a video screen or controlling traffic lights In the meantime I had gotten interested in digital electronic circuitry while building digital clocks and meters and finally I built and got running a Radio Electronics Typewriter the TVT 1 with the boards that are stacked like cordwood Then the bug hit me for sure I wanted my own computer So in November 1975 I devised a point system and rated all of the available hobbyist computers I had been renting time on IBM 360 30 ffor 30 per hour so I wanted the capability to run a high level language and later a disk operating system The clear winner was determined using my point system and right after New Year s my Altair 8080 kit arrived when I ordered my Altair I didn t know about the IMSAI computer At the present time I have up and running in my Altair a Processor T
15. ar ren Faire Chairperson You can participate in this ses sion or others scheduled for the Faire Write or call Jim Warren Box 1579 Palo Alto CA 94302 415 851 7664 or 323 3111 LETTER November 1976 Samuel H Daniel Vandenberg AFB CA sent a letter asking to be put on the mailing list and enclosed a donation He com mented as follows on his activities I presently have an 18K Digita Group 8080 System to which I may add a pair of Phi Decks and a controller It works as advertised and went from bits and pieces to assembied and tested in only 14 5 hours Needless to say Pm pleased with and recommend it Thank you for the product information and for the contribution to the Newsletter CONTRIBUTIONS The Homebrew Computer Club Newsletter is supported by contributions both of articles and money Your articles help keep informa tion flowing and all of us benefit In this issue you will read about what others are doing with their computers What are you doing Do you have a favorite software idea How about a product evaluation Send me your article for the Newsletter Money of course is another requirement of the Newsletter Printing and postage are very expensive and so it follows the Newsletter costs a reasonable amount to produce and distribute Please keep your contributions coming in Mail to Homebrew Computer Club Newsletter P O Box 626 Mountain View CA 94042 or meet me at the next Club meeting 0 ONE MAN S SYS
16. e to save memory space leaves 6K bytes remaining for data That s enough for 100 150 transactions with 3 6 data items per transaction using DATA statments A year s investment portfolio transactions are no prob lem I use line numbers of 10000 and up for DATA and less than 10000 for program code The command LIST 10000 stores the updated data file on paper tape The latter two needs are satisfied by programs I write in BASIC and use with the printer on my ASR 33 By following set conventions for line numbers and by using common subroutine for READing data a Newsletter Vol 2 Issue 11 12 December 10 1976 programmer may use a DATA file with several pro grams To print out or punch the program code only I type LIST and when the last statement starts to print I hit control C a couple of times to stop it Although my implementation of investment port folio is crude it illustrates that minimum hobbyist type equipment can be practically utilized for many small business needs A video display such as the Pro cessor Technology VDM 1 and a tape cassette storage system could be substitued for or used in addition to the ASR 33 The use of Extended BASIC would greatly facilitate separate storage and manipulation of data and programs and the display of formatted re ports My future plans as far as hardware is concerned include the acquisition of more memory a ROM monitor which can be used to load BASIC a video display cas
17. echnology motherboard 8 8 I O interface two 4KRA static memories and two 4K dynamic memories I use an ASR 33 Teletype machine for I O MITS BASIC version 8 2 is used for all ac counting applications at present aforementioned hardware is now being used to do investment portfolio and income tax analysis and to produce a cross reference index to magazine articles The hardware now being used represents a practical minimum for the performance pf the applications now being run Assuming that the necessary planning and analysis has been done computer inplementation of most sim ple business type applications not involving large amounts of data involves four basic needs a Some means of transferring original data from documents to the computer For an on line system this is done using a suitable keyboard and some type of edit update program b Some means of storing the data outside of com puter memory c Processing of data usually involving data selec tion or sorting logic and calculations d Reporting of the desired information to the user This is the end product of the sytem The BASIC line editor itself satisfies the first two needs in my applications Here is a complete on line data entry program which can add new data change existing data and delete data Of course the entire data file is in memory but allowing 6K for BASIC and 4K for a good sized program leave out comments and use multiple statements per lin
18. ential line num bers you can insert breakpoints in the program in the form of a line number with an illegal statement I like to use a single period because it is easy to type and does not take much space we we 10 LET A B 1234 11 20 GOSUB 100 A Here when you type RUN the program will stop with the error message 1184 AT 11 Now we can PRINT A B etc to see what might be wrong or type in GOTO 20 to resume with no loss to the original program As we have seen there is not much that TINY BASIC cannot do except maybe go fast Sure it is somewhat of a nuisance to write all that extra code to get bigger numbers or strings or arrays but you can always code up subroutines which can be used in sever al different programs like the floating point add above line 1000 1250 then save them off on paper tape or cassette Remember your computer with TINY BASIC in it is limited only by your imagination REFERENCES 1 TINY BASIC User s Manual Available from Itty Bitty Computers Box 23189 Jose 95153 2 Doctor Dobb s Journal No 7 p 26 Available from PCC P O Box 310 Menlo Park CA 94025 Finally it should be noted that GOTOs and GO SUBs always search the program from the beginning for their respective line numbers Put the speed sensitive part of the program near the front and the infrequent ly used routines set up error messages and the like at the end This way the GOTOs have few
19. er line num bers to wade through so they will run faster 1 INEXPENSIVE GRAPHICS Workshop Announcement A workshop regarding inexpensive graphics is being planned on the East Coast It will be held next year and is sponsored by Sigraph of the A C M Interested people may contact William Etra 42 E 23rd Street Floor New York NY 10010 O ABOUT RECONNECTING THE IMSAI POWER TRANSFORMER By Dave Kinkade When I changed the line input connections to my IMSAI transformer a Trane 3751 I was chagrined to learn that it did not match the diagram on the PS B schematic Rev 2 3 3 76 The terminals are actually 1 common 2 for 105 V 3 for 115 V 4 for 125 V For example I connected to 1 and 4 instead of 1 and 3 to lower the output voltage and generate less regulator heat Newsletter Vol 2 Issue 11 12 December 10 1976 ora om p isi Te ur Ex Dog lt Home Co IRA ition get cu eee april 1977 san francisco P O Box 1579 Palo Alto CA 415 851 7664 323 3111
20. ew from the Summit Rd area in the Santa Cruz mountains Must be willing to get going early as I like to avoid traffic Joel 415 962 3372 days or 408 353 2663 eves HOW TO GET THE NEWSLETTER Anyone interested in computers as a hobby may receive the Newsletter by sending a request to the Homebrew Computer Club Newsletter Box 626 Mountain View CA 94042 The Newsletter is distribu ted monthly at the club meetings and is also mailed to individuals who are unable to attend the meetings If you have an input to the Newsletter send it in and it will be published as quickly as possible However the editors cannot promise that everything sent will be published immediately All manuscripts must be typed and carefully proofed listings and diagrams should be as clear and easy to read as possible The Newsletter is made possible by your donations Please remember that we must pay for postage labels and printing Donations may be given to Ray Boaz at the club meetings or sent to the above address HCC Newsletter Vol 2 Issue 11 12 December 10 1976 STAND ALONE ADAPTER FOR VDM 1 By Lee Felsentein This circuit allows the operation of the Processor Technology VDM 1 as a stand alone terminal It in cludes a UART for serial data communication with EIA RS 232 signal levels All data to the VDM comes through the UART 80 local loopback connection is necessary from the Data Out terminal t
21. it on top of me was my son Chip who is only six Since he is not up to multiplication yet I had to do something else If Tiny BASIC could multiply that easy it must be at least as easy to do the addition facts So with a few chnges in the same program another member of the family was into the computer Well that accounts for two out of three What about my wife Glad you ask She does not glare at it when she walks by and has even started saying some al most nice things about it If this keeps up I may have to start on another computer for myself Oh one other thing Heidi is busy setting up times for her friends and making arrangements to take the new toy to school There seems to be no end of what can happen when your kids can compute O 111111 LEGALE For sale Cryptographic program that will baffle the codebreakers of the CIA ENCODE and or DECODE your private correspondence for maximum security Documentation of cypher technique program listing and punched paper tape in BASIC for only 6 Jon Stedman 1528 Summit Rd Berkeley CA 94708 Kleinschmidt 311 printer 40 char second 80 charac ters wide parallel ASCII input level conversion from 12 V can be tapped from printer power supply full documentation has modem card automatic shut off after 60 seconds of no data good operating condition needs cleaning 300 another 311 has power supply no other electronics excellent mechanical condition 150 extensive suppl
22. lectronies stores and pored over the Poly Pak catalog like it was a dirty book Because of this approach cheap parts did not present a major problem The CPU board and control panel board required the 18 gest outlay of time After some initial delays both were purchased through the club by group buy 4 Newsletter Vol 2 Issue 11 12 December 10 1976 Building the boards up took relatively little time The largest block of time during construction was devoted to running wire A total of nearly 1 000 feet of 26 ga and 100 feet of 16 ga was used Checkout was prolonged considerably by the unfortunate inser tion of the CPU board backwards in the motherboard The snaps crackles and pops would have done Rice Krispies up proud Invaluable assistance by a long suf fering friend Grant Connell finally got GEORGE up and running system at the present time consists of the 8080 microcomputer with 24K of 2102 RAM 12K of 1702 EPROMs a KSR 83 Teletype a cassette record er I O boards for the teletype and cassette plus a high speed paper tape punch Within the next six weeks GEORGE will acquire a high speed paper tape reader and a VTT 4000B video terminal I can tell the memory of the pain sweat and frus tration incurred during the construction is beginning to fade A few weeks ago I saw the ad for the Micro Nova minicomputer chip set and thought I bet that I can get one of those jewels up and ru
23. nning for almost nothing By the way I have a list of parts that you have pro bably got just sitting around gathering dust 0 MUTA STACK WO 9 e 9 AU 07 os an 959 eee 57 1 AM AIO eee TE 2 O Il 5 586 TINY BASIC OR HOW MY FAMILY CAME TO LOVE MY COMPUTER By Ray B One sure way to get the support of your family for all the hours that you spend with your computer only is to let them get some hands on time The problem is how many kids let alone wives understand binary octal hex or getting a program into the amp 1 thing to do something So how do you do it Well I got Tiny BASIC for my AMI Proto system by Tom Pitt man and it worked out just great The first thing I did was write a program for my nine year old girl Heidi to use for her multiplication facts After one minute she was really into it The pro gram generates two random numbers less than twelve prints them i e 11 waits for the product to be typed in and then compares the entered product to the calculated product If the answer is correct a new line is given The computer can keep score and if the problem was one a VERY GOOD is prin ted This is a short and simple program but to a nine year old girl it is like magic I didn t get off that easy however At my side all the time or was
24. o the Data In for half duplex operation Two switchable Baud rates are available if a SPDT switch is connected to switch Baud Rtn to Baud 1 or Baud 2 The Ready output from the UART allows operation from a generalized parallel interface at maximum speed The Break input moves the output to a space condition and is used as an escape character in various systems The circuit requires a connection to an external 16 V to 19 V supply 5 V power is supplied by pin 16 of IC23 from the regulator of the VDM The cir cuit draws very little current since most logic is CMOS 12 V and 5 V connections shown are for key board power On power up the circuit initializes to a clear screen with a cursor in the lower left corner Non control characters are displayed and rolled up when a 64 char acter line is filled will terminate a line and roll it up A LF immediately following the CR will be ig nored as will a LF following any number of DEL rub out characters which turn follow CR second LF or one without a CR preceding will be treated like a CR LF combination FF will initialize the screen BS will be recognized and the cursor will move back and will erase the last character At the left end of the line the cursor will jump to the right end and will cause a roll down of the line above This will not occur if there is not text on the line above The cursor wil jump to the 64th location whether or not it is visible there
25. one 415 941 0495 between 7 and 10 p m on week day eve nings would be preferred WISCONSIN AREA COMPUTER SOCIETY By Robert Reiling The Wisconsin Area Computer Society has been holding monthly meetings for the last twelve months and has a paid membership of over 80 persons They are establishing a good software library and can com municate via Cassette Tape Tarbell Digita Group and K C Standard and Paper Tape Recently they pub lished their first newsletter Contact Don Stevens Chairman Wisconsin Area Computer Society P O Box 159 Sheboygan Falls WI 53085 O GETTING THE MOST OUT OF TINY BASIC Tom Pittman Continued from last issue Execution Speed TINY BASIC is actually quite slow in running pro grams That is one of the hazards of a two level inter preter approach to a language processor But there are some ways to affect the execution speed One of these is to use the keyword LET in your assignment state ments TINY BASIC will accept either of the following two forms of the assignment statement and do the same thing R 2 3 LET 2 3 but the second form will execute much faster because it is unnecessary for the interpreter to first ascertain that it is not a REM RUN or RETURN statement In fact the LET keyword is the first tested so that it becomes the fastest executing statement whereas the other form must be tested against all twelve keyboards before it is assumed to be an
26. sette tape interface and hardware backup capability By the time this article is in print I will have a Processor Technology 8KRA RAM board and a MITS PROM board up and running with a system monitor in six 1702 PROMs The latter has loaders for MITS BASIC any version and for software in the Intel hex format a block move full TTY support and switchable hexidecimal or octal mode capability in addition to normal monitor functions It will be made available to hobbyists via the HBCC library and through the Byte Shop in Santa Clara My future plans for software include enhance ment of the monitor to support tape cassette I O and some type of video monitor display Memory diagnos tics games and other programs wil be developed for use with the run on a cross assember of my own design and written in ANSI COBOL for execution on a medium or large scale system A suitable alternative to this would be a Processor Technology ALS 8 develop ment system and a DECwriter or similar printer if the latter could be obtained at a reasonable cost I would be interested to hear from other hobbyists as to what they would like to see in the way of soft ware for the 8080 or Z80 How about a full operating system for multiple cassette tape drives What features would you like it to have Is there an interest in games such as Star Trek in machine language for small capacity systems I can be reached at 25470 Elena Rd Los Altos Hills CA 94022 Home ph
27. y obtain Astral 2000 information by writing M amp R Enterprises P O Box 61011 Sunnyvale CA 94088 S 100 SYSTEM SYMPOSIUM Nov 20 1976 Well over 100 people attended the S 100 System Sym posium held at Diablo Valley College Three perspec tives were given by Dr Harry Garland George Morrow and Lee Felsenstein It was noted by Lee Felsenstein that a large variety of products are available that utilize this bus Harry Garland pointed out that the bus sys tem is basically a good product George Morrow dis cussed the complex nature of the bus A panel discus sion moderated by Jim Warren brought out a number of opinions but the panel generally agreed the S 100 bus system will be used for several years because so many products use it In order to get better definition of bus signals and electrical requirements it was sug gested that publishers print more bus information and act as a clearing house for comments This was the first symposium held covering the 5 100 system It was very well done and certainly informative to all in attendance Indeed it seems everyone must have learned something new The organizers Dr J Schenker J Hendrickson are to be congratulated MORE ON THE S 100 Apri 1977 The First West Coast Computer Faire being held April 15 17 1977 at the San Francisco Civic Auditorium Northern California s largest convention facility will have a con ference session on the S 100 bus according to Jim W
28. y of spare parts 50 all of the above together asking 400 Wm J Schenker M D 2086 Essenay Walnut Creek CA 94596 415 939 6296 Computer store opens in Sunnyvale recreational Com puter Centers 1324 South Mary Ave Sunnyvale CA 94087 Phone 735 7480 CLUB LIBRARY Gordon French club librarian has lots of interes ting material and is able to loan it to anyone with a definite need but please adhere to the following wLimit your telephone calls to the hours of 7PM to 9PM weekdays only This is important Gordon s phone number is 415 325 4209 in Menlo Park Be specific with your requests and Gordon can probably help you he cannot randomly review the contents of the library for you No reproductions will be made of any materials materials loaned must be returned so they are available for others to use in the future For Sale IMSAI 8080 8K Dutonics memory Poly morphic video terminal interface Tarbell cassette in terface Altair 2SIO with one port keyboard and Penny audio cassette recorder Assembled 1775 Contact 4 Gill 497 4715 days 321 6289 evenings SOL User Group now forming If you own or have ordered Processor Technology s SOL computer please send your name address phone number and ideas to Bill Burns 4190 Maybell Way Palo Alto CA 94306 Wanted Carpool or riders to Fairchild or Ellis St area in Mountain Vi
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