From:	"smile773" <smile773 AT bigfoot DOT com>
Newsgroups:	comp.os.msdos.djgpp
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Subject:	Re: DPMI (How it works in simple terms, where to find)
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Date:	Tue, 20 Jun 2000 07:32:07 GMT
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Chris
DPMI (DOS Protected Mode Interface) is a program interface that allows an
application program running under the Disk Operating System (DOS) to take
advantage of a DOS extender, which lets the program address a larger range
of random access memory (RAM) than the 640 kilobytes to which PC programs
are basically constrained. To use the extender, the program must be in
"protected mode," a mode that ensures that program requests are not allowed
to access certain portions of "protected" memory. (Programs running in the
alternative "real mode" have access to all portions of memory, including
system data.)

Some programs are real mode (usually the older ones but not less important)
and they don't behave themselves in a protected mode setting and are quickly
terminated for taking matters into thier own hands. They are the progeny
of the old 8086 architecture.  We see many linux utilities ported to dos
despite the frustration of working without documentation. I wonder if
backward compatability of issues like pmode development is less
advantageous than Dosemu development with the documentation.

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