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<title>Notes for Mach32 X Server
<author>Bryan Feir (jenora@istar.ca)
<date>2 July 1997

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<sect>Supported Cards, RAMDACs, and Bits Per Pixel<p>
The base support in the Mach32 X server is for 8 bpp, with a dot clock
of up to 80 MHz.  At present 15/16 bpp is supported on only three of the
many RAMDACs; however those three cover the most commonly sold cards.
<p>
<verb>
 RAMDAC      Max Dot Clock   BPP   Max Resolution   Video RAM Required
--------     -------------   ---   --------------   ------------------
Default           80MHz       8      1280x1024i            2Mb
Default           80MHz       8      1024x768              1Mb

ATI68875         135MHz       8      1280x1024             2Mb
ATI68875          80MHz      16      1024x768              2Mb

AT&amp;T20C49x        80MHz       8      1024x768              1Mb
AT&amp;T20C49x        40MHz      16       800x600              2Mb

BT481             80MHz       8      1024x768              1Mb
BT481             40MHz      16       800x600              2Mb

</verb>

The RAMDAC is reported when you run the Mach32 X server with the
"<tt>-probeonly</tt>" command line option, or can be specified in the
XF86Config file.

The ATI68875 (or the TLC34075) is used on the Graphics Ultra + and
the Graphics Ultra Pro.  The Brooktree 481 is used on most Graphics
Wonder cards.  The AT&amp;T20C491 is used on many of the OEM cards
that are built into component systems.

The BIOS detection unfortunately lumps the BT481 and the AT&amp;T20C49x
together, while they require different configuration controls in 16 bit
mode.  SuperProbe can tell the difference, and will report which it finds.
In the server itself, the BT481 is considered the default value.  If you
have an AT&amp;TC49x RAMDAC on your card you will have to include the Ramdac
entry in the XF86Config file as below.

<sect>XF86Config options<p>
Several options are supported in the "Device" section for the Mach32 X
server.  Most of them should be auto-detected if needed, but a few may
need to be deliberately set.  For example, the "Clocks" entry should
almost certainly be set after first running the server with the
<tt>-probeonly</tt> option, so as to avoid the probe in later runs.

<descrip>
<tag>Option "composite"</tag>
		This option will set the composite sync for
		monitors that require this.
<tag>Option "dac_8_bit"</tag>
		This option enables 8 bits per RGB value.  Note
		this option does not work with all RAMDACs, and
                is not considered supported by the Mach32 itself.
<tag>Option "ast_mach32"</tag>
		This option sets some special handling for the AST
		version of the Mach32 card that comes soldered in to
		some of their motherboards.  This card will lock up
		without this option.
<tag>Option "intel_gx"</tag>
                This option sets the memory aperture address to
                the hardwired value for the Intel GX Pro.  It is
                equivalent to setting Membase to 0x78000000.
<tag>Option "no_linear"</tag>
                This option disables the use of the linear mapped
                framebuffer.  This should be auto-detected.
<tag>Option "sw_cursor"</tag>
		This option allows you to use the software cursor
                instead of the hardware cursor.
<tag>MemBase baseaddress</tag>
		This entry specifies the video memory aperture
		address.  Normally the aperture address is
		automatically determined, but on some VESA Local
		Bus systems the address chosen will not work.  If
		the Mach32 X server is dying with a seg. fault,
		then try setting the aperture address to another
		location.
<tag>Clocks <it>clock</it> ...</tag>
                This entry gives the clock rates for the server to use.
<tag>Ramdac "<it>type</it>"</tag>
		This entry specifies the RAMDAC type.  The following
		values are valid for <it>type</it>:
		<itemize>
		<item>ati68830
		<item>sc11483
		<item>sc11486
		<item>sc11488
		<item>ims_g173
		<item>mu9c4870
		<item>ati68875*
		<item>bt885
		<item>tlc34075*
		<item>bt476
		<item>bt478
		<item>inmos176
		<item>inmos178
		<item>bt481*
		<item>bt482
		<item>ims_g174
		<item>mu9c1880
		<item>mu9c4910
		<item>sc15025
		<item>sc15026
		<item>att20c490*
		<item>ati68860
		<item>stg1700
		<item>sc15021
		<item>stg1702
		<item>att21c498
		</itemize>
                Only the ones marked with &lsqb*&rsqb have an effect yet.
</descrip>

<sect>Known Problems and Bug Reports<p>
There are several known problems with the current version of the
Mach32 X server.  They include:
<itemize>
<item>Not all RAMDACs are supported at higher colour ranges, and not all
       that are can be detected properly.  In fact most of the RAMDAC values
       above have no effect except to block higher bit modes.
<item>Sixteen bit character support (e.g., Chinese and Japanese character
       sets) has been known to lose parts of characters.  While this should
       be fixed, if it occurs try running the server with Option
       "no_linear".
</itemize>

Bug reports should be sent to XFree86@XFree86.org or posted to the
comp.windows.x.i386unix newsgroup.

<p>

<verb>
$XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/Mach32.sgml,v 3.5.2.3 1998/11/07 13:37:47 dawes Exp $




$XConsortium: Mach32.sgml /main/4 1996/10/28 04:47:43 kaleb $
</verb>

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