Zuse Z3
More info
- Creator
- Konrad Zuse
- Released
- 12 May 1941
- Type
- Relay computer
- Predecessor
- Z1, Z2
The first automatic program-controlled computer that actually worked, assembled from telephone relays in a Berlin apartment while the rest of the world was still drawing plans.
It ran on 12 May 1941, built from roughly 2,000 secondhand telephone relays and part-funded by Zuse's family. It computed in binary using 22-bit floating point, held 64 words of memory and ticked over at 5 to 10 hertz. Addition took just under a second, multiplication about three. Programs were read from perforated 35 mm film, chosen because paper tape was hard to come by in wartime Berlin and discarded film stock was not.
There were no conditional jumps. A loop meant splicing the ends of the film together, and branching between two paths simply did not exist — the operator halted the machine and changed the reel. Raúl Rojas showed in 1998 that the Z3 is nonetheless Turing-complete in principle, via a construction no contemporary user would have had the patience to run.
The Z3 was destroyed in an air raid on Berlin in December 1943. Its successor the Z4 was moved to the Alps and leased to ETH Zürich in 1950, where for several years it was continental Europe's only working computer. A replica of the Z3 was built in 1961 and stands in the Deutsches Museum in Munich.