Konrad Zuse

Biography

The story begins with a tedious calculation. After graduating in 1935, Zuse worked as a structural analyst at the Henschel aircraft factory in Schönefeld, where he had to do routine calculations by hand for aircraft designs, and he soon left the post. He had started looking for a way to automate such calculations while still a student.

Zuse was born on 22 June 1910 in Berlin, in Wilmersdorf. When he was about two, the family moved to Braunsberg in East Prussia, where his father worked as a postal clerk. In 1923 they settled in Hoyerswerda, and there in 1928 he passed his school-leaving examinations. As a teenager he devised a machine that gave out fruit and change for a coin dropped in, and from a metal construction set he built a model of a coal-loading crane and received a certificate of honour from the manufacturer. He studied at the Technische Hochschule in Berlin-Charlottenburg (now the Technical University of Berlin) and called himself an idle student: he began with mechanical engineering, moved to architecture, then to civil engineering. For almost a year he worked as an advertising artist. He belonged to a student society, Motiv, where he drew posters and devised cheap stage effects. His pull towards drawing and towards technology ran side by side from his youth.

From 1935 he worked on his idea in his parents' flat in Berlin. The money came from family and friends, and his father even went back to work for the purpose. In 1938 the Z1 was finished, a binary mechanical calculator with an electric drive that read its program from perforated film and worked with floating-point numbers. Because the roughly thirty thousand parts lacked sufficient precision, the machine ran unreliably.

Zuse showed the Z2, built with telephone relays, to specialists of the German Research Institute for Aviation in September 1940. He was called up for military service more than once but never went to the front: thanks to the support of a superior at Henschel, he was kept on to work. There he worked on the Hs 293 glide bomb and built the special-purpose calculators S1 and S2 for measuring wings. In 1941 he founded an engineering office and workshop in Berlin to produce his machines.

On 12 May 1941 Zuse presented the Z3, a binary floating-point calculator built with telephone relays, constructed together with Helmut Schreyer. It was programmable and could run loops, but had no conditional jumps. The machine was used for calculations connected with wing flutter, but it never entered routine use. The original was destroyed in a bombing raid on 21 December 1943, and the Z1 and Z2 burned along with his parents' flat on 30 January 1944. Only the Z4, which he had begun building in 1942, survived.

In 1998 Raúl Rojas showed that the Z3, by means of certain tricks such as gluing the tape into a loop, is Turing complete. Zuse himself had never thought about such a property and had practical tasks in mind.

While working on the Z4 he realised that writing in machine code was too laborious, and between 1942 and 1946 he sketched Plankalkül (“plan calculus”). He could not publish it then. Brief excerpts appeared in 1948 and 1959, and the full text was published only in 1972. The first implementation of the language came in 1975. His doctoral thesis at Augsburg was rejected, rather comically, I think: he had forgotten to pay the 400-mark enrolment fee.

In February 1945 the unfinished Z4 was taken out of Berlin to Göttingen, and from there to the Allgäu. In the first months after the war there was almost no income: he painted chamois in oils and sold them to American tourists. In 1946, with money from ETH Zurich (the Swiss Federal Institute of Technology) and an IBM option on his patents, he founded an office at Hopferau, and in 1949 the firm Zuse KG at Neukirchen near Hünfeld. In 1950 the Z4 was delivered to Zurich, where it worked until 1955; at the time it was the only working computer in Central Europe. Zuse KG produced the Z5, the Z11, the Z22 (with magnetic storage memory) and the Graphomat Z64 plotter. By 1967 the firm had built 251 machines in all. Rapid growth undermined its finances, from 1964 Zuse no longer took part in management, and in 1967 Siemens took the firm over. He stayed on as a consultant and wrote the book Rechnender Raum (“Calculating Space”, 1969), in which he suggested that the universe is built like a cellular automaton.

In 1987–1989, after suffering a heart attack, he rebuilt the Z1. It cost 800,000 marks and took the labour of four people. The money came from Siemens and five other firms.

In retirement Zuse painted a great deal in oils, signing his work with the pseudonym Kuno See; he made more than five hundred paintings in all. In 2012 his work was shown at documenta in Kassel.

Zuse died on 18 December 1995 in Hünfeld and was buried there. A replica of the Z3 and the original Z4 are in the Deutsches Museum in Munich, while the Z1 as a reconstruction and eleven more of his machines are on show in the Deutsches Technikmuseum in Berlin, alongside his paintings.