Acoustic Coupled Modem

From: Chuck McManis <cmcmanis_at_mcmanis.com>
Date: Mon Jun 21 13:48:13 1999

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.

>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.)

>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 - 13:48:13 BST