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From: hstroma@hubcap.clemson.edu (hepburn m stroman)
Newsgroups: comp.sys.ibm.pc
Subject: Re: ZIP question
Message-ID: <7534@hubcap.clemson.edu>
Date: 29 Dec 89 15:08:48 GMT
References: <890@thor.wright.EDU>
Distribution: comp
Organization: Clemson University, Clemson, SC
Lines: 24

From article <890@thor.wright.EDU>, by sdawalt@wright.EDU (Shane Dawalt):
> 
>   If you do indeed have PKUNZIP 1.01, then you need to upgrade.  Current
> version is PKUNZIP/PKZIP 1.02.  I'm not sure of 1.01's abilities, but 1.02
> allows imploding techniques.  This compression scheme is probably not provided
> in 1.01.  I do not remember exactly what 1.01 offered as far as compression
> schemes go.  
> 
>   Shane
Somebody may have said this already (what with Christmas and our flaky
feed), but
NO. All versions of PKZip 1.0 and greater use "imploding". 1.02 is a
minor bug-fix release.  Only "beta" versions of zip (like 0.90) do not
support "imploding".

Historical note: the algorithm used for imploding was not origainally
designed by P Katz for Zip. Shortly before planned release of 1.0, a
Japanese archiver (lharc) came out with a compression scheme which had
significantly (sp?) better compression that anything on the market, so
Katz delayed the official (1.0x) release of zip while he "studied" and
incorporated the technique used in lharc.

H Stroman
hstroma@hubcap.clemson.edu