Re: Any way to run .DSK images -directly- on Apple // ?

[ol.sc@web.de (Oliver Schmidt)]

Hi vladitx,

First of all thanks for thinking about it in detail :-)

>> The general approach would be copy the running ProDOS from MAIN RAM to
>> AUX RAM. Then the .dsk image would be "booted" into MAIN RAM. A rather
>> small hook into the DOS 3.3 RWTS would switch to AUX RAM, call into
>> ProDOS to read/write the appropriate data from/to the .dsk image(s)
>> and swtich back to MAIN RAM.
>
>Oliver, don't forget to context-switch all ProDOS / Dos 3.3 global
>state like zero page, $3xx page, text-screen holes, whatever else was
>there.

All this should be taken care of by using ALTZP - which I certainly
want to do because I for sure need both the MAIN and AUX language
card.

>Also you'll have to deal with interrupts that may have been
>running under ProDOS,

That's something I didn't think about so far. The worst case would be
that they just don't work - but even that wouldn't be a showstopper in
my opinion...

>and redirected I/O vectors. Maybe bunch of other
>things.

Again this should work out-of-the-box because of ALTZP:
- The DOS 3.3 vectoring in MAIN isn't touched by me at all.
- The ProDOS vectoring in AUX is never ever used.

>Another thing that will require some hacking is to make possible
>ProDOS to run out of AUX memory - it probably likes to play with the
>soft-switches a lot.

Don't forget that ProDOS is designed to work on 64k machines. So my
educated guess is that the ProDOS core doesn't do so at all. And the
/RAM driver will be unhooked for obvious reasons anyway.

>Very interesting idea, though. Good luck!

Thanks,
Oliver