
  Parallel port driver


A cheap and easy way to get a few more digital I/O lines.  Steal
additional parallel ports from old computers or your neighbors'
computers.


Parallel Output Port Lines:

pin	channel	bit	aka
---	-------	---	---
1	2	0	strobe
2	0	0	data 0
3	0	1	data 1
4	0	2	data 2
5	0	3	data 3
6	0	4	data 4
7	0	5	data 5
8	0	6	data 6
9	0	7	data 7
10	1	3	acknowledge
11	1	4	busy
12	1	2	output
13	1	1	printer selected
14	2	1	auto LF
15	1	0	error
16	2	2	init
17	2	3	select printer
18-25	ground


Notes:

Channel 0 and 2 are output, channel 1 is input.  I know that it
is possible to change this with ECP/EPP parallel ports, but this
driver is a cheap hack.

Pins 13 and 14 are inverted once by comedi and once by the
hardware, thus cancelling the effect.

Pin 1 is a strobe, thus acts like one.  There's no way in software
to change this, at least on a standard parallel port.

Please report any sucesses/failures.

