3-input NOR, A = 0, B = 0, C = 1 — NOR gate
coreany high input forces the output low
Answer
output 0
Why this example is worth doing
One high input among three pulls the output low, because NOR's absorbing value is 1 inherited from OR. The page frames the wide NOR as an all-zeros detector, which is exactly the zero-flag circuit mentioned on the OR page, arrived at from the other side. Seeing the same hardware described twice from two starting points is worth more than either description alone.
Try your own input in the NOR gate. Truth table, symbol and algebraic form for (A + B)′, the other universal gate.
How the answer is reached
The probed row
A = 0, B = 0, C = 10— Row 1 of 8.
Truth table
| # | A | B | C | A ↓ B ↓ C |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 |
| 1 | 0 | 0 | 1 | 0 |
| 2 | 0 | 1 | 0 | 1 |
| 3 | 0 | 1 | 1 | 0 |
| 4 | 1 | 0 | 0 | 1 |
| 5 | 1 | 0 | 1 | 0 |
| 6 | 1 | 1 | 0 | 1 |
| 7 | 1 | 1 | 1 | 0 |