Procedure TextBackground(Backg:Byte)

    Updates VX and VY       : No
    Updates Cursor Position : No

    The value of  TextAttr  is  updated.   All  text  displayed  will now
    use the text  background  colour  specified  by  Backg.   Backg  is a
    value from 0 to 7.   If  you  place  the  CGA,  EGA  or VGA in high -
    intensity background mode  (no  flashing  text),  you  may use values
    from 0 to 15 (not tested).

    Be aware  that  the  CGA  and  VGA  use  different  methods  to  turn
    off flashing text.