INT 14h,  01h (1)        Send One Character
 
    Sends one character to the specified serial port.
 
       On entry:      AH         01h
                      AL         Character
                      DX         Serial port number (0 - COM1, 1 - COM2, etc.)
 
       Returns:       AH         Line status (see Service 03h)
 
  --------------------------------------------------------------------------
 
    If an error occurs, bit 7 of AH will be set. SInce bit 7 is used as a
    general error flag, this service is unable to identify a time-out
    error. For complete diagnostic information, use Service 03h (Get
    serial port status).

Seealso:


 INT 14h, 02h 
 INT 14h, 03h