76 Half Adder
76 : Half Adder
- Author: Janani P Srinivasan
- Description: 1 bit Half Adder
- GitHub repository
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How it works
A Half adder is used to perform a single bit addition where the sum and carry is displayed in the output.
The sum of the adder is given by XORing the inputs A and B.
The carry of the adder is given by performing an AND operation between A and B.
How to test
Half adder can be tested and expressed by:
Sum (S) = A XOR B
Carry (C) = A . B
| A | B | S | C |
|---|---|---|---|
| 0 | 0 | 0 | 0 |
| 0 | 1 | 1 | 0 |
| 1 | 0 | 1 | 0 |
| 1 | 1 | 0 | 1 |
| Table: Truth table for the half adder |
External hardware
Two LED bulbs are connected at the output of sum and carry. The LED will blink when the respective values are high.
IO
| # | Input | Output | Bidirectional |
|---|---|---|---|
| 0 | IN0 | OUT0 | |
| 1 | IN1 | OUT1 | |
| 2 | |||
| 3 | |||
| 4 | |||
| 5 | |||
| 6 | |||
| 7 |