I'm not sure . The m6502 uses encrypted opcodes and the m6502 core we're using doesn't separate ops and args. I went through the core as best I could and replaced all fetches except for the one calling the opcode in m6502_execute with a new routine (hardwired to read from rom atm). I also had to hook it up to the burntimer system.
So along the way, one of these things isn't working properly and I have to track it down. Hard to tell really, as the m6502 does seem to be working. I'll definitely pass it on if you feel like giving it a looksee.