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

Michael Gardi posted instructions for making a replica of the GENIAC ("GENIus Almost-automatic Computer") that was sold in kit form in the 1950s and 1960s for $20.

GENIAC consisted of a Masonite back panel with six areas of concentric perforations, six similarly perforated Masonite disks, and some additional hardware listed in the supplies section below.

Slotted brass bolts were positioned on the main back panel in such a way that brass "jumpers" inserted into the underside of the Masonite disks would create electrical connections when the disks were rotated over them. The bolts were wired together along with a battery and some lights to create "programs," basically single purpose "machines."

Technically GENIAC was a collection of configurable N-pole by N-throw rotary switches, which could be set up to be cascaded and thus perform logical functions. As a result GENIAC could use combinational logic only, its outputs depending entirely on inputs manually set. However, projects outlined in the manual, which started with basic logic circuits, ultimately progressed to such things as a NIM machine and TIC-TAC-TOE machine.

Michael Gardi previously on Boing Boing:

Above, a video by Brian Moriarty. "A description and simulation of 'The Uranium Shipment and the Space Pirates,' the first computerized interactive story, published in 1955 as Project 23 of the GENIAC hobby kit." Read the rest