!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!!!!                                                               !!!! 
!!!!   NOTE: The ET4000 register layout changed stepping from      !!!!
!!!!         svgalib 0.98 to 0.99. See  8. Problems  below first   !!!!
!!!!                                                               !!!! 
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[this README for the ET4000 registers was provided by Hartmut Schirmer]

1. Basics of ET4000 cards 
2. How to configure SVGALIB
3. Creating card dependent register values
4. Defining new modes
5. Redefining standard modes
6. Available examples
7. ET4000/W32 support
8. Problems
9. Using dynamic loading with other cards


1. Basics of ET4000 cards 
-------------------------

Basicly all ET4000 cards are equal, some are even more equal ...

The Chipset is well documented (by Tseng Labs and eg. the vgadoc2.zip)
and all graphics functions can be used the same way on different cards
(including the ET4000/W32 based ones). There are three important points
to be kept in mind :

  a.) amount of available, the organisation and timing of video memory
  b.) type and capabilities of the DAC
  c.) available oscillator frequencies

SVGALIB will check the available video memory during startup. This
should work on all DRAM cards. If there are any problems concerning
VRAM equipped cards, please tell us about.

By now we found is no reliable way to detect the memory organisation/
timing and the DAC type/capabilities. Most modern card use a frequency
synthizier and provide the following pixel frequencies (in MHz):

	50.350 56.644 65.0 72.0 80.0 89.8 63.0 75.0

Checking older ET4000 cards we found a wide spread range of available
frequencies. Since the video timing is based on the pixel frequency,
the required register values are card dependent.

2. How to configure SVGALIB
---------------------------
 
SVGALIB has a somewhat 'standard' registers set that may work with
modern ET4000 cards. If SVGALIB fails on your machine or you have
a HiColor dac, you need to configure your SVGALIB.
 
The SVGALIB may use hard linked or dynamical linked register values.
If you use hard linked values, the binary will be smaller and start
up faster but might fail on other machines.

Compiling the SVGALIB with DYNAMIC defined (see config.h) will set 
up dynamic register loading. Otherwise the value from 
           svgalib/et4000.regs 
will be hard linked.

The dynamic configuration will be read from 
		/usr/local/lib/libvga.et4000
which is an ASCII file (see config.h for exact naming). If you have
a working et4000.regs for your system just copy this file to
/usr/local/lib/libvga.et4000 or link /usr/local/lib/libvga.et4000 
to your svgalib/et4000.regs file.

The actual scanner/parser will handle the following entries:

  #define DAC_TYPE <integer>      /* Overwrite the DAC detection        */
  #define <MODE1>  <MODE2>        /* Enable MODE1 using MODE2 registers */
				  /* eg. 64K modes like 32K modes       */
  #define <MODE>   DISABLE_MODE   /* do not use MODE (eg. from vgadrv)  */
  char <MODE><strg>[..] = { <integer>,<integer>,... }; /* register definition */

with

  <MODE>    ::= 'g'<decimal>x<decimal>x<color><ignored>
  <integer> ::= <decimal>|<hex>
  <hex>     ::= '0x'<hexdigit>{<hexdigit>}
  <decimal> ::= ['+'|'-']<digit>{<digit>}
  <hexdigit>::= <digit>|'a..f'|'A..F'
  <digit>   ::= '0..9'
  <color>   ::= '2'|'16'|'256'|'32k'|'32K'|'64k'|'64K'|'16M'
  <strg>    ::= <empty>|[(<aplha>|'_'){<digit>|<alpha>|'_'}]
  <alpha>   ::= 'a..z'|'A..Z'

C style comments will be skipped. See et4000 subdirectory for
examples.


3. Creating card dependent register values
------------------------------------------

You may create a et4000.regs on your own with the tseng3.exe.
Just boot MS-DOG and start

  tseng3 et4000.reg

The tseng3.exe will measure the video timing for each available mode.
Check the et4000.regs file against your monitor documentation and
disable all non conformant modes, eg.

    #define g1024x768x256_regs DISABLE_MODE
    /*
    static unsigned char g1024x768x256_regs[71] = {
      ...
    };
    */

will disable the 1024x768x256 mode. You *mustn't* disable the
640x480x256 mode!

Your et4000.regs must define the following symbols (register values
or #define ... DISABLE_MODE) for hard linking :

  g320x200x32K_regs,  g640x400x256_regs, g640x480x256_regs,
  g640x480x32K_regs,  g640x480x16M_regs, g800x600x16_regs,
  g800x600x256_regs,  g800x600x32K_regs, g1024x768x16_regs,
  g1024x768x256_regs, g1280x1024x16_regs

and all 64K modes handled like 32K modes by the driver :

  #define g320x200x64K_regs g320x200x32K_regs
  #define g640x480x64K_regs g640x480x32K_regs
  #define g800x600x64K_regs g800x600x32K_regs

You may omit every unusable mode in  /usr/lib/libvga.et4000 .


4. Defining new modes
---------------------

All standard SVGALIB modes may be selected by the mode constants 
defined in vga.h (eg. G320x200x16). You may define new modes on
your own. Just use dynamic register loading and add the register
definition of the new mode. Your program may determine the related 
modenumber by checking the vga_getmodeinfo(1..vga_lastmodenumber()).

Most ET4000 cards provide 640x350 and 640x400 graphics modes. The
tseng3.exe generates the related register sets. You may also use
dumpreg from an X window to grab you favourite X graphics mode.
The X mode normaly isn't usable directly. See cardex.w32 for an
example and et4000.c for a brief description of et4000 registers.
  

5. Redefining standard modes
----------------------------

Using dynamic register loading you may redefine any standard VGA 
mode except of TEXT and 640x480x16. Just add the ET4000 specific
register set to /usr/local/lib/et4000.regs.


6. Available examples
---------------------

In the et4000 subdir you'll find some sample register sets :

  cardex.w32    Cardex ET4000/W32 card, Music TrueColor DAC
  speedstar+	SpeedSTAR PLUS card, Normal DAC
  morse.kp1024	Morse KP1024 card, Normal DAC
  et4000.old1	unknown older et4000 card, normal DAC
  boca		BOCA register set from svgalib 0.81


7. ET4000/W32 support
---------------------

The actual driver seems to be ET4000/W32 compatible. Tell us about
any problems (and solutions). If you've got any information about
the ET4000/W32 blitter, we would be pleased to receive it.


8. Problems
-----------

As mentioned before, the DAC detection isn't very reliable. vgatest
should print equal screens in 256 color and HiColor/TrueColor modes.
You may have to edit your libvga.et4000 register file by hand to setup
the correct DAC.
The tseng3 may fail due to incompatible mode numbering. You might use
a VESA driver (eg. tlivesa.com from VPIC 6.0) or edit and recompile
the tseng3.exe.
Newer ET4000 chipsets (eg. W32 and W32i) allow up to 32 clock 
frequencies. Two additional register values were added just before the
old extened register value. The new registers are CRTC/30h and CRTC/31h.
The old register set had 71 values, the new growed to 73.
You may update your old register set by hand :
   - run the dumpreg program, remember the first two values from last
     data line.
   - edit your libvga :
       for each mode 
         change the number of register values from 71 to 73
         add the values from dumreg output at front of last data line
   - run vgatest to check the new register set


9. Using dynamic loading with other cards
-----------------------------------------

The dynamical register loading may be used in other drivers.
Since hard linked register values work fine for Cirrus and Trident
cards, we didn't include this feature.

