[Sussex] Laptop challenge

[John Crowhurst]

On Fri, February 3, 2006 0:24, Gavin Stevens said:
> Thanks for showing that old laptops (especially free ones!) can still
> have a good life. I will look into the laplink idea. Would a
> male-to-male parallel cable (like on my data switch for my printer) do
> the job?

No, you need to swap some of the pins over, the pinout follows:

Pin 2 -> Pin 15
Pin 3 -> Pin 13
Pin 4 -> Pin 12
Pin 5 -> Pin 10
Pin 6 -> Pin 11
Pin 10 -> Pin 5
Pin 11 -> Pin 6
Pin 12 -> Pin 4
Pin 13 -> Pin 3
Pin 15 -> Pin 2
Shield -> Shield

This creates your laplink (or Mode 0 null parallel) cable. You need to use
the plip module to get this to work. Typically you'll get a /dev/plip0
device for the first parallel port ready for assigning an ip with
ifconfig.

If the parallel ports are bi-directional, you can create the faster Mode 1
null parallel cable with this pinout:

Pin 1 -> Pin 11
Pin 2 -> Pin 2
Pin 3 -> Pin 3
Pin 4 -> Pin 4
Pin 5 -> Pin 5
Pin 6 -> Pin 6
Pin 7 -> Pin 7
Pin 8 -> Pin 8
Pin 9 -> Pin 9
Pin 10 -> Pin 16
Pin 11 -> Pin 1
Pin 12 -> Pin 14
Pin 13 -> Pin 17
Pin 14 -> Pin 12
Pin 15 -> Pin 18
Pin 16 -> Pin 10
Pin 17 -> Pin 13
Pin 18 -> Pin 15
Pin 19, 20, 21, 22, 23, 24 Not Connected
Pin 25 -> Pin 25

Mode 0 uses a 4 bit encoding with a data line to signal whether its the
top or bottom nibble. Mode 1 uses 8 bit but will only work between Linux
computers.

For more information on the PLIP driver, look at the kernel source in
linux/Documentation/networking/PLIP.txt

-- 
John