At a trade show, I bought a
utility that allowed me to run PC-DOS under
PC/IX. I'm sure it wasn't a virtual machine.
Rather, it just swapped back and forth.
(Guessing a bit there.)
Hmm ... you sure it was not
either VPIX or DOS/Merge -- ISC built VPIX in
cooperation with the Phoenix Tech folks for
PC/IX. I always bought a copy with it, but it
may have been an option. LCC did DOS/Merge
originally as part of the AIX work for IBM and
would become a core part of OS/2 Warp IIRC.
Both Merge and VPIX had some rough edges but
certainly worked fine for DOS 3.3 programs.
The issue tended to be Win and DOS
graphics-based programs/games that played fast
and loose, bypassing the DOS OS interface and
accessing the HW directly. For instance, I
never got the flight simulator (Air War over
Germany) for Dad's WWII plane (P-47
Thunderbolt) to run under either (i.e., only
under DOS directly on the HW. FWIW: In that
mode, Dad said the simulator flew a lot like
how he remembered it).
Both Merge and VPIX used the
386 VM support and a bunch of work in the core
OS. Heinz would have to fill us in here.
The version of the 386 port ISC delivered to
AT&T and Intel only had the kernel changes
to allow the VM support for VPIX to be linked
in, but it was not there. IICR (and I'm not
sure I am) is that Merge could run on PC/IX
also, but you had to replace a couple of
kernel modules. It certainly would work on
the AT&T and Intel versions.