Similar to the RES and SET instructions, there are undocumented instructions for
BIT.
Unlike the other, as BIT only tests a bit and does not change anything, these opcodes have the same behaviour to
the officially documented BIT instruction.
| 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 | |
|---|---|---|---|---|---|---|---|---|
| \(Z \longleftarrow \overline{(IX+d)_b}\) | ||||||||
| BIT b, (IX+d) | ||||||||
| 1 | 1 | 0 | 1 | 1 | 1 | 0 | 1 | DD |
| 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | CB |
| d | ||||||||
| 0 | 1 | b | r | |||||
| \(Z \longleftarrow \overline{(IY+d)_b}\) | ||||||||
| BIT b, (IY+d) | ||||||||
| 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | FD |
| 1 | 1 | 0 | 0 | 1 | 0 | 1 | 1 | CB |
| d | ||||||||
| 0 | 1 | b | r | |||||
| Register | r |
|---|---|
| B | 000 |
| C | 001 |
| D | 010 |
| E | 011 |
| H | 100 |
| L | 101 |
| A | 111 |
| Value | b | |
|---|---|---|
| 0 | 000 | |
| 1 | 001 | |
| 2 | 010 | |
| 3 | 011 | |
| 4 | 100 | |
| 5 | 101 | |
| 6 | 110 | |
| 7 | 111 | |
Z is set if the specified bit in the source is 0, otherwise it is cleared.
r=%110 does exist, it is the official, documented operation.