Originally Posted by hap
I didn't find bit errors in TMNT rom. The game hits unemulated/undocumented opcodes*. I'll need to wait for more games before being able to emulate that.

*: opcode $01 especially, I assume it's a double byte opcode, or prefix to more opcodes

I will have the Contra info finished in a few days, then you can check that code to see if it also uses opcode 01.

If that's not helpful, we could try to RE the instruction PLAs, and compare Top Gun and TMNT. I haven't found any info about them in the Sharp docs, but with our experience with the TMS stuff, we might figure it out.

Maybe they had already written the code for SM510, then wanted to used the melody hardware in the SM511, so Sharp modified the instruction PLA of an SM511 to use SM510 opcodes?

I haven't had any luck tracking down any more TP0320/TP0456/TP0458 info than the 2 patents listed on Datamath.