*BSD News Article 25526


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Newsgroups: comp.os.386bsd.bugs
Path: sserve!newshost.anu.edu.au!munnari.oz.au!sgiblab!swrinde!news.dell.com!obiwan!bob
From: bob@obiwan.uucp (Bob Willcox)
Subject: Re: PROBLEMS WITH FreeBSD
References: <CIq8w7.7rM@csi.compuserve.com> <2g0kdl$2d9@cleese.apana.org.au>
Organization: Bob's Place, Austin TX
Date: Mon, 3 Jan 1994 04:51:34 GMT
Message-ID: <CJ1EuC.2E2@obiwan.uucp>
Lines: 35

In article <2g0kdl$2d9@cleese.apana.org.au>,
Mark Newton <newton@cleese.apana.org.au> wrote:

 [ discussion and good advice on using sio deleted ]

>The solution?  Re-config your kernel to use sio, and make yourself some
>*REAL* terminal cables.  For modems, you just need a straight-through
>25pin cable (or, at least, a cable which has TD, RD, CTS, RTS, DCD and
>DTR connected).  For terminals, you should tie DTR at the terminal's 
>end to DCD at the computer's end, and perhaps bridge CTS and RTS at
>the computer's end (assuming that your terminal is fast enough to not need
>any hardware flow control when it's displaying data.  You'll need to wire
>the flow-control properly if that isn't the case.  Most modern terminals
>can cope happily with 9600bps with no flow control, though).

I run my terminals (a collection of Dell MT-15's and Wyse 160) in
DTR flow control mode using 4-wire cables with the terminals wired
like this:

  COMPUTER END                     TERMINAL END
        Shield  1 ------------- 1  Shield
            RD  2 ------------- 3  TD
            TD  3 ------------- 2  RD
        SigGnd  7 ------------- 7  SigGnd
           CTS  5 ------------ 20  DTR

The terminals raise and lower DTR to allow or stop data from being
sent to them.  Therefore, wiring DTR to CTS and enabling RTS/CTS
flow control in the sio driver (stty crtscts) results in very
effective hardware flow control on the terminals.

-- 
Bob Willcox                ...!{rutgers|ames}!cs.utexas.edu!uudell!obiwan!bob
Phone: 512 258-4224 (home)
       512 838-3914 (work)