HARPER@finuh.bitnet ("ROBERT HARPER, FINLAND") (05/08/89)
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No 7
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INDEPENDANT NEWSLETTER PRODUCED AT HELSINKI UNIVERSITY, FINLAND
<< EDITED BY ROBERT HARPER >>
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After writing BIOBIT no 6 which dealt with ARC, I had a number of
private letters asking about the alternatives to ARC. The most
authoritative document which deals with compression is called
COMPRESS.ARC. It is a HUGE file put together by ROBERT D. TOLZ. I have
extracted the table of contents from the archive so you can see the
wide selection of compression programmes that are available. If there
is any interest in the complete document then I could upload it to
NET.BIO.NET for FTP downloading.
Anyway for openers, here are some interesting snippets from the
original document. Hopefully they will give you an insight as to what
you might come across in the future, so you can be half way prepared
when a file with a strange looking extension is presented to you.
%%%%%%%%%%%%%%%%%EXTRACT%%%%%%%%%%%%%%%%%%%%%
TABLE OF CONTENTS
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
ABOUT COMPRESS.NW? . . . . . . . . . . . . . . . . . . . . . . . . . . 3
CURRENT EVENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
FUTURE EVENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
AN INVITATION FOR COMPRESSION AUTHORS . . . . . . . . . . . . . . . . . 4
HOW TESTING WAS DONE . . . . . . . . . . . . . . . . . . . . . . . . . 4
HOW TO READ THE TEST RESULTS . . . . . . . . . . . . . . . . . . . . . 5
QUICK SUMMARY OF RESULTS . . . . . . . . . . . . . . . . . . . . . . . 6
CAVEAT EMPTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
SIZE OF EXTRACTION CODE . . . . . . . . . . . . . . . . . . . . . . . . 7
OTHER FACTORS TO CONSIDER . . . . . . . . . . . . . . . . . . . . . . . 8
COMMENTS ABOUT THE PROGRAMS . . . . . . . . . . . . . . . . . . . . . . 8
ARC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ARCA/ARCE . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
COMP16 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
DEARC7 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
DWC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
MDCD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
PAK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
PKPAK/UNPAK . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
PKZIP/PKUNZIP . . . . . . . . . . . . . . . . . . . . . . . . . . 15
QARC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
SCRNCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
ST/EXP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
ZOO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
AVAILABILITY OF PROGRAMS . . . . . . . . . . . . . . . . . . . . . . . 19
COMMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
A WORD FROM OUR SPONSOR . . . . . . . . . . . . . . . . . . . . . . . . 22
TEST RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
%%%%%%%%%%%%%END%%%%%%%%%%%%%%%%%%%%%%%
As can be seen there are about 13 different compression programmes to
choose from, but the "standards" that you most often come across are
ARC, ZOO, or ZIP. However in the future you never now what is going to
become the new "standard". You should be aware that the ARCHIVING world
is in a state of ferment at the moment, and what is fashionable today
is out tomorrow.
When you are looking for a compression programme the two things that
most people look for are percentage compression, and speed of packing
and extraction. You want the files to be as small as possible, and when
you extract them from the archive they should "unpack" themselves as
quickly as possible. Below is a quick summary of the results. Someone
was asking recently what programmes can you use to extract from
"original" *.ARC files. You will find the answer below.
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QUICK SUMMARY OF RESULTS
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For general purpose compression/archiving programs, if you're
looking for speed of compression, then check out PKZIP, DWC, PKPAK
and QARC. If you're looking for degree of compression (the amount
that the file shrinks) in a general purpose program, then look at
PAK (not to be confused with PKPAK), PKZIP or DWC. If you're
looking for the ability to extract from original format *.ARC
files, then restrict your search to ARC, ARCE, PAK, PKPAK and
DEARC7. If you're distributing disks and must have the absolutely
greatest degree of compression regardless of the time it takes for
the computer to get the job done, then investigate SCRNCH. PKZIP
may also be worthy of consideration. If you want to squeeze ASCII
files to the greatest degree possible, then look at ST/EXP. If
you're concerned about portability (the ability for someone using
a non-MSDOS system to extract files from something you
compressed), then consider COMP16, DWC, ARC and ZOO.
%%%%%%%%%%%%%%%%END%%%%%%%%%%%%%%%%%%
One problem which many people encounter is that they receive an ARC
file and they do not have a ARC programme to UNARCHIVE it. Well some
developers have overcome this by producing SELF-EXTRACTING ARCHIVERS. A
sender can use these to produce an EXE file which when executed
"unpacks" itself, so the receiver does not have to have any programmes
to do the unpacking. This is rather convenient for novices.
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SIZE OF EXTRACTION CODE
-----------------------
Software developers are likely to be concerned about how much space on
a distribution disk must be devoted to the program (or self-extraction
code) that is needed to extract the files from the distribution
archives. Selfextraction code converts an archive into an EXE file
which, when run, will extract into the archive's component files. This
comparison is unlikely to be a concern for persons who are not worried
about distributing files to potentially novice users who don't know an
archive from an elbow.
The following table illustrates the sizes of the extraction programs
and the self-extraction code where available:
Extraction Program Self-Extract Code
------------------ -----------------
ARC 39K 8K
ARCE 7K n/a
COMP16 27K n/a
DEARC7 13K n/a
DWC A501 46K 20K
DWC A495 45K 20K
MDCD 51K n/a
PAK 60K 7K
PKUNPAK 15K 13K
PKUNZIP 16K n/a
SCRNCH 0K 0K
ST/EXP 100K n/a
ZOO 10K (LOOZ) 2K
For a rough comparison of the combined effect of a program's compression
ratio and the efficiency (in size) of its self-extraction code, here's a
listing of the smallest possible final size of PAL.DOC, compressed and made
into a self-extracting file. These are placed in order of smallest to
largest:
SCRNCH 71K
PAK 78K
ZOO 84K
PKZIP 91K
ARC 93K
PKUNPAK 95K
DWC 100K
%%%%%%%%%%%%%%%END%%%%%%%%%%%%%%%%%%
And finally before you decide on what type of compression programme to
use here are a few facts to keep in mind. And as a final check list the
most recent versions of the various programmes are included, so you can
check them against the versions that you have at the moment, and
discover whether you are in step or out of step with the rest of the
world.
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OTHER FACTORS TO CONSIDER
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Other factors to consider in making your selection:
* Licensing arrangements, cost
* Source availability
* Size of extraction programs
* Availability of self-extraction
* Ease of use
* Compatibility with original *.ARC files
* Portability to other operating systems
* Reliability
The programmes and there version number are listed below.
The programs compared are:
ARC version 5.32
ARCA/ARCE versions 1.28 and 3.1c, respectively
COMP16 version 4.2
DEARC7 version 4.0
DWC4size version A495 optimized for size
DWC4speed version A495 optimized for speed
DWC5size version A501 optimized for size
DWC5speed version A501 optimized for speed
MDCD version 1.0
PAK version 1.51
PKPAK (old) version 3.61 (compatible with original ARC format)
PKPAK/UNPAK version 3.61
PKZIP/PKUNZIP version 0.80 beta
PKZIP1\
PKZIP2 \ These notations in TABLES.NW5 refer to command
PKZIP3 / line switches for PKZIP which permit higher
PKZIP4/ degrees of compression.
QARC/ARCE versions 1.00 and 3.1c, respectively
SCRNCHsize version 1.02 optimized for size
SCRNCHspeed version 1.02 optimized for speed
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Rob "I have seen the future and it is compressed" Harper