TL;DR

How do you tell which side of an XOR wins?

Hi!

I was wondering if there’s a systematic way to find out which operand of an XOR is true?

Not directly because the operation is symmetric: it provides the same result for 0^1 and 1^0 (where the caret is the xor operator).

However, you can construct a more complicated expression that does what (I think) you're looking for. Try A&(A^B), which will be one or zero according to whether A or B was the "winner" when A and B are different.
If they're not different there is no "winner" and this expression will evaluate to zero indicating that A didn't win; and likewise B&(A^B) will indicate that B didn't win either.

Last edited: Tuesday, 11:55 PM

If A,B aren't accessible you can still know the Tac Tbc delays ( C = A XOR B )
In that case recording the transitions you can estimate which transition has caused C 0-> 1
This works only on real systems.

The system can be "observable" also if not "directly observable"