Xref:	news2.mv.net comp.os.msdos.djgpp:4843
From:	Shawn Hargreaves <slh100 AT york DOT ac DOT uk>
Newsgroups:	comp.os.msdos.djgpp
Subject:	Re: Allegro Compatibility
Date:	Tue, 11 Jun 1996 11:10:41 +0100
Organization:	The University of York, UK
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On Tue, 11 Jun 1996, Lee Braiden wrote:

> Is there a list of config settings that OS/2 needs ?  I'd like to be 
> able to give instructions (or an installation script) for different 
> setups if poss.

Anyone used Allegro under OS/2, who could answer this?

> Well, I'm using a basic (well, almost - SVGA, but 256K, and no 
> blitter, etc) VGA card at the minute, although it's an Oak OTI-37C, 
> so I've got the UniVBE program running, meaning I can forget 
> supporting non-VBE cards if I have to, but how many cards are there 
> that have bad or no VBE support still ?

Quite a lot, unfortunately :-) Most have VBE drivers, but a) only VBE 
1.2, which requires a real mode interrupt call every time you switch 
banks so it is sloooow, and b) there are a lot of _really_ buggy drivers  
around. Out of the three cards and eight VBE implementations that I have 
access to, only three of them pass SciTech's VBETEST program (and one 
of those is UniVBE).

> Basically, I want to know that the graphics will be as fast as 
> possible on a basic card like mine, and a top of the range VESA card  
> (at least, as much as possible without separate drivers for every 
> card).

That's a bit of a tall order :-) For low-end hardware, mode-X is almost 
always going to be faster. On more recent cards, the lower resolutions 
can actually be slower because the PCI bus can generally only use the 
high speed burst mode with the VBE 2.0 linear addressing, and this often 
only works in SVGA modes. Depending what you're doing, it could be worth 
implementing several different screen refresh strategies and timing them 
at startup to determine which to use (a lot of win95 games do this).


/*
 *	Shawn Hargreaves.        Why is 'phonetic' spelt with a ph?
 *	Check out Allegro and FED on http://www.york.ac.uk/~slh100/
 */

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