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From: brucek@emperor.scs.com (Bruce Klein)
Newsgroups: comp.dcom.modems
Subject: Re: Over 1000 CPS with PEP?
Keywords: pep throughput
Message-ID: <1991Jun27.193651.2682@emperor.scs.com>
Date: 27 Jun 91 19:36:51 GMT
Organization: Mentor Graphics IC Group, San Jose, CA
Lines: 44

A while back I posted to the net wondering how so many of you were
achieving over 1000 cps throughput between telebits when I had trouble
getting 500 cps.  

Many of the responders pointed out that I should have been using a 19.2K
port instead of a 9600 port.  That is certainly true in general, but
I believe I should be able to achieve over 500 cps even on the 9600
baud port.

The most promising lead came from uunet!rwing!pat (Pat Myrto),
who suggested that my problems sounded indicative of a flow control
problem:  

>No they aren't.  I suspect you have flow control problems, because of
>the CRC error pattern.  It might take that long to fill up the buffer,
>it overflows, things stop for the resend, and the cycle starts over again.

>Be sure your port and modem agree on the flow control used, and that both
>SUPPORT it - many drivers don't support RTS/CTS control, or don't
>do it right.  You should be getting around 900 or more cps, depending
>on several factors.   Its either that, or the port is losing characters
>causing errors.  I *KNOW* the modems will do better than that, if things
>are correct, I do it all the time.  Uucp is delivering peaks of 1400 cps.

>The fix, without being there and going over your hdwe AND software setup
>and settings, is not obvious - it could be several or a combination of
>things.  All relating to overruns or other similar forms of character
>loss introducing errors, and thus resends.

Thank you to those who responded:

uunet!pacdata!jimh (Jim Harkins)
mpd@anomaly.sbs.com (Michael P. Deignan)
loft386!dpi@cs.utexas.edu (Doug Ingraham)
dspeed@sactoh0.SAC.CA.US (Dave Speed)
uunet!rwing!pat (Pat Myrto)

and any others who may have posted to the net that I haven't got yet (our feed
is a week+ behind).

-- 
   Bruce Klein
   brucek@emperor.sjc.mentorg.com
   ... uunet!emperor!brucek