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Path: utzoo!mnetor!seismo!rutgers!clyde!cbatt!ihnp4!inuxc!pur-ee!uiucdcs!uiucuxc!clio!berger
From: berger@clio.Uiuc.ARPA
Newsgroups: net.dcom
Subject: Re: Racal-Vadic and Data General
Message-ID: <3900004@clio>
Date: Tue, 28-Oct-86 17:06:00 EST
Article-I.D.: clio.3900004
Posted: Tue Oct 28 17:06:00 1986
Date-Received: Wed, 29-Oct-86 22:48:27 EST
References: <505@uw-nsr.UUCP>
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Nf-ID: #R:uw-nsr.UUCP:505:clio:3900004:000:862
Nf-From: clio.Uiuc.ARPA!berger    Oct 28 16:06:00 1986


I don't know enough about your hardware to determine how likely it is,
but is it possible that your baud rate clock was affected by the new
software?  I ran into a problem similar to what you describe - dialup
lines with high grade commercial modems had lots of errors, but the
ones with cheap plastic modems worked better.  The problem turned out
to be a design flaw - the baud rate master clock operated at a rate
that had a 1.7% error when divided down - the Western Electric 212a
specs call for a maximum 1% (high) error (1.5% low).  The commercial
modems wouldn't tolerate a higher-than-spec error, but the cheap
modems did.

We resolved the problem by changing the baud rate master clock speed
and all the baud rate divisors programmed into the comm board.  And
our new NEC modems have a switch for Western Electric specs vs.
wider speed fault tolerance.