Konrad Ernst Otto Zuse (; German: [ˈkɔnʁaːt ˈtsuːzə]; 22 June 1910 – 18 December 1995) was a German civil engineer, pioneering computer scientist, inventor and businessman. His greatest achievement was the world's first programmable computer; the functional program-controlled Turing-complete Z3 became operational in May 1941. Thanks to this machine and its predecessors, Zuse is regarded by some as the inventor and father of the modern computer.
Zuse was noted for the S2 computing machine, considered the first process control computer. In 1941, he founded one of the earliest computer businesses, producing the Z4, which became the world's first commercial computer. From 1943 to 1945 he designed Plankalkül, the first high-level programming language. In 1969, Zuse suggested the concept of a computation-based universe in his book Rechnender Raum (Calculating Space).
Much of his early work was financed by his family and commerce, but after 1939 he was given resources by the government of Nazi Germany. Due to World War II, Zuse's work went largely unnoticed in the United Kingdom and United States. Possibly his first documented influence on a US company was IBM's option on his patents in 1946. The Z4 also served as the inspiration for the construction of the ERMETH, the first Swiss computer and one of the first in Europe.
Konrad Zuse was born in Berlin on 22 June 1910. In 1912, his family moved to East Prussian Braunsberg (now Braniewo in Poland), where his father was a postal clerk. Zuse attended the Collegium Hosianum in Braunsberg, and in 1923, the family moved to Hoyerswerda, where he passed his Abitur in 1928, qualifying him to enter university.
He enrolled at Technische Hochschule Berlin (now Technische Universität Berlin) and explored both engineering and architecture, but found them boring. Zuse then pursued civil engineering, graduating in 1935.
After graduation, Zuse worked for the Ford Motor Company, using his artistic skills in the design of advertisements. He started work as a design engineer at the Henschel aircraft factory in Schönefeld near Berlin. This required the performance of many routine calculations by hand, leading him to theorize and plan a way of doing them by machine.
Beginning in 1935, he experimented in the construction of computers in his parents' flat on Wrangelstraße 38, moving with them into their new flat on Methfesselstraße 10, the street leading up the Kreuzberg, Berlin. Working in his parents' apartment in 1936, he produced his first attempt, the Z1, a floating-point binary mechanical calculator with limited programmability, reading instructions from a perforated 35 mm film.
In 1937, Zuse submitted two patents that anticipated a von Neumann architecture. In 1938, he finished the Z1 which contained some 30,000 metal parts and never worked well due to insufficient mechanical precision. On 30 January 1944, the Z1 and its original blueprints were destroyed with his parents' flat and many neighbouring buildings by a British air raid in World War II.
Zuse completed his work entirely independently of other leading computer scientists and mathematicians of his day. Between 1936 and 1945, he was in near-total intellectual isolation.
In 1939, Zuse was called to military service, where he was given the resources to ultimately build the Z2. In September 1940 Zuse presented the Z2, covering several rooms in the parental flat, to experts of the Deutsche Versuchsanstalt für Luftfahrt (DVL; German Research Institute for Aviation). The Z2 was a revised version of the Z1 using telephone relays.
In 1940, the German government began funding him and his company through the Aerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute, forerunner of the DLR), which used his work for the production of glide bombs. Zuse built the S1 and S2 computing machines, which were special purpose devices which computed aerodynamic corrections to the wings of radio-controlled flying bombs. The S2 featured an integrated analog-to-digital converter under program control, making it the first process-controlled computer.
In 1941 Zuse started a company, Zuse Apparatebau (Zuse Apparatus Construction), to manufacture his machines, renting a workshop on the opposite side in Methfesselstraße 7 and stretching through the block to Belle-Alliance Straße 29 (renamed and renumbered as Mehringdamm 84 in 1947).
In 1941, he improved on the basic Z2 machine, and built the Z3. On 12 May 1941 Zuse presented the Z3, built in his workshop, to the public. The Z3 was a binary 22-bit floating-point calculator featuring programmability with loops but without conditional jumps, with memory and a calculation unit based on telephone relays. The telephone relays used in his machines were largely collected from discarded stock. Despite the absence of conditional jumps, the Z3 was a Turing complete computer. However, Turing-completeness was never considered by Zuse (who was unaware of Turing's work and had practical applications in mind) and only demonstrated in 1998 (see History of computing hardware).
The Z3, the first fully operational electromechanical computer, was partially financed by German government-supported DVL, which wanted their extensive calculations automated. A request by his co-worker Helmut Schreyer—who had helped Zuse build the Z3 prototype in 1938—for government funding for an electronic successor to the Z3 was denied as "strategically unimportant".
In 1937, Schreyer had advised Zuse to use vacuum tubes as switching elements; Zuse at this time considered it a "crazy idea" (Schnapsidee in his own words). Zuse's workshop on Methfesselstraße 7 (along with the Z3) was destroyed in an Allied Air raid in late 1943 and the parental flat with Z1 and Z2 on 30 January the following year, whereas the successor Z4, which Zuse had begun constructing in 1942 in new premises in the Industriehof on Oranienstraße 6, remained intact.
On 3 February 1945, aerial bombing caused devastating destruction in the Luisenstadt, the area around Oranienstraße, including neighbouring houses. This event effectively brought Zuse's research and development to a complete halt. The partially finished, telephone relay-based Z4 computer was then packed and moved from Berlin on 14 February, arriving in Göttingen approximately two weeks later.
These machines contributed to the Henschel Werke Hs 293 and Hs 294 guided missiles developed by the German military between 1941 and 1945, which were the precursors to the modern cruise missile. The circuit design of the S1 was the predecessor of Zuse's Z11. Zuse believed that these machines had been captured by occupying Soviet troops in 1945.
While working on his Z4 computer, Zuse realised that programming in machine code was too complicated. He started working on a PhD thesis detailing the first high-level programming language, Plankalkül ("Plan Calculus") and, as an elaborate example program, the first real computer chess engine.