Ubiquitous computing has delivered a world in which there seem to be few devices left that no longer contain a microprocessor of some sort. Thus should a student wish to learn about the inner workings of a computer they can easily do so from a multitude of devices. For an earlier generation though this was not such a straightforward process, in the 1950s or 1960s you could not simply buy a microcomputer and set to work. Instead a range of ingenious teaching aids providing the essentials of computing without a computer were created, and those students saw their first computational logic through the medium of paper, ball bearings, or flashlight bulbs.
The DigiComp II was just such a device, performing logic tasks through ball bearings rolling down trackways. Genuine machines are now particularly rare, so [Mike Gardi] created a modern 3D printed replica that delivers all the fun without the cost. It’s a complicated build with a multitude of parts and wire linkages, and there is an element of fine tuning of its springs required to achieve reliable operation. You’ll neither run a Beowulf cluster of DigiComp IIs nor will you mine any Bitcoin with one, but it’s definitely one of the more unusual computing devices you could have in your collection.
Of course, should you need a truly authentic period computing device, there is always the slide rule.
Via Hacker News.
Would be lovely to own one of those, but there is an alternative: minivac601. Not paying for this one on ebay, but the books are available scanned online. I am working on a simple emulation using a solderless breadboard and 12 miniPCBs. https://www.ebay.co.uk/i/173807001873?chn=ps Hardware is ready and tested, just need the time to work my way through the examples.
That’s one of the things that got me into computers – my 5th/6th grade teacher had one, and I would borrow it on weekends.
The minivac 601
Anyone who’s a fan of DigiCompII would also be interested in DigiCompI, which implements a 3-bit finite state machine. Models for the parts are available on Thingiverse. https://www.thingiverse.com/thing:1477209
My older brother had one as a kid. I never understood it myself. I wonder if I would as an adult.
Modern equivalent? https://www.turingtumble.com/
Looks like it uses the same “cpu” as Dr Nim (a game that fascinated me as a kid)
https://en.m.wikipedia.org/wiki/Dr._Nim
Astute observation! Both Digi-Comp II and Dr. Nim were designed by the same man John Thomas Godfrey. If you are looking for something that is much easier to build but still pretty cool check out my Dr. Nim Instructable: https://www.instructables.com/id/The-Amazing-Dr-Nim-Scale-Model/