INT 14h,  1Ah    Break begin or end

      Entry:  AL         01h - Start sending 'break'
                         00h - Stop sending 'break'

              DX         port number

      Exit:   None

    Send a break signal to the modem. If AL=01h the driver will commence the
    transmission of a break.  If AL=00h the driver will end the break.  This
    is useful for communications with devices that can only go into 'command
    mode' when a BREAK is received. Note: the application is responsible for
    the timing of the BREAK.  Also,  if the FOSSIL has been restrained by an
    Xoff received from the modem, the flag will be cleared.   An Init or Un-
    Init will stop an in-progress BREAK.