[Coco] calling all MM/1 owners

Joel Ewy jcewy at swbell.net
Wed Jan 23 22:26:26 EST 2008

Bob Devries wrote:
> Mark,
> Even if I hold the MM/1's reset button until I feel sure the drive is
> properly initialised, it still locks up the SCSI bus.
> Another niggling problem which has just been recalled to my memory (I
> just saw it happen) is that occasionally the computer comes up in
> weird screen colours instead of those set in the INIT module.
I occasionally get the weird palette as well.
> These problems are of course very minor, but detract somewhat from an
> otherwise perfectly working unit.
> BTW has anyone thought of doing an MM/1 (or similar) emulator?
I've thought about it.  Not so much about actually doing it myself, but
about how it might be done.  Here is my idea:  do it in stages, starting
with the Aranym Atari emulator.  Aranym is capable of running Debian
M68k, and in fact is used to build Debian packages for the 68k
architecture.  Unfortunately, my attempts to run Atari OS-9 on Aranym
have so far failed.  But the first step would be to make Aranym run
OS-9.  Then replace the emulated Atari hardware with MM/1 compatible
emulated hardware on an OS-9 module-by-module basis.  E.g:  Add support
to Aranym for the MM/1's floppy controller chip (which could probably be
stolen from some PC emulator), add the MM/1's floppy, SCSI, RTC, DAC/ADC
device driver and descriptors to an already working system, and then
remove the corresponding Atari hardware when the MM/1 equivalent is
working properly.  Finally, emulate the VSC and you've got an emulated
MM/1.  The Atari already has the MC68901 MFP that the MM/1 has two of,
so some of the hardware is already there, albeit being used in a
somewhat different way.

And an emulated MM/1 is just a couple steps away from an emulated CD-i
player.  Add a second VSC and figure out how to emulate the CD-i's
CD-ROM interface -- or don't, and just replace the driver in the CD-i's
ROM with an MM/1 SCSI driver and you have a functional equivalent
without having to reverse engineer and emulate the underlying hardware. 
CD-i titles weren't allowed to hit the hardware directly, so as long as
you can provide an OS-9 driver that presents the same interface, the
underlying hardware for doesn't matter.  Such is the beauty of OS-9.

> Regards, Bob Devries, Dalby, Queensland, Australia
> Isaiah 50:4 The sovereign Lord has given me
> the capacity to be his spokesman,
> so that I know how to help the weary.
> website: http://www.home.gil.com.au/~bdevasl
> my blog: http://bdevries.invigorated.org/

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