INT 17,2 - Read Printer Port Status

	AH = 02
	DX = printer port to be used (0-2)


	on return:
	AH = status:

		|7|6|5|4|3|2|1|0|  Printer status bits
		 | | | | | | | `---- time out
		 | | | | | `------- unused
		 | | | | `-------- I/O error
		 | | | `--------- selected
		 | | `---------- out of paper
		 | `----------- acknowledge
		 `------------ not busy


	- returns status of specified printer port