That the presence of voltage across a switch encodes 12 is purely arbitrary… Jeff Duntemann’s book mentions:
We could as well have said that the lack of voltage indicates a binary
1 and vice versa (and computers have been built this way for obscure
I find this (italicized part) quite fascinating. It would be great if someone could shed some light on what “obscure” reason(s) may motivate people to do so?