Hercules Graphics Support
-------------------------
Learn C also supports the Hercules display adapter. Below is a brief summary
of this feature; see your Hercules documentation for more details. 

  Cards Supported
  ---------------
  Learn C supports the Hercules Graphics Card, Graphics Card Plus, Incolor
  Card, and 100% compatibles.

  Display Characteristics
  -----------------------
  Only monochrome (two-color) text and graphics are supported. The screen
  resolution is 720 x 348 pixels, monochrome. The text dimensions are 80 x 25
  (9 x 14 character box). The bottom two scan lines of the 25th row are not
  visible.

  The MSHERC.COM Driver
  ---------------------
  You must load the Hercules driver MSHERC.COM before running your program.
  This file is located on distribution disk #1 (this disk). Type MSHERC to
  load the driver. This can be done from an AUTOEXEC.BAT file.


  If you have both a Hercules monochrome card and a color video card, you
  should invoke MSHERC.COM with the /H (/HALF) option. The /H option causes
  the driver to use one instead of two graphics pages. This prevents the two
  video cards from attempting to use the same memory. You do not have to use
  the /H option if you have only a Hercules card.

  Using a Mouse
  -------------
  To use a mouse, you must follow special instructions for Hercules cards in
  the Microsoft Mouse Programmer's Reference Guide. (This must be ordered
  separately; it is not supplied with either Learn C or the Mouse package.)

  Setting Graphics Mode
  ---------------------
  In the file GRAPH.H, note that the manifest constant _HERCMONO sets the
  video mode to 720 x 348 monochrome for Hercules graphics, and that the
  constant _HGC has been added in the section "videoconfig adapter values."
