Question about IPC900 ports

~XT6561110~Frank McGee~C23~L25~6326~ fmcgee at cuuxb.ATT.COM
Mon Apr 9 08:12:11 AEST 1990

In article <387 at mtndew.UUCP> friedl at mtndew.UUCP (Steve Friedl) writes:
>Hi folks,
>     I went out to a customer today to do some wiring on their
>IPC 900 card, and I was astounded to find that their modular
>wiring scheme bears no resemblance to that used on the 3B2.  Even
>Bell Tech/Intel did it the same way on the ACE card, and I find
>it hard to believe that it was made incompatible for no good
>reason.  Does anybody know the story on this?

There is a reason for what they did on the IPC 900 and IPC 1600.
There is a PDS standard that is followed by the DSO PDS engineers,
and also by the folks that do ISN.  Since the DSO people usually are
just selling wire, they aren't too concerned with what you run
through it.  However, ISN does follow the standard, and the wiring
leads on the IPC 900 are compatible with ISN.  What that means is
that you can directly connect an IPC 900 or 1600 into an ISN AIM
port without any intervening adaptors, and all will work as
expected.  Make sure the AIM port isn't more than 50 feet away
however; that's the design limit on how far you can drive the IPC
900/1600 serial ports at 9600 baud.

In addition, the IPC 900 and 1600 extend the PDS standard to a
10-wire standard so that it covers the use of DSR.  This was
necessary for the cards to be able to be used in government bids.
However, the wiring has been arranged so that the cards are still
backward-compatible to 8-wire PDS, and for terminals, printers, and
ISN's you can run through 8-wire PDS.  8-wire RJ45 and 10-wire RJ45
jacks have the same form factor, and both types of receptacles will
accept an 8 or 10-wire jack.  Under Unix, there isn't anything you'd
attach to the IPC 900 or 1600 that couldn't be run through 8-wire
PDS, since our Unix driver ignores the status of DSR.  Presumably,
somewhere there's a driver that does use DSR that is used for weird
government stuff.

The only thing I know that you can't run through 8-wire in
conjunction with the IPC PDS TERMINAL/PRINTER adaptors is
alternate/remote/redirected console (a feature of our 6386/SX,
6386/25, 6386/33, and the Model S) since it requires DSR.  But since
you can't run it over the IPC 900/1600 (only over the COM2 internal
serial port) I consider it unrelated.  If you're really interested
in the redirected console features, I can post or email some info I
have on how to build your own cable.

In the sense of the 3B2/TRW cabling being a "standard", the IPC 900
and 1600 violate that standard.  However, they do conform to AT&T's
PDS standard.

Frank McGee, AT&T
Entry Level Systems Support
attmail!fmcgee (preferred)
att!cuuxb!fmcgee (those that can't reach attmail)

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