From:	Glen Miner <gminer AT ca DOT newbridge DOT com>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Memory Protection
Date:	Mon, 18 Nov 1996 07:37:51 -0500 (EST)
Organization:	Newbridge Networks Corporation
Lines:	24
Message-ID:	<Pine.SUN.3.90.961118073549.499B-100000@coop10>
NNTP-Posting-Host:	138.120.136.238
Mime-Version:	1.0
To:	Bill Currie <billc AT blackmagic DOT tait DOT co DOT nz>
In-Reply-To:	<328EE8E4.6E0C@blackmagic.tait.co.nz>
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

> > Hmm, how would this be better than the dosmemput/get functions? (Sorry,
> > I'm a new to pmode and this whole selector buisness is confusing)
> 
> dosmemput/get uses the dos selector which is set to have a 4gb limit and
> a base of 0, thus no protection and all refrences have to add in the 
> base of the screen (ie 0xa0000+x+y*320 for mode 13h).
> 
> Using a specialized selector provides protection because it's limit is
> 64k (the size of the screen segment) and because the base is set to 
> 0xa0000, you don't need to add an offset to your calculated address (ie 
> x+y*320) which saves 2 clocks 
> on a 386 (my computer).

Hey, I thought I was the only one still using a 386 :) 

I see your point, though. It's a good one, too. Thanks for the snippet; I 
hope you don't mind me using it :)

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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