$420B is a the register that starts DMA transfer. So it's likely that it is the right line.

I hate to say it, but the debugger is horribly buggy. You're lucky it didn't crash on you. :x It really needs to be replaced with a more reasonable debugger solution. (Oh, it feels like 2002 all over again, *sigh*)

Building on what NC said, have you hacked the game any yet or are you still dismantling the original code? It sounds like you've corrupted the stack with your RTL.

Corrupting the stack would involve pushing and pulling the wrong number of bytes within a subroutine. For example:


That would corrupt the stack because you used a JSR instruction to get to $8080 but used an RTL instruction to return.

The JSR pushes two bytes (the return address) onto the stack and RTL pulls three bytes off of the stack (a 3 byte return address that also sets the program bank)

Thus, you would likely end up in completely different bank after the RTL executes and for all you know you could be executing data rather than code, which is very bad, mmkay. For all intents and purposes that's losing control of your code and the code will likely not recover and will probably end up in an infinite loop, wreaking havoc with the rest of the game, and eventually crashing. Since CPUs execute things so quickly it appears to us in real time to crash extremely quickly, usually.

Other ways to corrupt the stack are to push bytes to the stack like with PHA, and not pull them off the stack at the end of the routine. Sometimes there's a clever reason to not pull bytes off the stack but usually it will cause you problems.

Is there anything else to use really? Everything I've seen when trying to find out about SNES hacking has mentioned Geiger's SNES9x Debugger as what to use. Any up-and-comers that are any good?

I know what byuu would recommend... @#$% with the bsnes source for great searching! D:

Right... Someone who doesn't know what stack corruption is for an RTL instruction is going to get so much out of looking at heaps of C++ code....

I disagree with trying to pass off the idea of modifying source code for an emulator as an adequate debugging solution for all. I also disagree with source code as a replacement for documentation. Source code is a good supplement, but it's not documentation. One should not be required to know a specific programming language to read documentation.

Sorry, these things really bother me. People with this mentality assume everyone knows C++, there's no need for written explanation, everyone can code an emulator, and everyone is at an advanced level. That's just not reality.