ZUSE,KONRAD LEGACY - THE ARCHITECTURE OF THE Z1 AND Z3

This paper provides a detailed description of the architecture of the Z1 and Z3 computing machines that Konrad Zuse designed in Berlin betwe en 1936 and 1941. The necessary basic information was obtained from a careful evaluation of the patent application Zuse filed in 1941. Addit ional insight was gained from a software simulation of the machine's l ogic. The Z1 was built using purely mechanical components; the Z3 used electromechanical relays. However, both machines shared a common logi cal structure, and their programming model was the same. I argue that both the Z1 and the Z3 possessed features akin to those of modern comp uters: The memory and processor were separate units, and the processor could handle floating-point numbers and compute the four basic arithm etical operations as well as the square root of a number. The program was stored on punched tape and was read sequentially. In the last sect ion of this paper, I put the architecture of the Z1 and Z3 into histor ical perspective by offering a comparison with computing machines buil t in other countries.