Path: utzoo!utgpu!water!watmath!clyde!att!osu-cis!tut.cis.ohio-state.edu!mailrus!ncar!noao!arizona!naucse!rwi
From: rwi@naucse.UUCP (Robert Wier)
Newsgroups: comp.sys.mac
Subject: Re: MacKermit 0.9(40) problem?
Summary: Kermit 1K packets
Message-ID: <938@naucse.UUCP>
Date: 28 Sep 88 23:03:37 GMT
References: <13825@cs.tcd.ie> <10735@coherent.com>
Organization: Northern Arizona University, Flagstaff, AZ
Lines: 60



Subject: Re: MacKermit 0.9(40) problem?
Newsgroups: comp.sys.mac
Summary: Kermit extended packet size
References: <13825@cs.tcd.ie> <10735@coherent.com>



 I will second the extended packet size as making a *BIG* difference
 in the effective speed of Kermit.  Going to a 999 byte packet (the
 maximum allowed on our VAX) nearly doubled the throughput. Still,
 at 9600 baud, I'm only getting about 425 bytes/sec.  I'm not sure
 where the bottleneck is.

 I also have used XMODEM (128 byte packets) and it seems to run 
 effectively about 30% faster than Kermit, but unfortunately it
 doesn't have the nice user interface that Kermit does.  For 
 example, I need to be able to wildcard my file specifications
 but can't do multiple file transfers at once with my version
 of Xmodem.  I also tried Xmodem with 1K packets and found about
 a 15% increase in speed.  

 The table below summarizes the results of my experiments:

 File size transferred: 134,561 bytes.
 Nominal transmission speed (Mac<->Vax) 9600 baud

 protocol            time required    effective thruput

 Xmodem (128 byte packets)  3:30           640 bytes/sec
 Xmodem (1k byte packets)   3:00           747 bytes/sec
 Kermit (1k packets)        5:17           424 bytes/sec


  So, Xmodem with 1k packets is achieving about 80% of the 
  maximum possible speed (assuming no overhead).  Kermit is
  doing a rather dismal 44%.  If anyone has other suggestions
  on speeding up Kermit (or Xmodem - I havn't tried Ymodem or
  Zmodem)  I'd be very interested.

 - thanks



       Bob Wier -- College of Engineering & Technology
                   Northern Arizona University
                   NAU Box 15600
                   Flagstaff, Arizona 86011

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