Good demonstration of a computer that runs on marbles

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This gives new meaning to “lose your marbles”.


This is some of that mostly wonderful content that keeps me coming back :slightly_smiling_face:


I have this, and it’s awesome. It appears to be geared towards kids, but it’s actually a really interesting way to spend an afternoon. Highly recommended.


He jumped from addition to subtraction without explaining what was different about the set-up to make it a subtract operation rather than an add one.


Yeah he was trying to keep it simple, so simple that he had to explain binary numbers. Explaining the set-up would have taken some time but that was the interesting part.


If you have enough time and rocks, you can compute anything:

Embiggened version:


I try to teach these kind of fundamental concepts to my kinder kiddo. We made a hand crank dynamo for electricity. I’ve wanted to get a mechanical Turing-like thing like this for computing. Knowing the foundations of things (flight, engines, maybe photography when he’s older) is so important to understanding the world and with so much we use today black box digital magic, a lot of that mechanical wonder gets skipped over. I think one of my main jobs as a (mutant) parent is trying to keep that natural curiosity and love of learning fed until he’s old enough to seek out things himself.


:thinking: Um… I’m being a picky guy here… not to detract from a nice demo, but…

I’m pretty sure he didn’t demonstrate enough for Turing completeness there since he’s missing a “branch on test”, which I usually think of as required along with arithmetic.

Also, something about the unidirectional information flow in that machine makes me think it won’t quite pass, but I’m too rusty and busy to sit down and prove it. Can he take a register value, compare it and reset another register with this?

Still, nice demo of some basic gates…

The Dreamboat kids got this for Xmas. Super gift from a super friend.

I love the sound of them playing with it from the next room.

Also new meaning to “Field Programmable Gate Array.”

it reminds me of pachinko machines

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I was so close to kickstarting this but didn’t because of financial reasons and now I can’t find it anywhere for a decent price! !

Heck yeah! Here’s to a new generation of do-ers!
One of my favorite books growing up was this 4 volume set of “How Things Work”. some of it is a bit dated by now, but I totally credit this book for giving me a super solid foundation for understanding physical stuffs.


I initially took this to mean, you tried it with the less kind kiddo, but they just slapped the marble out of your hand and said your bangs don’t really work with your face shape

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So, is it Turning complete, or Tumbling complete?

The bits are self-testing, the marbles go different directions depending on the value of the bit when they encounter it. But also I bet the Turing-completeness was proven by the designer before they named it and… checking… ah, it looks like completeness requires a part not shown here (but which TT does ship with), a gear, which lets you transmit information vertically back up the marble’s path.

Looks like there might not be a formal proof yet but it’s probably Turing-complete, and it can certainly can do things real computers can do… but it might need an arbitrarily large board and an arbitrarily large number of marbles. And in practice I expect the long chains of gears would probably jam. But, in theory!


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