Minivac 601

Manufactured By: Scientific Development Corporation

Designed By: Claude Shannon

Release Date: 1961

Created by information theory pioneer Claude Shannon as an educational toy for teaching digital circuits, the Minivac 601 Digital Computer Kit was billed as an electromechanical digital computer system. Produced by Scientific Development Corporation in the early 60's it sold for $85.00 (about $720 today).

Minivac 601 used electromechanical relays as logic switches as well as for very basic storage. Simple DPDT switches and SPDT push buttons made up the binary inputs, with lights to represent the outputs. A large motorized dial allowed the user to enter decimal or hexadecimal numbers, and to output numbers, or to act as a clock signal generator.

I made a full size replica of that Minivac 601 from 1961. I tried to remain as true to the original as possible given the technologies and resources available to me. I didn’t have a "vintage" unit so this replica was constructed based on photos and from the original manuals that were available online.

As with the Digi-Comp II, the top panels were printed in pieces then assembled into a wooded frame. What’s a little different here is that all of the labels and text on those panels was achieved by “extruding” the letters above the panel surface and pausing the print then switching the filament color at the point that the letters began. This is a technique that I will use in many projects to come.

To build a Minivac 601 you need to add a lot of small rivets (388 by my count) to the front panels along with their corresponding solder lugs on the back. The rivets or eyelets provide a place to insert and connect the jumper wires used to create circuits, and the solder lugs allow you attach the rivets to the switches, lights, and such. Each rivet had to be set by hand with an “Eyelet Punch Setter Anvil”. A little tedious to say the least.

Between the Minivac 601 and a subsequent product the Minivac 6010 which was sold into corporations, scores of people learned about digital circuits and computer concepts. Truly a very cool device worth remembering.