DOS Fn 03H: Auxiliary Input

                                                         Compatibility: 1.0+ 
 Expects: AH    03H
 Returns: AL    character fetched from the Standard Auxiliary Device
    Info: Reads (waits for) a character from the Standard Auxiliary Device,
          COM1 or AUX, returning that character in AL.

   Notes: ■ Input is not buffered and must be polled (not interrupt

          ■ When DOS starts up, the AUX port (COM1) is initialized to:
             2400 baud
             no parity
             1 stop bit
             8-bit word

          ■ The DOS MODE command can be used to initialize various

See Also: INT 14H
          COM Ports
          Character I/O Functions
          DOS Functions