This file was taken from the XFREE86 documentation.
---------------------------------------------------


		Information for Tseng Chipset Users
		-----------------------------------

Contents
--------
	1) Supported chipsets
	2) Clock selection problems with some ET4000 boards
	3) Text mode restore problems

1 - Supported chipsets
----------------------
  The Tseng chipsets supported by XFree86 are ET3000, ET4000, and
ET4000/W32.  At this time, the accelerated features of the ET4000/W32
are not supported; the chipset is treated as a standard ET4000.

2 - Clock selection problems with some ET4000 boards
----------------------------------------------------
  XFree86 has some problems getting the clock selection right with some
ET4000 boards when the server is started from a high-resolution text mode.
The clock selection is always correct when the server is started from a
standard 80x25 text mode.

This problem is indicated when the reported clocks are different when the
server is started from the high-resolution text mode from what they are
when it is started from the 80x25 text mode.  To allow the server to work
correctly from the high-resolution text mode, there are some Option flags
that may be set in Xconfig.  To find out which flags to set, start the
server with the -probeonly flag from an 80x25 text mode and look at the
information printed by the server.  If the line:

  VGAXXX: ET4000: Initial hibit state: low

is printed, put the following in the VGA256 and VGA2 sections of your Xconfig:

  Option "hibit_low"

If the line:

  VGAXXX: ET4000: Initial hibit state: high

is printed, put the following in the VGA256 and VGA2 sections of your Xconfig:

  Option "hibit_high"


3 - Text mode restore problems
------------------------------
  In XFree86 1.3, an option flag "force_bits" was provided as an experiment
to attempt to alleviate text-restoral problems that some people experienced.
We have now made the behavior of this option the default, hence the flag
has been removed.  Hopefully the past text-restoral problems are alleviated 
in XFree86 2.0.

$XFree86: mit/server/ddx/x386/etc/README.tseng,v 2.0 1993/10/18 12:18:03 dawes Exp $

--------------------------------------------------------------------------------------

 ##############################################################################
 #                                                                            #
 #  >>>>>>>>>>>>>>>   IMPORTANT NOTE FOR SVGATEXTMODE   <<<<<<<<<<<<<<<<<<<<  #
 #                                                                            #
 ##############################################################################
 #                                                                            #
 #  Users of SVGATextMode with an ET4000 board MUST put the "hibit_high" or   #
 #  "hibit"low" option in their XF86Config as well. This means the option     #
 #  MUST be in TextConfig AND in XF86Config, and it must of course be the     #
 #  same one in both files. Failure to do so may cause either X or            #
 #  SVGATextMode to select the wrong clock. Your monitor may not like that.   #
 #                                                                            #
 ##############################################################################

Note also that changing the "hibit" option from low to high or vice versa is
equivalent to swapping the lower 8 clocks with the higher 8 clocks in the
"clocks" line in XF86Config or TextConfig.

Example:

  clocks  25.1 28.3 32.5 36 40 44.9 50 65
  clocks  50 56.6 65 72 80 90 63 75
  option "hibit_high"
  
is equivalent to:

  clocks  50 56.6 65 72 80 90 63 75
  clocks  25.1 28.3 32.5 36 40 44.9 50 65
  option "hibit_low"

   