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DEC (SPC700)
From SnesLab
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Accumulator | 9C | 1 byte | 2 cycles | ||||
| Direct Page | 8B | 2 bytes | 4 cycles | ||||
| Direct Page Indexed by X | 9B | 2 bytes | 5 cycles | ||||
| Absolute | 8C | 3 bytes | 5 cycles | ||||
| Implied (type 1) | 1D | 1 byte | 2 cycles | ||||
| Implied (type 1) | DC | 1 byte | 2 cycles | ||||
| Flags Affected | |||||||
|---|---|---|---|---|---|---|---|
| N | V | P | B | H | I | Z | C |
| N | . | . | . | . | . | Z | . |
DEC is an SPC700 instruction that decrements its operand by one.
Syntax
DEC A DEC dp DEC dp+X DEC !abs DEC X DEC Y
The above are official, but some people prefer alternate mnemonics like:
DEA DEX DEY
See Also
External Links
- Official Super Nintendo development manual on DEC: Appendix C-7 of Book I
- anomie: https://github.com/yupferris/TasmShiz/blob/8fabc9764c33a7ae2520a76d80ed7220bb939f12/spc700.txt#L415