The SWTPC 6800 was the first computer system made by The SouthWest Technical Products Corporation and the first based on the Motorola 6800 microprocessor. Before manufacturing computers, SWTPC sold home audio kits and a kind of computer terminal called "Television Typewriter".
The SWPTC 6800 was introduced in 1975. The first system included a case with power supply housing a SS-50 and SS-30 bus based motherboard, a 6800 CPU card, a 2 KB. static RAM card and a serial I/O card. User had to buy an additional terminal to enter information, and thus a ROM monitor allowed him to examine and modify memory, load/save programs on tape or boot from a floppy disc unit.
Every original card was built around the Motorola family chips which made the SWTPC 6800 an inexpensive system for the time. The system was sold in a 2 KB kit version ($395) or 4 KB, 8 KB or 40 KB assembled versions. It came with a complete documentation including the 6800 programming manual and a program examples book.
The ROM and RAM was organized as follow: The MikBug chip (instant-on ROM BIOS) was 1024 bytes, of which 512 bytes were useable; MikBug let you write programs immediately in hex. The CPU board had a 2K bit RAM chip on it organized as 256 Bytes. The memory board included with the kit was 4K but it came with only 2K of RAM chips, 16 X 1024 bit.
Dave O'Neil reports:
Loved seeing the old 6800 on your site. I am a high school physics teacher (I just retired). I built one in early '76 and two of my students went on to build one, too! At least 5 were immediately guided into computers when they saw it that year. I sent a passle of my BASIC physics programs to Wayne Green at Microcomputing and he published them in the June '80 issue of Microcomputing, p. 138.
There were a few newsletters printed and sent out free with all sorts of great stuff to input. Everyone grabbed the hex-binary one for finding bad memory chips. There soon was an assembler that everyone started writing programs with. Then a co-resident assembler/desembler. When Uiterwyck's 4K BASIC came out everyone, went to 8K or 12K. When his 8K came out, we went from 8K to 12K or 16K. I tell people that if IBM had gone Motorola instead of Intel, he'd be the richest man, now.
Chip Gill replies:
I am one of Dave O'Neil's students that also built this machine. Loved using it through 2 years of high school and 4 years of college. My college senior project was a 32K byte memory card for this system which replaced the 4 cards that were 4K each. Thank you very much Mr O'Neil for the inspiration and understanding of computers that I've enjoyed for over 30 years now.
While in medical school in 1978, I bought and built a SWTPC 6800, with CPU, SS-50 bus, and 4k static ram card. Couldn''t afford an ASCII kbd ($$300!) and had no display - so a friend retrieved a Burroughs 32 character Plasma display (Ascii parallel interface) and a kbd removed from a pulp and paper mill - but it had 5-bit Hollerith-encoded outputs. Rewrote the monitor in EPROM to do the kbd code translation to ascii, and to make display on the 32 character display work. Later added a custom board to do file read/write to tape, based on software that directly drove an op amp connected to the audio-in of a stereo cassette deck. Had to add a 1 MHz crystal to the board (replaced the RC circuit) - Then added a board that mapped memory to an 80 x 24 character monochrome video display, and a massive 16kb dynamic memory board. Then with tiny basic (3.95kb), was able to program to heart''s content. It played star trek too.
Friday 13rd July 2018
Geoff Rutledge (California)
I worked with a brilliant engineer named Charlie Moore at a GM plant doing manufacturing R$D. When micros came out we wanted to experiment with one to see how it worked. Our IT people had to approved any computer purchase. They refused, claiming any micro was a toy and unusable in business. We called SWTP and told them our purchasing dept was sending them a RFQ for a "machine controller". They were to quote $395 and when a purchase order came in, ship the 6800 Kit always calling it a "machine controller" in all correspondence. We hooked it to an old ASR-33 teletype machine and later a tape recorder (Kansas City Std) By the time IT found out we had it, we were building a 16 channel high speed data acquisition system for our Detroit Diesel Test Dept for $71K that DEC could not touch for under $500K. Charlie wrote software and I designed hardware. Charlie was using an assembler he bought from a tiny startup named "Microsoft". Several times I answered the phone and the voice at the end asked, " Is Charlie Moore there? This is Bill Gates."
Wednesday 15th November 2017
David Monnier (Indianapolis, In)
I was 16 back in 1976 and had fallen in love with computers after using teletype programs in Basic attached to modems with acoustic couplers to mainframes. Our high school had an Altair but I decided to buy the SWTPC6800. I was working as a dishwasher for $1.40 an hour and it took about five months to save for the kit and then it was another couple of months to solder everything together to get it to work. I did get it to work and still have my old system although I haven''t started it in years. I ended up working in IT for most of my career and it all started with this system.