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From: chris@umcp-cs.UUCP (Chris Torek)
Newsgroups: net.unix-wizards
Subject: Re: How to open a modem which isn't asserting carrier-detect?
Message-ID: <2919@umcp-cs.UUCP>
Date: Thu, 31-Jan-85 19:11:02 EST
Article-I.D.: umcp-cs.2919
Posted: Thu Jan 31 19:11:02 1985
Date-Received: Sun, 3-Feb-85 08:49:49 EST
References: <340@lsuc.UUCP>
Organization: U of Maryland, Computer Science Dept., College Park, MD
Lines: 16

What we did was add another major device, which uses all the same entry
points except two (open and close).  The ``outgoing mode'' open routine
asserts the software carrier, and also checks to make sure the line isn't
in use incoming (actually that the real carrier is off), which prevents
people from ``dialing out'' on the line you're using to log *in*.

Actually, the entire open and close routines in the outgoing-mode driver
consists of one call, to the open and close routines in the regular
driver, but with the ``flag'' argument being -1 (since it's always >= 0
for normal opens).
-- 
(This line accidently left nonblank.)

In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7690)
UUCP:	{seismo,allegra,brl-bmd}!umcp-cs!chris
CSNet:	chris@umcp-cs		ARPA:	chris@maryland