FA: TRS-80 Model IV with Corvus Omninet Network Interface

From: Louis Florit <florit_at_unixville.com>
Date: Thu Jan 16 21:33:15 2003

Hullo fellow classiccmp enthusiasts; I'm in the process of clearing up
some 'never started' project space, and have put my TRS80 Model IV find
from a few years ago up on ebay. I had intended to make the system a
serial terminal, but it doesn't have a serial port and I never got around
to buying one. I then thought of gutting it and making it into a modern
PC. I was talked out of wrecking working vintage hardware just for the

The neato thing about this TRS80 is (what I was told to be through usenet)
the Corvus Omninet Network interface, aka Network 4 board; this is a
diskless client for the network. Unfortunately I have no documentation,
software, or proof, that it actually is Corvus Omninet, so take my
commentary with a grain of salt. My limited probing on the inside of the
system did not show any boards with the company name on them, for example,
but I did not break open the shielded board area for a closer look (see

If this in fact was a real Omninet client system, you would also need a
server or controller and the software to run it; again, from word of
mouth, I was told it was likely a x86 or the like with a hard drive in it
and the Omninet interface on it.

On the auction page you will find a load of nicely sized pictures for it,
and perhaps another TRS80 enthusiast will be able to determine if I was
told correctly or not about the network.

Here's the auction link:

Here's the thread archived on google groups here:

Interesting tidbits from the above thread, thanks to "Frank Durda IV":

"Corvus Omninet and Network 4 are the same beast. Tandy bought Omninet
chipsets and made their own boards for the Model 4 and 1000HX/EX
computers. The educational operating system that Tandy sold for use with
Network 4 was written by a guy in his garage (living in the northwest as I

"Omninet/Network 4 are trunk networks, more like Thinnet Ethernet in
topology. (Some people came up with repeater/boosters that allowed
non-daisy-chain wiring for Omninet/Network 4, but that is an extension of
the basic design.)"

"The underlying signaling in Omninet/Network 4 is differential, which
means unshielded twisted pair works great (even using RJ11 plugs for
interconnects work fine), but Tandy decided they would make more money by
selling shielded wire and making you use those irritating wing-nut
connectors. Tandys choice also meant that if you had one computer in the
lab plugged into an outlet with a hot neutral, Tandys wiring scheme would
promptly blow-out all of the machines on the network the moment you
plugged that one computer in since they tried to share a shield ground via
the shielded cable. This happened fairly often, and 30+ computers would
simultaneously make Bing-Pop-Zing sounds as the tops blew off integrated
circuits inside the case, followed by burning smells. Later, Tandy
included an outlet tester with the installation kit and recommended its


No burning smell from this one, however. This system was bought from a
store in Sunnvyale, CA called 'Weirdstuff' that takes old computers and
resells or strips them for their valuables. Wierdstuff is a cool store,
check them out if nothing else to visit a blast to the computer and
electronics past. They had a stack of these TRS-80 Models IVs at the
time. They had been there for some time in the warehouse. Some of the
systems had Tracking ID tags talking about 'Fremont School District',
which is an area in Silicon Valley. My guess is they were traded or given
away to make space for a more modern setup and weirdstuff ended up with

Hope you liked all the background on it. I love collecting these old
'puters and hope to pass it on to someone equally enthusiastic.

Received on Thu Jan 16 2003 - 21:33:15 GMT

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