Z4 (computer)
The Z4 was the world's first commercial digital computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

, designed by German
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...

 engineer Konrad Zuse
Konrad Zuse
Konrad Zuse was a German civil engineer and computer pioneer. His greatest achievement was the world's first functional program-controlled Turing-complete computer, the Z3, which became operational in May 1941....

 and built by his company Zuse Apparatebau between 1942 and 1945.

In 1944 Zuse was working on the Z4 with around two dozen people, including several women. Some engineers who worked at the telecommunications facility of the OKW
Oberkommando der Wehrmacht
The Oberkommando der Wehrmacht was part of the command structure of the armed forces of Nazi Germany during World War II.- Genesis :...

 also worked for Zuse as a secondary occupation. To prevent it from falling into the hands of the Soviets, the Z4 was evacuated from Berlin
Berlin is the capital city of Germany and is one of the 16 states of Germany. With a population of 3.45 million people, Berlin is Germany's largest city. It is the second most populous city proper and the seventh most populous urban area in the European Union...

 in February 1945 and transported to Göttingen
Göttingen is a university town in Lower Saxony, Germany. It is the capital of the district of Göttingen. The Leine river runs through the town. In 2006 the population was 129,686.-General information:...

. The Z4 was completed in Göttingen in a facility of the Aerodynamische Versuchsanstalt (AVA, Aerodynamic Research Institute), which was headed by Albert Betz
Albert Betz
Albert Betz was a German physicist and a pioneer of wind turbine technology.In 1910 he graduated as a naval engineer from Technische Hochschule Berlin...

. But when it was presented to scientists of the AVA the roar of the approaching front could already be heard, so the computer was transported with a truck of the Wehrmacht
The Wehrmacht – from , to defend and , the might/power) were the unified armed forces of Nazi Germany from 1935 to 1945. It consisted of the Heer , the Kriegsmarine and the Luftwaffe .-Origin and use of the term:...

 to Hinterstein in Bad Hindelang
Bad Hindelang
Bad Hindelang is a municipality in the district of Oberallgäu in Bavaria in Germany. As of 2008 it has a population of 4,915. Its sulphur spring was used for cures in the 19th century and today the municipality is a major health resort.-Geography:...

, where Konrad Zuse met Wernher von Braun
Wernher von Braun
Wernher Magnus Maximilian, Freiherr von Braun was a German rocket scientist, aerospace engineer, space architect, and one of the leading figures in the development of rocket technology in Nazi Germany during World War II and in the United States after that.A former member of the Nazi party,...


Relation to other work

The Z4 design which extended the Z3 was Zuse's final concept and the computer he intended to sell.

Usage after WWII

In 1949 the Swiss mathematician Eduard Stiefel
Eduard Stiefel
Eduard L. Stiefel was a Swiss mathematician. Together with Cornelius Lanczos and Magnus Hestenes, he invented the conjugate gradient method, and gave what is now understood to be a partial construction of the Stiefel–Whitney classes of a real vector bundle, thus co-founding the study of...

, after coming back from a stay in the USA where he inspected American computers, visited Zuse and the Z4. When he formulated a differential equation for Zuse, who immediately programmed the Z4 to solve it, Stiefel decided to acquire the computer for his institution in Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....

, the Swiss Federal Institute of Technology Zurich (ETH Zurich
ETH Zurich
The Swiss Federal Institute of Technology Zurich or ETH Zürich is an engineering, science, technology, mathematics and management university in the City of Zurich, Switzerland....


It was delivered to ETH Zurich in September 1950. In 1954, the Z4 was transferred to the (Franco-German Institute of Research) in France
The French Republic , The French Republic , The French Republic , (commonly known as France , is a unitary semi-presidential republic in Western Europe with several overseas territories and islands located on other continents and in the Indian, Pacific, and Atlantic oceans. Metropolitan France...

, where it was in use until 1959. Today, the Z4 is on display in the Deutsches Museum
Deutsches Museum
The Deutsches Museum in Munich, Germany, is the world's largest museum of technology and science, with approximately 1.5 million visitors per year and about 28,000 exhibited objects from 50 fields of science and technology. The museum was founded on June 28, 1903, at a meeting of the Association...

 in Munich
Munich The city's motto is "" . Before 2006, it was "Weltstadt mit Herz" . Its native name, , is derived from the Old High German Munichen, meaning "by the monks' place". The city's name derives from the monks of the Benedictine order who founded the city; hence the monk depicted on the city's coat...


The Z4 inspired the ETH to build its own computer (mainly by A. Speiser and E. Stiefel
Eduard Stiefel
Eduard L. Stiefel was a Swiss mathematician. Together with Cornelius Lanczos and Magnus Hestenes, he invented the conjugate gradient method, and gave what is now understood to be a partial construction of the Stiefel–Whitney classes of a real vector bundle, thus co-founding the study of...

), which was called ERMETH, an acronym for ("Electronic Computing Machine ETH").
In 1950/1951 the Z4 was the only working digital computer in continental Europe, and the second digital computer in the world to be sold, beating the Ferranti Mark 1 by five months and the UNIVAC I
The UNIVAC I was the first commercial computer produced in the United States. It was designed principally by J. Presper Eckert and John Mauchly, the inventors of the ENIAC...

 by ten months, but in turn being beaten by the BINAC
BINAC, the Binary Automatic Computer, was an early electronic computer designed for Northrop Aircraft Company by the Eckert-Mauchly Computer Corporation in 1949. Eckert and Mauchly, though they had started the design of EDVAC at the University of Pennsylvania, chose to leave and start EMCC, the...

 (although that never worked at the customer's site). 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, the first computer with a memory based on magnetic storage.

The Z4 was used for calculations for work on the Grande Dixence Dam
Grande Dixence Dam
The Grande Dixence Dam is a concrete gravity dam on the Dixence River at the head of the Val d'Hérens in the canton of Valais in Switzerland. At high, it is the tallest gravity dam in the world and is part of the Cleuson-Dixence Complex...


By 1967, the Zuse KG had built a total of 251 computers. Due to financial problems, the company was then sold to Siemens
Siemens AG
Siemens AG is a German multinational conglomerate company headquartered in Munich, Germany. It is the largest Europe-based electronics and electrical engineering company....



  • Frequency: (about) 40 hertz
    The hertz is the SI unit of frequency defined as the number of cycles per second of a periodic phenomenon. One of its most common uses is the description of the sine wave, particularly those used in radio and audio applications....

  • Average calculation speed: 400 ms
    A millisecond is a thousandth of a second.10 milliseconds are called a centisecond....

     for an addition
  • Input: Decimal numbers, punch tape
  • Output: Decimal numbers, punch tape
  • Word length: 32 bits
  • Elements: (about) 2,500 relays, 21 step-wise relays
  • Memory: Memory of the Z1 (64 words, 32 bit)
  • Power consumption: (about) 4 kW

External links

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