Re: EMM386 not installed - protected mode software already running.

[Bryan J Smith <b.j.smith@ieee.org>]

If it's PharLap286, I want to almost say -- for certain -- it's first-gen, Ring 
0 gobbling VCPI.

Again, an additional test is to try it on 32-bit NT (4-6) and its NTVDM.  If it 
doesn't work (try several), then it's not DPMI compatible and taking issue with 
something else holding Ring 0.  DPMI really addresses all of the shortcomings of 
VCPI, and allows multi-tasking (really task sharing, to a point, long story) in 
DOS.  As such, real, 32-bit Virtual86/Protected386 operating systems (NT/NTVDM, 
Linux/DOSEmu, etc...) can then offer DPMI with the same capabilities.

I also mentioned DOSBox.  DOSBox can actually emulate Ring 0, including for some 
VCPI programs.  According to the status page, it seems to be limited to Origin 
games, don't know what extender they used.  Could be unrelated to PharLap and 
most early, VCPI-based implementations.  But it's worth a shot.
  http://www.dosbox.com/status.php?show_status=1  

DOSBox isn't a full DOS in the traditional sense, but a DOS emulator that 
doesn't require DOS itself.  DOSEmu is more like a virtualized DPMI environment, 
and then you run DOS under it -- like NTVDM in NT/Windows, although Microsoft 
bundles the required DOS support (DOS kernel, COMMAND.COM instead of NT's native 
CMD.EXE, etc...).

-- Bryan

P.S.  For several years Concurrent (among others) was marketing itself as a 
networked/remote terminal, multiuser DOS solution.  Understand these solutions 
are based on DR-DOS and DPMI-based DPMS, and will also be incompatible with VCPI 
if those services load.  Only Real86 DOS without anything using DPMI or an 
emulated DOS under another OS, with Ring 0 available (emulated) will work, for 
most of those early extenders.


----- Original Message ----
From: Steve Cohen <stevecoh1@comcast.net>

Thanks for this information, Bryan.  Unfortunately, it, together with 
further investigations into our source code base, convinces me that our 
application does indeed depend on the VCPI-based early versions of 
PharLap (I didn't know where to look previously) and will ultimately 
prove to be incompatible with DOSEmu.  Some of the PharLap links are 
pretty loose and could possibly be converted to work differently, but 
some of the third party stuff like Greenleaf Comms is pretty tightly 
linked with PharLap286 and I don't think we want to be changing that.

But that's okay, this little walk down "memory lane" (pun intended) 
didn't waste too much time and has given me some other ideas besides 
rewrite that may ultimately prove more fruitful.

I'd like to thank all you guys here for your support,  Viva Open Source.



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