Archive: Computer Collector Newsletter / Technology Rewind, Jan. 2004 - March 2006

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Digi-Comp comes back to life

by Evan Koblentz

Ever feel like putting aside the complicated digital dinosaurs and getting back to binary basics? If so, the DigiComp kit from Minds-On Toys ( might be just what you need, but don't be surprised if your child is equally fascinated.

The original Digi-Comp 1 was a mechanical, plastic computer made by Montclair, N.J.-based ESR Inc. starting in the mid-1960s. It sold for just $6 and now they're on eBay for hundreds. A discussion group formed in 1999 ( but things turned more exciting when Minds-On Toys last year began selling its replica kit called the Digi-Comp 1 v.2.0 for just $55.

Originally the idea for a modern replica was discussed at various times in the Yahoo group, but the commercial version was the brainchild of Minds-On (a play on "hands-on") which is owned by Tim Walker. Walker has an impressive history in computers and education: he studied social psychology at Harvard, worked as a high school teacher, earned a masters degree in interactive telecommunications at New York University, studied under Seymour Papert at the MIT Media Lab (, and worked on Hypercard for a contractor to Apple Computer.

Walker decided to build the replica as part of his ongoing research into the history of educational toys. His first round of 100 kits quickly sold out, so now it's in the second run. An interesting experience happened while building early prototypes out of heavy paper and similar materials -- he realized how much better it would function out of precision-cut metal -- akin to the experiences of Charles Babbage, whose ideas exceeded his technical resources. Luckily, Walker has access to modern production companies, although a large amount of reverse-engineering was required because he didn't own an original Digi-Comp while designing the replica.

So what can the replica kit actually do? First, it can count from 0 to 101 (seven); if you have patience it can solve math problems and even play games. There isn't any memory, so you have to assist the machine by keeping track of values. But that's the point! Digi-Comp is for learning, not computing. You can literally view every step as it happens, and the 48-page instruction manual is simple enough for a 10-year-old, yet elegant enough for a trained programmer. After reading a few pages, it's clear why the original Digi-Comp was successful.