From: utzoo!decvax!cca!mark.umcp-cs@Udel-Relay@sri-unix
Newsgroups: net.unix-wizards
Title: Re:  Disabling Break
Article-I.D.: sri-unix.4420
Posted: Thu Nov 25 23:44:44 1982
Received: Sat Nov 27 01:16:13 1982

From:     Mark Weiser <mark.umcp-cs@Udel-Relay>
Date:     23 Nov 82 11:28:40 EST  (Tue)
I once had a problem with a bad modem which kept thinking it had seen a 
break.  Of course, an actual BREAK is supposed to be a tug on the
transmission line for x milliseconds, which looked like a framing error
to our modem, so it had code to convert all framing errors into
whatever the DEL character.  Interestingly, in the DH device driver
for 4.1bsd, there is some #ifdef'd out code which throws away framing
errors rather than returning them as the DEL character.  Unfortunately,
recompiling to fix this means that other peoples BREAK keys will not longer
work because the framing error will not be noticed.  Oh well.  Maybe 
some of this information will be useful to you.  (It is possible that
the ifdef'ed out code has not been attached to a mode bit.  Take a look.)