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The Digi-Comp I was a $5 plastic computer powered by rubber bands [1]

['Mark Frauenfelder']

Date: 2026-08-17  

The Digi-Comp I was a plastic and rubber band toy that sold for $5 in 1963. According to Chris Staecker, a Fairfield University math professor who posted a video about its operation, "This was the first digital computer."

It didn't use electricity; instead, it required the user to push and pull a "clock" lever. The display was three sliding plates that displayed either a one or a zero. To program the Digi-Comp, you would slide plastic tubes into various locations to restrict the movement of rubber-band-powered rods that changed the display.

The company that made the Digi-Comp sold it to raise funds to build real computers. But the Digi-Comp was so successful that the company pivoted its business model to selling over 100,000 units. "That means in the mid-1960s, there might have been more Digi-Comps in the world than real computers," says Staecker.

Staecker's video channel features nice demos of other interesting mechanical devices, such as Curta calculators, pedometers, pocket sundials, and wind speed indicators.

Previously:

• 3D printed replica of the Digi-Comp II marble computer

• Here's a working paperclip computer from the 1967 book, "How to Build a Working Digital Computer"

• How to make a replica of the GENIAC Electric Brain from 1955

How I use AI. Fountain pen source: page 1, page 2. Pangram: rough draft, final draft.

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[1] Url: https://boingboing.net/2026/08/17/fountain-pen-digi-comp-1.html

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