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Wow, check out the video tour of Evil Mad Scientist Laboratories’ functional recreation of the classic educational binary computer Digi-Comp II.

Several weeks ago, we talked about bringing our giant Digi-Comp II to Maker Faire. But now we’re back, and we wanted to show everyone how it works– not just the many folks who came by to see it at Maker Faire. For those of you just joining us: The Digi-Comp II is a classic 1960’s educational computer kit– an automatic binary digital mechanical computer, capable of conducting basic operations like adding, multiplying, subtracting, dividing, counting, and so forth. These operations are all conducted by the action of marbles rolling down a slope, directed by mechanical switches and flip flops that act as logic gates. Our version is a modern, larger-than life remake. A functional clone, but sized up to use billiard balls instead of small marbles.


Becky Stern

Becky Stern

Becky Stern ( is a DIY guru and director of wearable electronics at Adafruit. She publishes a new project video every week and hosts a live show on YouTube. Formerly Becky was Senior Video Producer for MAKE. Becky lives in Brooklyn, NY and belongs to art groups Free Art & Technology (“release early, often, and with rap music”) and Madagascar Institute (“fear is never boring”).

  • Anonymous

    That was delightful ..(nostalgic as well) thank you!

    So the “halting problem” ( has been solved!  it’s when the balls stop dropping ;)

  • TulsaTV

    I had a Digi-Comp II in the 1960s. Watching this video felt so familiar.

  • Anonymous

    This way of visualizing computation is COOL~~~~~~~