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WDM: Difference between revisions
From SnesLab
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* [[Eyes & Lichty]] page on WDM: https://archive.org/details/0893037893ProgrammingThe65816/page/n549 | * [[Eyes & Lichty]] page on WDM: https://archive.org/details/0893037893ProgrammingThe65816/page/n549 | ||
* snes9x implementation of WDM: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3335 | * snes9x implementation of WDM: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3335 | ||
* undisbeliever on WDM: https://undisbeliever.net/snesdev/65816-opcodes.html#wdm-reserved-for-future-expansion | |||
[[Category: ASM]] | [[Category: ASM]] | ||
[[Category:65c816 additions]] | [[Category:65c816 additions]] | ||
Revision as of 04:15, 18 May 2023
WDM (the initials of William David Mensch, the designer of the 65c816) is an instruction that reserves its signature byte for future expansion of the instruction set. None of these extra 256 opcodes were ever implemented, so WDM functions essentially as a two-byte NOP.
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| 42 | 2 byte | 2 cycles | |||||
| Flags Clobbered | |||||||
|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C |
| . | . | . | . | . | . | . | . |
Trivia
The Labiak textbook does not describe the WDM instruction.
External Links
- Eyes & Lichty page on WDM: https://archive.org/details/0893037893ProgrammingThe65816/page/n549
- snes9x implementation of WDM: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L3335
- undisbeliever on WDM: https://undisbeliever.net/snesdev/65816-opcodes.html#wdm-reserved-for-future-expansion