Extended initizlize (PS)

        Entry:
          AH = 04h
          AL = break status
                0: If break
                1: If no break
          BH = parity
                0: No parity
                1: Odd parity
                2: Even parity
                3: Stick parity odd
                4: Stick parity even
          BL = number of stop bits
                0: One stop bit
                1: Two stop bits (1.5 if 5 bit word length)
          CH = word length
                0: 5 bits
                1: 6 bits
                2: 7 bits
                3: 8 bits
          CL = baud rate
                0: 110
                1: 150
                2: 300
                3: 600
                4: 1200
                5: 2400
                6: 4800
                7: 9600
                8: 19200
        Return:
          AL = modem status (see above)
          AH = line control status (see above)