This is a slight digression, but I strongly suspect that master/slave in technical contexts originated as a pun. It was normal practice to refer to a canonical

This is a slight digression, but I strongly suspect that master/slave in technical contexts originated as a pun. It was normal practice to refer to a canonical or primary object as the "master _____", with the same meaning as "main". My guess is that some point someone wanted to refer to a subordinate object, noted that "master" can also mean "owner of a slave", and the obvious pun fit well enough to stick.