INT 16 - pcANYWHERE III - COMMUNICATIONS I/O THROUGH PORT
        AH = 7Eh
        AL = subfunction
            01h port input status
                Return AX = 0 if no characer ready,
                       AX = 1 if character ready
            02h port input character
                Return AL = received character
            03h port output character in CX
            11h hang up phone