Konrad Zuse (German: [ˈkɔnʁat ˈtsuːzə]; 22 June 1910 – 18 December 1995) 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.
Konrad Zuse in 1992
22 June 1910|
Berlin, Prussia, German Empire
18 December 1995 (aged 85)|
Hünfeld, Hesse, Germany
|Alma mater||Technical University of Berlin|
Calculating Space (cf. digital physics)
Werner von Siemens Ring in 1964, |
Harry H. Goode Memorial Award in 1965 (together with George Stibitz),
Wilhelm Exner Medal, 1969
Order of Merit of the Federal Republic of Germany in 1972
Computer History Museum Fellow Award in 1999
|Institutions||Aerodynamic Research Institute|
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).
Much of his early work was financed by his family and commerce, but after 1939 he was given resources by the Nazi German government. Due to World War II, Zuse's work went largely unnoticed in the United Kingdom and the United States. Possibly his first documented influence on a US company was IBM's option on his patents in 1946.
There is a replica of the Z3, as well as the original Z4, in the Deutsches Museum in Munich. The Deutsches Technikmuseum in Berlin has an exhibition devoted to Zuse, displaying twelve of his machines, including a replica of the Z1 and several of Zuse's paintings.
Pre-World War II work and the Z1
Born in Berlin, Germany, on 22 June 1910, he moved with his family in 1912 to East Prussian Braunsberg (now Braniewo in Poland), where his father was a postal clerk. Zuse attended the Collegium Hosianum in Braunsberg. In 1923, the family moved to Hoyerswerda, where he passed his Abitur in 1928, qualifying him to enter university.
He enrolled in the Technische Hochschule Berlin (now Technical University of Berlin) and explored both engineering and architecture, but found them boring. Zuse then pursued civil engineering, graduating in 1935. For a time, he worked for the Ford Motor Company, using his considerable 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, which he found mind-numbingly boring, leading him to dream 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. 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.
Between 1987 and 1989, Zuse recreated the Z1, suffering a heart attack midway through the project. It cost 800,000 DM, (approximately $500,000) and required four individuals (including Zuse) to assemble it. Funding for this retrocomputing project was provided by Siemens and a consortium of five companies.
The Z2, Z3, and Z4
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; i.e. German Research Institute for Aviation). The Z2 was a revised version of the Z1 using telephone relays.
The DVL granted research subsidies so that 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).
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. However, Turing-completeness was never considered by Zuse (who 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 (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, relay-based Z4 was packed and moved from Berlin on 14 February, only arriving in Göttingen two weeks later.
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 (Eidgenössische Technische Hochschule (ETH) Zürich) who ordered one in 1950. On 8 November 1949, Zuse KG was founded. The Z4 was delivered to ETH Zurich on 12 July 1950, and proved very reliable.
S1 and S2
In 1940, the German government began funding him 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.
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 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 Luisenstadt bombing, he flew from Berlin for the rural Allgäu, 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 PhD thesis was submitted at University of Augsburg, but rejected for formal reasons, because Zuse forgot to pay the 400 Mark university enrollment fee. (The rejection did not bother him.) 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. Donald Knuth suggested a thought experiment: What might have happened had the bombing not taken place, and had the PhD thesis accordingly been published as planned?
Konrad Zuse married Gisela Brandes in January 1945, employing a carriage, himself dressed in tailcoat and top hat and with Gisela in a wedding veil, for Zuse attached importance to a "noble ceremony". Their son Horst, the first of five children, was born in November 1945.
While Zuse never became a member of the Nazi Party, he is not known to have expressed any doubts or qualms about working for the Nazi war effort. Much later, he suggested that in modern times, the best scientists and engineers usually have to choose between either doing their work for more or less questionable business and military interests in a Faustian bargain, or not pursuing their line of work at all.
According to the memoirs of the German computer pioneer Heinz Billing from the Max Planck Institute for Physics, published by Genscher, Düsseldorf, there was a meeting between Alan Turing and Konrad Zuse. It took place in Göttingen in 1947. The encounter had the form of a colloquium. Participants were Womersley, Turing, Porter from England and a few German researchers like Zuse, Walther, and Billing. (For more details see Herbert Bruderer, Konrad Zuse und die Schweiz).
After he retired, he focused on his hobby of painting.
Zuse the entrepreneur
During World War 2, Zuse founded one of the earliest computer companies: the Zuse-Ingenieurbüro Hopferau. Capital was raised in 1946 through ETH Zurich and an IBM option on Zuse's patents.
Zuse founded another company, Zuse KG in Haunetal-Neukirchen in 1949; in 1957 the company’s head office moved to Bad Hersfeld. The Z4 was finished and delivered to the ETH Zurich, Switzerland in September 1950. At that time, it was the only working computer in continental Europe, and the second computer in the world to be sold, beaten only by the BINAC, which never worked properly after it was delivered. Other computers, all numbered with a leading Z, up to Z43, 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.
By 1967, the Zuse KG had built a total of 251 computers. Owing to financial problems, the company was then sold to Siemens.
In 1967, Zuse also suggested that the universe itself is running on a cellular automaton or similar computational structure (digital physics); in 1969, he published the book Rechnender Raum (translated into English as Calculating Space). This idea has attracted a lot of attention, since there is no physical evidence against Zuse's thesis. Edward Fredkin (1980s), Jürgen Schmidhuber (1990s), and others have expanded on it.
Awards and honours
Zuse received several awards for his work:
- Werner von Siemens Ring in 1964 (together with Fritz Leonhardt and Walter Schottky)
- Harry H. Goode Memorial Award in 1965 (together with George Stibitz)
- Wilhelm Exner Medal in 1969.
- Bundesverdienstkreuz in 1972 – Great Cross of Merit
- Computer History Museum Fellow Award in 1999 "for his invention of the first program-controlled, electromechanical, digital computer and the first high-level programming language, Plankalkül."
The Zuse Institute Berlin is named in his honour.
The Konrad Zuse Medal of the Gesellschaft für Informatik, and the Konrad Zuse Medal of the Zentralverband des Deutschen Baugewerbes (Central Association of German Construction), are both named after Zuse.
Zuse Year 2010
The 100th anniversary of the birth of this computer pioneer was celebrated by exhibitions, lectures and workshops to remember his life and work and to bring attention to the importance of his invention to the digital age. The movie Tron: Legacy, which revolves around a world inside a computer system, features a character named Zuse, presumably in honour of Konrad Zuse. German posts DP AG issued a commemorative stamp at this occasion, June 6, 2010: a Zuse portrait, composed solely by the binary code numbers 1 and 0 in fine print.
- Editor, ÖGV. (2015). Wilhelm Exner Medal. Austrian Trade Association. ÖGV. Austria.
- PDF Raúl Rojas: Konrad Zuse’s Legacy: The Architecture of the Z1 and Z3
-   Raúl Rojas: How to make Zuse's Z3 a universal computer.
- RTD Net: "From various sides Konrad Zuse was awarded with the title "Inventor of the computer"."
- GermanWay: "(...)German inventor of the computer"
- Monsters & Critics Archived May 22, 2013, at the Wayback Machine.: "he [Zuse] built the world's first computer in Berlin"
- About.com: "Konrad Zuse earned the semiofficial title of 'inventor of the modern computer'"
- Inception of a universal theory of computation with special consideration of the propositional calculus and its application to relay circuits (Zuse, Konrad, (1943) "Ansätze einer Theorie des allgemeinen Rechnens unter besonderer Berücksichtigung des Aussagenkalküls und dessen Anwendung auf Relaisschaltungen"), unpublished manuscript, Zuse Papers 045/018.
- A book on the subject: (full text of the 1945 manuscript) Archived 2012-02-10 at the Wayback Machine.
- Talk given by Horst Zuse to the Computer Conservation Society at the Science Museum (London) on 18 November 2010
- "Weapons Grade: How Modern Warfare Gave Birth To Our High-Tech World", David Hambling. Carroll & Graf Publishers, 2006. ISBN 0-7867-1769-6, ISBN 978-0-7867-1769-9. Retrieved March 14, 2010.
- Hasso Spode, „Der Computer – eine Erfindung aus Kreuzberg, Methfesselstraße 10/Oranienstraße 6“, in: Geschichtslandschaft Berlin: Orte und Ereignisse: 5 vols., Helmut Engel, Stefi Jersch-Wenzel, Wilhelm Treue (eds.), vol. 5: 'Kreuzberg', Berlin: Nicolai, 1994, pp. 418–429, here p. 418. ISBN 3-87584-474-2.
- Hasso Spode, „Der Computer – eine Erfindung aus Kreuzberg, Methfesselstraße 10/Oranienstraße 6“, in: Geschichtslandschaft Berlin: Orte und Ereignisse: 5 vols., Helmut Engel, Stefi Jersch-Wenzel, Wilhelm Treue (eds.), vol. 5: 'Kreuzberg', Berlin: Nicolai, 1994, pp. 418–429, p. 426. ISBN 3-87584-474-2.
- "Konrad Zuse" Archived 2011-08-29 at the Wayback Machine., Gap System. Retrieved March 14, 2010.
- Hasso Spode, „Der Computer – eine Erfindung aus Kreuzberg, Methfesselstraße 10/Oranienstraße 6“, in: Geschichtslandschaft Berlin: Orte und Ereignisse: 5 vols., Helmut Engel, Stefi Jersch-Wenzel, Wilhelm Treue (eds.), vol. 5: 'Kreuzberg', Berlin: Nicolai, 1994, pp. 418–429, p. 424. ISBN 3-87584-474-2.
- Lippe, Wolfram-M. "Kapitel 14: Die ersten programmierbaren Rechner" [Chapter 14: The First Programmable Computer]. Die Geschichte der Rechenautomaten [The History of Computing Machines]. Archived from the original (PDF) on 2008-05-03. Retrieved 2010-06-21.
- Hasso Spode, „Der Computer – eine Erfindung aus Kreuzberg, Methfesselstraße 10/Oranienstraße 6“, in: Geschichtslandschaft Berlin: Orte und Ereignisse: 5 vols., Helmut Engel, Stefi Jersch-Wenzel, Wilhelm Treue (eds.), vol. 5: 'Kreuzberg', Berlin: Nicolai, 1994, pp. 418–429, p. 425. ISBN 3-87584-474-2.
- Kathrin Chod, Herbert Schwenk and Hainer Weißpflug, Berliner Bezirkslexikon: Friedrichshain-Kreuzberg, Berlin: Haude & Spener / Edition Luisenstadt, 2003, p. 52. ISBN 3-7759-0474-3.
- St. Amant, Kirk; Still, Brian. Handbook of research on open source software Idea Group. 2007. ISBN 978-1-59140-999-1. Retrieved March 14, 2010.
- Zuse, Konrad (2010) , Wössner, Hans, ed., The Computer – My Life (Translation of Der Computer – Mein Lebenswerk), Heidelberg: Springer Verlag, ISBN 978-3-642-08151-4
- Hasso Spode, „Der Computer – eine Erfindung aus Kreuzberg, Methfesselstraße 10/Oranienstraße 6“, in: Geschichtslandschaft Berlin: Orte und Ereignisse: 5 vols., Helmut Engel, Stefi Jersch-Wenzel, Wilhelm Treue (eds.), vol. 5: 'Kreuzberg', Berlin: Nicolai, 1994, pp. 418–429, p. 428. ISBN 3-87584-474-2.
- Chronik, Bernd Selig, Kreuzberger. "Kreuzberger Chronik: Bomber Ã¼ber Kreuzberg - Sie lesen das Original! aus Berlin-Kreuzberg". www.kreuzberger-chronik.de.
- "Mathematicians during the Third Reich and World War II", Technische Universität München. Retrieved March 14, 2010.
- "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 March 14, 2010.
- "The S1 and S2 Computing Machines — Konrad Zuse´s Work for the German Military 1941–1945", Atypon Link. Retrieved March 14, 2010.
- K. Zuse: Der Plankalkül Archived 2015-05-12 at the Wayback Machine.. PhD thesis, 1945
- Knuth & Pardo: The early development of programming languages. In Nicholas Metropolis (Ed): History of Computing in the Twentieth Century, p. 203
- "get-it: Ursula Walk". www.get-it.tu-berlin.de.
- Rojas, Raúl; Hashagen, Ulf (2002). The First Computers: History and Architectures. MIT Press. p. 292. ISBN 978-0262681377. Retrieved October 25, 2013.
- Joachim Hohmann: Der Plankalkül im Vergleich mit algorithmischen Sprachen. Reihe Informatik und Operations Research, S. Toeche-Mittler Verlag, Darmstadt 1979, ISBN 3-87820-028-5.
- Zuse, Konrad. Der Computer, mein Lebenswerk [The Computer, My Life's Work]. Berlin: Springer. 1984. page X. ISBN 978-3-540-13814-3
- Bruderer, Herbert. "Did Alan Turing interrogate Konrad Zuse in Göttingen in 1947?" (PDF). Retrieved 7 February 2013.
- Jane Smiley (2010). The Man Who Invented the Computer: The Biography of John Atanasoff, Digital Pioneer. Random House Digital, Inc. ISBN 9780385527132.
Like Alan Turing, Zuse was educated in a system that focused on a child's emotional and philosophical life as well as his intellectual life, and at the end of school, like Turing, Zuse found himself to be something of an outsider—to the disappointment of his very conventional parents, he no longer believed in God or religion.
- Konrad Zuse (1993). The Computer, My Life. Springer. pp. 12–13. ISBN 978-3-540-56453-9.
The only problem was that the progressive spirit at our school did not always correspond to my parents' ideas. This was particularly true for religious instruction, which now and again seemed even to us pupils to be rather too enlightened. After the 'Abitur' my parents wanted to go to communion with me; it was a terrible disappointment to them when I wouldn't go. They had lived under the illusion that I was a good student when it came to religion, too, which wasn't the case. ...I remember a poem presented by a student, which made a great impression on me. The essence of the poem read, "Basically, you are always alone". I have forgotten the name of the poet, but have often experienced the truth of these words in later life.
- "Part 7 (continued): The Zuse KG". Archived from the original on May 11, 2009. Retrieved July 4, 2011. Prof. Horst Zuse, EPE Online, archived on May 11, 2009 from the original Archived 2008-12-28 at the Wayback Machine.
- "The Life and Work of Konrad Zuse". Archived from the original on June 29, 2009. Retrieved April 18, 2010. Prof. Horst Zuse, EPE Online, archived on June 29, 2009 from the original Archived April 18, 2010, at the Wayback Machine.
- Rechnender Raum (PDF document), Elektronische Datenverarbeitung, 8: 336–344, 1967.
- "Konrad Zuse". ei.cs.vt.edu.
- Konrad Zuse 1999 Fellow Award Recipient Archived 2012-07-03 at the Wayback Machine. Computer History Museum
- Zwernemann-Blech, Irene. "Zuse-Jahr 2010". www.horst-zuse.homepage.t-online.de.
- Zuse-Jahr 2010 – zum 100. Geburtstag des Computerpioniers Konrad Zuse Deutsches Technikmuseum Berlin, 19 April 2010 (in German)
- Zuse, Konrad (1993). The Computer – My Life. Berlin/Heidelberg: Springer-Verlag. ISBN 0-387-56453-5 (translated from the original German edition (1984): Der Computer – Mein Lebenswerk. Springer. ISBN 3-540-56292-3.) ( Electronic version from Springer)
- Zuse, Konrad (1969). Rechnender Raum Braunschweig: Vieweg & Sohn. ISBN 3-528-09609-8
- Rechnender Raum (PDF document), Elektronische Datenverarbeitung, 8: 336–344, 1967.
- Calculating Space English translation as PDF document
- Zuse, Konrad. Direction-bound engraving tool with program control. U.S. Patent 3,163,936
- U.S.Patents 3,234,819; 3,306,128; 3,408,483; 3,356,852; 3,316,442
- Konrad Zuse: The Computer – My Life, Springer Verlag, ISBN 3-540-56453-5, ISBN 0-387-56453-5
- Jürgen Alex, Hermann Flessner, Wilhelm Mons, Horst Zuse: Konrad Zuse: Der Vater des Computers. Parzeller, Fulda 2000, ISBN 3-7900-0317-4
- Raul Rojas (Hrsg.): Die Rechenmaschinen von Konrad Zuse. Springer, Berlin 1998, ISBN 3-540-63461-4.
- Wilhelm Füßl (Ed.): 100 Jahre Konrad Zuse. Einblicke in den Nachlass, München 2010, ISBN 978-3-940396-14-3.
- Jürgen Alex: Wege und Irrwege des Konrad Zuse. In: Spektrum der Wissenschaft (dt. Ausgabe von Scientific American) 1/1997, ISSN 0170-2971.
- Hadwig Dorsch: Der erste Computer. Konrad Zuses Z1 – Berlin 1936. Beginn und Entwicklung einer technischen Revolution. Mit Beiträgen von Konrad Zuse und Otto Lührs. Museum für Verkehr und Technik, Berlin 1989.
- Clemens Kieser: „Ich bin zu faul zum Rechnen“ – Konrad Zuses Computer Z22 im Zentrum für Kunst und Medientechnologie Karlsruhe. In: Denkmalpflege in Baden-Württemberg, 4/34/2005, Esslingen am Neckar, S. 180–184, ISSN 0342-0027.
- Mario G. Losano (ed.), Zuse. L'elaboratore nasce in Europa. Un secolo di calcolo automatico, Etas Libri, Milano 1975, pp. XVIII-184.
- Arno Peters: Was ist und wie verwirklicht sich Computer-Sozialismus: Gespräche mit Konrad Zuse. Verlag Neues Leben, Berlin 2000, ISBN 3-355-01510-5.
- Paul Janositz: Informatik und Konrad Zuse: Der Pionier des Computerbaus in Europa – Das verkannte Genie aus Adlershof. In: Der Tagesspiegel Nr. 19127, Berlin, 9. März 2006, Beilage Seite B3.
- Jürgen Alex: Zum Einfluß elementarer Sätze der mathematischen Logik bei Alfred Tarski auf die drei Computerkonzepte des Konrad Zuse. TU Chemnitz 2006.
- Jürgen Alex: Zur Entstehung des Computers – von Alfred Tarski zu Konrad Zuse. VDI-Verlag, Düsseldorf 2007, ISBN 978-3-18-150051-4, ISSN 0082-2361.
- Herbert Bruderer: Konrad Zuse und die Schweiz. Wer hat den Computer erfunden? Charles Babbage, Alan Turing und John von Neumann Oldenbourg Verlag, München 2012, XXVI, 224 Seiten, ISBN 978-3-486-71366-4
|Wikimedia Commons has media related to Konrad Zuse.|
|Wikiquote has quotations related to: Konrad Zuse|
- Konrad Zuse Internet Archive
- The Life and Work of Konrad Zuse at the Wayback Machine (archived April 18, 2010) – By Prof. Horst Zuse (K. Zuse's son); an extensive and well-written historical account
- O'Connor, John J.; Robertson, Edmund F., "Konrad Zuse", MacTutor History of Mathematics archive, University of St Andrews.
- Technical University of Berlin
- Free University of Berlin
- Konrad Zuse and his computers, from Technische Universität Berlin
- Konrad Zuse
- Konrad Zuse, inventor of first working programmable computer
- Zuse's thesis of digital physics and the computable universe
- Deutsches Technikmuseum Berlin
- Konrad Zuse Museum Hoyerswerda
- Konrad Zuse and The Invention of the Computer
- Computermuseum Kiel Z11
- Computermuseum Kiel Z22
- Computermuseum Kiel Z25 at the Wayback Machine (archived July 25, 2011)
- Video lecture by Zuse discussing the history of Z1 to 4