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From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Using the sio ports for terminals w/o modem ctl signals
Message-ID: <1993Aug16.190323.6894@fcom.cc.utah.edu>
Sender: news@fcom.cc.utah.edu
Organization: Weber State University, Ogden, UT
References: <24grraINNl92@kralizec.zeta.org.au> <1993Aug15.232601.17314@fcom.cc.utah.edu> <CBv07B.Hzy@willcox.uucp>
Date: Mon, 16 Aug 93 19:03:23 GMT
Lines: 48
In article <CBv07B.Hzy@willcox.uucp> bob@willcox.uucp (Bob Willcox) writes:
>
>>Why would getty leave CLOCAL set on a modem? I don't understand. If DCD
>>drops, my applications are supposed to get SIGHUP. You are suggesting that
>>it's OK to leave my root shell up there for the next caller. It's possible
>>that the DCD dropped not because I was stupid and didn't log out first, but
>>because I had a power failure on my end but not the host end. Is it still
>>implied to be "my fault" that the next caller gets root access to the machine?
>
>For my situation, getty is not talking to a modem. My original objective
>in starting this slightly diverged thread was to obtain advice on
>connecting my *local* terminals up using sio via a board that is
>brain-damaged w/o modem control signal support. (I knew this at the
>time I bought it, but driving local terminals is all I wanted it for.)
>It sounds like (from what Bruce is saying) that if I cooerce getty to
>not turn off CLOCAL that it should work. I am going to give this a try.
SIO Terminal # on 25 pin cable
SD ------------------------ RD 2
RD ------------------------ SD 3
RTS -+ 4
|
CTS -+ 5
GND ------------------------ GND 7
DTR -+ 8
|
DCD -+ 20
On a 9 pin connecter, not all of RTS, CTS, DTR, and DCD are present. Tie
the three that are together; this will satisfy the board.
Generally, terminals will not need CTS/RTS or DCD/DSR signals; however, I
see by your posting you are from IBM. IBM-3101 and similar terminals have
no way to switch off the requirements for for some signals; pick a line
that the terminal holds high and use it to hold the needed signals high,
but don't use the same line for more than 2 or 3 at the same time or you
may sink too much current.
Terry Lambert
terry@icarus.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.