 Z4 on display at theDeutsches Museum,Munich | |
| Developer | Konrad Zuse |
|---|---|
| Manufacturer | Zuse Apparatebau |
| Type | Programmable, fully automaticdigitalelectromechanical computer |
| Release date | 1945; 80 years ago (1945) |
| Introductory price | SFr 30,000 for five years |
| Units sold | 1 (toETH Zurich in a loan deal)[1]: 1077, 1139 |
| CPU | @ (about) 40 Hz |
| Memory | Mechanical, 32 bits word length |
| Display | Decimal floating point numbers,punch tape orMercedestypewriter |
| Input | Decimal floating point numbers, punch tape |
| Power | (about) 4 kW |
| Weight | Ca. 1,000 kg (2,200 lb) |
| Predecessor | Z3 |
| Successor | Z5 |
TheZ4 was arguably the world's first commercialdigital computer, and is the oldest surviving programmable computer.[1]: 1028 It was designed, and manufactured by early computer scientistKonrad Zuse's companyZuse Apparatebau, for an order placed byHenschel & Son, in 1942; though only partially assembled in Berlin, then completed in Göttingen in theThird Reich in April 1945,[2] but not delivered before the defeat of Nazi Germany, in 1945.[3][4][5] The Z4 was Zuse's final target for theZ3 design.[6] Like the earlierZ2, it comprised a combination of mechanical memory andelectromechanical logic.[7]
The Z4 was used at theETH Zurich from 1950 to 1955,[1]: 14 also serving as the inspiration for the construction of theERMETH,[1]: 1009 the first Swiss computer, created under the direction of ETH engineerAmbros Speiser.[1]: 1087
The Z4 was very similar to theZ3 in its design but was significantly enhanced in a number of respects. The memory consisted of 32-bit rather than 22-bitfloating pointwords. The Program Construction Unit (Planfertigungsteil) punched the program tapes, making programming and correcting programs for the machine much easier by the use of symbolic operations and memory cells. Numbers were entered and output as decimal floating-point even though the internal working was in binary. The machine had a large repertoire of instructions including square root, MAX, MIN and sine. Conditional tests included tests for infinity. When delivered toETH Zurich in 1950 the machine had a conditional branch facility added[8] and could print on a Mercedes typewriter. There were two program tapes where the second could be used to hold a subroutine. (Originally six were planned.)[9][10]
In 1944, Zuse was working on the Z4 with around two dozen people,[11] includingWilfried de Beauclair. Some engineers who worked at the telecommunications facility of theOKW also worked for Zuse as a secondary occupation. Also in 1944 Zuse transformed his company to theZuse KG (Kommanditgesellschaft, i.e. a limited partnership) and planned to manufacture 300 computers.[12] This way he could also request additional staff and scientists as a contractor in theEmergency Fighter Program.[12] Zuse's company also cooperated withAlwin Walther's Institute for Applied Mathematics at theTechnische Universität Darmstadt.[13]
To prevent it from falling into the hands of the Soviets, the Z4 was evacuated fromBerlin in February 1945 and transported toGöttingen.[11][14] The Z4 was completed in Göttingen in a facility of theAerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute), which was headed byAlbert Betz. But when it was presented to scientists of the AVA the roar of the approaching front could already be heard,[2] so the computer was transported with a truck of theWehrmacht to Hinterstein inBad Hindelang in southern Bavaria, where Konrad Zuse metWernher von Braun.[2][15]
By 1947 it was possible for constants to be entered by the punched tape.[10]
In 1949, the Swiss mathematicianEduard Stiefel, after coming back from a stay in the US where he inspected American computers, visited Zuse and the Z4. When he formulated adifferential equation as a test, Zuse immediately programmed the Z4 to solve it. Stiefel decided to acquire the computer for his newly foundedInstitute for Applied Mathematics at theETH Zurich.[16] It was delivered to ETH Zurich in 1950.[17][18]
At least Zürich has an interesting nightlife with the rattling of the Z4, even if it is only modest.
In 1954,Wolfgang Haack tried to obtain the Z4 forTechnische Universität Berlin,[12] but it was instead transferred to theInstitut Franco-Allemand des Recherches de St. Louis (ISL, Franco-German Institute of Research) inFrance, where it was in use until 1959, under its technical headHubert Schardin. Today, the Z4 is on display in theDeutsches Museum inMunich. The Z4 inspired the ETH to build its own computer (mainly byAmbros Speiser andEduard Stiefel), which was calledERMETH, an acronym forGerman:Elektronische Rechenmaschine ETH ("Electronic Computing Machine ETH").[1]: 1009
In 1950/1951, the Z4 was the only working digital computer inCentral Europe, and the second digital computer in the world to be sold or loaned,[1]: 981 beating theFerranti Mark 1 by five months and theUNIVAC I by ten months, but in turn being beaten by theBINAC (although that never worked at the customer's site[19]). Other computers, all numbered with a leading Z, were built by Zuse and his company. Notable are theZ11, which was sold to the optics industry and to universities, and theZ22.
In 1955 the Z4 was sold to the French-German Research Institute of Saint-Louis (Institut franco-allemand de recherches de Saint-Louis) inSaint-Louis, close to Basel, and in 1960 transferred to theGerman Museum inMunich.[20]
The Z4 was used for calculations for work on theGrande Dixence Dam in 1950.[1]: 1081
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