🚀 go-pugleaf

It seems that it is not generally known that each printer port contains
three registers (some cheapo printer cards only implement two). 

The register at offset 0 from the I/O location of the printer is write-only,
for data (there is a diagnostic read-back, which is the same as what was
written if the card is working properly).

The register at offset 1 contains:

	Bit		Fxn
	---		---
	7		Busy			(~read)
	6		Ack			(read)
	5		Out of paper		(read)
	4		Printer selected	(read)
	3		Error			
	2		IRQ occurred		(read)
	1-0		Reserved		(read)

The register at offset 2 contains:

	Bit		Fxn
	---		---
	7-5		Reserved
	4		Enable IRQ
	3		Select printer		(~read, ~write)
	2		Init printer		(read, ~write)
	1		Auto LF			(~read, ~write)
	0		Strobe			(~read, ~write)

I think that it is at offset 2 that you must write all 1's to the port
before you can use it to read.

There may be typo's here -- caveat emptor!