What does Exclusive in XOR really mean?

Question

Maybe this is just obvious to everyone but can someone explain where XOR (or Exclusive-OR) got its name from? What does the word ***Exclusive*** really mean? Not that it matters, but its just stuck in my head since morning. OR: 0 0 0 0 1 1 1 0 1 1 1 1 XOR: 0 0 0 0 1 1 1 0 1 1 1 0 Is it "exclusively 0 for inputs 1,1", "special version of OR" or something else?

Answer 1

A B A OR B A XOR B

0 0 0 0

0 1 ! 1

1 0 1 1

1 1 1 0

"Exclusive" means that it excludes the case when both inputs are "1".

Note that to add binary digits:

A + B = (A XOR B) with a carry of (A AND B) [do this for many bits and you have a computer]