INT 53 - ??? - API
        BX = function
            0000h ???
                AX = ???
                Return: AX = ???
            0004h ???
            0009h ???
            0015h
                AX = ???
                DX = ???
            0017h
Return: ???
Notes:  the installation check consists of looking for the signature "WEBCO"
          immediately prior to the interrupt handler
        the above calls are made by Show Partner F/X v3.6 (see INT 10/AH=53h)