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From: gordon@eecea.eece.ksu.edu (Dwight Gordon)
Newsgroups: comp.sys.ibm.pc
Subject: Re: DesqView  (VGA line correction)
Message-ID: <1990Jun1.123423.29240@maverick.ksu.ksu.edu>
Date: 1 Jun 90 12:34:23 GMT
References: <4aba9e1a.20b6d@apollo.HP.COM> <2476@zipeecs.umich.edu>
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shim@zip.eecs.umich.edu (Sam Shim) writes:

>In article <4aba9e1a.20b6d@apollo.HP.COM> nelson_p@apollo.HP.COM (Peter Nelson) writes:
>>  I dunno about "most" programs.   I don't know *any* commercial graphics
>>  programs which are well-behaved in the sense that they don't make 
>>  direct writes to the VGA control registers instead of only going
>>  through the BIOS calls, except for a few which are written explicitly
>>  for a multi-tasking environment, like CorelDraw for Windows.  Certainly
>>  popular programs like PC Paintbrush IV Plus are downright naughty.  

>You can tell Desqview that the program writes directly to the screen, and
>if you want, you can turn off virtualization.  Even if the program writes
>directly to the screen and if virtualization is on, Desqview will run it
>in the background in a window.  Some programs are very naughtly (heavily
>graphics based programs and some games usually) and won't run at all or
>very well in any windowed 386 multi-tasking environment.  I guess it's a
>limitation of DOS multi-taskers.  But DOS was never designed to run in a
>multi-tasking environment in the first place so I consider multi-tasking
>programs (such as Desqview and Windows) to be remarkable programs and just
>accept the fact that not everything will work under them.

  Agreed (about DOS and multi-taskers)!  One interesting thing that I've
discovered is that certain misbehaved programs are sensitive to the '386
"protection level" setting of DesqView.  That is - they work at a particular
protection level, but don't at another.  (Maybe I should say that 
DesqView's "protection level" setting is sensitive to certain misbehaved
programs! :-)
  Another difficulty I had was with my version of "Twin" 
(spreadsheet).  Twin's auto-detection code on the monitor-type does some
reads and writes at B000:0-F.  If it detects memory there, then it assumes
that you have a Hercules card (not QEMM with back-filled memory as I
had).  Such programming style _may_ yield problems with ANY multitasker.
  By the way, I did receive written correspondence from Quarterdeck
regarding my questions about problems with VGA 320x200x256 virtualization.
They confirmed that they were aware of the problems and were "working
on them."  This is not terribly satisfying in light of the fact that the
problems have been around since version 2.22 (and we are now at version
2.26).  One positive statement is that they advised me to _not_ get the
upgrade at this time because it wouldn't necessarily have the fix that
I wanted.  (Note:  It took several weeks to answer my letter!)

- DWG -
Dwight W. Gordon, Ph.D.  |   913-532-5600    |   gordon@eecea.eece.ksu.edu
Electrical & Computer Engineering Department |     dwgordon@ksuvm.bitnet
Kansas State University - Durland Hall       | rutgers!ksuvax1!eecea!gordon
Manhattan, KS 66506      | {pyramid,ucsd}!ncr-sd!ncrwic!ksuvax1!eecea!gordon