GraphMode                Sets Screen to Black-and-White Graphics Mode

 GraphMode;                                                              [TP]

    Sets the display to a 320x200 "black and white" display, clearing the
    screen as it does so.

          Notes:    X coordinates (columns) range from 0..319; Y
                    coordinates (rows) range from 0..199. To get back to a
                    regular text display, call Textmode.

                    Text can also be displayed in this mode, allowing 40 x
                    25 characters.

                    This display mode displays only black and white
                    graphics, except on an RGB monitor, where a limited
                    set of palettes can be used (See Palette).

                    This procedure resets the graphics window to
                    (0,0),(319,199), destroying any previous graphics
                    window setting.

  -------------------------------- Example ---------------------------------

           GraphMode;               { set to 320x200 "B&W" mode }