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From: lauren@vortex.UUCP (Lauren Weinstein)
Newsgroups: net.dcom
Subject: Re: modem evaluation - Telebit Trailblazer
Message-ID: <924@vortex.UUCP>
Date: Sat, 3-May-86 14:59:03 EDT
Article-I.D.: vortex.924
Posted: Sat May  3 14:59:03 1986
Date-Received: Tue, 6-May-86 04:07:26 EDT
Organization: Vortex Technology, Los Angeles
Lines: 25

The Telebit modem definitely wants robust flow control.  Without it,
the system loading and noise overrun errors rapidly become very 
significant and bring throughput way down.  The most recent version
of the modem firmware also has some apparent problems in internal
buffer management that can result in incorrect data
being sent to the host computer under conditions that are fairly
easy to hit in normal use.  This latter problem has been reported
to them and hopefully will be fixed in a future firmware release.  There
is also a possibility that a "reverse channel" could be added to the
modem which would simplify use of the device with existing, unmodified
software, this would help by providing a "true" full-duplex circuit.

The modem firmware is in a state of flux right now--that's one of the 
reasons I recommend a "wait and see" philosophy for the time being.
Minor changes in the firmware may make major differences in terms of
improving or degrading performance with any given communications protocols,
so putting too much effort into this area at this time, with the firmware
being subject to change in some significant areas shortly, doesn't seem 
like a really good idea.  In the meantime, my own experiments with a pair
of these modems are continuing, and I've been promised alpha releases of
all new firmware for the beasties.  Once the firmware settles down and I
have some solid results from my experiments, I should be able to make some
more concise recommendations one way or another.

--Lauren--