jgrafton (jgrafton) wrote in hardware_pr0n,

Circa 1983 modem

I was looking for random hardware in Newell-Simon hall at Carnegie Mellon a few months ago and came across this jewel. (Note: it was in the "Take this random junk" pile, so I was allowed to take it.)

Here you can see the front of it with its indicator LEDs.

Here we see the power connector (note the old style), a 25-pin serial connection, and a 0.75 amp fuse. Note also the serial number, 17138, etched on here by hand.

This is the bottom of the unit; curiously, the serial number here is different than the one on the back (and on the inside, as we'll soon see). Also note the date listed here, Sept 13, 1983.

Here you can see the modem opened up, along with some of the random crap on my desk.

Other side.

Here you can see a better shot of the inside. Note the serial number etched here again.

I haven't yet tested to see if it works, as I lack the proper cables (specifically the appropriate power cable). Anybody have an idea where I can get one that would fit appropriately?
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Looks to me like the power cable is somewhat standard. Hell if I know the pinout, but each prong on the socket corresponds to a standard plug. Least that's what it looks like to me.

Also, the phone plug asks for an acoustic coupler. I'd advise heavily against plugging that into a wall, unless you want a catastrophic short.
Yeah, I seem to remember seeing that sort of plug on Wikipedia at one point or another, but I don't happen to have a cable of that sort on me... at the moment, anyway.

That is very true. I was thinking I'd more just like to plug the thing in and see if I can at least connect to it in a terminal emulator.
As in, over serial? Yeah, that should, theoretically, work.. RS232C was long-standardized by 1983. The Hayes command set, though.. good luck communicating coherently with it once you get it hooked up and talking.
From the general appearance of the board, it is probably safe to conclude that this is not a modem in the modern sense, but in the original sense. That is, you dialed a number on a phone and hooked up an accoustic coupler to the handset and to this guy.

Can't read the part numbers, but I'd guess that the chips are all 74xx discrete logic components and so your chance of this thing speaking any command set, much less Hayes, is slim.

Let me know, though.


June 6 2005, 21:19:17 UTC 11 years ago

I couldn't find any 74xx chips from looking at the pics, but they are 74xx-like, very discrete. One was a darlington transistor array, and another was three separate NAND gates and one inverter. So, yeah, pretty basic stuff.