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From: jerry@oliveb.UUCP (Jerry Aguirre)
Newsgroups: net.info-terms
Subject: Re: ADM42 Quirks? (Copy from net.periphs)
Message-ID: <215@oliveb.UUCP>
Date: Tue, 6-Nov-84 21:57:29 EST
Article-I.D.: oliveb.215
Posted: Tue Nov  6 21:57:29 1984
Date-Received: Fri, 9-Nov-84 08:00:51 EST
References: <5576@brl-tgr.ARPA>
Distribution: net
Organization: Olivetti ATC, Cupertino, Ca
Lines: 22

I saw a similar problem when I hooked up a Racal Vadic modem thru our
Micom port selector.  The symptoms were not so precise but when a large
burst of characters was sent to the terminal some of the characters would
be lost or garbled.

I finally resolved that the problem was that the Micom was not talking
exactly 1200 baud.  As others have pointed out the 1200 baud modems are
really synchronous and use internal buffering to appear asynchronous.
Thus they have a limited ability to handle data faster than 1200 baud.
If the data is sent at 1204 baud the modem's internal buffer will
gradually fill up and when full a character will be lost.

The Racal Vadic modem that I was using has a "allow 1205 baud" switch
in it.  After I set this everything worked fine.

Your loss of data seems to be more repeatable than I would expect for
this kind of problem.  Also I can't understand why the problem only
occurs on a particular terminal.  It may be that other terminals require
delays that allow the modem to catch up.

				Jerry Aguirre @ Olivetti ATC
{hplabs|fortune|idi|ihnp4|ios|tolerant|allegra|tymix}!oliveb!jerry