16-bit HCMOS computer is a wire wrapping wonderland

The D16/M is a 16-bit computer built using HCMOS logic chips. It’s a thing of beauty from every angle thanks to the work [John Doran] put into the hobby project. But he didn’t just take pictures of the build and slap them on a webpage. He took the time to publish a remarkable volume of documents for the computer too!

The processor can execute a total of 73 instructions and offers a 100-pin bus for accessing main memory and peripherals. So far he has documented three different peripheral boards, each of which is pluggable thanks to an edge connector that accepts the board. The expansion boards are for system memory, serial communication port, and a clever four-position SD card interface for persistent storage.

Got a question about the system? He wrote a FAQ. Want to learn from his obvious mastery of wire-wrapping? He wrote a wire wrapping tips guide. Like we said, there’s a mountain of documentation and the links to it all are included in his main project page.

[Thanks Allen]

Comments

  1. harleydk says:

    That’s a piece of beauty!

  2. Sven says:

    I wire-wrapped a simple blinking circuit with 2 transistors and 2 40xx logic chips, that was enough for me :P

  3. nah! says:

    I dont get the Point of wire wrapping, since the main board is a but, wouldnt it be enough to have jumpers to give an extension board an adress?

  4. geonomad says:

    This is awesome.

    It makes me nostalgic for that earlier, simpler, time, when I understood what every gate in my computer was there for.

    I hope he finds a wire wrapped Lear-Siegler ADM terminal to connect to the serial board.

    The last wire wrapped computer I had, was actually a Radio Shack CoCo prototype. What would become the custom chips were a stack of wire wrapped boards filled with logic chips.

  5. dattaway2 says:

    4MHz. Not bad!

  6. Cyril says:

    Wire wrap AND sd-card: Golden.

  7. Mr Sheesh says:

    Back in 1970’s we didn’t have multi layer PC boards, basically just 1-layer PWBs (Printed Wire Boards) and they were not all that good – so a lot of boards were wire-wrapped, it let hobbyists build it from parts, change it as needed, and in general ate a lot of time. Plus for extra annoyance, the wire you needed to redo was usually the bottom most one under 3 others; And occasionally you’d get a bad wrap (from oxidation) and it would quit working. It was the best we had, then. It worked :)

    • You’re off by a decade or two.

      Double sided PCBs were common in the hobbyist market by 1973, and reasonably available in the 1960’s. Just look at DEC gear, or transistor radios.

      And they had existed in the 1950s and before – it’s just that point to point wiring was adequate for most pre-radar vintage electronics and production rates.

      The reason many computers of that vintage and before were wire wrapped was mostly because of frequent design changes – the expense to get a PCB correctly laid out and fabbed was very high, and wire-wrap offered greater density and flexibility at a lower cost.

      The development of inexpensive Wirewrap guns and pre-cut pre-stripped wire had a lot to do with it – and if you had the wirewrap right, you could solder the connections to make it a bit more permanent.

      Multi-layer PCBS had been ghetto-fabbed using two separate very thin boards that were glue-laminated together by the mid-1970’s, with manual through hole vias. They didn’t work well.

      Modern multi-layer boards didn’t take-off until CAD pcb layout programs became common.

      • Mr Sheesh says:

        OK, let me rephrase to clarify; For poor high school students, we could make our own PCBs with the old burnish-on tape and decals, or use an etch resist pen (usually a sharpie type marker basically) – I didn’t have access to a photographic setup, and I suspect more students were in the same boat. Took a lot of lawn mowing to pay for our CP/M system, back then. I’m fairly clear on the dates, just didn’t communicate clearly. (I also remember our Electronics teacher ordering 3 7410s, and getting about 4 cubic FEET of them, they were apparently still using them 5 years after I graduated from there!)

      • I’ll chime in here….

        I was pretty young in 1973 but it was probably the year I got into electronics at the tender age of 9 and I can attest that double sided PC boards were NOT common in hobby or consumer electronics of the day.

        During my early years of tinkering I took apart many radios, cassette, 8-tracks, walky-talkies and clock radios and none of them had double sided PC boards. It wasn’t until 1979 when I bought a Netronics ELF II microcomputer kit that I got to see real a double sided PC board. At some point double sided boards started coming into the hobby market in the late 70’s, early 80’s but the sure weren’t plentiful in 1973.

      • Sorry for the name changes, but…

        I was also amazingly young circa 1970, but since I got into electronics with surplus junk I could scrounge, much of it came from yard sales by the widows of guys who caught the bug circa 1930.

        Hobby Hackers often live short lonely lives, and although that huge collection of stuff you value will likely be unceremoniously dumped in the bin when you kick the bucket, sometimes it ends up on a blanket for sale to the little kid with the wagon. I was the little kid.

        Interestingly, I also obtained a lot of military “surplus” – IE, “we’re going to bury a large number of expensive current production bombers/fighters in giant pits and burn them part of an elaborate scheme to get more of them, do you guys want any parts?”… and so, by the time I was 20, I realized that the more outlandish the story about “them cats”, the more likely it is to be 100% true. But back to PCBs.

        Thanks to the second-hand yard sale time warp effect, I effectively started in electronics sometime around 1960. As a voracious reader (you have no idea – holler to all those kids who had cargo bikes so they could exchange 40 lbs of library books per visit!), I had certain advantages over my peers in a non-google world!

        One was my discovery that libraries were converting their back issue collections to microfilm, and sold the paper originals for very little. One day I exchanged $10 for every copy of popular electronics (and predecessors) ever written, along with sundry other magazines.
        It took 3 trips.

        While my peers were perusing penthouse and playboy, I was working my way through the history of modern electronics (and computing) by osmosis.
        I remember the first time I saw artwork for a double sided PCB quite clearly, and I assure you – double sided PCBS were quite common to hobbyists by 1970, and appeared earlier. However, I think what you mean is that few of us could afford those (often buggy) circuit boards.

        I know that perf board and point to point wiring was pretty much the method of choice for most people, since perf board was cheap and could be reused. Many kits (audio amps, receivers, FM transmitters, sirens, etc) used single sided boards, but once ICs showed up, it became necessary to do this. Don Lancaster regularly used double sided PC Boards by 1971.

        Double sided PCBS were not common in low-end consumer electronics, but they were used in higher-end consumer/business gear by 1972, especially if it was a really compact product.
        However, I concur that commercial non-digital products with double sided PCBS were rare. However, I have late 60’s vintage computer hardware (just a few souvenir boards in display cases – space program stuff) hanging in my hall, so I guess my generalizations may be biased.

        I would like to bring up a long lost name for anyone who stuck with this diatribe: John Sargrove
        He’s Hungarian – they produced their share of genius engineers from 1900 to 1960.
        Look him up, because he got the ball rolling on this stuff!

  8. Miroslav says:

    Very nice, and a lot of effort went into it. I’m in awe.

  9. AussieTech says:

    Now that is a REAL computer!

    Take 10 Internets sir.

  10. lwatcdr says:

    Even Vaxen where wire wrapped in the day. When done correctly is is actually the most reliable way to make circuits.

    • Back in the day, the DEC tech installing our new PDP computers admitted that DEC routinely put used parts into new computers when I showed him the rounded off spots on many wire-wrap pins when he took the skins off them during installation. Yeah, RSX-11M, that brings back memories… :-)

  11. rktokomak says:

    awesome!

  12. NewCommentor1283 says:

    cant use CAD to design a multilayer board without a computer to run the CAD software on!!!!!!

    lol a computer to build a computer.

  13. Roberto Leibman says:

    I did quite a lot of wirewrapping in college. This is really cool, but I do have to ask… you know they make wirewrap in different colors, right? I mean, you can use color schemes to make the design much easier to figure out (e.g. I always used the resistor color code to label data/address lines) I would not like to try to find a problem in this build.

  14. Rob says:

    Makes me almost long for the days when EVERYTHING was not disposable.

  15. Michael says:

    guys – you are great! May this help the world when all ghz, 22nm processor stuff collapses and one has to go back to the roots ;-)

    • Miroslav says:

      It may happen sooner than you think. Smaller pathways are more prone to random electron fluctuations due to cosmic rays and radioactivity.

      We just need a good solar storm, or even limited nuclear war.

  16. Galane says:

    Is this using the S-100 bus?

  17. Glitch says:

    re Galane: it appears to be using S-100 protoboards, but the electrical layout is definitely not S-100.

    Concerning wire wrap, it’s still my construction method of choice for one-off projects. It’s pretty quick, reliable, and you can change the design halfway through testing. I wouldn’t use it for a modern uC project, but for anything where you’re dealing with parallel address + data buses it’s one of the quicker prototyping methods available.

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