Retrotechtacular: The Cryotron Computer


Have you ever heard of a Cryotron Computer before? Of course not. Silicon killed the radio star: this is a story of competing technologies back in the day. The hand above holds the two competitors, the bulkiest one is obviously the vacuum tube, and the three-legged device is what became a household name. But to the right of that tube is another technological marvel that can also be combined into computing machines: the cryotron.

[Dudley Allen Buck] and his contributions to early computing are a tale of the possible alternate universe that could have been cryotrons instead of silicon transistors. Early on we find that the theory points to exotic superconductive materials, but we were delighted to find that in the conception and testing stages [Buck] was hacking. He made his first experimental electronic switches using dissimilar metals and dunking them in liquid helium. The devices were copper wire wrapped around a tantalum wire. The tantalum is the circuit path, the copper wire acts as the switch via a magnetic field that alters the resistance of the tantalum.

The name comes from the low temperature bath necessary to make the switches work properly. Miniaturization was the key as it always is; the example above is a relatively small example of the wire-wound version of the Cryotron, but the end goal was a process very familiar to us today. [Buck] was searching for the thin film fabrication techniques that would let him shoe horn 75,000 or more into one single computing platform. Guess who came knocking on his door during this period of his career? The NSA. The story gets even more interesting from there, but lest we rewrite the article we leave you with this: the technology may beat out silicon in the end. Currently it’s one of the cool kids on the block for those companies racing to the quantum computing finish line.

[Thanks Frederick]

Retrotechtacular is a weekly column featuring hacks, technology, and kitsch from ages of yore. Help keep it fresh by sending in your ideas for future installments.


  1. polossatik says:

    A very interesting read, keep those Retrotechtacular posts coming !

  2. onebiozz says:

    Do computers not use tubes any more? my top of the line ZEBRA personal computer does!

  3. robomonkey says:

    quite interesting.

  4. Tom the Brat says:

    Perhaps we need to honor Dudley Buck’s birthday.

  5. Hirudinea says:

    Where’s room temperature superconductors when you need them? And since the wire rap is just to switch the circuit (kill the superconductivity with a magnetic field) the superconductor could be a ceramic, which I understand is the way superconductors seem to be going.

  6. Alan says:

    “The three-legged device is what became a household name.” Is that a fancy word-wasting way of saying “transistor”?

  7. Jerry Tremble says:

    I like “the three-legged device”, personally.

  8. markaeric says:

    Very interesting read. It’s a shame about his untimely death.

    • mikuslaw says:

      Don’t want to create here any spy theories, but the guy died 32 of “mysterious disease” ( according to on 21st May 1959. Three days later he was supposed to meet with Louis Ridenour on topic of advising in NSA advisory board (board was advising the president on technical matters and preventing Russian attacks). Louis Ridenour died 48 from brain hemorrhage on… 21 May 1959.
      Coincidence? … Probably :)

      • Blue Footed Booby says:

        Yeah, you just know there are some amazing stories of intrigue from that time period, but we’ll likely never know more than a tiny fraction. Even if every single piece of paper still existing is declassified, so much was either either destroyed or just never put to paper.

      • Megol says:

        The explanation in the linked article is more likely to be true – if one handles dangerous chemicals and later develops a disease that could be caused by the aforementioned chemicals it’s likely to be due of mishandling.

        • Blue Footed Booby says:

          Hadn’t gotten to that part. Given that the chemicals he was handling immediately before cause symptoms like pneumonia, his official cause of death, I’d bet you’re right. Funny how missing one detail turns a tragic accident into an obvious conspiracy.

  9. BotherSaidGCHQ says:

    I read somewhere that magnesium had once been considered as an alternative to other metals ie aluminium for chip interconnects.
    Who knows, if he had recovered Buck might have discovered MgB2 in 1959, and with superconductive energy shields and advanced cryotron logic a mission to Mars in 1985 would have been feasible..

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