Geniac
Geniac was an educational toy sold as a mechanical computer designed and marketed by Edmund Berkeley, with Oliver Garfield from 1955 to 1958, but with Garfield continuing without Berkeley through the 1960s. The name stood for "Genius Almost-automatic Computer" but suggests a portmanteau of genius and ENIAC.
Construction
The Geniac kit consisted of a wedge-shaped case, a console panel, and nearly 400 other parts available for assembly. It was powered by a flashlight battery.Basically a rotary switch construction set, the Geniac contained six perforated masonite disks, into the back of which brass jumpers could be inserted. The jumpers made electrical connections between slotted brass bolt heads sitting out from the similarly perforated masonite back panel. To the bolts were attached wires behind the panel. The circuit comprised a battery, such wires from it to, and between, switch positions, wires from the switches to indicator flashlight bulbs set along the panel's middle, and return wires to the battery to complete the circuit.
Setting up Geniac to solve a new problem or perform a new operation involved rewiring the jumpers on the back panel, a task advertised as taking only a few minutes.
Operation
With this basic setup Geniac could use combinational logic only, its outputs depending entirely on inputs manually set. It had no active elements at all – no relays, tubes, or transistors – to allow a machine state to automatically influence subsequent states. Thus, Geniac didn't have memory and couldn't solve problems using sequential logic. All sequencing was performed manually by the operator, sometimes following fairly complicated printed directionsThe main instruction book, as well as a supplementary book of wiring diagrams, gave jumper positions and wiring diagrams for building a number of "machines," which could realize fairly complicated Boolean equations. A copy of Claude Shannon's groundbreaking thesis in the subject, A Symbolic Analysis of Relay and Switching Circuits, was also included.