Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cornell!rochester!rit!ultb!awpsys
From: awpsys@ultb.UUCP (Andrew W. Potter)
Newsgroups: comp.unix.ultrix
Subject: Re: Wierd problem with incoming CXY08 tty lines
Message-ID: <555@ultb.UUCP>
Date: 31 Mar 89 16:23:04 GMT
References: <89Mar30.164842est.30755@snow.white.toronto.edu>
Reply-To: awpsys@ultb.UUCP (Andrew W. Potter(752DCO))
Organization: Rochester Institute of Technology, Information Systems
Lines: 31

In article <89Mar30.164842est.30755@snow.white.toronto.edu> cks@white.toronto.edu (Chris Siebenmann) writes:
>
>
> Normally, everything works fine. However, every now and then when
>someone dials in at 2400 baud the getty on the port refuses to
>autobaud; a burst of what appears to be the initial 9600 baud banner
>appears, and then nothing further appears, despite carriage returns
>and breaks being sent. 

We have had a similar problem where we traced it to what I believe is a serious
problem in unix "autobauding".  When switching between baudrates by hitting
break, you subject your terminal to garbage data until you "hit" the correct
speed.   This is trash!  We had a situation where cycling from 9600 to 1200
baud caused our terminals to interpret the 9600 baud banner to include
an X-off character.  This effectively locked up the terminal. The only way
to clear it up was to reset the terminal dropping the connection.  We worked
arround it by changing the order of the selected baud rates in gettytab.

What is really needed is "true" carrage-return autobauding.  This needs to
be done at a low level in the device driver because of the timing constraints
involved.

	- Andy



-- 
Andrew W. Potter                         Email: awpsys@ritvax.BITNET
Systems Programmer                          awp8101%ritcv@cs.rit.edu
Information Systems and Computing
Rochester Institute of Technology, Rochester NY, 14623 (716) 475-6994