[cctalk] Re: the 1968 how to build a working digital computer

I would say digital a common relay has two states open or closed, when you energize the coil it draws in the armature which will open or close the relay's contacts. Konrad Zuse built his first digital computer using largely relay logic in 1940, but his work was not widely known until well after WWII due to him working mostly by himself in Germany.  He was aware that vacuum tubes could be used as logic elements, even having one demonstrated to him by a friend, but stuck with relays as they where easier to obtain.

Paul.

There is a replica of this Model in the Museum of Traffic and Technology in Berlin. Back then it didn't function well, and in that regard the replica is very reliable — it also doesn't work well. — Konrad Zuse