The half adder in one table
A reminder from Module 2. The half adder adds two bits and produces a sum bit and a carry bit. Its truth table:
| a | b | carry | sum |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 |
| 1 | 0 | 0 | 1 |
| 1 | 1 | 1 | 0 |
Read carry and sum together and they are the 2-bit total of a + b.