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Date:      Mon, 23 Sep 1996 10:10:20 -0400
From:      dennis@etinc.com (Dennis)
To:        "Louis A. Mamakos" <louie@TransSys.COM>
Cc:        hackers@freebsd.org
Subject:   Re: VC support, *BSD and atm/frame/isdn 
Message-ID:  <199609231410.KAA14738@etinc.com>

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>
>> I don't think it's particularly efficient, but it's
>> not expected to be running under very heavy usage in this version.
>> I believe that they went out and did a scan of several providers to
>> see if they could use them but somehow ended up doing it that way.
>> I do know that they had a hard time trying to work out what pinouts to
>> use for connecting a V35 connector to a connector small enough  for
>> a back plate, and that they liked your DB25 implimentation.
>> I've scanned the literature but I haven't found an "Official"
>> or even "defacto" standard on how to do this.. the V35 connector is SOO
>> clunky. I've been meaning to ask you... did you find that pinout
>> somewhere, or did you make it up..?
>
>Please, don't invent a new pin out for the connector!  Use a DB25 and
>have it be EIA-530 compatible.  This is essentially a superset of the
>V.35 "spec" in terms of the line drivers and receivers, and using a
>simple adapter cable, you can get to a V.35.  I think that EIA-530 is
>recommended for new applications, and certainly the cost is lower, too.

Well, I think that the V.35 "hack" that most of us use is a "subset" of the
standard
EIA-530, rather than the other way around....but you are correct.

>
>Though in most cases, your customers can just purchase EIA-530 compatible
>CSU/DSUs, and use a straight-thru DB25 cable.  That way, there are no
>large, clunky Winchester connectors around at all to cause injury.

Be careful, you really should use a twisted pair 25pin cable, not a cheapo
RS-232 25 pin cable, particularly for high speeds. Its still cheaper than
V.35....

Dennis





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