SWTP 6800 system - PRELIMINARY Web page

SWTP 6800 system - (still) PRELIMINARY Web page

This page slightly updated Mar 25 2024, but I've not worked on this SWTPC 6800 system since 2020 and earlier. Look at all my 6800/6809 work on a page of Web links.

In mid-June 2010 I recieved a SWTP 6800 system from Bruce J. Black: some notes from him are included below. What I got is described below. In July I cleaned up the 6800 system, and powered up the dual floppy-drive portion. This page last updated Nov 21 2019 and July 7 2020, when I added or corrected links. I'm poking at other 6800 and 6809 stuff, like this 6809 EXORset system and a 6800 assembler. Web search will find other such pages on my Web domain. (c) Herb Johnson all rights reserved; quotes are copyrighted by the person quoted. - Herb Johnson

SWTP hardware

[SWTP 6800]

SWTP 6800 system cabinet with:

  • MP-B motherboard, MP-P power supply
  • MP-A 6800 CPU (50-pin board to rear of bus)
  • MP-8M2 8K RAM (3 boards), MP-?? 8K RAM (in front of MP-A)
  • MP-C serial, MP-S serial (30-pin I/O cards)
  • wirewrap card, KC cassette interface (30-pin at edge of motherboard)
  • MP-R EPROM programmer 2716 (30-pin nearest transformer)
  • DC-2 floppy controller (30-pin)

    Bruce describes some of these cards, as below.

    SWTP MF-68 dual drive cabinet with two Wangco model 82 5.25-inch drives

    Loose boards included a MP-A2 CPU board; MP-S serial; and unpopulated wirewrap board, bus only wired up. Bruce says "I thought the unfinished card had a UART chip installed, but then I couldn't figure out why all the chips!"

    ...and two boxes 5.25" diskettes

    Documents from SWTP, TSC (Technical System Consultants)

    black binder #1: Flex 1.0 1978, BASIC 3.0 1978, MiniFLEX 1.0 1978
    ROM monitor 1.0 1977, various utility program descriptions

    black binder #2: TSC 6800 Text Editing Sysetm SL68-24, TSC 6800 Text Processing Sysetm SL68-29d,

    Black binder #3; hardware documents:

  • MF-68 disk system
  • MP-S serial
  • MP-8M memory
  • MP-R eprom programmer
  • MP-B motherboard
  • MP-MX memory expansion for MP-M
  • MP-M 4K memory
  • MP-C serial
  • MP-A 6800 CPU/ROM/RAM
  • MP-P power
  • Wangco 82 floppy drive manual

    Notebook #1:

  • notes on cassette board, TV Typewriter, wirewrapping
  • TVT serial interface and keyboard (parallel) interface
  • data sheets from MOS Technology on 6500 series chips

    Notebook #2: TSC Space Voyage (text-based Star Trek game), source listing in 6800 assembler

    Notebook #3: MP-P documents, 6800 co-resident assember docs, 8K BASIC ver 2.0 from SWTP, Motorola MkBUG documents

    Also provided: a Seimens FDD 100-8d 8-inch floppy drive, 3rd party box (Floppy Disc Services); with FDD 100-8 introduction manual and maintenance manual

    System cleanup and checkout

    Check this Web page for details of the 6800 system by board, and some cleanup.

    Bruce's story

    Bruce contacted me and said, among other things: "I also have my original SWTPC M6800 computer with a galloping 24 k of memory. It has a dual floppy drive attached. I think they had a 72k capacity. It's gotta go too. Don't know if it still works. It was my first. Somewhere I think the manuals and disks are around I used to use a model 43 teletype as a terminal. Like the floppy drives it was expensive." We corresponded and I obtained the system. Here's a bit of Bruce's history with it - Herb Johnson

    "...I decided to start cleaning out the garage and found the documentation. The disks I found in a pile in the house. The system has 24K of memory, two floppy drives, a Kansas City cassette interface, and I think an EEPROM programmer. The original KC tapes are long since gone. The KC interface is homemade, but a schematic is included. There are also some websites dedicated to this stuff and I think they may have additional backups and data on this system."

    The wire wrap [in the computer] is the KC card. There is a schematic for it on a hand drawn sheet of sketch vellum. I may have used a drawing template for the logic symbols. The cards in the chassis are for the serial control port, the floppy controller, and an EEPROM programming card. I think the serial card is wired to the KC card also. I made pictures and it looks like a second serial card is installed."

    "The TV typewriter is another story!" Bruce describes it below.

    A little personal history by Bruce M. Black

    "In 1972 I decided to hang it up on law school and stick with what I do best, engineering. I interviewed for work with two companies and took the best job offer. Four years later they decided to dispense with my services for the usual reason, no work. I approached the other company again for a job and they said that If I didn't mind few trips out of town to support a contract they had with the Naval Academy I could have a job. I agreed and two years later those few trips turned into almost a year in Annapolis MD." Bruce added later: "Just for info I graduated U of Florida in '64 with a BEE degree. Bachelor of Electrical Engineering". Later I think it became the more standard BSEE. Spent most of my career designing controls for tracking systems to track missiles and aircraft or whatever."

    "[In 1976] I thought the MITS Altair [8800] too pricey for me. I liked the instruction set of the 6800 better, and the SWTP machine came in board sized kits which was fine by me. So for a while, about every trip to Annapolis a kit went with me. Nights in the Motel were spent building each board kit until I had the computer together that you now have. I thought I was a big man on campus when I reached a total of 24k of memory."

    "Somewhere about the time the "build" [of my 6800 system] was going on Radio Electronics magazine published the TV Typewriter article. A technician friend and I teamed together to build the beast. He was into photography and made pictures of the PC board layouts. [PC boards can be made using photo negatives and photosensitive resist, and ferric chloride to etch out the copper outside the resist. - Herb]

    "These things were huge, about 12" by 15" inches or so. He etched about 3 or 4 of them. They were not clean etches so we selected the two best boards and started construction. The boards required some cuts and jumpers to fix the poor etching. I also added some extra circuitry for interfacing and maybe some extra memory. I had also acquired a keyboard made by TI."

    "The whole thing was put in a chassis and covered with mahogany vinyl. I made a slopping wood frame for the keyboard and bolted it to the chassis. We used a 12" Zenith TV for the display. This set was modified with an input selector switch and coax connector. You could either watch TV or have a 40 character by 16 line display."

    "Later this was replaced by a Teletype Model 43 teletype which gave me both a data entry method and a printout. The Zenith TV eventually was used as such by my son until it died. The Teletype gathered dust until I trashed it many years ago."

    "Computer number two was a Kaypro 10. It had a 10 meg hard drive. Two weeks after the warranty was up the drive died and it cost me $600.00 to replace it. Number three was hand-built so I could do my hardware thing. After that it was mostly home assembled PC's running MS-DOS until the Microsoft Windows switch, which once again denied me hardware access. So then I became a Linux fan where I could write hardware drivers and screw the computer up to my hearts content. I fired the Kaypro up about six months ago and it worked though it did produce a curl of smoke. I did an orderly shut down. I suspect a cap failed in a non-destructive manner. One of these days....."

    - Bruce J. Black

    Web links to related SS-50 stuff

    In Nov 2019, I was referred to this yakowenk cache of SWTPC documents and links. But it's a dead link in the 2020's. Anyone have a copy?

    In May 2019, I obtained a Z80 based CPU board for the SS-50 bus! Check out the details on the SSZ-80 from Design Ltd.

    In March 2013 I restored a Motorola MEK6800D2 board to operation. Sold it a few years later. But in 2019 I added some JBUG information to the page.

    Years ago, Michael Holley had a WEb site, swtpc.com. The site was last edited in mid-2006. That's four years before the start of this Web page. That Web domain is now a honeypot, do not go there! By Feb 2020, deramp mirrored the swtpc.com Web site - Herb

    I took some time in Nov 2011, to revive William Colley's 6800 cross assembler A68. It was written in C by William Colley and submitted by him to the old "C User's Group. Here's a ZIP file of my edited version of Colley's A68 cross assembler. Its compiled for 32-bit Windows in MS-DOS mode, using the lcc-32 C cross compiler which is freely available. To use it as a full Windows program, you have to recompile it or "wrap" it in some GUI. To use it as a 16-bit MS-DOS program, you have to recompile it in, for instance, Borland Turbo C 1.5 for MS-DOS. I've done similar work with Colley's A18 cross assembler for the RCA 1802, which you can find at this linked Web page. - Herb Johnson

    In the fall of 2011, I corresponded with Martin Eberhard, another 6800 system owner. He has a number of MITS "Altair 680" systems. MITS created what became the S-100 bus with their Altair 8800 with the Intel 8080 processor. They are less-well known for their Altair 680. I created a Web page from Martin's correspondence about his work on restoring his Altair 680 system and some software he wrote to support it. [I do not have a MITS 680 system.] - Herb Johnson

    I have some correspondence with Frédéric Le Duigou in France. He has a number of Motorola-based vintage systems. Here's a Web page I made in Jan 2013 about his SWTPC 6800 and his collection.

    Contact information:
    Herb Johnson
    New Jersey, USA
    To email @ me, see
    see my ordering Web page.

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