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From: dhinds@portia.Stanford.EDU (David Hinds)
Newsgroups: comp.sys.ibm.pc,comp.sys.ibm.pc.programmer
Subject: Re: programs crashing in Desqview
Message-ID: <9631@portia.Stanford.EDU>
Date: 28 Feb 90 17:46:41 GMT
References: <48e591a9.20b6d@apollo.HP.COM> <29312@amdcad.AMD.COM>
Sender: David Hinds <dhinds@portia.stanford.edu>
Followup-To: comp.sys.ibm.pc
Distribution: usa
Organization: Stanford University
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In article <29312@amdcad.AMD.COM>, phil@pepsi.amd.com (Phil Ngai) writes:
> In principle a 386 PC should be able to run DOS jobs in a 
> virtual 8086 and any crashes should not affect the other jobs.
> In practice I do not know if DV does this. I think DV still
> runs in real mode even on a 386. However, OS/2 R 2 is supposed
> to use the virtual 8086 mode.
> 
    QEMM puts an 80386 PC in virtual 86 mode.  It is reasonably good at
insulating things, but occasionally gets confused if you use unsupported
hardware.  So, for example, I can use super VGA software in DV, but if I
try to ctrl-alt-del from an extended mode, DV is sometimes unable to
restore the video card to a reasonable state.  It will always recover
when my ethernet drivers hang, though, which is nice because my PC/IP
software is less than perfect.  The virtual 8086 mode is crucial for all
of QEMM's memory mapping functions, because the 80386's memory management
can only be played with in protected mode.  QEMM is the protected-mode
supervisor for DV.

 - David Hinds
   dhinds@popserver.stanford.edu