Restoring An Unusual Piece Of Computing History

Trawling classified ads or sites like Craigslist for interesting hardware is a pastime enjoyed by many a hacker. At a minimum, you can find good deals on used tools and equipment. But if you’re very lucky, you might just stumble upon something really special.

Which is exactly how [John] came into possession of the TRANSBINIAC. Included in a collection of gear that may have once belonged to a silent key, the device is a custom-built solid-state computer that appears to have been assembled in the early 1960s. Featuring a large see-through window not unlike what you might find on a modern gaming computer and a kickstand that tilts it back at a roughly 45° angle, it was obviously built to be shown off. Perhaps it was a teaching aid or even a science fair entry.

After some digging, it looks like the design of the TRANSBINIAC was based on plans published in the January 1960 issue of Electronics Illustrated. Though there are some significant differences. This computer uses eight bistable flip-flip modules instead of the original six, deletes the multiplication circuit, and employs somewhat simplified wiring. Whoever built this machine clearly knew what they were doing, which for the time, is really saying something. This truly unique machine may well have been one of the first privately owned digital computers in the world.

Which is why we’re glad to see [John] trying to restore the device to its former glory. Naturally it’s a little tricky since the computer came with no documentation and its design doesn’t exactly match anything out there. But with the help of other users, he’s hoping to get everything figured out. It sounds like the first step is to try and diagnose the 2N554 germanium transistor flip-flop modules, as they appear to be behaving erratically. If you have experience with this sort of hardware, feel free to chime in.

We’re supremely proud of the fact that so many of these early computer examples (and the people that are fascinated by them) have recently found their way to They’re literally the building blocks on which so much of our modern technology is based on, and the knowledge of how they were designed and operated deserves to live on for future generations to learn from. If it wasn’t for 1960s machines like the TRANSBINIAC or the so-called “Paperclip Computer”, Hackaday might not even exist. It seems like the least we can do is return the favor and make sure they aren’t forgotten.

[Thanks to Yann for the tip.]

46 thoughts on “Restoring An Unusual Piece Of Computing History

  1. I remember reading the Electronics Illustrated article as a lad. The computer is essentially a binary counter driven by a telephone dial, but I learned a lot from reading the article. I learned about flip-flops and two’s complement arithmetic. I no longer have the magazine, but I was so impressed by the computer, I decided to look for the article 50 years after it was published. I finally asked if anyone remembered the computer in an online forum, and someone pointed me to EI which is online. So the article was easy to find.

  2. I suggest that you check every carbon composition resistor and paper capacitor. Really, all capacitors. Carbon comp resistors frequently shift value over time, sometimes a lot, 50+%. But the worst problem is always capacitors. Paper and early metalized polymer caps go leaky and shift value, and electrolytic caps dry up and become non-capacitors. I’ve seen 10+ year old 100uF caps become <5uF, or just an open circuit. Unless the power supply hit the flip flops with surges, I bet the transistors are OK. However, they can be easily checked with a meter, a few resistors, and a small power supply. Check online.

    Nice piece of equipment! Have fun!

    BTW, if you're not familiar with prehistoric electronics, carbon composition resistors are the ones with dark brown Bakelite-looking bodies, with the flat ends at a sharp 90 degree angle to the leads, unlike modern thru hole resistors that sorta taper down between the body and the leads. I think (?) those red and black body caps are paper parts. Be sure to check them for leakage. My experience indicates that's their most common failure mode. I've seen many of them become essentially resistors, 1K or less.

    If you are keen to preserve the period look, I believe that some of the guitar amp and tube hifi parts sellers still sell parts of this type. But modern thru hole parts are of vastly superior quality, and way cheaper.

    1. In the (Dutch) navy we called these resistors Allen Bradley resistors.
      Good HF properties but a lot of failures because they absorb water and that never happens on a navy ship :-).
      There is actually a glass tube with compressed carbon powder inside.
      Indeed no need to keep them in this device but searching for Allen Bradley give many hits on wifi webshops.

      1. Real Allen Bradley carbon comp resistors can indeed drift, but they are just about the most stable of the bunch (others being IRC, CTS, Ohmite, etc. – not so much!). If this gizmo was kept relatively dry, all the resistors may still be in spec, or at least close enough to not need changing. I get AB carbon comps all the time, and I would say 80 to 90 percent are still in spec. Those that are generally are not so far out in the fields, either.

        From the pictures, they look lie Allen Bradleys, but there just is not enough detail to tell.

        Likewise, at these low transistor voltages, the caps really might not need replacing. Any leakage may not matter, and the risk of developing a fatal short goes way down.

    2. I’ve tried testing old germanium transistors with one of those fleabay clone AVR transistor testers. Either I found a whole stack of mostly bad ones or these new devices aren’t equipped or aren’t programmed to test old germanium transistors. I don’t actually know for certain which but I suspect it’s the latter.

      1. Oh yes. Germanium transistors have fairly large leakage current. Furthermore, Vbe is around 0.15 V, not around 0.6 V. Polarity is mostly PNP. Differences don’t stop there.

        Germanium transistors have been considered obsolete since the 1970s. I don’t know if anyone is still producing them, unlike vacuum tubes.

    1. Check out page 26 of that magazine
      “This unusual horn antenna, designed by Bell Telephone Laboratory engineers, will be used in an experimental ground station to explore the possibility of sending phone calls and live television to distant parts of the world”

      Isn’t that the antenna that lead to the discovery of the cosmic background radiation by Wison and Penseas?

        1. Pages 82/83 “microwave hazards”, or how to try to cook rats, mice, rabbits, chicks or even beagles using radar beams!
          They talk about a 24,000 mc frequency. What unit is this?

          1. “The mc stands for mega cycles, the term used before Hertz was chosen as the standard.”

            I thought it stood for ‘mice cooking’ frequency. Capable of 24,000 mice cooked per minute.

          2. Indeed!

            It was discovered that there was a direct linear relationship between frequency and the rate (time period) of clocking mice and hence the mc mice cooking unit of frequency.

            Later it was discovered that human exposure to these higher frequencies caused pain so the unit was changed to Hertz.

  3. I never read that issue electronics illustrated but I do remember seeing the cover with the computer prominently displayed it was a sloped metal cabinet with the indicator lights and dial. What memories that brings back.

  4. I’ll be shocked if several of the transistors aren’t bad. Our potting techniques just weren’t what they are now. A friend gave me a small bag of germanium transistors some years ago, and most were bad.

    Replace paper capacitors pre-emptive. They seemed like a good idea at the time, but they tend to fail short. A couple of years ago, I was getting a Tek 310 going and I kept track. Right at 30% were bad. Replace the filter caps in the power supply, too.

    Someone else mentioned carbon composition resistors, but those don’t drift too far very often unless in high voltage circuits. Be on the lookout, but most should be fine.

    1. Apparently, a ‘quick fix’ to tin whiskers is to desolder the transistor, tie base, emitter, and collector together, then take a charged capacitor and connect it to the case and the tied-together legs. The zap will melt the whiskers, and the transistor might be good for another few years.

  5. Despite the language of the article, this device is not in any sense we would recognize today a computer; it does not run programs and is not even approximately Turing-complete. What it is is a “computer concept demonstrator,” in particular it seems to be a partial simplified arithmetic unit capable of doing simple math operations under manual control. Calling such a device a “computer” was a common sham in the days before microprocessors arrived, but even Radio Shack sold a “computer kit” that was similarly a binary logic demonstrator.

    It is also worth remembering that in the 1960’s, the actual computer industry was soaking up a great deal of the early transistor production, and what was offered for sale to hobbyists were generally units that had failed Q&A (yields were terrible in early manufacturing processes) and worked “well enough” for amateur use but didn’t meet spec for industrial customers.

    1. It computes numbers, so it’s a computer.

      What we call ‘computer’ these days does much more than just compute numbers. But somewhere in history, the ‘computer’ got renamed to the ‘calculator’, and the ‘computer’ as we now know it came into being.

  6. Germanium transistors deteriorate with time. They tend to run hot, which doesn’t help and many types generate “tin whiskers” as they age. I’ve never seen a 30+ year-old germanium transistor that still met specs. I’m actually quite surprised when I find one that works at all.

  7. Well, the problem is obviously that one bit should be flipping but it’s really just flopping.

    Once fixed, the real challenge is finding something useful to do with this thing, aside from looking pretty and collecting dust.

  8. What a cool project! It must have been built by a well-off engineer, because those transistors were pretty expensive at the time.

    When you repair this, I’d take a look at what radio restorers to do make the radio look original and hide all the replacement parts underneath the boards (or possibly inside the old capacitors). would be a source for ideas.

    If all else fails with the passives, I’d look at the transistors. They can still be found, but are expensive. Many modern transistor checkers won’t test them properly and I’ve found NOS period replacements dead in the box. Germaniums can be temperature sensitive but I’ve had them so temperature sensitive that their gain drops every time you test them. European replacements from the 80’s might be more reliable.

      1. I wonder if things like this were the origin of the name accumulator for the special purpose register in modern CPUs and UC’s.

        This configured as a binary counter perfectly fits the English language definition of accumulator.

  9. Electronics Illustrated is here

    Courtesy of my favourite search engine (hint: it ain’t the one
    with G, That What Cannot Be Named).

    This, and the hint that it was the Jan, 1960 issue leads to:

    The article is on page 84 (yes, they have an old-fashioned table
    of contents). It’s page 86 in the pdf, for… reasons.

    Kids, learn to use search engines!

    1. Page 84 (86 in the PDF):

      “Electronic Brain
      Have you any question on electronics? Send it in
      and the Electronic Brain will provide the answer. ”

      > Kids, learn to use search engines!

      Meh, but apparently they should not learn from you. :)

      The article is on page 65 (67 in the PDF).

  10. TRANSBINIAC guy here. Thanks for the support everyone. I’ll be updating the project soon as I have more time for it. Cliff Notes response to the comments to this article are that I am replacing the original caps with axial mylar caps, the resistors I’ve checked are all on-spec, and the transistors seem OK although there’s a little more leakage than I’d expect with modern components. Stay tuned…

  11. I recall seeing something like that on display as a child about maybe 1962 – 1964? It was in Ohio and the businesses in the town participated in letting people come in and see what they did and made. There wasn’t much to see at the Ohio Bell building without windows, but they let us in and it was right inside the door. It was a COMPUTER! And you could go up and look at it and it was suppose to be the FUTURE.

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