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Charles Babbage (1782-1871) proposed two machines, the Difference machine (1823) and the Analytical Machine (1834). These machines were never finished. This was not because of design errors, but was instead the problem of precision mechanics. Both machines were based on a decimal number system of 27 digits. Babbage formulated the first ideas of programming. Konrad Zuse, who did not come aware of Babbages work until 1945-46, independently developed similar ideas of programming, but extended this with his Plankalkül language. |
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The ABC machine invented by Atanasoff, finished in 1942, was a special purpose computer and was not freely programmable. The instructions to the machine were given by buttons. The ABC can be seen as the prototype of a parallel computer with a binary fixed point arithmetic unit. The ABC was only constructed for the Gauß-Elimination Method. The machine consisted of 30 processors for the subtraction of vectors of integer numbers. It was not a machine for universal arithmetic calculations. In 1958, Konrad Zuse designed a parallel computer, which was never built. He called it the Feldrechenmaschine (field calculation machine) consisting of 50 processors. |
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The MARK I of Aiken, finished in 1944, was freely programmable, but it did not contain the concept of the separation of control unit, memory, arithmetic unit and input and output devices. It also did not use floating point arithmetic, but a decimal arithmetic unit. This machine weighed approximately 35 tons! |
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The ENIAC, designed by Eckert and Mauchly and finished around 1945/46, consisted of about 18000 vacuum tubes, was not freely programmable, and worked with a decimal arithmetic unit. The program had to be plugged with cables. However, this was the first big general-purpose electronic computer (the ABC mentioned above was a special-purpose machine). |
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From 1943-1945, ten COLOSSUS computers were built in UK in order to analyze the German codes used in World War II. The machines, which were not freely programmable and were developed for special tasks, were constructed from vacuum tubes and very fast optical punch tape readers. In 1946 Churchill gave the order to destroy the ten built machines. |
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In 1946, John von Neumann [NEUM45], [BURK46] postulated the architecture of a modern stored program computer. He required, among other things, the separation of the control unit, the memory (addressable), the arithmetic unit (Floating point was discussed) and the input and output devices. However, only a few people know, that this architecture had already been postulated in 1936 by Konrad Zuse [ZUSE36], [ZUSE37a] and implemented by him in 1938 with the Z1.
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