Function  03h   Auxiliary Input 
      Get (or wait until) character from device\driver\AUX-
entry   AH      03h 
return  AL      char from auxiliary device 
note 1) AUX, COM1, COM2 is unbuffered and not interrupt driven 
     2) This function call does not return status or error codes. For greater  
	control it is recommended that you use ROM BIOS routine Int\14 or
	write an AUX device driver and use device\IOCTLs.
     3) At startup, PC-DOS initializes the first auxiliary port (COM1) to 2400  
	baud, no parity, one stop bit, and an 8-bit word. MSDOS may differ. 
     4) If Ctrl-C is has been entered from STDIN, Int\23 is executed.