Konrad Zuse builds first freely programmable computer
The Z1 was a mechanical computer designed by Konrad Zuse from 1935 to 1936 and built by him from 1936 to 1938. It was a binary electrically driven mechanical calculator with limited programmability, reading instructions from punched tape. A reproduction of this machine (pictured) is housed in the Deutsches Technikmuseum Berlin.
The machine was a 22-bit floating point value adder and subtracter, with some control logic making it capable of more complex operations such as multiplication (by repeated additions) and division (by repeated subtractions). Z1's ISA had nine instructions and its CPI ranged from 1 to 20.
The Z1 was the first in a series of computers designed by Konrad Zuse. The Z2 and Z3 were follow-ups based on many of the same ideas as the Z1.
The computer had a 64-word floating point memory, where each word of memory could be read from and written to by the control unit. The mechanical memory units were unique in their design and were patented by Konrad Zuse in 1936. The machine was only capable of executing instructions read from the punch tape reader, so the program itself was never loaded into the memory.
The Z1 was the first freely programmable computer of the world which used Boolean logic and binary floating point numbers. It was completed in 1938 and financed completely from private funds. Konrad Zuse's first computer, built between 1936 and 1938, was destroyed in the bombardment of Berlin in December 1943, during World War II, together with all construction plans.
The Z1 contained almost all parts of a modern computer, e. g. control unit, memory, micro sequences, floating point logic (Only the logical unit was not realized) and input output devices.
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