Variables

      VideoCard             :Array [MonoCard..ColorCard] of OneVideoCard

    This holds information on the one or two cards in the system.

      Card                  :MonoOrColor

    This determines the currently active card.

      TextAttr              :Byte

    This has the  background  colour  in  the  left  nibble  and the text
    colour in the right nibble.

      LastMode              :Byte

    This is defined on startup.  It  contains  the  video mode before the
    program  started.   Unlike   the   CRT.LastMode   variable,   it   is
    not updated with every call to TextMode.

      Cursor                :Boolean

    If  Cursor  is  True  then  procedures  such  as  WriteStr  move  the
    flashing cursor when they are  called.   If  however Cursor is False,
    the cursor position is not updated  and is left where it is.  This is
    by default True but can  be  changed  by  the user at any time during
    the program.

      VX                    :Word

    The position of the cursor on the virtual screen.

      VY                    :Word

    The position of the cursor on the virtual screen.