ProDOS filecracking

[Steve Nickolas <usotsuki@buric.co>]

I used a few different methods when I filecracked Qix, Pick-A-Dilly Pair 
and Rocky's Boots for ProDOS, and these are probably the most viable 
methods.

For Galaxian and Ms. Pac-Man (not ProDOS-cracked but they'll work on 
ProDOS) I simply did a memory dump and saved it.  This is the most basic 
method and works well with files that do not need a lot of memory to load.

For Qix, I did a memory dump, but it was too big to hold in one file, so I 
wrote a multistage loader around the memory dump.  This method works best 
for stuff that loads all at once, but will not fit in one file.

For Rocky's Boots, which was already separate files and mostly vectored 
through DOS 3.3, I replaced its weird "load-through-reboot" mechanism with 
a more normal one, but the in-game reload strategy was just to replace the 
function that reloaded the menu, in 0800-08FF, with a ProDOS equivalent.

For Pick-A-Dilly Pair, I took a function that did sector reads, and 
replaced it with one that read the corresponding files.

Generally I only need 512 bytes free at *all* times, with an additional 
1-1.5K free when doing loads.

With Donkey Kong, I have found the functions, but not the code to set 
their parameters.  This is an RWTS program; I have plenty of room (up to 
1K) for my loader code.

With Karateka and Arkanoid, I haven't found anything yet.

With Mr. Do!, there just isn't enough memory to use this technique.

I haven't tried anything else yet.

I'd like to find as many games as possible and adapt them to ProDOS, so 
that they aren't tied to floppy disks.

-uso.