Function  06h	Direct Console I/O
      Get character from STDIN; echo character to STDOUT 
entry   AH      06h 
	DL      0FFh for console input, or 00h-0FEh for console output 
return  ZF      set   (1) = no character 
		clear (0) = character recieved 
	AL      character 
note 1) Extended ASCII codes require two function calls. The first call returns 
	00h to indicate the next call will return an extended code. 
     2) If DL is not 0FFh, DL is assumed to have a valid character that is  
	output to STDOUT.  
     3) This function does not check for Ctrl-C or Ctrl-PrtSc. 
     4) Does not echo input to screen 
     5) If I/O is redirected, EOF or disk full cannot be detected. 

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