Re: Ripping sound routines?

[Toinet <antoine.vignau@laposte.net>]

On 8 mar, 21:08, lyricalnan...@dosius.ath.cx (Steve Nickolas) wrote:
> Toinet wrote:
> > On 8 mar, 14:53, lyricalnan...@dosius.ath.cx (Steve Nickolas) wrote:
> >> This is more an experiment than anything. I'd like to isolate the
> sound
> >> code for the Munchers/Odell Lake games (they use the same sound effects),
> >> though I'm not sure where to start, there's only one reference to $C030
> >> in
> >> main memory of Odell afaict, at $7FC8, and the routine it's in doesn't
> >> seem
> >> to be the one that generates the sounds I'm looking for. I might need
> to
> >> look a bit deeper.
>
> >> -uso.
>
> > - Replace AD 30 C0 or 2C 30 C0 or whatever the opcode is with a BRK
> > opcode and see whether it is that routine that is called.
> > - Otherwise look at $0300, short sound routines like that page.
> > - If the sound code plays after a Hi-Res is displayed, search for
> > $C050 as well and trace the code.
>
> > It reminds me of some old cracks...
>
> > antoine
>
> I used ApplePC to stuff a BRK over the $2C 30 C0 at 7FC7 (the 30 C0 I found
> with KEGS), and lo and behold it crashed into the monitor.  So I guess I'd
> need to trace around that.
>
> 7FC9-    M=0A A=1D X=02 Y=01 P=30 S=EB
> *
>
> Right over the graphics display.  I guess that means I'm on to something,
> but I'd prolly need to figure out *what* ...
>
> -uso.

Good.

Now, reverse boot trace:
- go backwards from 7FC9 to 7F00 then 7E00, etc. and find a RTS
e.g. you find a RTS at $7F51. That means a routine "may" begin at
$7F52. Then perform a search of $7F52, you will probably find a JSR
$7F52, etc. etc. etc. You will then find the real entry point of your
sound routine

Feel free to send one disk image to my email address, I'd be glad to
have a look at it.

antoine