Path: utzoo!utgpu!jarvis.csri.toronto.edu!rutgers!usc!cs.utexas.edu!ut-emx!walt.cc.utexas.edu!nghiem
From: nghiem@walt.cc.utexas.edu (Alex Nghiem)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Vga Boards, and Seiko's new monitor
Keywords: vga,graphics,windows,video-7,wonder,fastwrite,ati
Message-ID: <14995@ut-emx.UUCP>
Date: 8 Jul 89 23:54:49 GMT
References: <2565@PEDEV.Columbia.NCR.COM> <[304.1]comp.sys.ibm.pc;1@vpnet.UUCP> <1685@netcom.UUCP> <14867@ut-emx.UUCP> <5513@tekgvs.LABS.TEK.COM>
Sender: news@ut-emx.UUCP
Reply-To: nghiem@walt.cc.utexas.edu (Alex Nghiem)
Organization: The University of Texas at Austin, Austin, Texas
Lines: 34

In article <5513@tekgvs.LABS.TEK.COM> keithe@tekgvs.LABS.TEK.COM (Keith Ericson) writes:
>I and some co-workers evaluated the ATU Blunder card a couple of months ago.
>We concluded that for our uses it was absolutely unacceptable because of its
>slow speed (actually, "speed" is the wrong word here.)
>So why does the ATI card seem to be so fast in other peoples tests?
>Well, I think it has mostly to do with "Does The Test Use BIOS Calls" or
>"Does The Test Access The Screen Directly?"  Our tests access the screen
>memory directly.  

The PC Magazine Benchmark tests video bios and video register compatibility 
and speed. [It includes a Windows-based instruction benchmark test.]
I hope that the article was based on both types of access, not just one
or the other. Also, I thought that accessing the registers directly was
inherently faster than using the bios.

>In each and evey one of these tests the ATI card showed itself to be one of
>the slowest cards we had ever used.

Yikes! Which version of the ATI card did you evalute? Did you evaluate
the ATI VGA Wonder 512K or did you evaluate the older ATI VIP card.
How much memory did you have. Which specific operating system 
did you use--SCO Xenix or Interactive, or something else?

>Because of the difference in how "slow" is determined, and
>because a UNIX driver may very well manipulate the display memory
>direclty, I would be EXTREMELY reluctant to link DOS-based speed
>measurements to UNIX, X-Windows or any other performance metrics.

If a test is measuring pure register-level or bios-level response,
why would the operating system make a difference? Isn't it risky
to write a Unix VGA driver that accesses the registers directly?

Thanks,
nghiem@vondrake.cc.utexas.edu