ARC versus Zoo
==============

Lots of you out there will wonder what the difference is between 
ARC and Zoo, and why they need to consider changing in the first 
place.

Well, both ARC and Zoo are archivers: you feed them a list of 
files, which they will compress (unless you forbid them to do 
that explicitly) and put in one big file, the archive. Another 
common point is that both ARC and Zoo sources are freely 
available (ARC is shareware, Zoo is Public Domain) and that 
versions of Zoo and ARC are available for a lot of different 
computers: UNIX boxes, PC's, Amiga's and now ST's.

Let's discuss the most striking differences in some detail:

DIRECTORY SUPPORT
The numbero uno difference: ARC does not support directories, 
only plain files. Zoo DOES support directories: when adding 
files, Zoo usually also stores the paths as specified in the 
list of files to be added. At extraction time, Zoo can be 
instructed to place the members of an archive in the directories 
they were coming from- a big plus. It's even possible to let Zoo 
create all directories needed.

RECOVERING DATA FROM CORRUPTED ARCHIVES
If you have experience with corrupted ARC archives, you will 
like this Zoo feature very much! Zoo marks both the beginning of 
(file) headers and the beginning of file data with special 
tokens, allowing extraction of all (except the corrupted one) 
files from the archive. Zoo even has a special utility to aid 
the recover operation: a program called "Fiz". Offcourse there 
is also a ST version of Fiz.

SPEED
Zoo/ST 2.01 (compiled with Turbo C for the ST v1.0) is on 
average +- 40% faster than ARC 5.21 (compiled with Mark Williams 
C 3.0.6); some operations are even twice as fast with Zoo (eg 
adding new files to an existing archive).
Difference of compilers explaines part of the difference, 
entirely different archive organisation explains the rest. See 
the source for more info.

COMPRESSION TECHNIQUES
ARC has several compression methods and, after analyzing which 
compressing technique will yield the smallest result, usually 
decides to "crunch" the file using a so-called Lempel-Ziv 
compression scheme. Zoo only has one compression technique (the 
same Lempel-Ziv algorithm, seems slightly better implemented). 
Zoo doesn't have to analyze (saves time); ARC always uses the 
most optimal technique (saves space).

SLICK POSSIBILITIES
Let's name some of them:
   -  listing the contents of several archives with one command;
   -  ability to add ASCII comments to every member of an 
      archive and to the archive as a whole;
   -  keep multiple generations of your source files in one Zoo 
      archive;
   -  Zoo usually refuses to extract a file when the file which 
      will be overwritten is newer than the file in the archive. 
      You have to force Zoo to extract the file using a special 
      comand-line option. Safe!


Many thanks to Rahul Dhesi for writing this excellent program!

Enjoy! 
Daan*                    / .    .                                      
                     __ /                                              
                    (  /  /    /                                       
                   (__/  /    /      (Daan Josephus Jitta)             
                        /    /                                         
                     __/  __/