Parallel Printer Port

	Port 3BC printer data output  (readable)

	 │7│6│5│4│3│2│1│0│  ports 278, 378, 3BC
	  │ │ │ │ │ │ │ └──── data bit 0, hardware pin 2
	  │ │ │ │ │ │ └───── data bit 1, hardware pin 3
	  │ │ │ │ │ └────── data bit 2, hardware pin 4
	  │ │ │ │ └─────── data bit 3, hardware pin 5
	  │ │ │ └──────── data bit 4, hardware pin 6
	  │ │ └───────── data bit 5, hardware pin 7
	  │ └────────── data bit 6, hardware pin 8
	  └─────────── data bit 7, hardware pin 9

	Port 3BD printer status register   (Parallel Printer Port)

	 │7│6│5│4│3│2│1│0│  ports 279, 379, 3BD
	  │ │ │ │ │ │ │ └──── 1 = time-out
	  │ │ │ │ │ └─┴───── unused
	  │ │ │ │ └──────── 1 = error,	pin 15
	  │ │ │ └───────── 1 = on-line,  pin 13
	  │ │ └────────── 1 = out of paper,  pin 12
	  │ └─────────── 0 = Acknowledge,  pin 10
	  └──────────── 0 = busy,  pin 11

	Port 3BE printer control register   (Parallel Printer Port)

	 │7│6│5│4│3│2│1│0│  ports 27A, 37A, 3BE
	  │ │ │ │ │ │ │ └──── 1 = output data to printer,  (pin 1)
	  │ │ │ │ │ │ └───── 1 = auto line feed,  (pin 14)
	  │ │ │ │ │ └────── 0 = initialize printer,  (pin 16)
	  │ │ │ │ └─────── 1 = printer reads output,  (pin 17)
	  │ │ │ └──────── 0 = IRQ disable,1=IRQ enable for ACK
	  └─┴─┴───────── unused