Relays and relay computers

Summary

A relay is an electromagnetic switch: a magnet is activated via a circuit, so that another circuit can be switched on. This principle has been tested since ca. 1835. Relays are very robust and their switching condition is visually and acoustically easily recognizable.

The engineer student Konrad Zuse is well known for this technique. With the help of his fellow student Helmut Schreyer, he constructs the first program-controlled computer in Berlin from a total of 2000 relays. The finished Zuse 3 will be presented to the public in May 1941. Three years later, however, the Z3 was destroyed during a bomb attack during the Second World War. A replica is now available at the Deutsches Museum in Munich.

The Z3 is capable of performing all basic mathematical calculations as well as square roots and decimal-to-binary conversions. Unlike British or American researchers who develop comparable computers at the same time, Zuse and Schreyer do not receive state support for their invention.