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From: guest@ucsfcgl.UUCP (guest account)
Newsgroups: comp.dcom.modems
Subject: Re: info request on USR Robotic 2400
Message-ID: <10002@cgl.ucsf.edu.ucsfcgl.UUCP>
Date: Fri, 9-Jan-87 19:46:14 EST
Article-I.D.: cgl.10002
Posted: Fri Jan  9 19:46:14 1987
Date-Received: Sat, 10-Jan-87 02:29:05 EST
References: <369@csustan.UUCP>
Organization: UCSF Computer Graphics Lab
Lines: 55
Summary: Need to check revision level for USR Courier 2400 modems

In article <369@csustan.UUCP>, elric@csustan.UUCP (Elric of Imrryr) writes:
> 
> 	Has anyone here had any experiences with the USR Robotics
> 2400 baud external modem? I am considering the purchase of one from
> Softline in NY, since the have them for $189. (Which seems to be
> a good deal, so I'm try to find the catch...)

Time to post this again:

    Any criticisms of the USR Courier 2400 which do not report
    the revision level should be treated with suspicion.
    The manual gives instructions for getting the modem to
    report the level.

    The original Courier 2400 units were shipped (I got 4) with
    level 240 (i.e. 2400 bps, revision 0) ROMs. These were pretty
    bad. Shame on USR. They didn't stop there and produced new
    ROMs which produced what I estimate to be a two order of
    magnitude improvement in their performance (error rate,
    connection reliability etc.) in my environment. The revision
    current when I last checked was 243. These were supplied
    FREE to owners of the older units (they asked for return
    of the old ROMs -- seems reasonable). Hoorah for USR.

    These units have been in operation with the revised ROMs
    for enough months now that I have lost count. No problems
    with them during this period. They are in use on a variety
    of terminals and micros.

There is a caveat for these; they are designed to be used with
a device like a computer or terminal. Some front end systems
(multiplexors, port selectors) that were designed before the
current generation of modems may not handle these or similar
modems well.

I presume the reason you are seeing such a spectacular buy on
these is that USR recently announced the 2400e which has the MNP
error correction protocol handler built-in.

Terminology Note: You quickly mark yourself as a neophyte in data
communication if you refer to the Courier 2400 as a 2400 baud modem.
Similarly the 212 type modems are not 1200 baud; they code two bits
in each signal element (four allowed states) and thereby achieve
a 1200 bit-per-second data rate at 600 baud, i.e. 600 signal-states-
per-second on the line. The data rate (bits-per-second) only equals
the signaling rate (baud, signal-states-per-second) when each state
encodes a single bit, i.e. two allowed states.

Thos Sumner       (thos@cca.ucsf.edu)
(The I.G.)        (...ucbvax!ucsfcgl!cca.ucsf!thos)

When ideas fail, words come in very handy. -- Goethe (via L. Creighton)
When ideas fail, computations come in very handy. -- Sumner (via USENET)

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