Question about modems

John Labovitz johnl at
Wed Nov 13 12:02:06 CST 2019

On Nov 13, 2019, at 11:17 AM, Jim Brain via cctalk <cctalk at> wrote:

> On 11/13/2019 7:47 AM, Alexandre Souza via cctalk wrote:
>> Jim, its a long time I don't use it, but I've used other configurations beyond 8N1 and I remember when you put the modem in 7E1 it mirrored the configuration of the other side. If you had a vax with a 2400 7E1 port, you gotta have in the terminal 2400 7E1
> Yeah, I agree with your statement, but I am wondering what happened if you "mismatched" things.  Did the AT commands continue to work, but the raw data was sent out to the other side, or did it silently try to adapt?

I used Smartmodem 300’s and 1200’s a lot as a kid dialing up to BBSes in the 80s (also ran a BBS myself). I  recall that the modem itself — eg, the AT command interpretation — automatically handled 7E1/8N1/etc., but that’s as far as it went. If I was dialing up a non-8N1 BBS (rare, but they did exist), I had to set my terminal program accordingly. I think I also had to set the speed (although later modems would respond with the speed as an ASCII number in the CONNECT message).

Of course, I might be completely misremembering.


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