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From: ralf+@cs.cmu.edu (Ralf Brown)
Newsgroups: comp.os.msdos.apps
Subject: Re: Desqview and Ctrl/Alt/Del
Keywords: desqview ctrl/alt/del trapping programming
Message-ID: <1991Apr20.032202.16205@cs.cmu.edu>
Date: 20 Apr 91 03:22:02 GMT
References: <1991Apr19.174531.15849@midway.uchicago.edu>
Sender: netnews@cs.cmu.edu (USENET News Group Software)
Organization: School of Computer Science, Carnegie Mellon
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In article <1991Apr19.174531.15849@midway.uchicago.edu> valley@gsbsun.uchicago.edu (Doug Dougherty) writes:
}But the real question is, "Suppose you have an application that does its
}own C/A/D trapping and run it in a DV window.  DV does its own C/A/D handling,
}and the question is which one overrides.  Answer: DV."
}
}My question to the net is, "Is there a way to have the application see
}the C/A/D first?"  Any and all help appreciated; TIA...

Short answer: definitely not in the general case, and probably not at all.

Long answer: DV reprograms the interrupt controller so that it gets first
dibs on all hardware interrupts, and passes the interrupts along to the
original handlers as appropriate.  You would have to hook the reprogrammed
IRQ vector to have any chance of seeing Ctrl-Alt-Del before DV, but to do
so, you first have to find the reprogrammed IRQ....

For DESQview versions through 2.22 (and possibly as high as 2.25), IRQ1 got
moved from INT 09h to INT 51h.  For DESQview version 2.26 and up (possibly
as early as 2.23), it gets moved to the first free block of interrupts in
a search list which varies from version to version.  If you are running
QEMM 5.00 or higher, it is possible to use a VCPI INT 67h call to ask
where the IRQs are vectored.

Even if you do successfully grab C/A/D, there are other ways of killing a
DV window....
--
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