The modes provided with TWEAK range from the obscure to the useful.
This file has some hints and some vital information.

First of all, a small warning:

All mode files with an 's' at the and of the name (for example 
800x600s.16) use special dot clocks available on my Chips & 
Technologies 80c451 SVGA card.  Feel free to try them on your card, but 
don't expect them to work on a vanilla VGA.

Modes with a 'c' at the end of the name are chained modes, to 
distinguish them from unchained modes of the same resolution.

Then, some info about modes of particular interest:

256x256c.256 - The chained Mode Q:
  o  256x256 in 256 colors
  o  exactly 1 page, uses every single byte of the video segment
  o  1-to-1 linear pixel-to-address mapping, like mode 13h
  o  keep (x,y) coordinates in a single word, and use that word as
     an offset.  (Both x and y fit in a byte!)  No more MULs!
  o  I named it 'Mode Q' for 256-cubed (256x256x256 = 256^3).

256x256.256 - The unchained Mode Q:
  o  256x256 in 256 colors
  o  exactly 4 pages
  o  4-to-1 planar mapping, like Mode X

The 256-column modes have been provided in several other vertical
resolutions: 224 and 240 lines

400x600.256 - new, more stable version
  o  400x600 in 256 colors (unchained)
  o  1 page + 22144 bytes (55.36 lines)
  o  4-to-1 planar mapping
  o  good multisync monitor is still required

400x300.256 - New square aspect ratio mode
  o  400x300 in 256 colors (unchained)
  o  That means a square aspect ratio if stretched to fill the screen!
  o  2 pages + 22144 bytes (55.36 lines)
  o  4-to-1 planar mapping
  o  NOT based on the above 400x600 mode!  Uses the lowest vertical
     frequency, and should thus prove much more stable than the
     600-line mode.

360x360.256
  o  Interesting mode, which should work on most VGAs.

360x270.256
  o  New square aspect ratio mode


Known problems:
---------------
  o  The 400x-modes won't work on LCDs and similar equipment

  o  They also fail (won't synchronize) on cheap, basic VGA monitors
     like the Samsung I used to have.  I think your monitor must
     support SVGA resolutions of 800x600x16 and up for the 400x-modes
     to work.  Your card can probably be plain, vanilla VGA though!

  o  Don't expect the modes to line up perfectly with your monitor
     screen's edges!  You might have to adjust the size and position of
     the image with your monitor's control knobs.

I have yet to see a VGA setup which doesn't support Mode Q.  Let me
know if you have trouble.


Disclaimer:
-----------
I can't guarantee that any of the above modes will be compatible with
your VGA card.  I will accept no responsibility for damages arising
from the use or abuse of the files included in this archive.

If any of the above modes don't work on your configuration, send me
an email stating the name/chipset of your (S)VGA card, and monitor
type.  I'm especially interested in any changes you could make to get
them to work!  Also mail me comments and suggestions to the TWEAK
archive.  I will probably release a new version by the end of the
summer.  Current ideas include:

  o  A tutorial on tweaking in general, with focus on unchained, 256
     color modes.  I ought to explain the significance of all timing
     registers, and their relevance for the resulting resolution.
  o  A program which takes as input a description of a screen mode
     (i.e. resolution, colors) and outputs a list of suggested
     registers settings.
  o  A method of linking TWEAKed 256-color modes to Themie Gouthas' XLIB.
  o  Context sensitive help on most registers and their individual bits
     within the TWEAK utility.
  o  Support for assembler and Pascal output.


Regards from
Robert Schmidt of Ztiff Zox Softwear, Norway

e-mail: robert@stud.unit.no