From:	Endlisnis <s257m AT unb DOT ca>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro and VESA 2.0
Date:	Thu, 17 Sep 1998 18:04:42 -0300
Organization:	NBTel Internet
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Message-ID:	<3601796A.99FAB0B7@unb.ca>
References:	<3600AE89 DOT 4D194557 AT mailexcite DOT com> <19980917122929 DOT 27796 DOT 00000443 AT ng153 DOT aol DOT com>
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To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

ElvenForst wrote:
> It's almost as if the drawing functions (mostly blitting, rle and compiled
> sprites) return before they've done the job, and complete it in the background
> while the program moves on.  This resulting in the image not being completely
> finished when the buffer is copied to the screen.  Also, there seems to be some
> sort of wierdness with this and the sync (or lack thereof) with the vertical
> retrace.
	You may not be able to blit the entire screen in a single vertical retrace if
you are using hi-res modes.

> Does my hypothisis make any sense?  I can't figure it out on my own because I
> don't know exactly what vesa is or how it works, as opposed to a "normal" video
> mode like 13h.
	There is no 'real' difference.  Using mode 0x13, you have a linear frame
buffer starting at 0xA0000, and is 65000 bytes long.  In VESA2 800x600x8bit
mode, you have a linear frame buffer starting at some other address and is
480000 bytes long.  I may take longer to blit the screen espectially if you
are using something large like 1024x768x32bit (if you have a 4 Meg card)
because that requires you to copy 4Megs of data when 0x13 only requires 64k.
-- 
     (\/) Endlisnis (\/)
          s257m AT unb DOT ca
          Endlisnis AT GeoCities DOT com
          Endlis AT nbnet DOT nb DOT ca

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