NOR — and its inverted-input AND equivalent — logic gate symbols
coreDe Morgan drawn twice
Answer
verified equivalent (both sides → A′ · B′)
Why this example is worth doing
The same physical NOR gate has two legal symbols: an OR body with an output bubble, and an AND body with bubbles on both inputs. They are De Morgan's law in picture form, and both appear in real schematics — designers choose whichever makes the bubbles cancel against the neighbouring gates. The page presents them as alternates rather than as a puzzle, because a student meeting the inverted-input form for the first time in someone else's drawing usually assumes it is a different part.
Try your own input in the Logic gate symbols. Every gate in both symbol standards, side by side, on a printable one-page chart.
How the answer is reached
The law
(A + B)′A′ · B′— Both sides have the same truth table over the union of their variables.
Truth table
| # | A | B | F |
|---|---|---|---|
| 0 | 0 | 0 | 1 |
| 1 | 0 | 1 | 0 |
| 2 | 1 | 0 | 0 |
| 3 | 1 | 1 | 0 |