Path: utzoo!attcan!uunet!van-bc!ubc-cs!news-server.csri.toronto.edu!utgpu!watserv1!maytag!xenitec!zswamp!root
From: root@zswamp.fidonet.org (Geoffrey Welsh)
Newsgroups: comp.dcom.modems
Subject: Re: INFO-MODEMS Digest V90 #286
Message-ID: <3416.27350163@zswamp.fidonet.org>
Date: 5 Nov 90 03:48:11 GMT
Organization: Izot's Swamp BBS - Kitchener, Ontario
Lines: 34

Kim Letkeman (kim@Software.Mitel.com ) wrote: 

 > [re: my comment that MNP5 'loses ground' with pre-compressed files]

 >My new ATI with MNP5 was actually able to maintain 274cps over
 >a long .ZIP file. This kind of blows your argument up a bit.

   No, it proves only that you weren't paying attention to what I was saying.

   The boost that your ATI modem gives to transferring .ZIP files is due to the 
stripping of start and stop bits, which is done at MNP level 3, not MNP5 data 
compression.

   I think you'll find that the ATI, set to use MNP levels up to 4 but *not* 
MNP5 data compression will give better performance than the same modem & files 
with MNP5 data compression enabled. There will, of course, be files for which 
this does not hold, but I stand by my statement as a general rule.

   Hayes' Toby Nixon has corrected my comment about MNP5 being based on LZW (he 
pointed out that it uses the Huffman, not LZW, algorithm). I stand corrected on 
that point.

 >I certainly won't be turning off compression for ZMODEM transfers.

   Don't be so quick to make a rule of that. Try it!
 

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