INT 67 - LIM EMS - MAP MEMORY
        AH = 44h
        AL = physical page number (0-3)
        BX = logical page number
        DX = handle
Return: AH = status
            00h function successful
            80h internal error
            81h hardware malfunction
            83h invalid handle
            84h undefined function requested
            8Ah invalid logical page number
            8Bh illegal physical-page number