Re: Remove plip(4)?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> I'll test it out on one of the other machines [...]

> So, it turns out the "LapLink" cable I acquired is actually not to
> spec and has slightly different wiring than what is considered
> standard.  [...]

> 2			15
> 3			13
> 4			12
> 5			10
> 6			11
> 10			5
> 11			6
> 12			4
> 13			3
> 15			2
> 1,7,8,9,14,16,17			unused
> 18-25			18-25		Common as one

> The test setup included one Linux and one NetBSD machine. Initially,
> a successful SSH session was established, however connectivity was
> unable to be replicated on subsequent attempts, which lead to
> verifying the wiring of the cable.

> The cable does not have a working pin 17, [...]

> https://gitlab.com/FreeDOS/net/crynwr/-/blob/master/DOC/CRYNWR/PLIP.DOC
> ---------------FreeDOS---crynwr--------------------
> This is the wiring diagram for the cable [...]

> 14 - 14

> 16 - 16
> 17 - 17

> -------------Linux--------------------------------

>     SLCTIN      17 - 17

This looks dubious to me.

Connecting pins 2/3/4/5/6 to pins 10/11/12/13/15, that looks sensible.
Those are output pins on one end and input pins on the other.

Pins 14, 16, and 17, though, are output pins, meaning that connecting
those between the ends risks the two ends arguing over its logic level,
possibly frying an output driver if there's too little resistance
between the drivers.

It's possible this worry is unwarranted.  It's possible pins 14/15/17
can, on some parallel ports, be switched to inputs.  Unlike serial
ports[%], I don't know whether there's an electrical spec for those
drivers, nor if so what it is.  But I'd be concerned enough to leave
those pints out, or at least put, say, 100 ohms in line with them, and
I'd treat your unidirectional communication as a debugging problem,
since it sounds as though the cable you have _should_ work.

[%] Serial ports are really nice in this regard.  I once got hold of a
copy of EIA-RS232-C.  It specifies something like "any pin or
combination of pins may be shorted indefinitely to any voltage source
within range [which for RS232 means, I think, -25V to +25V]
indefinitely without damage".  Of course, it also specifies other
things which get ignored (I've heard of "serial ports" that drive 0V
and 5V instead of the correct voltages)....

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