Konrad Zuse was a German civil engineer, inventor and computer pioneer. 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 has often been regarded as the inventor of the modern computer.
Zuse was also noted for the S2 computing machine, considered the first process control computer. He founded one of the earliest computer businesses in 1941, producing the Z4, which became the world's first commercial computer. From 1943 to 1945 he designed the first high-level programming language, Plankalkül. In 1969, Zuse suggested the concept of a computation-based universe in his book Rechnender Raum (Calculating Space).
Konrad Zuse was born in Berlin to Emil and Maria Crohn Zuse, on 22 June 1910. His father was a Prussian civil servant working for the postal service who relocated the family to Braunsberg (now Braniewo in Poland) when Konrad was still a child. Konrad attended elementary school in that town and began studying at the local Gymnasium Hosianum. The family moved again in 1923 to Hoyerswerda (a town in Germany near what is now the border with Poland).
In Hoyerswerda, Zuse was registered at the Realschule, a school that allowed pupils to continue studying at any of the several technical universities established in Germany. The family eventually moved back to Berlin and Konrad Zuse began his studies at the Technische Hochschule Charlottenburg (renamed Technical University of Berlin after World War II). Zuse started studying mechanical engineering, changed to architecture, thought for some time of becoming a commercial graphic designer, and settled finally on civil engineering.
Beginning in 1935 he experimented in the construction of computers. 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. He finished the Z1 in 1938. The Z1 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.
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. The Z2 was a revised version of the Z1 using telephone relays. In 1941 Zuse started a company, Zuse Apparatebau (Zuse Apparatus Construction), to manufacture his machines.
Improving on the basic Z2 machine, he built the Z3 in 1941. 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.
Zuse's workshop 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, remained intact. On 3 February 1945, aerial bombing caused devastating destruction. This event effectively brought Zuse's research and development to a complete halt. The partially finished, relay-based Z4 was packed and moved from Berlin on 14 February.
Work on the Z4 could not be resumed immediately in the extreme privation of post-war Germany, and it was not until 1949 that he was able to resume work on it. He showed it to the mathematician Eduard Stiefel of the Swiss Federal Institute of Technology Zurich who ordered one in 1950. On 8 November 1949, Zuse KG was founded. The Z4 was delivered to Zurich on 12 July 1950, and proved very reliable.
In 1940, the German government began funding him through the Aerodynamische Versuchsanstalt, 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.
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 doctorate thesis containing groundbreaking research years ahead of its time, mainly the first high-level programming language, Plankalkül ("Plan Calculus") and, as an elaborate example program, the first real computer chess engine. After the 1945 bombing, he flew from Berlin, and, unable to do any hardware development, he continued working on the Plankalkül, eventually publishing some brief excerpts of his thesis in 1948 and 1959; the work in its entirety, however, remained unpublished until 1972. The doctorate thesis was submitted at University of Augsburg, but rejected for formal reasons, because Zuse forgot to pay the 400 Mark university enrollment fee. Plankalkül slightly influenced the design of ALGOL 58 but was itself implemented only in 1975 in a dissertation by Joachim Hohmann. Heinz Rutishauser, one of the inventors of ALGOL, wrote: "The very first attempt to devise an algorithmic language was undertaken in 1948 by K. Zuse. His notation was quite general, but the proposal never attained the consideration it deserved". Further implementations followed in 1998 and then in 2000 by a team from the Free University of Berlin.
The Plankalkül corresponded to Zuse’s mature conception of how to build a computer and how to allocate the total computing work to the hardware and software of a machine. Zuse called the first computers he constructed “algebraic machines” in contrast to “logistic machines.” The former were specially built to handle scientific computations while the latter could deal with both scientific and symbolic processing. Zuse’s “logistic machine” was never built, but its design called for a one-bit word memory and a processor that could compute only the basic logic operations (conjunction, disjunction, and negation). It was a minimalistic computer in which the memory consisted of a long chain of bits, which could be grouped in any desired form to represent numbers, characters, arrays, and so on.
In addition to his computing-related work, described above, Zuse began to work in 1956 on a high precision, large format plotter. It was demonstrated at the 1961 Hanover Fair, and became well known also outside of the technical world thanks to Frieder Nake's pioneering computer art work.
Other plotters designed by Zuse include the ZUSE Z90 and ZUSE Z9004.
In the last years of his life, Zuse conceptualized and created a purely mechanical, extensible, modular tower automaton he named "helix tower" ("Helixturm"). The structure is based on a gear drive that employs rotary motion (e.g. provided by a crank) to assemble modular components from a storage space, elevating a tube-shaped tower; the process is reversible, and inverting the input direction will deconstruct the tower and store the components. The Deutsches Museum restored Zuse's original 1:30 functional model that can be extended to a height of 2.7 m. Zuse intended the full construction to reach a height of 120 m, and envisioned it for use with wind power generators and radio transmission installations.
Konrad Zuse married Gisela Brandes on 6 January 1945. Gisela gave birth to their first son a few months later, and four more children followed in the ensuing years. After his retirement he was much decorated in Germany, receiving, among other distinctions, the Federal Cross of Merit and the Siemens Ring. He was named a fellow of the Computer History Museum in California in 1999. Several honorary doctorates, as well as a professorship, were bestowed on him. Furthermore, the most important prize in Germany in the field of computer science bears Konrad Zuse’s name. Zuse died on 18 December 1995, at the age of eighty-five.
Konrad Zuse conceived all the elements of the computer sooner and more elegantly than any other computer pioneer but was living in Germany when the country was on the path to self-destruction. Outside of Germany, and outside a very small circle for that matter, nobody took notice of the Z1, Z2, Z3, and Z4. The S1 and S2 were secret machines. Zuse’s work was not rediscovered until the late 1940s, and by then it was too late for his machines to have had any serious impact on the design and construction of modern computers. Zuse’s work was worth a footnote, at most, in early scholarly books about the history of computing. This has changed since the 1990s, as more has become known about the life and work of this most remarkable computer pioneer.