Date: Mon, 29 Jan 1996 03:38:48 +0200 (EET) From: Heikki Suonsivu <hsu@clinet.fi> To: Terry Lambert <terry@lambert.org> Cc: hsu@clinet.fi (Heikki Suonsivu), hm@altona.hamburg.com, freebsd-hackers@freebsd.org Subject: Re: Multi-Port Async Cards Message-ID: <199601290138.DAA07721@katiska.clinet.fi> In-Reply-To: <199601282257.PAA01785@phaeton.artisoft.com> References: <199601280246.EAA23330@newzetor.clinet.fi> <199601282257.PAA01785@phaeton.artisoft.com>
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Terry Lambert writes:
> > mgetty would be useful as it can
> > actively reply calls instead of modems answering automatically, thus
> > avoiding callers getting modem answer when the terminal server has crashed
> > and won't be there.
>
> A properly configured modem and getty will do this as well.
>
> A properly configured modem will not answer unless DTR is asserted.
> When the open count coes from 1->0, the DTR is dropped. This causes a
> correctly configured modem to reset (reset on on-to-off transition of DTR).
Rockwell chipset based modems (all the ones I have seen) don't have DTR
option which would allow this. It can either reset itself when DTR goes
off (&D3), but then it will answer the phone even when DTR is off. If it
does not reset itself (&D2), it works correctly with DTR. The lesson is
not to use rockwell based modems, but they didn't have much competition
until last six months.
> If the machine crashes, getty goes away (the POST state on a proper serial
> port is to not assert DTR), and so the modems are not answered.
If the machine deadlocks, gettys won't go away. At least 1 of four crashes
are deadlocks where the machine freezes.
--
Heikki Suonsivu, T{ysikuu 10 C 83/02210 Espoo/FINLAND,
hsu@clinet.fi work +358-0-4375209 fax -4555276 home -8031121
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