Building a computer out of 555 chips

[M. Eric Carr] came up with an interesting build for the 555 contest earlier this year, and we’re pretty sure that it would have kicked the winner of the complex category off the throne if it were completed. Although it’s a few months late, we’re happy to feature at least part of his 555-based computer on Hack A Day.

[M. Eric Carr] started off implementing Boolean logic with a 555. After building a universal gate, he moved onto putting one bit of memory in a single 555. This design uses the 555 as a latch and is one of the craziest off-spec uses of a 555. While fitting 24 bits of memory on 5 large bread boards may seem like a waste, it’s a far cry from the square feet or acres of other computer builds we’ve seen.

From the post on the 555-based memory, [M. Eric Carr] says a completed design of his computer could be up and working this summer. It’s already August, so we’re hoping he’s still working on his design. Check out the video of the memory below.


  1. theodore says:

    Now it seams that with a good imagination and a lot of skill you can do anything with 555 timers, perhaps we should see what you can’t do with them. Great work by the way

  2. M. Eric Carr says:

    Thanks for the writeup! Please bear with my poor little webserver if you follow the link; it’s not used to this kind of traffic. The video is hosted at YouTube, though, so it should be good to go.
    I’m still working on the design, though a lot more slowly than I had planned, due to other projects that have come up. I’d be happy to answer any questions about the project; email me at eric @ (the website domain in the first link).

  3. Andy says:

    That is rather awesome, hope he gets it all up and working!

  4. HHH says:


  5. Jeremy says:

    That has to be one of the most intriguing uses of 555’s I’ve ever seen. What do you speculate the final operational speed to be when complete?

    Would be interesting if you can get it to the point where it could run Contiki (

    • M. Eric Carr says:

      I’m not sure what the final operational speed will be, although my guess would be somewhere in the 100kHz-to-1MHz range in “high speed” mode (555s aren’t designed for very high speeds.) More likely, I’d run it at slower speed (a few Hz) to show the operations as they run.
      I doubt it will ever run Contiki, if it needs 40kB of ROM. Right now, the address bus is four bits, limiting the design to 16 words of memory. Realistically, I might hope to add a few numbers. More ambitious would be to make an 8-bit machine with 256 bytes of memory. That might be able to make a very basic webserver (with an Arduino handling everything but the applications layer.)
      For something that large, though, I’d need a more efficient way of building large components. EDA for 555 logic design, maybe? 8-)

  6. 1000100 1000001 1010110 1000101 says:

    Although we all love great wire-porn (and this is looking pretty juicy!), if this is something you are going to continue pursuing, it might be the perfect scenario to order some custom PCBs.

    Fascinating work!

  7. CRJEEA says:

    Putting 100 breadboards into a CNC machine and give it a big stack of 555’s and a km or so of wire might speed things up a little. (or something like the auto wire wraping machine that was featured on here a while back)
    Maybe several all set to the same frequency but offset by a much higher frequency to enable you to create really high frequencies for out putting video possibly?
    I wonder how fast 555’s go if they are really pushed hard if they are liquid nitrogen cooled extra

  8. Michael says:

    Wicked cool… I really enjoyed the input method, I think I might try that on my next project! Great job!

  9. KillerBug says:

    Very neat…I think this guy just stole the “Craziest idea of the year” prize from the home-made electric chair guy.

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