Subject: Re: Are serial ports supported?
To: Nicholas Riley <>
From: Brad "Extra Crunchy" Grantham <>
List: macbsd-general
Date: 06/08/1995 11:19:51
> I've been trying without success to talk to the serial ports on my 
> SE/30...well, actually, to enable logins via them, but any kind of 
> communication would be great to start.  I connected a 2400 bps modem up 
> to it, to see what would happen, and all that happened was that the 
> lights on the modem flashed incessantly for about five minutes, then the 
> system complained "invalid login" from that port, and the lights stopped 
> flashing. I have no way of finding out what happened there, because when 
> I tried connecting a computer to the port and setting it to the same 
> settings (2400 bps, N81 and XON-XOFF flow control) I didn't receive 
> anything.  Should I be able to address the serial ports or not?

Sounds like you need to turn off echo from the modem.  What's happening
is that "getty" prints your login banner, and that gets echoed back from
the modem, and then is echoed back from getty, and so on.  You should try
giving the modem the command "ATE0" and then using that config.  In
addition, you'll probably want to turn off result codes with "ATQ1". 
If you don't turn off result codes, then the following will happen:
	1) your modem is called
	2) your modem says "RING" to MacBSD
	3) MacBSD says "RING" back to the modem, because it's at the
		login prompt
	4) your modem hangs up because it thinks you're giving it

Try these suggestions and let me know how they work.

Brad Grantham, 
True self-awareness begins with the acceptance of one's own vulnerability.