Function            scroll_up - scroll window up

  Syntax              void scroll_up(int left, int top, int right,
                                       int bottom);

  Prototype in        video.h

  Remarks             scroll a box, delineated by the coordinates, up 1
                      line. A blank line will be inserted at the bottom,
                      and the top line will be lost. The scrolling is
                      done via INT 0x10, Function 6. Coordinates are
                      absolute.

  Return value        nothing.

  See also            scroll_down()

  Example             #include <video.h>

                      main()
                      {
                           scroll_up(0,0,4,79); /* scroll top 4 lines */
                      }