Couldn'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

Couldn'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