Path: utzoo!mnetor!uunet!husc6!mit-eddie!uw-beaver!fluke!vince
From: vince@tc.fluke.COM (Craig Johnson)
Newsgroups: comp.sys.att
Subject: Unix-PC tty000 Problem
Message-ID: <2635@fluke.COM>
Date: 11 Jan 88 22:25:03 GMT
Sender: news@tc.fluke.COM
Lines: 31
Keywords: Non-blocking read, raw mode broken


Upon returning home after the holidays and firing up my 7300 I have
found that my serial port on /dev/tty000 no longer works correctly.
The first indication of trouble was when I tried to use it to log in on
a separate terminal and it failed to prompt for a password and was
subsequently locked up.  Further tests have reveiled that the port
works fine for normal (cooked) I/O, but as soon as a process tries to
set the port to raw mode (or cbreak? ua works, memacs doesn't) it seems
to go into a mode where the last character received by the uart is
repeated over and over.  It is similar to what you get when the flag is
set which causes reads to be non-blocking (used to test the port for
new input).

I have checked all the configuration items I can think of and cannot
find anything amiss (and it *did* work fine before xmas).  Part of what
makes this very difficult to debug is that each time the port is fouled
up, it takes a reboot to straighten it out, very time consuming.  I'm
just about to the point of reloading system software to my harddisk in
hopes that it is software that is causing my troubles.  At least then
if it still is messed up, I can start worrying more about the uart
hardware.

Before I do this I'd like to hear whether anyone else has encountered
this problem and found a solution.  I have heard of someone who had the
same (or a similar) problem and he chose to work around it by using a
non-passworded login, not hardly a satisfactory solution.  My system is
running V3.0, his is V3.51 I believe.  Ideas?  Comments?

	Craig V. Johnson		...!fluke!vince
	John Fluke Mfg. Co.
	Everett, WA