doesn't this require a dot-based PPU?
That was the joke, heh, sorry

r7695 /src/emu/cpu/g65816/ (g65816.c g65816op.h): Added boundary checks for MVN and MVP opcodes in the G65816 CPU core, fixes booting in Iso Zuri Ritou Hen
Also be sure to set the DB register for good from these opcodes. But yeah, when you have opcodes that touch A
and X+Y, it only cares about the state of
either M or X, and never both. In the case of MVN and MVP, it cares about the state of P.X, and always treats A as 16-bit.