A half adder and a full adder are both combinational logic circuits used in digital electronics to perform arithmetic operations. The main difference between the two is that a half adder adds two input bits and generates a carry and sum, while a full adder adds three input bits and generates two outputs, a sum and a carry).
A half adder consists of two input terminals, A and B, and two output terminals, sum (S) and carry (C). The output of the EX-OR gate is the sum of the two bits, while the output of the AND gate is the carry. The output carry is not used in the next addition). The truth table for a half adder is:
| A | B | C | S |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 |
| 1 | 0 | 0 | 1 |
| 1 | 1 | 1 | 0 |
A full adder, on the other hand, adds three input bits, A, B, and C-in, and generates two outputs, a sum (S) and a carry (C-out). The first two inputs are A and B, while the third input is an input carry as C-in. The output carry is designated as C-out and the normal output is designated as S which is SUM. The equation obtained by the EX-OR gate is the sum of the binary digits. The previous carry is used in the next addition). The truth table for a full adder is:
| 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 |
In summary, a half adder adds two input bits and generates a carry and sum, while a full adder adds three input bits and generates two outputs, a sum and a carry. The main difference between the two is the number of inputs they can handle and the use of the previous carry in the next addition).
