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From: bde@kralizec.zeta.org.au (Bruce Evans)
Newsgroups: comp.os.386bsd.misc
Subject: Re: Using the sio ports for terminals w/o modem ctl signals
Date: 16 Aug 1993 18:32:11 +1000
Organization: Kralizec Dialup Unix Sydney: +61-2-837-1183 V.32bis
Lines: 29
Message-ID: <24ngmbINNbfu@kralizec.zeta.org.au>
References: <CBJnzu.6nG@obiwan.uucp> <1993Aug10.193616.16846@fcom.cc.utah.edu> <24grraINNl92@kralizec.zeta.org.au> <1993Aug15.232601.17314@fcom.cc.utah.edu>
NNTP-Posting-Host: kralizec.zeta.org.au

In <1993Aug15.232601.17314@fcom.cc.utah.edu> terry@cs.weber.edu (A Wizard of Earth C) writes:

>In article <24grraINNl92@kralizec.zeta.org.au> bde@kralizec.zeta.org.au (Bruce Evans) writes:
>>There might still be problems from broken programs such as getty blindly
>>turning CLOCAL off.

>Why would getty leave CLOCAL set on a modem?  I don't understand.

The getty might be talking to a terminal.  Then the setting of CLOCAL is
irrelevant if DCD is wired on and needs to be on if DCD is not wired.  But
the 386BSD-0.1 getty blindly turns CLOCAL off, clobbering the second case.
It should either leave CLOCAL unchanged or provide a way to specify the
setting.

>>It is sufficient to have a non-broken board and/or cables with DCD wired on.

>I'd like to see you strap DCD on an internal modem.  If the answer is that I
>should buy different hardware, my answer is that software is to make up for
>the deficiencies of hardware (at least driver software).  It is the

A modem without DCD connected?  I think SIGHUP's from it would not be
reliable :-).

The original problem _was_ for serial devices without DCD connected.  You've
explained why these are unsuitable for use with modems.  They can be treated
the same as terminals: either wire DCD on or turn CLOCAL on and fix any
software that blindly turns it off.
-- 
Bruce Evans  bde@kralizec.zeta.org.au