Increment Decrement Instructions
How to decode increment and decrement instructions from binary
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| 0 | 0 | X | X | D | 0 | 1 | 1 | 16-bit |
| 0 | 0 | r | 1 | 0 | D | 8-bit | ||
| (IX+d) or (IY+d) | ||||||||
| 1 | 1 | Z | 1 | 1 | 1 | 0 | 1 | DD or FD prefix |
| 0 | 0 | 1 | 1 | 0 | 1 | 0 | D | |
| d | ||||||||
| IX or IY | ||||||||
| 1 | 1 | Z | 1 | 1 | 1 | 0 | 1 | DD or FD prefix |
| 0 | 0 | 1 | 0 | D | 0 | 1 | 1 | |
| 7 | nn | 0 | ||||||
| 15 | 8 | |||||||
| Register | r |
|---|---|
| B | 000 |
| C | 001 |
| D | 010 |
| E | 011 |
| H | 100 |
| L | 101 |
| A | 111 |
| Instruction | XX |
|---|---|
| BC | 00 |
| DE | 01 |
| HL | 10 |
| A | 11 |
| Direction | D |
|---|---|
| INC | 0 |
| DEC | 1 |
| Register | Z |
|---|---|
| IX | 0 |
| IY | 1 |
Last modified November 16, 2021: Optimise decoding pages (f08ceb7)