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STZ: Difference between revisions
From SnesLab
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Revision as of 07:08, 20 November 2023
| Basic Info | |||||||
|---|---|---|---|---|---|---|---|
| Addressing Mode | Opcode | Length | Speed | ||||
| Absolute | 9C | 3 bytes | 4 cycles* | ||||
| Direct Page | 64 | 2 bytes | 3 cycles* | ||||
| absolute indexed X | 9E | 3 bytes | 5 cycles* | ||||
| direct page indexed X | 74 | 2 bytes | 4 cycles* | ||||
| Flags Affected | ||||||||
|---|---|---|---|---|---|---|---|---|
| N | V | M | X | D | I | Z | C | |
| . | . | . | . | . | . | . | . | |
STZ (Store Zero) is a 65c816 instruction that zeros out memory. STZ takes one additional cycle if the accumulator is 16 bits wide, in all addressing modes. In direct page addressing modes only, STZ takes another additional cycle if the low byte of the direct page register is nonzero.
See Also
External Links
- Eyes & Lichty page on STZ: https://archive.org/details/0893037893ProgrammingThe65816/page/n533
- Labiak page on STZ: https://archive.org/details/Programming_the_65816/page/n198
- snes9x implementation of STZ: https://github.com/snes9xgit/snes9x/blob/master/cpuops.cpp#L1317
- undisbeliever on STZ: https://undisbeliever.net/snesdev/65816-opcodes.html#stz-store-zero-to-memory