Problem: To convert a decimal digit stored as an excess-3 number to a BCD number. Implement the circuit using AND-OR logic
Solution: This circuit will require 4 inputs and 4 outputs. Here is the truth table:
| Decimal | X-3 | BCD | ||||||
| Digit | w | x | y | z | A | B | C | D |
| 0 | 0 | 0 | 0 | x | x | x | x | |
| 0 | 0 | 0 | 1 | x | x | x | x | |
| 0 | 0 | 1 | 0 | x | x | x | x | |
| 0 | 0 | 0 | 1 | 1 | 0 | 0 | 0 | 0 |
| 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| 2 | 0 | 1 | 0 | 1 | 0 | 0 | 1 | 0 |
| 3 | 0 | 1 | 1 | 0 | 0 | 0 | 1 | 1 |
| 4 | 0 | 1 | 1 | 1 | 0 | 1 | 0 | 0 |
| 5 | 1 | 0 | 0 | 0 | 0 | 1 | 0 | 1 |
| 6 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | 0 |
| 7 | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 1 |
| 8 | 1 | 0 | 1 | 1 | 1 | 0 | 0 | 0 |
| 9 | 1 | 1 | 0 | 0 | 1 | 0 | 0 | 1 |
| 1 | 1 | 0 | 1 | x | x | x | x | |
| 1 | 1 | 1 | 0 | x | x | x | x | |
| 1 | 1 | 1 | 1 | x | x | x | x |
