INT 33H 0008H: Set Vertical Range

 Expects: AX    0008H
          CX    minimum Y coordinate (vertical pixel position)
          DX    maximum Y coordinate (vertical pixel position)
 Returns: none
    Info: This sets a vertical range out of which the mouse pointer will
          not be able to move.  Attempts by the user (or the program via
          INT 33H 0004H) to move above CX or below DX will cause the
          pointer to remain at the minimum or maximum value in the range.

          Use INT 33H 0007H to limit motion on the horizontal axis.

   Notes: All X,Y coordinates are virtual coordinates and when working with
          text mode, you must divide each value by 8 to get a character

See Also: INT 33H: Mouse Support
          Interrupts and BIOS Services