MORE 6386 UUCP WOES ...

[Marc W. Mengel]

In article <319 at argon.UUCP> daveb at argon.UUCP (Dave Berk) writes:
> [ Woes of using a Hayes compatable modem on a Unix box ]
>Can anyone out there shed any light on this problem ?  

Well, it's pretty simple, actually; the problem is that your "Hayes
compatable" modem doesn't lower CD (Carrier detect) when there is
no carrier.  Real Hayes modems can be configured to behave this way,
and most non-hayes modems *always* act this way.  If you set up
your modem this way, you just need to set "HUPCL" in the /etc/gettydefs
entries used by your modem and *not* set "CLOCAL", and you will
be just fine.  If your modem can't be taught to drop CD, then there
is no way in the world for Unix to magically determine that the
phone line was disconnected.

Once you do this, you will have to make some use of modem control
options in your uucp setup if you wish to call out -- namely
if the entry was:
	ACU tty00 - 2400 hayes
change it to
	ACU tty00,M - 2400 hayes
and your Dialers entry should go from
	hayes .... expect1 send1 expect2 send2 ...
to
	hayes .... "" \M expect1 send1 expect2 send2 ... "" \m
so the send expect pairs are done ignoring carrier.

>Is it just me or isn't this a fundamental problem with the tty driver ?

No, its a fundamental problem with some modems -- they don't signal
the host they are connected to that the line was disconnected.
This carrier-always-high kluge was done so that devices too brain-dead
to talk without carrier detect (like MS-DOS's COM1: device) could dial
the thing.

>How can I ever use it remotely without being paranoid that if the line
>drops I can't log back in unless I physically am there to kill the
>processes associated with the port and reset the modem ?

Make sure that your modem reflects carrier state properly, and your line
has has CLOCAL off in its /etc/gettydefs entry.  If your modem doesn't
have carrier detect right, and no way to configure it, you could try
running a wire from the carrier LED on the modem to the rs232 pin (1/2 :-)).

>Is it worth my while to upgrade to 5.3.2 ?

It could be -- there are a number of bug fixes, but also lots of new
features in order to fold in Xenix compatability.  Many common Xenix
app's run under 5.3.2, it would be worth your while if you need any 
of them...

>What fixes are actually in 5.3.2 ?

Alas, the lists I've seen all have Proprietary stamps on them...
The practice has been in the past that if you are suffering from
a bug known to be fixed in a later release and call the hotline
(assuming you are under warranty or have a support contract) you
get the upgrade as the bug fix -- hence the list isn't published
to prevent people picking a bug from the list, and calling in with
it (even though it hasn't been a problem for them) just to get an
upgrade...
>
>Thanx;
>
>David Berk


-- 
 Marc Mengel			       
 mmengel at cuuxb.att.com
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