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From: scs@m-net.UUCP (Steve C. Simmons)
Newsgroups: comp.unix.wizards,comp.unix.questions
Subject: Excessive buffering in tip?
Message-ID: <1390@m-net.UUCP>
Date: Tue, 7-Jul-87 16:49:26 EDT
Article-I.D.: m-net.1390
Posted: Tue Jul  7 16:49:26 1987
Date-Received: Tue, 21-Jul-87 00:48:55 EDT
Organization: M-NET, Ann Arbor, MI
Lines: 47
Keywords: buffer character delay timeouts vt100 emulation
Xref: mnetor comp.unix.wizards:3323 comp.unix.questions:3250

We have been using tip with a VT-100 emulator on our SUN systems, and
have recently found that one of our user complaints is not a problem
with the emulator but a "feature" of tip.

Here's the situation:

We have a large number of Suns running SunOS 3.2 (UCB 4.[23]) and some
large vaxes running VMS 4.5.  We connect the serial ports from Sun to
VAX terminal lines, run the VT emulator (henceforth called vtem) in a
window, and then give the tip command to access the serial port and
login to the vax.

For the most part things work fine.  However, when using full screen editors,
it appears that tip buffers up all the incoming characters following a
"clear screen" sequence until (effectively) you get into an input wait
from the keyboard.  At that point *all* the characters appear at once
(boom).  This honks off our users to no end, since at low baud rates
they see "<8-10 second pause>".

We've tried varying all the tip parameters that looked promising, but no
joy.  We've also tested it tipping thru modems to UNIX III and UNIX V
systems, and gotten the same results -- if you want to see it, try
"tip ", log in, and then "vi ".  Therefore we doubt
the problem is related to VMS or our emulator -- tipping without the
emulator gives the same problem.

An additional problem we have is with the propogation delay of ^S/^Q
for flow control from the host.  In tip, if you are reading a large file
from the vax and type ^S to pause the input, at higher baud rates a hell
of a lot comes thru before the stream pauses.

Our questions are:

1. Do other people see the same problems (ie, is it Sun's tip or tip in
   general)?
2. Does anyone know of tip settings we could put into a .tiprc or /etc/remote
   file to fix up the unexpected buffering?
3. Can we make tip react more quickly to xon/xoff, or, alternatively, stop
   displaying immediately and attempt to buffer what comes in after we hit
   ^S but before the host stops sending?

Worst case (ie, no-one has a fix for this) we'd be interested in a PD
version of tip and fix it ourselves.

Steve Simmons
...ihnp4!itivax!lokkur!scs
"It's my computer and I'll snub who I want to."