From:	Glen Miner <gminer AT ca DOT newbridge DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Memory Protection
Date:	Fri, 15 Nov 1996 12:37:02 -0500 (EST)
Organization:	Newbridge Networks Corporation
Lines:	24
Message-ID:	<Pine.SUN.3.90.961115123053.21409A-100000@coop10>
NNTP-Posting-Host:	138.120.136.238
Mime-Version:	1.0
To:	DJ Delorie <dj AT delorie DOT com>
In-Reply-To:	<199611151733.MAA21304@delorie.com>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

> > Ahh, this makes sense now. I suppose my next question is: how does the
> > dosmem put/get  functions get around this? Do they resize before and 
> > after? Wouldn't this be painfully inneffeicient?
> 
> They use a different segment, which overlaps the DOS memory instead of
> the program's memory.

Ahh, I see. I don't know much about pmode programming, but I know real 
mode inside and out, and this is starting to make more sense.

> For further protection, you can create a segment that covers only the
> video memory and use that instead.

How would this be done? This would be ideal; if you could setup another 
segment (a 64k window to vidoe memory), and it would be "unprotected", 
then you could just use the movedata function with that segment's 
selector, right?

Peace
===[ Gabo / [ABC] : gaminer AT undergrad DOT math DOT uwaterloo DOT ca ]===================
Latest ABC Shogi: http://www.undergrad.math.uwaterloo.ca/~gaminer/shogi.html
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