The Z1 was a mechanical computer designedby Konrad Zuse from 1935 to 1936 and built by him from 1936 to 1938. It was abinary electrically driven mechanical calculator with limited programmability,reading instructions from punched tape.
The machine was a 22-bit floating pointvalue adder and subtracter, with some control logic making it capable of morecomplex operations such as multiplication (by repeated additions) and division(by repeated subtractions). Z1's ISA had nine instructions and its CPI rangedfrom 1 to 20.
The Z1 was the first in a series ofcomputers designed by Konrad Zuse. The Z2 and Z3 were follow-ups based on manyof the same ideas as the Z1.
Z1
The computer had a 64-word floating pointmemory, where each word of memory could be read from and written to by thecontrol unit. The mechanical memory units were unique in their design and werepatented by Konrad Zuse in 1936. The machine was only capable of executinginstructions read from the punch tape reader, so the program itself was neverloaded into the memory.
The Z1 was the first freely programmablecomputer of the world which used Boolean logic and binary floating pointnumbers .It was completed in 1938 and financed completely from private funds.Konrad Zuse's first computer, built between 1936 and 1938, was destroyed in thebombardment of Berlinin December 1943, during World War II, together with all construction plans.
The Z1 contained almost all parts of amodern computer, e. g. control unit, memory, micro sequences, floating pointlogic (Only the logical unit was not realized) and input-output devices.
Z1
The input and output were in decimal with adecimal exponent and the units had special machinery for converting to and frombinary. The input and output instructions would read or write a floating pointnumber. The program tape was 35 mmfilm with the instructions encoded in punched holes.
Konrad Zuse constructed the Z1 in the apartment of his parents; infact, he was allowed to use the living room for his construction. In 1936 Zusequit his job in airplane construction to build the Z1. His parents were notenthusiastic, but they did support him any way they could.
It was a privately financed machine. KonradZuse got money by his parents, his sister Lieselotte, some students of theAkademischer Verein Motiv and Kurt Pannk, an entrepreneur in Berlin.
The Z1 was in many ways a remarkablemachine. 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 electricalengine in order to give the clock frequency of one hertz to the machine. The Z1was freely programmable via a punch tape and a punch tape reader. There was aclear separation of the punch tape reader, the control unit for supervising thewhole machine and the execution of the instructions, the arithmetic unit, andthe input and output devices.
The original Z1 was destroyed by allied airraids in 1943, but in 1986 Konrad Zuse decided to rebuild the machine. Heconstructed thousands of elements of the Z1 again, and finished rebuilding thedevice in 1989. The rebuilt Z1 is displayed at the Deutsches Technikmuseum in Berlin.