Half Adder
A Half Adder adds two 1-bit inputs (A and B), producing a Sum (XOR) and a Carry (AND) output.
Half Adder Circuit
SUM = 0
CARRY = 0
Binary result: A + B = 00
Truth Table
| A | B | Sum (XOR) | Carry (AND) |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 1 |
How It Works
SUM = A XOR B
XOR outputs 1 when inputs differ. This is the least-significant bit of the sum.
CARRY = A AND B
AND outputs 1 only when both inputs are 1. This carry feeds into the next bit position.
Example: 1 + 1 = 10₂
When A=1, B=1: Sum=0, Carry=1. Binary result is 10 (which equals 2 in decimal).