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From: bob@islenet.UUCP (Bob Cunningham)
Newsgroups: net.wanted,net.dcom
Subject: Re: info on micom dataswitches???
Message-ID: <1160@islenet.UUCP>
Date: Mon, 27-May-85 16:49:11 EDT
Article-I.D.: islenet.1160
Posted: Mon May 27 16:49:11 1985
Date-Received: Thu, 30-May-85 07:29:52 EDT
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Organization: Hawaii Institute of Geophysics
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[About the Micom series 600 port selector/PACX/switch]

Among other things, I maintain a Micom 600/2 here at the Institute
of Geophysics.  I tend to agree with Phil Ngai's notes except for:

> ... Configuration is done by asking the factory
> to burn you a new PROM, or you can make changes in battery backed RAM.
> No EEROM configuration.

Well, you can always cut your own EPROM as we do, takes a regular
2700-series, and the Micom-supplied firmware documentation is sufficient.

> The thing is big, sucks lots of power and generates
> lots of heat.

I don't have the specs at hand, but I'd say power consumption is not
excessive.  On the other hand, the fans are a bit noisy and sized
for a fully-configured unit -- definite overkill if you only have
a few hundred terminal lines.  A 600/2 heavily loaded with port/terminal
boards is best supplied with cooling air though a machine room type
false floor.  No need with the smaller, desk-top 600/1.

> If you have a campus environment where you can run twisted pair which
> can operate at T1 rates, then distribution to different buildings is
> pretty good. If you can only get 9600 baud links or 19200 links, the
> cost per line goes up a lot, plus you have to buy the modems or line
> drivers. They do have a stat mux on a card which helps hold the cabling
> mess for remote sites.

Micom has an extensive like of various modems, line drivers & muxes --
most of which work nicely with their 600-series switches (any and
all of which they'd be glad to sell you :-).  They've
recently announced an Ethernet interface, too.  No matter what brand
of switch you buy, it alone won't solve your trunk distribution problems
around a "campus" of buildings.  For the Micom 600, it costs about
$350 for a no-controls dumb terminal board capable of handling 4
terminals.  Add about $100 for full controls.  We run 9600bps to
and from our 600/2 to distances of about 1000 feet without line drivers.
(The 600/2 seems to re-generate the signal nicely).
So, our incremental cost to add an additional terminal is about $80 +
wire costs.  Sometimes we can run lines cheaply, sometimes not (how
does the saying go:  "your mileage will vary").  If the lines are
too expensive, then a high-speed private line modem + stat mux
certainly is indicated.

> ... It does not appear capable of sending a break ...

It can and does pass a break signal -- unless that's what you have
your configuration set up for disconnect signalling.  Those sorts
of configuration details can be specified on a line-by-line basis.

> They have a group termination
> option (comes out in telco 25 pair connectors) which can really help
> with cabling, assuming you are not scared of punch down blocks.

I highly recommend the group termination, either to R66-type punch-down
blocks or to "harmonicas".  Saves quite a bit in cable costs.  Note that
the Micom group termination scheme isn't Mod Tap's (or typically other
group cabling schemes).  That means making your own cables as we do 
(or paying for adaptive cabling, which -- for example -- Mod Tap would
be glad to sell you :-).


Additional notes ...

The other switches around our campus are all Gandalfs, and I think it's
fair to say that comparable models of the two companies are equivalent in
both performance and price.  Both manufacturers provide reliable,
very expandible gear.  Gandalf seems to give support and ship new
boards a bit quicker.  On the other hand, the Gandalfs somehow seemed
to take a little fiddling to get them up and running.  We plugged in
our Micom (ourselves, no installer came) and it worked just fine.

I suspect that -- especially for someone not planning to expand a
great deal -- the newer switches by Develcon, Equinox, Emulex, etc.
may give more capability for the dollar and are definitely worth
looking into.
-- 
Bob Cunningham  {dual|vortex|ihnp4}!islenet!bob
Honolulu, Hawaii