Thread: logic

Originally Posted by srk619

ive got a circuit diagram for which i need to make a truth table, the diagram is attach to the question


ive tryed to make the truth table but i am not sure if it is right, this is what i have come up with

A B Out
0 0 1
0 1 1
1 0 0
1 1 0

No, that's not quite right. Consider: Input A goes directly to one of the inputs of the or-gate. Thus Out will be 1 if A is 1: so the last two entries for Out in your table should both be 1 (not 0).
Otherwise, if A is 0, then all depends on whether the second input of the or-gate happens to be 0 or 1. Since B gets inverted before it is fed into this second input of the or-gate you find that Out is 1 if B is 0.

To sum up, the truth table, as I see it, should be
A B Out
0 0 1
0 1 0
1 0 1
1 1 1
So only the first row of your truth table was correct.

thanks for the help failure