The Z4 was arguably the world's first commercial
digital computer, and is the oldest surviving programmable computer.[1]: 1028 It was designed, and manufactured by early computer scientist
Konrad Zuse's company Zuse Apparatebau, for an order placed by
Henschel & Son, in 1942; though only partially assembled in Berlin, then completed in Göttingen in the
Third 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 the
Z3 design.[6] Like the earlier
Z2, it comprised a combination of mechanical memory and
electromechanical logic, so was not a true electronic computer.[7]
Construction
The Z4 was very similar to the
Z3 in its design but was significantly enhanced in a number of respects. The memory consisted of 32-bit rather than 22-bit
floating 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 to
ETH 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] including
Wilfried de Beauclair. Some engineers who worked at the telecommunications facility of the
OKW also worked for Zuse as a secondary occupation. Also in 1944 Zuse transformed his company to the Zuse 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 the
Emergency Fighter Program.[12] Zuse's company also cooperated with
Alwin Walther's Institute for Applied Mathematics at the
Technical University of Darmstadt.[13]
To prevent it from falling into the hands of the Soviets, the Z4 was evacuated from
Berlin in February 1945 and transported to
Göttingen.[11][14] The Z4 was completed in Göttingen in a facility of the Aerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute), which was headed by
Albert 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 the
Wehrmacht to Hinterstein in
Bad Hindelang in southern Bavaria, where Konrad Zuse met
Wernher von Braun.[2][15]
By 1947 it was possible for constants to be entered by the punched tape.[10]
Use after World War II
In 1949, the Swiss mathematician
Eduard Stiefel, after coming back from a stay in the US where he inspected American computers, visited Zuse and the Z4. When he formulated a
differential equation as a test, Zuse immediately programmed the Z4 to solve it, Stiefel decided to acquire the computer for his newly founded
Institute for Applied Mathematics at the
ETH 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.
—Konrad Zuse
In 1954,
Wolfgang Haack tried to obtain the Z4 for the
Technical University of Berlin,[12] but it was instead transferred to the Institut Franco-Allemand des Recherches de St. Louis (ISL, Franco-German Institute of Research) in
France, where it was in use until 1959, under its technical head
Hubert Schardin. Today, the Z4 is on display in the
Deutsches Museum in
Munich. The Z4 inspired the ETH to build its own computer (mainly by
Ambros Speiser and
Eduard Stiefel), which was called
ERMETH, an acronym for
German: Elektronische Rechenmaschine ETH ("Electronic Computing Machine ETH").
In 1950/1951, the Z4 was the only working digital computer in
Central Europe, and the second digital computer in the world to be sold or loaned,[1]: 981 beating the
Ferranti Mark 1 by five months and the
UNIVAC I by ten months, but in turn being beaten by the
BINAC (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 the
Z11, which was sold to the optics industry and to universities, and the
Z22.
In 1955 the Z4 was sold to the French-German Research Institute of Saint-Louis (Institut franco-allemand de recherches de Saint-Louis) in
Saint-Louis, close to Basel, and in 1960 transferred to the
German Museum in
Munich.[20]
Average calculation speed: 400
ms for an addition, 3 seconds for a multiplication. Approximately 1000 floating point arithmetic operations on average an hour.
Programming: holes in 35 mm film stock, punched on a programming machine
Input: Decimal floating point numbers, punch tape
Output: Decimal floating point numbers, punch tape or Mercedes typewriter
^
abcBruderer, Herbert (2021). Milestones in Analog and Digital Computing (3rd ed.). Springer. pp. 981, 1028, 1077, 1139.
ISBN978-3-03040973-9. (NB. This is the English translation of the German work "Meilensteine der Rechentechnik" in two volumes.)
^
abcSchillo, Michael[at Wikidata] (2001).
"Zuse"(PDF) (Lecture) (in German).
Archived(PDF) from the original on 2021-03-08. Retrieved 2010-06-21. (25 pages)
LaForest, Charles Eric (April 2007). "2.1 Lukasiewicz and the First Generation: 2.1.2 Germany: Konrad Zuse (1910–1995); 2.2 The First Generation of Stack Computers: 2.2.1 Zuse Z4".
Second-Generation Stack Computer Architecture(PDF) (thesis). Waterloo, Canada:
University of Waterloo. pp. 8, 11.
Archived(PDF) from the original on 2022-01-20. Retrieved 2022-07-02. (178 pages)