Full Adder
The full-adder is adds three one-bit binary numbers (C A B) and outputs two one-bit binary numbers, a sum (S) and a carry (C1). The full-adder is usually a component in a cascade of adders, which add 8, 16, 32, etc. binary numbers. The carry input for the full-adder circuit is from the carry output from the circuit "above" itself in the cascade. The carry output from the full adder is fed to another full adder "below" itself in the cascade.
Full adder symbol
Full adder circuits
Full adder truth table
| A | B | C.in | C.out | S |
|---|---|---|---|---|
| 0 | 0 | 0 | 0 | 0 |
| 0 | 0 | 1 | 0 | 1 |
| 0 | 1 | 0 | 0 | 1 |
| 0 | 1 | 1 | 1 | 0 |
| 1 | 0 | 0 | 0 | 1 |
| 1 | 0 | 1 | 1 | 0 |
| 1 | 1 | 0 | 1 | 0 |
| 1 | 1 | 1 | 1 | 1 |