backspace delays on 3B2 PORTS cards

[Ray Brownrigg]

In article <218 at cit5.oz> bron at cit5.oz (Barry Bron) writes:
>In article <55 at vsi.UUCP> friedl at vsi.UUCP (Stephen J. Friedl) writes:
>
>>     We've been running a 3B2/400 for a while ....  One chron-
>>ic problem is that PORTS cards ... seem to add delays when backspaces are
>>written.  
>
>	We have a 3B2/400 running Version 5.3 and had noticed the problem
>when I installed some new software and found that by using the command
>" stty ofill " the problem was solved. I don't know why but it works for us.
>It appears there is no diference if you use either " ofdel " or " -ofdel ".

I have been mildly bothered by this for a while also. Probably since we
installed SVR3.0.

Following up on the "stty ofill"; that works because the delays that are built
into each backspace (0.05 secs) are replaced by a single character (either
NUL or DEL depending on ofdel or -ofdel), so anything faster than 200 BAUD
will see a speed improvement.

Now the real problem is why delays at all?

It appears that "stty bs0", which should turn off backspace delays, is
the problem. Backspace delays are put in (by the tty driver?) independently
of the BSDLY field in the c_oflag entry of the termio structure for a terminal.

Thus the "stty ofill" is a workaround to the bug caused by backspace delays
being output regardless of whether or not they are requested. 

I have put an "stty ofill" command into my /etc/profile.
-- 
Ray Brownrigg	<ray at dsiramd.dsir.govt.nz>
DSIR Applied Maths Div		System:	OLIVETTI/AT&T 3B2/400B+, System V R3.0
PO Box 1335, Wellington, New Zealand			"UNX -rules -OK"