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From:	larryb AT comtch DOT iea DOT com (Larry Blanchard)
Newsgroups:	comp.os.msdos.djgpp
Subject:	interrupts - again
Date:	27 Dec 1995 16:22:39 GMT
Organization:	CompuTech
Lines:	24
Message-ID:	<4brrsf$n18@krel.iea.com>
NNTP-Posting-Host:	comtch.iea.com
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

First, let me say thanks to all who answered my previous question on
interrupts and DJGCC.

I read the FAQ, got the Intel spec, and perused PCTIME13 as well as the
timer sample that came with the compiler.  I'm still a little confused.

For example, the FAQ says "jump to the previous handler".  The info data
says "chain to the next handler".  Which is it?  Does this mean the
next/previous real mode or protected mode handler or either/both?

In PCTIME13 I more or less understand the real mode handler, but don't
see why the protected mode handler doesn't chain every time (thus getting
the clock off).  Does the EOI prevent the chaining?  Incidentally, I'm
surprised that the wrapper doesn't do the EOI but as I said, I'm still a
little confused.

Thanks for any help.

BTW, I'm also looking at an alternate solution to DJGPP.  There is a
package (SimTel) called "unreal" which turns off the limit registers
in real mode so you can access all of memory.  Its drawback is that
a 16 bit compiler can't generate the needed linear addresses, so some
amount of assembler is needed to do this.  It is, however, an interesting
concept.

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