Installation check

        Entry:
          AH = 60h

        Return:
          AL = 60h
          DX = CS of resident code

        Note:   FLASHUP.COM is part of Flash-Up Windows by
                The Software Bottling Co.
                FLASHUP also hooks INT 10 and received commands via
                INT 10/AH=09h,0Ah consisting of an 80h followed by the
                actual command