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<A HREF="trident.html"><EM> Information for Trident Chipset Users</EM></A>
 <b>:</b> <EM>Additional Notes </EM><BR>
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  <H2><A NAME="3"></A>3. Additional Notes </H2>
<p>We have had reports of the server failing to detect the amount of installed
memory and the correct dot-clocks on older TVGA8900 boards.  If the server 
fails to detect the correct amount of memory, use the <code>"Videoram"</code>
keyword in your <code>XF86Config</code> file to specify it.
(e.g. <code>Videoram 512</code> or <code>Videoram 1024</code>).  If 
the server has problems detecting the dot-clocks, try adding the following 
line to your <code>XF86Config</code> file:
<pre>
        Clocks  25 28 45 36 57 65 50 40
</pre>

This line gives the clock values provided by older Trident clock synthesizer
chipsets.  This also appears to be the standard first 8 clocks for the newer
clock synthesizers, but you should have no problems on newer boards.</p>
<p>Some newer Trident 8900B/C boards are apparently being built with the clock
synthesizers used on the 9000 and 8900CL boards.  If your board has a chip
labeled "Trident TCK900x" ("x" has been seen as 2 or 4; there may be others),
your board may actually have a 4th clock select bit.  The 9002 has twelve
distinct clocks (the other 4 are duplicates); the 9004 has 16 clocks (the
same 12 as the 9002 + 4 others).  If you see such a chip on a board with
an 8900B or 8900C, put the following line in the Device section of your
<code>XF86Config</code> file:
<pre>
        Option "16clocks"
</pre>

This will cause the same clock selection code as is used for the 8900CL to
be used for the board.</p>
<p>While developing the Trident driver, an interesting and perturbing hardware
phenomenon was discovered.  When using the default board jumper configuration,
dot-clocks above 57Mhz would frequently lock up the machine.  There appear
to be jumpers on all of the Trident boards that determine whether the
board will operate in zero-wait-state mode on the ISA bus.  Disabling the
zero-wait-state mode via jumpers cured the lockups, but at the expense
of performance.  Whether or not a given system will experience this problem
is likely a combination of (a) bus speed, (b) video memory speed, and (c) dot
clock speed.  So be prepared for this phenomenon to occur, and have the board
documentation handy.</p>
<p>NOTE: VLBus cards are also subject to the above. By specifying the Clocks
in the <code>XF86Config</code> file, these lockups are overcome. But it may
be worth checking wait states etc. on the card and in the BIOS setup.</p>
<p>
<pre>
$XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/trident.sgml,v 3.22.2.9 1999/06/25 08:57:15 hohndel Exp $






$XConsortium: trident.sgml /main/11 1996/10/28 04:24:08 kaleb $
</pre>
</p>

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<A HREF="trident.html"><EM> Information for Trident Chipset Users</EM></A>
 <b>:</b> <EM>Additional Notes </EM><BR>
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