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