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Notes for Mach32 X Server
Bryan Feir (jenora@istar.ca)
2 July 1997
1. Supported Cards, RAMDACs, and Bits Per Pixel
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 RAM-
DACs; however those three cover the most commonly sold cards.
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&T20C49x 80MHz 8 1024x768 1Mb
AT&T20C49x 40MHz 16 800x600 2Mb
BT481 80MHz 8 1024x768 1Mb
BT481 40MHz 16 800x600 2Mb
The RAMDAC is reported when you run the Mach32 X server with the "-probeonly"
command line option, or can be specified in the XF86Config file.
The ATI68875 (or the TLC34075) is used on the Graphics Ultra + and the Graph-
ics Ultra Pro. The Brooktree 481 is used on most Graphics Wonder cards. The
AT&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&T20C49x together,
while they require different configuration controls in 16 bit mode. Super-
Probe 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&TC49x
RAMDAC on your card you will have to include the Ramdac entry in the XF86Con-
fig file as below.
2. XF86Config options
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 cer-
tainly be set after first running the server with the -probeonly option, so
as to avoid the probe in later runs.
Option "composite"
This option will set the composite sync for monitors that require
this.
Option "dac_8_bit"
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.
Option "ast_mach32"
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.
Option "intel_gx"
This option sets the memory aperture address to the hardwired
value for the Intel GX Pro. It is equivalent to setting Membase
to 0x78000000.
Option "no_linear"
This option disables the use of the linear mapped framebuffer.
This should be auto-detected.
Option "sw_cursor"
This option allows you to use the software cursor instead of the
hardware cursor.
MemBase baseaddress
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.
Clocks clock ...
This entry gives the clock rates for the server to use.
Ramdac "type"
This entry specifies the RAMDAC type. The following values are
valid for type:
o ati68830
o sc11483
o sc11486
o sc11488
o ims_g173
o mu9c4870
o ati68875*
o bt885
o tlc34075*
o bt476
o bt478
o inmos176
o inmos178
o bt481*
o bt482
o ims_g174
o mu9c1880
o mu9c4910
o sc15025
o sc15026
o att20c490*
o ati68860
o stg1700
o sc15021
o stg1702
o att21c498
Only the ones marked with [*] have an effect yet.
3. Known Problems and Bug Reports
There are several known problems with the current version of the Mach32 X
server. They include:
o 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.
o 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".
Bug reports should be sent to XFree86@XFree86.org or posted to the comp.win-
dows.x.i386unix newsgroup.
Generated from XFree86: xc/programs/Xserver/hw/xfree86/doc/sgml/Mach32.sgml,v 3.7 1997/07/10 08:17:25 hohndel Exp $
$XConsortium: Mach32.sgml /main/4 1996/10/28 04:47:43 kaleb $
$XFree86$
|
