Editing Konrad Zuse (section)

===1939–1945===
[[File:2007-01-20 Gedenktafel Zuse Z3.jpg|thumb|right|Plaque commemorating Zuse's work, attached to the ruin of {{lang|de|italic=no|Methfesselstraße}} 7, Berlin]] 
In 1939, Zuse was called to [[Wehrmacht|military service]], where he was given the resources to ultimately build the [[Z2 (computer)|Z2]].<ref name="books.google.com"/> In September 1940 Zuse presented the Z2, covering several rooms in the parental flat, to experts of the {{lang|de|[[Deutsche Versuchsanstalt für Luftfahrt#History|Deutsche Versuchsanstalt für Luftfahrt]]}} (DVL; German Research Institute for Aviation).<ref name="Spode_1994"/>{{rp|page=424}} The Z2 was a revised version of the Z1 using telephone [[relay]]s.

In 1940, the German government began funding him and his company through the {{lang|de|Aerodynamische Versuchsanstalt}} (AVA, Aerodynamic Research Institute, forerunner of the [[German Aerospace Center|DLR]]),<ref>[http://www5.in.tum.de/~huckle/mathwar.html "Mathematicians during the Third Reich and World War II"], Technical University of Munich. Retrieved 14 March 2010.</ref> which used his work for the production of [[glide bomb]]s. 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.<ref name="Zuse_1993"/>{{rp|page=75}}

In 1941 Zuse started a company, {{lang|de|italic=no|Zuse Apparatebau}} (Zuse Apparatus Construction), to manufacture his machines,<ref>{{Cite book | last = Lippe | first = Wolfram-M. | title = Die Geschichte der Rechenautomaten | trans-title = The History of Computing Machines | chapter = Kapitel 14: Die ersten programmierbaren Rechner | trans-chapter = Chapter 14: The First Programmable Computer | url = http://cs.uni-muenster.de/Professoren/Lippe/lehre/skripte/geschichte/ | chapter-url = http://cs.uni-muenster.de/Professoren/Lippe/lehre/skripte/geschichte/pdf/Kap14.pdf | access-date = 21 June 2010 | archive-url = https://web.archive.org/web/20080503054847/http://cs.uni-muenster.de/Professoren/Lippe/lehre/skripte/geschichte/ | archive-date = 3 May 2008 | url-status = dead }}</ref> renting a workshop on the opposite side in {{lang|de|italic=no|Methfesselstraße}} 7 and stretching through the block to {{lang|fr|italic=no|Belle-Alliance}} {{lang|de|italic=no|Straße}} 29 (renamed and renumbered as [[Mehringdamm]] 84 in 1947).<ref name="Spode_1994"/>{{rp|pages=418, 425}}

In 1941, he improved on the basic Z2 machine, and built the [[Z3 (computer)|Z3]]. On 12 May 1941 Zuse presented the Z3, built in his workshop, to the public.<ref name="Spode_1994"/>{{rp|page=425}}<ref name="Chod 2003 52">Kathrin Chod, Herbert Schwenk and Hainer Weißpflug, ''Berliner Bezirkslexikon: Friedrichshain-Kreuzberg'', Berlin: Haude & Spener / Edition Luisenstadt, 2003, p.&nbsp;52. {{ISBN|3-7759-0474-3}}.</ref> The Z3 was a [[binary numeral system|binary]] 22-bit [[floating-point arithmetic|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<ref>St. Amant, Kirk; Still, Brian. [https://books.google.com/books?id=75KT6GdcWbYC&dq=z3%2C+nazi%2C+zuse&pg=PA62 ''Handbook of research on open source software''] Idea Group. 2007. {{ISBN|978-1-59140-999-1}}. Retrieved 14 March 2010.</ref>—for government funding for an electronic successor to the Z3 was denied as "strategically unimportant".

[[File:KZuse denkmal.jpg|thumb|right|Statue of Zuse in [[Bad Hersfeld]]]]
In 1937, Schreyer had advised Zuse to use [[vacuum tube]]s as switching elements; Zuse at this time considered it a "crazy idea" ({{lang|de|Schnapsidee}} in his own words). Zuse's workshop on {{lang|de|italic=no|Methfesselstraße}} 7 (along with the Z3) was destroyed in an [[Bombing of Berlin in World War II|Allied Air raid in late 1943]] and the parental flat with Z1 and Z2 on 30 January the following year, whereas the successor [[Z4 (computer)|Z4]], which Zuse had begun constructing in 1942<ref name="Zuse_1993"/>{{rp|page=75}} in new premises in the {{lang|de|Industriehof}} on {{lang|de|italic=no|Oranienstraße}} 6, remained intact.<ref name="Spode_1994"/>{{rp|page=428}}

On 3 February 1945, aerial bombing caused devastating destruction in the [[Luisenstadt]], the area around {{lang|de|italic=no|Oranienstraße}}, including neighbouring houses.<ref name="Selig_2011"/> 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.<ref name="Spode_1994"/>{{rp|page=428}}

These machines contributed to the Henschel Werke [[Henschel Hs 293|Hs 293]] and [[Henschel Hs 294|Hs 294]] guided missiles developed by the German military between 1941 and 1945, which were the precursors to the modern [[cruise missile]].<ref name="Zuse_1993"/>{{rp|page=75}}<ref>[https://books.google.com/books?id=wx7myVYenMcC&dq=s1,+s2,+HS-293&pg=PA51 "Germany's Secret Weapons in World War II"], Roger Ford. Zenith Imprint, 2000. {{ISBN|0-7603-0847-0}}, {{ISBN|978-0-7603-0847-9}}. Retrieved 14 March 2010.</ref><ref>[https://archive.today/20120731110116/http://www.atypon-link.com/OLD/doi/abs/10.1524/itit.2010.0566 "The S1 and S2 Computing Machines — Konrad Zuse´s Work for the German Military 1941–1945"], Atypon Link. Retrieved 14 March 2010.</ref> The circuit design of the S1 was the predecessor of Zuse's [[Z11 (computer)|Z11]].<ref name="Zuse_1993"/>{{rp|page=75}} Zuse believed that these machines had been captured by occupying [[Red Army|Soviet troops]] in 1945.<ref name="Zuse_1993"/>{{rp|page=75}}

While working on his Z4 computer, Zuse realised that programming in [[machine code]] was too complicated. He started working on a PhD thesis<ref>Konrad Zuse: [http://herbscorner.lepete.de/upload/plankalkuel.%28pdf%29 Der Plankalkül] {{Webarchive|url=https://web.archive.org/web/20150512112136/http://herbscorner.lepete.de/upload/plankalkuel.%28pdf%29 |date=12 May 2015 }}. PhD thesis, 1945</ref> detailing the first high-level programming language, {{lang|de|italic=no|[[Plankalkül]]}} ("Plan Calculus") and, as an elaborate example program, the first real computer chess engine.<ref name=knuthpardo>Knuth & Pardo: The early development of programming languages. In Nicholas Metropolis (Ed): ''History of Computing in the Twentieth Century'', p. 203.</ref>