First, let's see what we get if both a=0 and b=0, by tracing
what happens on the circuit diagram:
By repeating the above for (1) a=0 and b=1 (2) a=1
and b=0 (3) a=1 and b=1, our completed
Does this logic table look like that of a gate we already know?
Click here for the exciting
It's the logic table for the OR gate! This proves
that (theoretically) we really don't need OR; we can build it out
of AND and NOT!