Difference between revisions of "Z80 wait instructions"
From MSX Game Library
| Line 19: | Line 19: | ||
| <tt>NOP<br/>NOP<br/>NOP<br/>NOP</tt> || 20 || 4 || None | | <tt>NOP<br/>NOP<br/>NOP<br/>NOP</tt> || 20 || 4 || None | ||
|- | |- | ||
| − | | <tt>CP (IY+0)</tt> || 21 || 3 || | + | | <tt>CP (IY+0)</tt> || 21 || 3 || C, S, and Z flags modified by definition. P/V detects overflow. |
|- | |- | ||
| − | | <tt>BIT 0,(IY+0)</tt>|| 22 || 4 || | + | | <tt>BIT 0,(IY+0)</tt>|| 22 || 4 || Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |
|} | |} | ||
Revision as of 23:12, 2 March 2024
Z80 instruction set that don't change registers value (except for F register):
| Inst. | TS | Bytes | Flag modification |
|---|---|---|---|
| NOP | 5 | 1 | None |
| OR 0 | 8 | 2 | C and N flags cleared, P/V detects parity, and rest are modified by definition. |
| NOP NOP |
10 | 2 | None |
| LD R,A | 11 | 2 | ??? |
| NOP OR 0 |
13 | 3 | C and N flags cleared, P/V detects parity, and rest are modified by definition. |
| BIT 0,(HL) | 14 | 2 | Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |
| NOP NOP NOP |
15 | 3 | None |
| NOP NOP NOP NOP |
20 | 4 | None |
| CP (IY+0) | 21 | 3 | C, S, and Z flags modified by definition. P/V detects overflow. |
| BIT 0,(IY+0) | 22 | 4 | Opposite of the bit #0 is written into the Z flag. C is preserved, N is reset, H is set, and S and P/V are undefined. |