INT 33 - MS MOUSE - DEFINE INTERRUPT SUBROUTINE PARAMETERS
        AX = 000Ch
        CX = call mask
             bit 0 call if mouse moves
             bit 1 call if left button pressed
             bit 2 call if left button released
             bit 3 call if right button pressed
             bit 4 call if right button released
             bit 5 call if middle button pressed (Mouse Systems/Logitech mouse)
             bit 6 call if middle button released (Mouse Sys/Logitech mouse)
        ES:DX -> FAR routine
Notes:  when the subroutine is called, it is passed the following values:
          AX = condition mask (same bit assignments as call mask)
          BX = button state
          CX = cursor column
          DX = cursor row
          SI = horizontal mickey count
          DI = vertical mickey count
        some versions of the Microsoft documentation incorrectly state that CX
          bit 0 means call if mouse cursor moves, and swap the meanings of SI
          and DI