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2. Hardware required to use PLIP.

The hardware required to set up a PLIP interface is (obviously) a free parallel port in both the machines and the cable. If you can configure it with your BIOS, set it at least as "bi-directional", but if possible in ECP or EPP mode.

About the cable, this is what is written in the plip.c file, in the kernel 2.0.33 source:

  The cable used is a de facto standard parallel null cable -- sold as
  a "LapLink" cable by various places.  You'll need a 12-conductor cable to
  make one yourself.  The wiring is:
    SLCTIN      17 - 17        
    GROUND      25 - 25
    D0->ERROR   2 - 15          15 - 2
    D1->SLCT    3 - 13          13 - 3
    D2->PAPOUT  4 - 12          12 - 4
    D3->ACK     5 - 10          10 - 5
    D4->BUSY    6 - 11          11 - 6
  Do not connect the other pins.  They are
    D5,D6,D7 are 7,8,9
    STROBE is 1, FEED is 14, INIT is 16
    extra grounds are 18,19,20,21,22,23,24

But I strongly advice you to read the /usr/src/linux/drivers/net/README1.PLIP and README2.PLIP files for more info about the cable.

In my opinion you should avoid building your own parallel null cable. A self-made cable may save very little money, but can add lots of headaches. If you wish to build your parallel cable, remember that you're doing it at your own risk, I reported exactly what is written in plip.c but I don't give warranties.

A final word about cable length: long cables (i.e. more than 10 feet or 3 meters) may bring problems due to radio interference. If you need long cables you should use good and well shielded cables, but very long cables are not recommended: I think the maximal cable lenght should be 15 meters (50 feet).

Anyway, someone mailed me that his/her 100 feet (30 meters) cable works fine; if someone really wants to try a PLIP connection between the office and his/her home (200 meters away), and has the money to spend, can try it, but is at his/her risk.

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