Re: Digging Donkey Kong (for possible packing)

[Steve Nickolas <lyricalnanoha@usotsuki.hoshinet.org>]

Replying further to myself:

On Tue, 3 Jan 2012, Steve Nickolas wrote:

> When partly loaded, I dumped a postmortem.  Looks like B600-BFFF is a normal 
> RWTS?  Would it be hard to just gut this code and have it use a ProDOS-8 disk 
> file instead, say "DKONG.OVL", and read from that as if it were a disk image?
>
> -uso.

On the crack, the first 10 sectors of the disk correspond to the top 10 
pages of RAM (B600 and up).  Calls into this space from outside seem to 
always vector through B7B5, "Disable interrupts and call RWTS".  The 
"postmortem" is a memory image taken during the pause while the title 
screen is displayed (with Mario jumping the barrel).  In all 3 cases I 
saw, AY was set to B7E8.  There seem to be only these 3 cases outside of 
the RWTS image itself anywhere in the disk image.

I would have to investigate somewhat deeper to determine how it figures 
what sectors to load, and write a sort of "RWTS Emulator" to patch in, 
which would become part of DKONG.SYSTEM.  The remainder of the disk image 
consisting of the part used by the non-RWTS portion would be a single 
file, so all in all there would be 3 files on the disk - PRODOS, 
DKONG.SYSTEM and DKONG.DATA.  (There is plenty enough room on a 5.25" disk 
for this.)

The two files DKONG.SYSTEM and DKONG.DATA could be placed on any type of 
ProDOS-compatible device and run from anywhere.

I may also consider vectoring Ctrl-Reset into a block of code containing a 
ProDOS BYE call, so that a two-finger salute would exit to whatever 
program selector was active, e.g., GS/OS or whatall, and perhaps have the 
run code detect the IIgs and clock it down to 1 MHz.

-uso.