From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
Newsgroups: comp.os.msdos.djgpp
Subject: Re: newbie question about RAM, DPMI's, and the FAQs
Date: Wed, 10 Nov 1999 13:52:48 +0200
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On Mon, 8 Nov 1999, robin wrote:

> Maybe it's my Unix contamination, but I interpreted "Swap space" as using the hard
> disk as virtual memory.  I'm not sure why there would be a distinction between
> memory available and swap space if it all comes from RAM.

Think a bit how would *you* write the module inside Windows that reports 
the free memory, and you will see why.  Since Windows provides memory to 
many different programs, including to itself, how in the world can it 
know at any given moment which part of what the DPMI program will consume 
is going to be in RAM and which part on disk?

The DPMI spec intentionally leaves this vague, and most ``advanced'' 
operating systems that provide built-in DPMI services use some arbitrary 
logic to subdivide the maximum amount of memory they provide to DPMI 
clients.  For example, NT always reports zero as the swap space, which is 
clearly a lie.