To: dstamp@watserv1.uwaterloo.ca
Subject: IBM graphics performance
Cc: glove-list@karazm.math.uh.edu, glove-list@karazm.math.UH.EDU
Message-Id: <9110211354.AA09353@roi.ca41.csd.mot.com>
Date: 21 Oct 91 13:54:28 PDT (Mon)
From: Lance Norskog <lance@roi.ca41.csd.mot.com>
> I think I see the problem here.  The difference is between the IBM and Amiga
> designs.  Any real graphics work on the IBM PC requires multiple I/O space
> accesses with inportb() and ouportb() type routines.  Since most of the 
> available C compilers do not replace these with inline code, this results
> in much slower operation than with assembly code.  Also, many of the good 
> instructions on the 80x86 (such as LOOP or REP STOSB) are not used by 
> compilers.  Again, assembly code is the only solution.  
	
Nope!  The IBM PC bus was designed to be cheap, and support text.
It was not designed with NTSC video bandwidth in mind, while the
Amiga was.  The hardware is at fault, not the software.  The Toaster
people said they can't port to the PC because it's 7 times too slow.

The PC VR software is going to have use scan-line techniques, or
paint in real RAM and copy that into the VGA frame buffer.  Multiple
touches of the same pixel would be the kiss of death.

Actually, the 8514/A clone cards are appearing mass-market for $500
from Western Digital etc.  These things include a raft of 2D graphics
commands which you just poke at it and go away.  They have a limited
range of RAM buffering techniques, and thus can possibly do double
buffering for animation but can't do quad-buffering for stereo
animation.  This is why I don't have one.  But for high-res non-stereo
work, they might make the nut.  Also, they might support two cards
in one machine but I don't think so.  One of these cards might
supply a very nice environment for stop-motion stereo or monoscopic
animation.

Lance Norskog