Path: utzoo!mnetor!uunet!lll-winken!lll-lcc!ames!ucbcad!ucbvax!cbosgd!mandrill!neoucom!wtm
From: wtm@neoucom.UUCP (Bill Mayhew)
Newsgroups: comp.dcom.modems
Subject: Re: 9600 Baud Question
Message-ID: <896@neoucom.UUCP>
Date: 29 Dec 87 03:11:50 GMT
References: <195.004254@adam.DG.COM> <5969@fmsrl7.UUCP> <7951@g.ms.uky.edu>
Sender: red@neoucom.UUCP
Organization: Northeastern Ohio Universities College of Medicine
Lines: 33
Summary: Telebit ping-pong delay is not noticable


I use a Telebit trailblaizer from home at 9600 baud quite a bit.
The turnaround dealy really isn't objectionable.  All the other
attributes of the modem more than offset the small turnaround
delay.  When I know that I am going to be doing editing where I am
looking at the screen, and delay might confuse me, I switch to 2400
baud FDX.  2400 is fine for document entry.

I'm curious in hearing what people manage to get for real world
throughputs.  I typically get about 550 char/sec for uucp xfers
twixt the vax at work and my 3b1 at home using the g protocol
spoofing feature.  The instaneous line rate is usually about 14500
toward me and about 16000 bps toward the vax.  I suspect that the
load on the vax is keeping the xfer rate "so low".

One peculiarity I've noticed with the Trailblazer is that is always
sends ^S ^Q when it goes off hook receiving a call except in PEP
mode.  For some reason the ^S ^Q has peculiar interactions with
login on 4.2BSD.  You can hit \r a couple of times, get a couple of
"login:" prompts.  The first login attempt will fail, despite a
correct userid and passwd being entered!  This really drove me
crazy until I attached a serial line analyzer to see what was
happening.  This is only a "bug" in 1200 and 2400 baud connects.
PEP mode doesn't do it.   It is pretty easy to handle this in the
handshaking sequence in L.sys or Systems, as appropriate, once you
know what is going on.  I made sure that I had ATE0Q3 set.

I can see why they do it.  On a VMS machine (and probably some
others) you have to make sure the line wakes up by entering a ^Q.
Why they send a ^S first, I don't know.  Why not in PEP mode, I
don't know.

Happy holidays,
--Bill