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From: ralf@b.gp.cs.cmu.edu (Ralf Brown)
Newsgroups: comp.sys.ibm.pc
Subject: Re: MS-DOS Multitaskers
Message-ID: <2279@pt.cs.cmu.edu>
Date: 15 Jul 88 02:44:53 GMT
References: <10904@cisunx.UUCP> <5404@ecsvax.uncecs.edu> <3614@peora.ccur.com>
Sender: netnews@pt.cs.cmu.edu
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Organization: Carnegie-Mellon University, CS/RI
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In article <3614@peora.ccur.com> joel@peora.UUCP writes:
}In article <5404@ecsvax.uncecs.edu>, gas@ecsvax.uncecs.edu (Guerry A. Semones)
} to do BIOS writes rather than direct screen writes. Can Desqview really
} window stuff that bypasses the BIOS? I can't think of any any handy
} way to intercept the writes to the display memory on a non-386 based
} machine. Of course I'm not a hacker when it comes to my PC.

While DESQview can't intercept direct writes on less than a 386, more and more
programs are DESQview-aware.  Any program which writes directly to screen
memory has to determine where the screen memory is and store that value away
somewhere.  By adding ten lines of assembler or equivalent HLL code, it is
possible to make the program write into DESQview's shadow buffer, which can
then be windowed.

There is even a small TSR available that helps in patching in 
DESQview-awareness.  You change (with DEBUG) the actual instruction that
loads the screen address into an interrupt call, and the TSR replaces the
value with DESQview's buffer.
-- 
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