The German computer pioneer Konrad Zuse had already developed his first ideas for a computer in 1936 and subsequently built the mechanical computer “Z1”. This was one of the first universal computers to calculate in the binary system.  In the Arithmeum, participants will get to know the later, transistor-based computer “Z25” from 1961, which was used for research purposes at the University of Essen, among other things. Participants will learn about the binary system and the early beginnings of German computer development.