Four pairs - sounds like standard UTP LAN cable
Regards
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Rod Smallwood
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?????
?
-----Original Message-----
From: cctech-bounces at
classiccmp.org [mailto:cctech-bounces at
classiccmp.org]
On Behalf Of Tony Duell
Sent: 02 March 2012 21:27
To: cctalk at
classiccmp.org
Subject: Re: BA123 power supply, AUI cables
I could also use a handful of short AUI cables.
Depending on what "short" means here, you may be able to make your own
with a pair of DA15s and some 15-pin ribbon cable. It doesn't have the
right transmission-line characteristics, but for sufficiently short
cables that doesn't matter in practice. (I once experimented; I had to
get up to something like three metres before I started getting a
significant level of errors.)
I have certainly doen this with no problems with short (1 foot or less)
cables to link a small transceriver to the socket on a distribution
panel.
The correct cable is not easy to get, at least not by the metre. Last
time I needed soem I fond that it was generally only possible to get a
large drunm of it costing several hundred pounds :-(.
It seems to be difficult, at least for me, to find out just sort sort
of signals, in the electrical sense, run over AUI. But at 10Mb, bits
OK, ther are 4 pairs in the cable. 3 of them are digital signals, the
last is the power to the trnaceiver. In the proper calbe, the power pair
is actually thicker wire than the other 3 pairs.
The power pair is 12V. The logic signals are differnetial ECL IIRC. I can
certianly check the exact detials, I have schemaitcs of ethernet
interfaces nad transceives built from simple ICs. Acutally, looking at
osmething like the PERQ scheamtics (EIO or OIO board) or the DEUNA
printset, both, I think, on bitsavers, might help.
FWIW, the cabl from the DEUNA (or wahtever board) to the bulkhead panel
and the simialr cable i nthe PERQ 2 from the header on the backplane to
the DA15 on the cabinet carry the ethernet signals, (there's no signal
circuitry at the bulkhead/cabinet end in either case) and seem to be jsut
plain IDC ribbon cable. So it's not suprising that you can use this for
short traceiver drop cables.
-tony