Today we kick it old school. Compuserve style.

This is a modem like a business might have in the mid nineties to connect to a (at the time) broadband network.

This was manufactured in 1993 by UDS and from the asset tag seemed to have been owned by Compuserve.

I got this from a friend of my grandpa’s who did TV repair back in the day. Where he got it from I think I might never know. I do know that Compuserve was based out of Columbus so the fact this migrated up north to Cleveland isn’t a huge surprise.

Before I tear into this any more, I want to take a step back because I doubt that many of you have even heard of Compuserve. In its heyday they were the be-all end-all of dialup online services. This was in the days when the 1200bps modem was the speedy thing. They aggregated hundreds of different online services that you now take for granted — from reverse phone number lookups, to serious legal research on LexisNexis. Of course you had to pay through the nose for some of these — upwards of a dollar a minute for some super-premium services. Remember, this was the eighties, that was some serious coin!

My hypothesis is that this was one of the devices that linked up a local Cleveland dialup bank to the mothership in Columbus.

This modem doesn’t talk on the analog phone lines like people typically think of, but rather the dedicated leased lines that could push 56kbps or 64kbps reliably — digitally. What this device did was convert the serial signaling that you would get from a router or computer to the format that the phone company would deal with.

And it still powers on!

Ahh… an old fashioned EPROM — the one you can erase with UV.  :-)

There seems to be an Intel processor on the board. There’s a whole collection of 74-series chips on the board, along with a slew of discrete components as well.

My guess is all the discretes which are all on the front-end side handle the line equalization feature of the interface. We also have the optional V.35 interface which seems to be handled on the daughterboard. Interestingly, the daughterboard has surface-mount technology instead of through-hole. Go figure.

Here’s a more high level description of this CSU/DSU.

Feel free to browse about the pictures. I’m not going to get too detailed with this one since I’ve never personally used it.

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