Finding a bug in my emulator

Finding a bug in my emulator
by oRBIT2002 on 2010-03-17 (#58496)

Balloon Fight (PAL version) plays a song during the titlescreen in my emulator. This doesn't happen on any other emulator I've tried.
Do you guys have any good hints of locating a bug like this? Or is the only way to team up with a good disassembler to locate the songrelated code?

I've tried a few CPU-testing ROMs back in the days and they all pass (with except for the illegal opcodes but I'm pretty sure Balloon Fight doesn't use them...?)

by Jeroen on 2010-03-17 (#58500)

Which emulators did you try?

by oRBIT2002 on 2010-03-17 (#58501)

FCE Ultra and Rocknes.

by qeed on 2010-03-17 (#58508)

Well if its sound then its just the APU, rather than the CPU. Check your $4015/$4017 code to see if the logic is correct or not, see if it is turning on when its not supposed to.

by Dwedit on 2010-03-17 (#58514)

I know of a bad dump of Balloon Fight floating around that plays music at the title screen if you zero-initialize your RAM. It doesn't play music if the ram is initialized to something else.
But this may or may not be a different problem.