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

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

On Mon, 24 May 2010 16:06:35 -0700, "Michael J. Mahon"
<mjmahon@aol.com> wrote:

>[...] I know that
>others here have considerable first-hand knowledge of them.  I also
>recall that there is a bit of fiddling required that I'm not familiar
>with.  (I've just never been very interested in computer games.  ;-)
>
>Search the group for DOSMASTER, I think, and perhaps another...
>
>Experts on this topic, please chime in!  ;-)

I second that - but for a slightly different reason...

I'm considering to implement a program that would allow to "run" .dsk
images on an Apple2 but I'd like to understand two things:


1. Is there already such a software?

The only thing I could find is DOS MASTER but from the documentation
its usage is way more complicated than just using a .dsk image as-is.

Don't get me wrong: DOS MASTER is surely a great piece of software and
btw. more flexible than being bound to the 140kB of .dsk images...


2. Is there a need for such a software?

To help you forming your opinion some additional info on what I have
in mind:

It would be a ProDOS system program requiring a 128kB machine. It
would know the .dsk image name to run from the 'startup file' method
and bring up a UI to choose the .dsk image if no startup file was
given. It would allow to assign up to four .dsk images to s5,1 s5,2
s6,1 s6,2.

It would be compatible _only_ with .dsk images containing software
that does its disk I/O through a "DOS 3.3 like" RWTS. That explicitly
includes DOS 3.3 clones like Diversi-DOS, David-DOS, ...

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.

That approach would require a double buffering of the data slowing
down disk access performance but on the other hand much of AUX RAM
could be used as (write-through) cache speeding up things.

Regards,
Oliver