INT 14,2 - Receive Character from Communications Port


	AH = 02
	DX = zero based serial port number (0-1) (0-3 for AT)


	on return:
	AH = port status  (see INT 14,STATUS)
	     bit 7 = 0 if successful
	     bit 7 = 1 if call failed
	AL = character received if call was success


	- INT 14,3 should be used to determine the actual cause of
	  the error since the time-out bit of the status register is
	  always set during an error on this call
	- uses hardware flow control