Question

Draw logic symbol, timing diagram and truth table of
(i) Half adder
(ii) Half subtractor.

Answer 1

(i) Half adder

| Inputs | Sum | Carry |
| --- | --- | --- |
| A | B | Y = A + B | Y = AB |
| 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 1 |

(ii) Half subtractor.

| Inputs | Outputs |
| --- | --- |
| A | B | Difference | Borrow |
| 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 1 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 0 |