Re: Making a Parallel Port Laplink cable
By: kirkspragg to All on Sat Aug 09 2025 18:36:32

I have recently moved house...

Where'd you move it to? ;)
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I am not an expert on such things but I think twisted pairs only really help for balanced signals, not unbalanced (ground reference) signals. I

I'm pretty sure you are right there.

could be wrong. In fact I'll drop my tame electrical engineer friend a note and see what he thinks.

I'd appreciate it if you did check with someone who knows better than I do!

I imagine he will think "What's that idiot doing now? Bodging again, no doubt".

Yes very much so. But then data transfer (and even networking) between computers via parallel port was always a bit of a bodge. The original parallel port really wasn't designed with this in mind!

... If you can't laugh at yourself, I'll laugh at you.

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You could try just extending the cable, with just a regular 25pin serial cable from Amazon, and maybe a gender changer if needed?

If its a serial cable it won't have all 25 pinns connected at both ends as serial doesn't use them all. So thats unlikely to work.

A 25 pin pass through cable might work if it's also shielded, maybe those exist? I'll have to look.

... If brains were taxed, he'd get a rebate.

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Re: Re: Making a Parallel Port Laplink cable
By: kirkspragg to Bob Worm on Mon Aug 11 2025 20:30:15

could be wrong. In fact I'll drop my tame electrical engineer friend a note and see what he thinks.

I'd appreciate it if you did check with someone who knows better than I do!

For what it's worth I asked my friend. He fired back a super long question about something he's trying to figure out and didn't answer - I will give him another kick shortly!

By the time he answers you might already have tried it out, though :)

BobW
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For what it's worth I asked my friend. He fired back a super long
question about something he's trying to figure out and didn't answer - I will give him another kick shortly!

By the time he answers you might already have tried it out, though :)

BobW

Maybe! I have figured out that I probably don't need a 18 core cable for this, 12 should do if I wire it up following the linux kernel docs for plip (docs.kernel.org/networking/plip.html) & use the "Parallel transfer mode 0 cable" schematic. That is for older non-bidirectional parallel ports, which is what my retro PC has so that should work.

So I could do it with 3 runs for 4 core shielded cabling I can get locally. Also less soldering involved! A win on two fonts!

... Is it ignorance or apathy? I don't know and don't care.

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