Zuse Z1

The Zuse Z1 was a mechanical calculator built by the German engineer Konrad Zuse in his parents' home between 1936 and 1938, combining mechanical components with an electric motor that supplied a one hertz clock signal to drive its operation. It worked in binary and floating point, could be programmed from punched film tape, and is considered the first freely programmable computer to use Boolean logic and binary floating point numbers, built from about 30,000 metal sheet parts and weighing roughly a tonne with sixteen words of mechanical memory. Poor synchronization caused by mechanical stress made it unreliable in practice, and the original machine was destroyed in an Allied bombing raid on Berlin in December 1943 along with its construction documents; Zuse built a replica in the 1980s, now on display at the German Museum of Technology in Berlin.