       
                      ZW-DOS SOFTWARE NOTES 

                       (c) Ya-Gui Wei 1992

! Note: Changes related to version 2.1 are preceeded with an exclaimation 
  mark (!).

  ZW-DOS seeks to simulate a text-mode screen that is Chinese-compatible
using the graphic capabilities of the various video adaptors. Since
the graphic capabilities of the video systems vary, it is not always
possible to simulate all the text-mode features completely, -- this
results in some visual peculiarities. The incomplete simulation some-
times affects program execution, therefore incompatibilities. Sometimes,
due to programmer inaptitude or oversight, the computer is not doing
what the programmer wanted it to do, these are bugs.

  This file is intended to document the various peculiarities of
ZW-DOS that the user needs to be aware of.
   
  (1) Visual peculiarities due to incomplete simulation of text 
mode. Note: These peculiarities occur only when the screen display
is in Chinese mode.  In ASCII mode, you should not see any of 
these.

 a. ZWEGA/ZWVGA:  The EGA and VGA versions of ZWDOS have
    the most complete simulation of the text modes. Character 
    color and intensity are well-simulated. Yet some of the
    EGA/VGA features are no longer supported:
    - Loading of alternate ASCII text fonts are no longer 
      supported. The default system fonts are always used.
    - Switching of the screen to 43-line mode (or anything
      other than a 80x25 dimension) is no longer supported.
    - Blinking characters are no longer supported -- they will
      appear with a high-intensity background color instead.

 b. Hercules Monochrome version:  The Hercules version simulates 
    the original monochrome character attributes such as 
    invisibility, underscore, and reversed vido. Yet:
    - Blinking characters are no longer supported. They appear
      the same as regular characters.
    - There will be no visual difference between low-intensity
      and high-intensity attributes.
    - Control of cursor size is not implemented. 

 c. CGA version (including CGA version for AT&T laptop 640x400 
    mode): The color capabilities of these adaptors in their 
    graphic mode is pitiful (so is the resolution of the CGA 
    adaptor). The programmer has done what he can under the 
    circumstances, yet the simulation of text mode is quite 
    unsatisfactory.
    - Colors, intensity difference, and blinking of characters
      are no longer supported. All characters are in black-
      and white and with the same intensity. Those characters
      with a background color value higher than the foreground
      value will appear as reverse video.

 d. AT&T 640x400 mode version. (These problems are due to the
    fact that the addresses of text mode and graphic mode video
    buffers conflict with each other.)    
    - Direct reading of screen buffer content is no longer
      supported. Any programs that try to read, copy or scroll
      the screen directly will produce garbage dots on screen.
      This can be fixed by simply redrawing the screen, if your
      application can do that.
    - Text output to screen occasionally may be lost, resulting
      in non-updating on a few locations of the screen. This too
      can be fixed by redrawing the screen.
!   (These restrictions used to apply to ZWCGA in version 2.0
     but is no longer the case with version 2.1.)

  (2) Incompatibilities related to mice:
!   (Note: mouse incompatibilities seem to be related to particular
    mouse drivers - some mouse drivers seem to be more compatible
    than others. Therefore the following descriptions may not
    apply to you.)

 a. The CGA and VGA versions:  If you load these versions of ZWDOS
    AFTER you load the mouse driver, the graphic mouse cursor may
    appear when the screen is in Chinese mode. While the graphic 
    mouse cursor is nicer-looking than the text-mode counter-part, 
    it causes trouble with ZWDOS's screen updating. Therefore it is 
    best to load the mouse driver after loading these versions of 
    ZWDOS.

 b. The EGA version:  You may not be able to load the mouse driver
    when the display is in Chinese mode.
 
 c. The Hercules version:  There are no known incompatibility with
    mouse drivers.


  (3) Incompatibilities related to graphic applications

  ZWDOS only simulates a Chinese-compatible text mode. It does nothing
with the graphic modes of the video systems. You cannot input or display
Chinese characters with graphic mode applications.


  (4) Running ZWDOS with DESQview/386, Windows 3.0, or OS/2:

  Despite what is said about the multi-tasking capabilities of these
systems, they may still be confused when the screen is switched to
Chinese mode by ZWDOS. Therefore it may be best to load ZWDOS within
a DOS session of these systems, and run that DOS session in full
screen mode at all times. When you are done with ZWDOS, try to make
the screen switch back to ASCII mode before closing that DOS session.

!   Running ZWDOS in DESQview: To run ZWDOS in a DOS session in
DESQview, the DOS session must be set up as follows: (1) it allows
writing directly to screen; (2) it uses graphics; (3) screen output
must NOT be virtualized; (4) it allows use of 2 graphic pages. Also,
protection level must be set to 0.

!   Running ZWDOS in MS Windows 3.x: ZWDOS should run in a full 
screen DOS session just fine. Sometimes you may be able to shrink that
DOS session into a window (while suspended). In that window you should
be able to copy the Chinese characters and transfer their graphic
image into other Window applications.


  (5) HZ Spec Related Matters

! Version 2.1 has a better implementation of HZ, with some of the
misunderstandings in version 2.0 corrected. 

! Version 2.1 now recognizes ~ as an escape character so that 
~~{ will not be interpreted as starting a Chinese string, but the
~~'s are NOT corrupted back into one ~ as the HZ spec seems to
specify. This choice was an intentional one and was intended to
reduce disruption on non-HZ ASCII texts that might contain the
string.


! (6) Removing ZWDOS from memory.

  You can use any of the comercial or PD utilities that remove
memory resident programs to remove ZWDOS from memory, however,
be sure that the display is NOT in Chinese mode when you do this.
  

  (7) Bug List:

! I hope that those of you who had problem running ZWDOS with certain
  versions of PC Telnet will find the problem gone by now.

    If you discover some bugs or problems with the programs that 
    have not been described in this file, report it to the programmer.
    The programmer will try to fix the bug.  If it is too much
    trouble, the bug will appear in this file in future releases.


