Subject: DEC AUI Cable

From: chris <[email-masked]>
Date: Wed Mar 19 14:21:00 2003

What is DEC AUI Cable? ie: What is it used for, and what kind of wire is 
inside?

I have 3 lengths of the stuff, and its stiff as hell. Feels like maybe 
multiple strands of co-ax or something. The jacket is labeled 4PR so that 
might make sense. It has 15 pin D-shell right angle connectors on it.

I'm just curious about it.

-chris
<http://www.mythtech.net>

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From: David Woyciesjes <[email-masked]>
Date: Wed Mar 19 14:53:00 2003

> <http://www.mythtech.net>

	Good old fashioned ethernet cable. Ever see one of those 15 pin
connectors with a slide-lock on a NIC? That's what they hook to.

	BTW, when are you gonna stop by up here, and get your goodies? ;)

--
---Dave Woyciesjes
---ICQ# 905818

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From: Tothwolf <[email-masked]>
Date: Wed Mar 19 15:03:00 2003

On Wed, 19 Mar 2003, chris wrote:

> multiple strands of co-ax or something. The jacket is labeled 4PR so
> that might make sense. It has 15 pin D-shell right angle connectors on
> it.
>

It's used to connect an AUI transceiver to an AUI network interface. Ages
ago (well, has it really been *that* long ago?), you'd have a run of RG11
coax that you would literally drill into and attach a tap to. You would
then attach the ethernet transceiver to the tap, which would be cabled to
the computer's network interface with an AUI cable. Later on, as RG11
backbones were replaced UTP, fiber, and even RG58 in some cases, other
transceivers were produced, and conversion kits were also available for
the older tap-type transceivers so they could use a BNC connector.

The cable contains, if memory serves, 4 twisted pairs each with a foil
wrap shield, possibly a 5th unshielded pair for 12VDC (can't remember for
sure, maybe one of the 4 pairs is normally used for this), and everything
is then covered with a mylar plastic wrap, a foil shield, and then a
braided shield. To top it off, many cables use a Teflon jacket, which
makes them suitable for use in air plenums (suspended ceilings). PVC
jacketed cables are not suitable for plenum use, since PVC will release a
toxic gas if heated above a certain temperature, as would happen in a
fire.

(Yep, I'm back. My ISP had major issues for ~2 months, and I finally got
someone to take notice and do something about them. Now I have a 2500-3000
classiccmp message backlog to read over...)

-Toth

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From: [email-masked] (Tony Duell)
Date: Wed Mar 19 17:38:29 2003

> What is DEC AUI Cable? ie: What is it used for, and what kind of wire is 

AUI = Attachment Unit Interface (IIRC), the interface between an ethernet 
controller and the MAU (Media Access Unit). It's the cable for an 
ethernet tranceiver, therefore.

At one time ethernet transceivers were not built into the 
computer/interface card. They were semi-permanently fixed to the coaxial 
cable. And you used an AUI cable to connect the computer to the transceiver.

It's 4 twisted pairs. 3 are identical and carry the 3 transceiver signals 
(transmit data, receive data, collision detect). The other pair is 
thicker wires (officially) and carries the 12V power supply to the 
transceiver.

A few years about I had to make up one of these cables because my PERQ 
uses 4-40 screw-down jackposts and not the normal slidelock posts on the 
ethernet connectors. Getting a couple of metres of the cable was the 
hardest part of the job!

-tony

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From: Andreas Freiherr <[email-masked]>
Date: Thu Mar 20 07:49:00 2003

AUI cable? - Oh yes, I do remember: when I was at the University of 
Darmstadt, getting those four pairs and all the shields into the shell 
of a 15-pin connector was the hardest test somebody had to stand before 
she/he was allowed to "officially" join the network/cabling crew.

Tony, we should have met earlier: I would have been happy to cut a 
couple of feet from the reel for you.

We found that there was a difference between |d|i|g|i|t|a|l| and other 
brands: the DEC cables had the common shield isolated from the 
individual shields of the pairs, while at least some other manufacturers 
had them connected.

I still have a self-made one connecting my 11/23-PLUS to a new-fangled 
BNC mini transceiver, because even the mini transceiver would not fit 
under the hood when directly plugged into the DEQNA (Ethernet) bulkhead 
at the back of the BA23 box.

Andreas

--
Andreas Freiherr
Vishay Semiconductor GmbH, Heilbronn, Germany
http://www.vishay.com

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From: [email-masked] (Tony Duell)
Date: Thu Mar 20 18:31:46 2003

> of a 15-pin connector was the hardest test somebody had to stand before 

I got the type of shell that's made in 2 halves, so I didn't have to feed 
the cable through a small hole...

> couple of feet from the reel for you.

That's exactly what happeend it the end -- I found a friendly 
network-cabling person and he gave me a couple of metres of the cable.

-tony

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From: Andreas Freiherr <[email-masked]>
Date: Mon Mar 24 02:48:00 2003

> the cable through a small hole...

That's what we used, too. However, it is still kind of an advanced 
exercise to cut the wires to a suitable length before stripping and 
soldering, so that after these steps they will fit into the small shell 
together with the strain relief clamp, in particular if you want the 
metalized shell to be properly grounded from the inside...

If you had managed that for the first time, you would usually discover 
that you forgot to slip that rubber tube onto the cable to prevent it 
from breaking where it leaves the plug. If it happens when you managed 
the second time, then it's worse, because you cannot drop it in from the 
other end of the cable... - But this is nothing special with transceiver 
cable, it happens with all sort of cabling, all the time. It only seems 
to vary in proportion to the number of pins inside the connector... ;-)

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From: [email-masked] (Tony Duell)
Date: Mon Mar 24 17:44:00 2003

> that you forgot to slip that rubber tube onto the cable to prevent it 

Been there, done that, got a semi-infinite number of T-shirts :-) It's 
particularly annoying wben I forget to fit the outer cover of a mini-DIN 
plug before soldering and sleeving all the wires, but then mini-DIN plugs 
are always annouying!

-tony