Subject: Re: warning on problems with ati mach-64 (card has noise problems)
To: Ron Minnich <>
From: Jeremy Chatfield <>
List: current-users
Date: 03/30/1995 12:57:17
Ron Minnich writes:
> we have two machines here with ati mach-64 cards. We have noticed that in
> 1024x768 mode there is a fine pattern of lines on the display that looks
> like a high-frequency clock making its way out to the analog rgb lines. 
> We're not sure if it's shielding or poor card design, but a matrox card
> set to the same settings does not show the problem; the problem follows
> the mach-64 cards around to other machines/monitors. The pattern is
> visible enough to be annoying; we're sending the cards back and replacing
> them with matrox. 
> We did notice that the matrox has a nice embedded ground plane, and the 
> ati is yer basic cheapo two-sided card. I have no idea if this is a 
> factor. 

ATI change their boards very frequently.  Defects are rare, changes
are very frequent.

The problem may be a new RAMDAC that ATI started using recently, or
it may be the new IBM VRAM that they are using.  I assume that you
are using XFree86; I have no idea if XFree86 have resolved these
problems.  We have (though we have one customer report of an echo of
any screen object, right-shifted by 8 pixels, which we can not
currently reproduce).  Module updates are available on our Anon-FTP
Server, for our Server, to correct Mach64 display problems resulting
from these two changes.

The fine-pattern problem sounds like the report that we get if using
the RAMDAC that started shipping around January, with software support 
for the older rev of the RAMDAC only.  The IBM VRAM has been shipping 
for only a few weeks (Feb something).

We work more closely with Matrox than with ATI, but I still think that
ATI needed some defending :-)  They do provide pretty fast boards,
for the price.  There are limitations, relative to the Matrox boards,
but the boards are a good mass-market quality product.

Apologies to NetBSD users, we do not yet have a port for NetBSD.  

Cheers, JeremyC.
Jeremy Chatfield, +1(303)470-5302, FAX:+1(303)470-5513,
        X Inside Inc, P O Box 10774, Golden, CO 80401-0610, USA.
   Commercial X Server - for more information please try these services