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The 6510 (C64 6502 with extra ports) has secret opcodes, basically holes in the circuitry, which emulators have to support because they're used in demos for ext
by zandorg 16y ago
The 6510 (C64 6502 with extra ports) has secret opcodes, basically holes in the circuitry, which emulators have to support because they're used in demos for extra speed (eg, write to x what's in a).
I wonder if this simulation also has secret opcodes?
- kragen 16y agoI thought TAX was one of the standard 6502 opcodes?
- zandorg 16y agoCouldn't think of a decent example off the top of my head. Also, proper term is 'undocumented opcodes' for further searching. Try "AXS * (SAX) AXS ANDs the contents of the A and X registers (without changing the contents of either register) and stores the result in memory. AXS does not affect any flags in the processor status register." http://www.ffd2.com/fridge/docs/6502-NMOS.extra.opcodes http://www.ffd2.com/fridge/docs/6502-NMOS.extra.opcodes