<P> 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 celluloid film . </P> <P> The Z1 was the first freely programmable computer in the world which used Boolean logic and binary floating - point numbers, however it was unreliable in operation . It was completed in 1938 and financed completely from private funds . This computer was destroyed in the bombardment of Berlin in December 1943, during World War II, together with all construction plans . </P>

Who built the world's first binary digital computer z1