Newsgroups: comp.graphics
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From: schultz@schultz.kgn.ibm.com (Karl Schultz)
Subject: Re: VESA standard VGA/SVGA programming???
Sender: @watson.ibm.com
Message-ID: <1993Apr16.202141.23563@watson.ibm.com>
Date: Fri, 16 Apr 93 20:21:41 GMT
Reply-To: schultz@vnet.ibm.com
References:  <C5L2rK.K2A@constellation.ecn.uoknor.edu>
Organization: IBM AWS Graphics Systems
Keywords: vga
Lines: 45

|> 1. How VESA standard works?  Any documentation for VESA standard?

	The VESA standard can be requested from VESA:
	VESA
	2150 North First Street, Suite 440
	San Jose, CA 95131-2029

	Ask for the VESA VBE and Super VGA Programming starndards.  VESA
	also defines local bus and other standards.

	The VESA standard only addresses ways in which an application
	can find out info and capabilities of a specific super VGA
	implementation and to control the video mode selection
	and video memory access.

	You still have to set your own pixels.

|> 2. At a higher resolution than 320x200x256 or 640x480x16 VGA mode,
|>    where the video memory A0000-AFFFF is no longer sufficient to hold
|>    all info, what is the trick to do fast image manipulation?  I
|>    heard about memory mapping or video memory bank switching but know
|>    nothing on how it is implemented.   Any advice, anyone?  

	VESA defines a "window" that is used to access video memory.
	This window is anchored at the spot where you want to write,
	and then you can write as far as the window takes you (usually
	64K).  Windows have granularities, so you can't just anchor 
	them anywhere.  Also, some implementations allow two windows.

|> 3. My interest is in 640x480x256 mode.  Should this mode be called
|>    SVGA mode?  What is the technique for fast image scrolling for the
|>    above mode?  How to deal with different SVGA cards?

	This is VESA mode 101h.  There is a Set Display Start function
	that might be useful for scrolling.

|>   Your guidance to books or any other sources to the above questions
|> would be greatly appreciated.  Please send me mail.

	Your best bet is to write VESA for the info.  There have also
	been announcements on this group of VESA software.

-- 
Karl Schultz                             schultz@vnet.ibm.com
These statements or opinions are not necessarily those of IBM
