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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Cirrus XFree86 Driver: Alpha testers wanted
Message-ID: <1993Mar27.072527.1925@fcom.cc.utah.edu>
Sender: news@fcom.cc.utah.edu
Organization: Weber State University (Ogden, UT)
References: <BILL.93Mar24005259@yossarian.ucsd.edu>
Date: Sat, 27 Mar 93 07:25:27 GMT
Lines: 37
In article <BILL.93Mar24005259@yossarian.ucsd.edu> bill@yossarian.ucsd.edu (Bill Reynolds) writes:
>I see the following problems:
>
>-Sparklies. Could be a hardware problem on my bus, could be a bogus
>register someplace. I'm open to suggestions.
Happens when you access memory that's being displayed by the raster at the
time. You don't simply unset or set bits at absolute locations when you
write pixels to memory; generally video hardware shifts them in.
>-Diagonal Lines. When a client (like xv) really beats on the colormap,
>diagonal lines appear on the display, going from the lower left to the
>upper right. This is undoubtedly some kind of software problem. As to
>what that problem is, I'm clueless.
Happens when you shift in a 1 while vertical retrace is going on. Basically,
you have to wait for vertical retrace is done before accessing the last
written pixel.
You should be able to get around both problems either by enabling and
trapping IRQ 2 or by looking at how the ROM code avoids retrace.
Good luck!
Terry Lambert
terry@icarus.weber.edu
terry_lambert@novell.com
---
Any opinions in this posting are my own and not those of my present
or previous employers.
--
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