Introduction to Logic Gates
XOR
Contents
XOR stands for exclusive OR. XOR gates count the number of “1s” available at their inputs and if it is an even number, the output will be “0,” and if it is an odd number, the output will be “1.” (Don’t forget that zero is an even number, so when all inputs are “0”, the output will be “0”.) XOR operation is represented by the symbol ⊕. So Y = A ⊕ B. You can see XOR logic gate symbol in Figure 10 and its truth table right below it.
Figure 17: XOR logic gate.
| A | B | Y |
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
If you need more than two inputs, you will need to add another XOR gate as shown in Figure 18.
Figure 18: Expanding XOR inputs.
The most famous XOR gate integrated circuit is the 7486 and you can its pinout in Figure 19.
Figure 19: 7486 integrated circuit provides four two-input XOR gates.