Digi-Comp II: teaching computing with pachinko balls

I posted in 2011 about the Digi-Comp I, a 1963 mechanical digital computer made of polystyrene and used to teach the fundamentals of boolean logic, binary, and computer programming. I’d just discovered that Evil Mad Scientist Labs sells a wooden version of its successor, the Digi-Comp II, which uses a pachinko-style marble-run to do the… READ THE REST

I would comment about this, having a LOT of experience with both the Digi-comp I AND II. They were some of the sweet toys we had in the 60s that taught us about computing machines and programming.

I have no idea where this comment will end up, so I’ll stop here.

It’s great to see such a nice version of this available. Back when I worked & volunteered at the Santa Fe Children’s Museum a guest artist used to bring in a home-built similar computer to run, alongside other simple electronics projects kids could take home. I had the pleasure of watching a lot of faces light up when kids had the ah-ha moment where it suddenly made sense how computers worked.

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There used to be a giant version of this at the Ontario Science Centre with tennis balls being shot into the logic gates through transparent pneumatic tubes. It was about 2 stories high.

I’m glad to see on their page that they’re working on a cheap plastic version.


Me too. I still have the Dr. Nim that it closely resembles.

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I can’t be the only one who would love to see a video of this in action

Take that, Moore’s Law!


This takes me back on the way back machine. I think it was this that started me thinking about computers. My mom always wanted me to go into CS but it was the original machine that made me think about studying CS in the first place.

If you hook enough of these in tandem, could you build PRISM?

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Me too :slight_smile: . I’d love to have one to go along with my original DigiComp1 (found while cleaning out parents’ attic), but not at @$279, for sure.

This is fantastic. It gets to the heart of a serious problem: how to teach how computers actually work, in an age when people’s exposure to the technology is far removed from its underlying operating principles.

A five year old child with an iPad has dozens (hundreds?) of “layers” of technology between what his experience and what’s actually going on.

Is there an online version of it?

It is right on the page the article links to:

It is right on the page this article links to:


(I have no idea how to embed a video)

Funny, because the original was cheap and plastic.

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