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
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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 ]===================
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