VP/ix ran on both System III and UNIX System V/386 Release 3.2.
I do still have a copy of the VP/ix Environment documentation
and the diskettes for the software. I have the "Introduction to the
VP/ix Environment" for further reference for interested folks.

Also found some information about VP/ix on these web pages:
     1. 
https://virtuallyfun.com/2020/11/29/fun-with-vp-ix-under-interactive-unix-system-v-386-3-0-and-86box/
     2. 
https://techmonitor.ai/technology/interactive_systems_is_adding_to_vpix_with_a_little_help_from_its_friends
     3. 
https://manualzz.com/doc/7267897/interactive-unix-system-v-386-r3.2-v4.1---release

It's been a long time since I looked at this.

Heinz

On 3/13/2024 8:53 AM, Clem Cole wrote:
> Thanks.  Fair enough.  You mentioned PC/IX as /ISC's System III/
>
> I'm not sure I ever ran ISC's System III port—only the V.3 port - 
> which was the basis for their ATT, Intel, and IBM work and later sold 
> directly. I'm fairly sure ISCalso called that port PC/IX, but they 
> might have added something to say with 386 in the name—I've forgotten. 
> [Heinz probably can clarify here]. Anyway, this is likely the source 
> of my thinking. FWIW: The copy of PC/IX for the 386 (which I still 
> have on a system I have not booted in ages) definitely has VPIX.
> ᐧ
>
> On Wed, Mar 13, 2024 at 11:28 AM Marc Rochkind <mrochkind@gmail.com> 
> wrote:
>
>     @Clem Cole <mailto:clemc@ccc.com>,
>
>     I don't remember what it was. But, the XT had an 8088, so
>     certainly no 386 technology was involved.
>
>     Marc
>
>     On Wed, Mar 13, 2024 at 8:38 AM Clem Cole <clemc@ccc.com> wrote:
>
>         @Marc
>
>         On Tue, Mar 12, 2024 at 1:18 PM Marc Rochkind
>         <mrochkind@gmail.com> wrote:
>
>             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.
>         ᐧ
>
>
>
>     -- 
>     /My new email address is mrochkind@gmail.com/
>