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From: jsp@unccvax.UUCP (Joel Patterson)
Newsgroups: net.micro.mac
Subject: Re: Mac-tty pinouts?
Message-ID: <154@unccvax.UUCP>
Date: Fri, 8-Mar-85 08:57:12 EST
Article-I.D.: unccvax.154
Posted: Fri Mar  8 08:57:12 1985
Date-Received: Mon, 11-Mar-85 07:08:09 EST
References: <2362@nsc.UUCP>, <16500011@ur-univax.UUCP>
Organization: UNC-Charlotte
Lines: 17

Most of the mac<->modem pinouts I have seen on the net have neglected DTR.
Some modems require a high signal on pin 20 (DTR) in order to connect,
answer the phone, or do anything but sit there.  On some this is an
option which can be switched off.  In any case you must either turn the
option off or strap DTR high.  Most modems supply a constant high on pin
9 and jumpering it to pin 20 should do the trick.  Pin 6 (DSR) may also
be an alternate source for this signal.

*  Strapping DTR high also implies that the modem always thinks the mac
is ready and waiting to communicate so it may answer your phone when you
least expect it.  This can be very annoying to sweethearts, customers, 
and bosses, since the modem usually answers on the first ring and you
don't. So turn the modem off when not actually in use or awaiting calls.

happy telecommunicating

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