Newsgroups: comp.os.msdos.djgpp
From: "William A. Barath" <wi534 AT victoria DOT tc DOT ca>
Subject: Re: Physical address of convenstional memory
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Date: Thu, 4 Dec 1997 12:47:57 GMT
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On Thu, 4 Dec 1997, Fabrice ILPONSE wrote:

|> When executing this program under MD-DOS(CWSDPMI.EXE),
|> linear memory address(segment*16 + offset) is equal to
|> physical memory address.
|> But under DOS-BOX of Windows95, linear address is not
|> equal to physical address.
|
|	HeuuuuU!!
|	If you've allocated dos memory, the physical adress still equal to the
|logical adress. How have you detected the logical and physical mismatch?
|	Generally, DPMI server do not remap the memory under the 1M!!

Actually, Windows will remap memory under 1M quite frequently.  Here's a
simple premise for you: if you have two DOS sessions open under Windows,
both having 640k of addressable ram, how do you fit those both under the
1M mark?  The answer is "you don't," and you allocate other ram, remap it
logically and put the processor in V86 mode so anything running in that
environment won't know the difference.

However, since DOS programs using the Soundblaster require the base memory
they are using to have logical addresses equal to physical addresses, you
are safe to assume that any DOS session running under Windows that has
control of the SoundBlaster will in fact be mapped physically.  I guess
there's little cause to ponder further why only one Windows DOS session
can be open with access to the Soundblaster?  ;) 

Wil Barath, aka WseM : "I feel as though I see my pen to write"
Author of VPM, EDITPLN, and other VGA Planets support programs
Visit my homepage! -------------> http://victoria.tc.ca/~wi534