From: vporguen@unlinfo.unl.edu (victor porguen)
Subject: The new Swedish Archiver
Keywords: SQZ Compression archive Squeeze
Organization: University of Nebraska - Lincoln
Distribution: na
Date: Tue, 13 Oct 1992 05:17:33 GMT

Writes Harald Zappe (zappe@mikro.ee.tu-berlin.de) on the subject of 
the new SQZ archiver:

> - where is the use of 'Yet Another Compressor',  WHEN
> - it's not compatible to any other packer  (1)
> - the compression ratio is not significantly better 
>  than that of others

The evolution of data compression has been a progressive affair. On 
the IBM PC, the early ARC program gave rise to the Katz clones of 
it.  Then came Yoshitake's LHarc, then ARJ showed up.  Each one of 
these was a milestone, an ORIGINAL advance in the state of the art.  
Now there is this new Swedish thing called SQZ - it seems to follow 
in the same tradition, although it's less revolutionary than its 
predecessors. 

> - it's not compatible to any other packer  (1)

On the IBM PC, none of the CURRENT archivers is compatible with any 
of the others. The standardization was broken when Katz introduced
PKZIP, responding to pressure from SEA to stop using their format.

There is a notable exception: NoGate's PAK.EXE.  PAK can handle 
.ARC, .ZIP and .PAK archives, and has several other valuable 
features, such as a yet-to-be-broken encrypted compression method 
which has found use in the distribution of shareware on the SDN 
Network (using its Security Envelope to guarantee protection against 
viruses and tampering). Unlike the PKZIP method (which has been 
broken long time ago, including its very weak password protection), 
and unlike the ARJ method, (whose password can be externally derived 
under certain circumstances) PAK's security method appears sturdier
- at least for now.

> - the compression ratio is not significantly better 
> than that of others

Yes it is.  SQZ is about as much better than ARJ, than ARJ is 
compared to LHA, or LHA compared to PKZIP.  Same order of 
improvement.  This may not seem like very much, but data compression 
has been steadily advancing in such small steps for a while now, and 
the overall improvement has been very significant. "Piano, piano, si
va lontano..."

> (1) What I would like to see is a general pack/unpack utility, 
>   which is able to - automaticly detect to type of an existing 
>   archive (.tar.z, lha, lzh, arj, zoo, zip, (sqz???) to extract 
>   the contents. 

Any one of several "shells" available on the shareware market do 
exactly that. They determine which archiver was used to produce a
given archive, and activate it to handle that format. You could 
probably even do it with a batch file...

> I think with the permanent increase of machine speed (HW) the 
> compression is more worth than the speed (algorithm).

It's always been so. Disk space and transmission time are more
expensive than processing and off-line time. 

The Swedish SQZ is an interesting program, albeit it may never 
become any kind of "standard" (bewcoming a "standard" would seem to 
depend less on quality than on political influence, as has been 
demonstrated... :-)  Look at ARJ: it's so significantly better than 
PKZIP it's not even funny.  Yet, it's not "become a standard"...

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    Victor Porguen                                      
    SMTP/Internet: vporguen@unlinfo.unl.edu             
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Newsgroups: comp.compression