The Zuse Z4 is considered the oldest preserved computer in the world. Manufactured in 1945 and overhauled and expanded in 1949/1950, the relay machine was in operation on loan at the ETH Zurich from 1950 to 1955. Today the huge digital computer is located in the Deutsches Museum in Munich. The operating instructions for the Z4 were lost for a long time. In 1950,  ETH Zurich was the only university in continental Europe with a functioning tape-controlled computer. From the 1940s, only one other c...