Z1 (computer)
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The Z1 was a mechanical computer created by Konrad Zuse in 1936. It was a binary electrically driven mechanical calculator with limited programmability, reading instructions from punched tape. A reproduction of this machine (pictured) is currently housed in the Deutsches Technikmuseum Berlin.
The machine was basically 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 program punch cards and 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 program punch cards, so the program itself was never loaded into the memory.
Today the Z1 is considered the first freely programmable computer of the world using 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 December 1943 destroyed in the bombardment of Berlin in 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).
Konrad Zuse constructed the Z1 in the apartment of his parents; in fact, he was allowed to use the living room for his construction. In 1936 Zuse quit his job in airplane construction to build the Z1. His parents were not enthusiastic, but they did support him any way they could.
It was a privately financed machine. Konrad Zuse got money by his parents, his sister Lieselotte, some students of the Akademischer Verein Motiv and Kurt Pannk, an entrepreneur in Berlin.
The Z1 was in many ways a remarkable machine. Konrad Zuse used thin metal sheets in order to construct this machine. There were no relays in it. The only one electrical unit was an electrical engine in order to give the clock frequency of one Hertz to the machine. The Z1 was freely programmable via a punch tape and a punch tape reader. There was a clear separation of the punch tape reader, the control unit for supervising the whole machine and the execution of the instructions, the arithmetic unit, and the input and output devices.
In 1986 Konrad Zuse decided to rebuild the Z1. The reason was that the Z1 contained almost all the important features of a modern computer. In 1986 he constructed thousands of elements of the Z1 again, because the original Z1 was destroyed by allied air raids in 1943. In 1989 the rebuilt Z1 was finished and can be visited in the Deutsche Technik Museum Berlin-Kreuzberg.
