The Digi-Comp II is a rolling-ball binary digital mechanical computer — and a recreation of a classic 1960s educational computer kit:
It’s an automatic binary digital mechanical computer, capable of conducting basic operations like adding, multiplying, subtracting, dividing, counting, and so forth. And what’s more, all of these operations are conducted by the action of balls rolling down a slope, directed by mechanical switches and flip flops, and all powered by gravity.
Overall, it is slightly smaller than the original (mid 1960s) Digi-Comp II, which used half-inch diameter glass marbles. Rather than marbles, we’ve opted for pachinko balls, which are shiny steel balls 11 mm (about 7/16″) in diameter. Using the smaller size has allowed us to reduce some of the feature sizes, and reduce the overall size of the machine from 14×28.5″ to 10×24″, while retaining all of the original functions and remaining finger-friendly.
The Digi-Comp II: First Edition is CNC carved from rock-solid half-inch hardwood plywood, laser-engraved to provide it with labels, and hand fitted with over 60 laser-cut parts. It comes assembled, tested, and ready to use.