Acoustic Coupled Modem

From: Don Maslin <donm_at_cts.com>
Date: Mon Jun 21 14:12:59 1999

On Mon, 21 Jun 1999, Chuck McManis wrote:

> Just guessing here, but intelligent guessing :-)
>
> >QUESTION #1:
> >Now, I assume that the "Disconnect" switch is to pick-up and release the
> >phone line when the direct coupled plugs are used but, what does the
> >"Connect" button do?
>
> Cause the modem to issue the "ORIGINATE" tone rather than the ANSWER tone.
> Usage, dial the number you want to talk to, the other modem answers, you
> press connect and the modem squeals out 'Hiya cuties, how do you like these
> bits?' (although to humans it sounds more like a high pitched squeal). The
> other modem then answers with the ANSWER tone and you're off to the races.
                               ^\ 'Watch your mouth, buster!' or
> >QUESTION #2:
> >There is a 300/1200 baud switch. all of the acoustic modems I have ever
> >used only ran at 300 or slower. Can you run 1200 baud over an acoustic
> >coupled modem?
>
> Sheesh, kids these days. Why when I was younger we used to have to whistle
> the Bell 212 standard for five minutes before they would even let us use
> the computer. :-) Seriously, yes there were acoustically coupled 1200 baud
> modems (I've got a couple of Racal-Vadics, considered "da-best" :-) but
> they weren't all that reliable. (hence all the error checking in the xmodem
> protocol) 1200 baud pushed manufacturers to include the _much_ more
> expensive "Data Access Arrangement" devices on the modem for direct
> connection. (This was one of the most amazing things about the original
> Hayes modem, it was direct connect and still pretty darn cheap.)

There were IIRC also some 2400 baud couplers (A-J I believe) and even some
9600 baud (yeh, I know, bps) units though I think they were not very
successful!

                                                 - don

> >QUESTION #3:
> >The place I bought this at has a few more. Anyone interested?
>
> If you want to keep it running your should buy a couple more yourself. The
> 212 model used active filters mounted on ceramic substrates that could (and
> did) fail. I don't believe they were repairable without surface mount gear.
>
> --Chuck
>
>
Received on Mon Jun 21 1999 - 14:12:59 BST

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