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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.

### 8 Responses to Binary marble adding machine

1. Dax420 on said:

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 on said:

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 on said:

Hmm…hrefs seem to have some issues. The ball computer blog link should go to http://ballcomputer.blogspot.com.

4. See http://ballcomputer.blogspot.com for Eric Urhane’s design of an entire computer based on this principal.

5. nertzy on said:

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 on said:

The Wandels have amazed me for years.

7. Mac-Guyver on said:

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.