Re: tlug: serial connection with laptop

[Karl-Max Wagner <karlmax@example.com>]

> I have tried to figure this one out on my own too, but how do you (or can
> you) connect a laptop via serial port.  I know that just because it is a
> laptop doesn't make much of a difference.
Correct.
> I suppose that in theory I could connect via nullmodem (what is that?) and
> use slip/mgetty????
Better ( simpler ) is PPP. A nullmodem is a cable wired in a special
way. It is the same stuff you use for Laplink, Fastlynx or the
like. Here is a wiring list taken from the Fastlynx manual:

============================================================

Following is a description of the pin connections for a FastLynx
7-wire serial cable.  The cable is a 4-headed cable with a 9-pin
and 25-pin female connector on both ends.  The cable is wired as
follows:

    9 pin   25 pin          25 pin  9 pin
    -----   ------          ------  -----
    pin 5   pin 7   <---->  pin 7   pin 5   (Ground - Ground)

    pin 3   pin 2   <---->  pin 3   pin 2   (Transmit - Receive)
    pin 7   pin 4   <---->  pin 5   pin 8   (RTS - CTS)
    pin 6   pin 6   <---->  pin 20  pin 4   (DSR - DTR)

    pin 2   pin 3   <---->  pin 2   pin 3   (Receive - Transmit)
    pin 8   pin 5   <---->  pin 4   pin 7   (CTS - RTS)
    pin 4   pin 20  <---->  pin 6   pin 6   (DTR - DSR)

The ground wire is connected to the same pin on both ends.  The
last three wires are a reverse of the prior three.

Following is a description of the pin connections for a FastLynx
parallel cable.  The cable has a male DB25 connector at both
ends.

            25 pin          25 pin
            ------          ------
            pin 2   <---->  pin 15
            pin 3   <---->  pin 13
            pin 4   <---->  pin 12
            pin 5   <---->  pin 10
            pin 6   <---->  pin 11

            pin 15  <---->  pin 2
            pin 13  <---->  pin 3
            pin 12  <---->  pin 4
            pin 10  <---->  pin 5
            pin 11  <---->  pin 6

            pin 25  <---->  pin 25

The second set of 5 wires is the reverse of the first set.

=============================================================

The second wiring list is what you can use to use PLIP between
two printer ports. Read the PLIP-MINI-HOWTO for details.

And now get Olaf Kirch's "Linux Network Administrator's Guide".
Get it NOW ! Yes, NOW ! Read it carefully ! I see that you need
the information contained in it URGENTLY now. If you don't
understand something, come back.

The beauty of Linux is that litterally anything that is attached
to a computer and can be (ab)used to carry information can be
used for advanced networking. I personally use a mix of PPP,
PLIP and ethernet regularly. It means some gateway defining and
the like, but it allows you to shuffle information around at
your ease just with a few keystrokes. The above book tells you
how to do that. That's why I insist that you should read it NOW.

Happy networking !

                                Karl-Max Wagner
                                karlmax@example.com
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