Support for Unofficial Opcodes

[airloaf]

If we look at the op code table we have defined, there are many gaps. These gaps represent unofficial opcodes. While they were not intended to be used as instructions, an actual 6502 cpu can still process it as an instruction.

NESDev Unofficial opcodes This site right here has a list of unofficial opcodes. It even details some NES games which utilize such opcodes. For a true NES emulator these would have to be implemented into the 6502 CPU library.