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Old 12-01-2005, 08:22 PM   #3
Senior Member
Join Date: Mar 2002
Location: Albany, NY
Posts: 4,014
Default Re: Any Genesis emulators with good debuggers?

] If you know enough about the Genesis to write a tracked
] music format, and you know enough about its hardware to
] create the necessayr CPU emulator for such a format, and you
] know enough abrout programming to accomplish both these
] tasks, you should know enough to add a basic debugger to the
] existing code (assuming the author bothered to comment
] anything).

I said I was looking into the potential for one, not that I was looking to explicitly create one along with the player to go with it. So please, lose the high-horse act and the generally unhelpful "do it yourself" attitude. It's not helping anyone.

I was experimenting with MESS and Megaman: The Wily Wars, and managed to locate an appropriate memory location that, when written to, would trigger various sound effects. The problem is the fact that MESS never actually progresses past a black screen on the game, so I was "running blind". The 68000's program had crashed/looped infinitely or whatnot, but it at least ran far enough to have uploaded the main sound-related code to the Z80, so I was able to poke about in MESS's debugger and see where it was reading some locations. After plugging in some values where the Z80 was reading, I found that it started playing a different sound effect based on the value I put in. The issue is that without the 68k running, the Z80 didn't have any music data uploaded to it, just the sound program itself, so sound effects were all I'd be able to get out of it.

Perhaps it's beyond such a great hacker like you to realize this, but sometimes people try to do things not with the end result of coming up with some wonderful utility, but simply out of intellectual curiosity and a desire to experiment. If I were able to find a Genesis emulator with a debugger that supports breakpoints, I would at least be able to satisfy my curiosity by figuring out what memory location, for Megaman: The Wily Wars at least, controls what music track is currently playing. I find it an intriguing question to think about how a ripped music format might be created for the Genesis. I think the most likely way to create one would be to have the same general idea as an SPC - save a dump of the registers and memory of the sound processor (in this case, a Z80 instead of an SPC700) just before the play command is issued. A problem arises from the fact that the Z80 can communicate with the 68k a bit more thoroughly than the SNES's SPC can communicate with the 65816, especially for things like DMA-driven sound samples. I'm curious as to how that could be avoided without explicitly emulating the 68k as well as the Z80, and without requiring the full cartridge ROM (since the Z80 can request data transfers from the cartridge) to be distributed with the rip.

So as you can see, I'm not looking to create a ripped format. I'm looking into how feasible a ripped format would be, which you'd have realized had you actually read my post instead of reading it halfway, then diving in head-first at the slightest chance to talk down to me, you arrogant prick. <img src=smilies/headshake.gif>
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