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Binary marble adding machine

Craft & Design
Binary marble adding machine

Marble Adder

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Matthias Wandel has the coolest project ever, a binary marble computer –

It had occurred to me that perhaps with an insane amount of perseverance, it might be possible to build a whole computer that runs on marbles. My second marble machine was however much less based on logic – more on just making lots of noise.

But a few months ago, I had an idea as to how the divide by two mechanisms from my first marble machine could be cascaded together to actually function as a sort of adder or counter. Once I had that idea, I knew I had to try it at some point, and recently, I finally got around to building my marble binary adding machine.

The core of the invention is a modification of the divide by two flipflop to retain the marble that falls off the right side, and retain it until the flipflop is flipped to the left by the next marble. See small diagram above right. The retention of this extra marble allows the state of the marble accumulator to be dumped. The adder would just as well add without it, but the number would have to be read off by the angle of the rockers, rather than have the device dump the count out. Really, if such an adder were integrated into a hypothetical marble computer, reading out the result as a series of marbles would be an essential element.

Binary marble adding machine – Link.

18 thoughts on “Binary marble adding machine

  1. Dax420 says:

    Wow thats pretty cool. It’s not hard to imagine each “flip-flop” as a single transistor on a chip of 10 million transistors and mentally “see” how your computer works.

    Good video!

  2. uranium says:

    For a look at the logic involved in a full ball-based computer, you can take a look at my ball computer project blog. It’s all in simulation at present, but I do hope to build it some day.

  3. uranium says:

    Hmm…hrefs seem to have some issues. The ball computer blog link should go to

  4. Falk says:

    See for Eric Urhane’s design of an entire computer based on this principal.

  5. nertzy says:

    Some students at Olin College made a 4-bit adder with mechanical logic gates made out of K’NEX.

    The K’NEX Computer

    It stands over 10 feet tall!

  6. tms10000 says:

    The Wandels have amazed me for years.

  7. Mac-Guyver says:

    Take a look at the Digi-Comp II:

    It had an accumulator and a separate counter register that was supposed to allow it to multiply, but the one I built was so unreliable that it never got through an entire multiply, even with human assistance.

    This page says the II came out around 1967.

    I remember designing my own marble logic with runs of clay on a tilted bench.

    ESR may also have been the company that made the marble-logic toys called “Dr. Nim” and “Think-A-Dot”. In any case they were all available through Edmund Scientific.

  8. Wooden Marble Run says:

    One game involves drawing a circle in sand, and players will take turns
    knocking other players’ marbles out of the circle with their own marble.
    This game is called ringer. Other versions involve shooting marbles at target marbles or into holes in the ground (such as rolly or rolley hole).

  9. face products says:

    Write more, thats all I have to say. Literally, it seems as though you relied on the video to make your point.

    You definitely know what youre talking about, why throw away
    your intelligence on just posting videos to your blog when you could be giving us something enlightening to read?

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