Focus: Boolean expressions, symbols, truth tables and universal gates.
1) OR Gate
Boolean expression:
Y = A + B
Truth Table:
| A | B | Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
2) AND Gate
Boolean expression:
Y = A · B
Truth Table:
| A | B | Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
3) NOT Gate
Boolean expression:
Y = A̅
Truth Table:
| A | Y |
|---|---|
| 0 | 1 |
| 1 | 0 |
4) NAND Gate
Boolean expression:
Y = (A · B)̅
Truth Table:
| A | B | Y |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
5) NOR Gate
Boolean expression:
Y = (A + B)̅
Truth Table:
| A | B | Y |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 0 |
6) XOR (Exclusive OR) Gate
Boolean expression:
Y = A̅B + AB̅
Truth Table:
| A | B | Y |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
7) Universal Gates
- NAND and NOR gates are called universal gates.
- Any logic gate can be constructed using only NAND gates.
- Any logic gate can be constructed using only NOR gates.
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Last modified: December 14, 2025
