The Digi-Comp I was a functioning, mechanical digital computer sold in kit form. It was originally manufactured from polystyrene parts by E.S.R., Inc. starting in 1963 and sold as an educational toy for US$4.99 ().
A successor, the Digi-Comp II, was not programmable, but in effect a visible calculator. A two-level Masonite platform with guides served as the medium for a supply of marbles that rolled down an inclined plane, moving plastic cams as they fell.
Operation
The Digi-Comp I contained three mechanical flip-flops, providing an ability to connect them together in a programmable way using thin vertical wires that were either pushed, or blocked from moving, by a number of cylindrical pegs. The whole arrangement was 'clocked' by moving a lever back and forth. Different configurations of these cylinders caused the Digi-Comp to compute different Boolean logic operations. With a three binary digit (3-bit) readout of the state of the flip-flops, it could be programmed to demonstrate binary logic, to perform various operations such as addition and subtraction, and to play some simple logic games such as Nim.
Reproductions
Starting in 2005, Minds-On Toys has made available the Digi-Comp I version 2.0 as a relatively inexpensive binder's board version of the original Digi-Comp, albeit with a much enhanced instruction manual.
See also
Dr. Nim - game based on the computer
Geniac
WDR paper computer
CARDboard Illustrative Aid to Computation
Turing Tumble, a 2019 mechanical computer inspired by it
Robert C. Martin, who credits playing with this toy at the age of 12 as being what made him decide to become a programmer for the rest of his life. Little man computer
References
Bibliography
External links
The Old Computer Museum - Collection of old analog, digital and mechanical computers Friends of Digi-Comp - Discussion of this toy. Images, links, manuals and programming information Digi-Comp I v2.0 - Online vendor of working replica kit; historical details Digi-Comp I Emulator - Emulator for the original Digi-Comp I written in JavaScript