Born in Berlin, Germany, Zuse graduated in engineering from the Technische Hochschule Berlin-Charlottenburg (today the Technische Universität Berlin or Technical University of Berlin) in 1935. He started work at the Henschel aircraft factory in Dessau, but only one year later he resigned from his job to build a programmable machine. Working in his parents' apartment in 1938, his first attempt, called the Z1, was a binary electrically driven mechanical calculator with limited programmability, reading instructions from punched tape. The Z1 never worked well, though, due to the lack of sufficiently precise parts. The Z1 and its original blueprints were destroyed during World War II.
World War II made it impossible and undesirable for Zuse and contemporary computer scientists in the UK and the USA to work together, or even to stay in contact. In 1939, Zuse was called for military service but was able to convince the army to let him return to building his computers. In 1940, he gained support from the Aerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute), which used his work for the production of guided missiles. Zuse built the Z2, a revised version of his machine, from telephone relays. The same year, he started a company, Zuse Apparatebau, to manufacture his programmable machines.
Satisfied with the function of the basic Z2 machine, he built the Z3 in 1941. It was a binary calculator featuring limited programmability, with memory and a calculation unit based on telephone relays. Calculations could be specified in advance. Conditional jumps and loops were not available as convenient instructions, but the Z3 was a Turing-complete computer (ignoring the fact that no physical computer can be truly Turing complete due to limited storage size). However, its Turing-completeness was never envisioned by Zuse and only proven in 1998. (See History of computing hardware)
Zuse's company was destroyed in 1945 by an Allied attack, together with the Z3. The partially finished, relay-based Z4 had been brought to a safe place earlier. Zuse also developed the first high-level programming language, the Plankalkül in 1945, for which no compiler or interpreter was available until 2000.
In 1946 Zuse founded world's first computer startup company: the Zuse-Ingenieurbüro Hopferau. Venture capital was raised through ETH Zürich and an IBM option on Zuse's patents.
Zuse founded another company, Zuse KG, in 1949. The Z4 was finished and delivered to the ETH Zürich, Switzerland in September, 1950. At that time, it was the only working computer in continental Europe, and the first computer in the world to be sold, beating the Ferranti Mark I by five months and the UNIVAC I by ten months. Other computers, all numbered with a leading Z, were built by Zuse and his company. Notable are the Z11, which was sold to the optics industry and to universities, and the Z22, the first computer with a memory based on magnetic storage.
In 1967 Zuse also suggested that the universe itself is running on a grid of computers (digital physics); in 1969 he publishes the book "Rechnender Raum" (translated by MIT into English as "Calculating Space", 1970); in the new millennium such wild ideas have suddenly started to attract a lot of attention, since there is no compelling physical evidence against Zuse's thesis.
Between 1987 and 1989, Zuse recreated the Z1, suffering a heart-attack midway through the project. The final result had 30,000 components, cost 800,000 DM, and required 4 individuals (including Zuse) to assemble it. Funding for the project was provided by Siemens and a consortium of around five companies.