INT 60 - FTP Packet Driver - BASIC FUNC - ACCESS TYPE
        AH = 02h
        AL = interface class
        BX = interface type
        DL = interface number
        DS:SI -> type
        CX = length of type (0000h for all packets)
        ES:DI -> receiver
Return: CF set on error
            DH = error code (see AX=01FFh)
        CF clear if successful
            AX = handle

Receiver is called with:
        AX = subfunction
            00h get packet buffer
                DX = lookahead length (v1.10+)
                DS:SI -> lookahead buffer if DX nonzero (v1.10+)
                DI = error flags (class dependent) (v1.10+)
                Return: ES:DI -> packet buffer
                                0000h:0000h means throw away packet
                        CX = size of buffer (v1.10+), may be smaller than
                                incoming data
            01h copy completed
                DS:SI -> buffer
                CX = bytes actually copied (v1.10+)
        BX = handle
        CX = buffer length
when a packet is received