RE: Revisited: Sega XY freeplay

> It is pretty easy to recompile MAME and change all the ROM loader
> functions so that
> you can edit them in the debugger. If anyone needs help with this or is
> interested
> I can help with any questions.
>
> The biggest PITA about the MAME debugger is that it will only break on
> 'writes' to
> a memory location and not on a read :-( (Unless this has changed in the
> last
> 3 months).
>
Yeah, I patched the CPU emulation in a couple processors (6502 and 6809) to
allow logging of reads and writes to "computed" (for lack of a better word)
addresses like EA on the 6809. I was having trouble finding where the Exidy
gun games were hitting some copy protection since it was all EA stuff.
Since they keep chan--- 'er... improving everything in MAME my patches
usually get broken from one version to the other though so I kinda give up
keeping them working and just re-write when I need to.

The whole debugger is a little bizarre, IMHO, but since I'm not spending any
of my time to help improve it I won't bitch. A "watch" window would be nice
though. (The ICE for my SNES devsys has that-- very cool. Of course it's
also non-intrusive so you can watch areas of memory in real-time while the
code is running. Makes it incredibly easy to see what locations are used
for what functions. ;-)

I dug around at lunch and couldn't find any notes about where I found that
damn debouncing routine. Never ceases to amaze me how cryptic code can look
after you've been away from it a while! I knew the Sega G-80 really well
for a while there, and I was just scratching my head trying to follow it
now. (...and of course I only commented the sections I was working on, so
my "accidental" discoveries like the debounce are apparently not noted.
Grrrr. "Oh, that's obvious, I'll remember where that is..." ;-)

-Clay
Received on Wed Sep 1 15:34:11 1999