Michael Gardi's Digi-Comp I Redux Brings Back the Early Days of Educational Computing Toys
Inspired by educational toys and full-function computers of the past, Gardi's Digi-Comp I Redux is a 3D-printed electromechanical marvel.
Vintage computing enthusiast Michael Gardi has published instructions and design files for creating a brand-new educational "computer" based on the ESR Inc. Digi-Comp I mechanical computer kit from the 1960s.
Even as early as the late 1950s, children were getting switched on to the idea of digital computation through educational kits creating mechanical computers. Rather than electronics, these systems were based on physically moving parts — card, plastic, or even polystyrene — and aimed to provide a physical demonstration of the concept at a time when a true electromechanical or electronic computer filled a room and emptied a national budget.
Gardi, a fan of devices from the era, has recently published a novel electromechanical computer based on the 1963 ESR Inc. Digi-Comp I — dubbed, unsurprisingly the Digi-Comp I Redux. Building on earlier reproduction sof the Digi-Comp I and its successor, plus concepts borrowed from replicas of the Minivac 601 and GENIAC, the project boasts full compatibility with programs designed for the original Digi-Comp I - plus an extra bit of precision, allowing for an increase in the maximum possible number it can handle from 8 to a whopping 16.
"I can't give enough credit to companies and the original designers of these awesome educational machines," Gardi writes. "Digi-Comp I, ESR, Inc. — William H. Duerig, Irving J. Lieberman, and C. David Hogan; Digi-Comp II, ESR, Inc. — John Thomas Godfrey; Minivac 601, Scientific Development Corporation — Claude Shannon; GENIAC, designed and marketed by Edmund Berkeley. My design is based solely on their inspiration and skill. All of the 3D printable parts were modelled using Fusion 360.
"Digi-Comp I Redux works much like the original. There are still 'logic rods,' but in this case they are made up of magnetic reed switches. Instead of programming 'tubes' we have programming 'pegs' with magnets, but there are still identical T and F positions (holes) on the flip flops to place them. 'Clock rods' have been replaced with solenoids, but still perform sets and resets based on the position of the programming pegs. The 'programming model' is the same but the implementation is different. And of course we have an extra flip flop and two extra logic columns to play with."
The full build, including a bill of materials and STL files for 3D printing, is available on Gardi's Instructables page.