                                 What is "ARC"?
                                 ==============

     Around CompuServe, and maybe on your local BBS, you have begun to
notice files with the ARC file extension (xxxxxx.ARC).  What makes these
files so special is that they are actually compressed files that don't
take as long to download, and they are actually many files within a file.
A compressed library of files you can download in a single operation.

     But the ARChived file looks like gibberish.  You can't run it, you
can't really use it in any way.  That is until you run your copy of the
ARC program to EXTRACT the data, programs, etc out of it -- essentially
de-compressing the file and un-packing the programs, data files, text files,
etc that the author squeezed, crunched, and packed in there before he
uploaded it.  Complicated?  Not really.  Thanks to ARC it is a one-step
operation.

     ARC -- The ARChive utility -- was written as a Shareware program and
is available widely here on CompuServe and on many local BBS boards.  You
will find it a handy addition to your toolbox of utilities.

     As a Shareware program you can pick it up, or download it almost
anywhere.  If you like it, make a contribution to the folks who wrote it.
You get to "Try it before you Buy it".  The premise is that you and I are
basically trustworthy souls.  Together we all benefit.  Are you up to it?


                             Why file compression?
                             =====================

     Whether you run 300, 1200, or 2400 baud, transfering a large file to or
from CompuServe or your favorite local BBS, time is of the essence.  Time is
indeed money.  The faster you can get in and out, the better.

     As microcomputers proliferated, more and more people began transfering
data electronically.  It wasn't long before simple data compression programs
began to circulate through the user community.  Using a variety of 
techniques a 100K file could be compressed into 70 or 80K.  Once received
an complimentary program could be used to DE-compress the file back to it's
original 100K size.  Meanwhile, you've saved 20-30% in transfer time,
phone charges, connect charges, etc.

     Most popular of those to follow this SQUEEZE -- TRANSFER -- UNSQUEEZE
scenario were two programs named, quite appropriately, SQ and USQ.

     A SQueezed file can always be identified by a "Q" in the middle of the
file extension.
          Example:  xxxxxx.xQx

     A SQueezed file is NOT usable or runnable in it's squeezed form.  It
must be UnSQueezed on your end before using it.


                          So what is a "LIBRARY" file?
                          ============================

     A "Library" file is another simple idea.  You have a dozen related files
that you wish to download via modem.  That's a dozen separate downloads. 
What happens if you miss one?  Can you easily identify the one you missed?

     A "library" file is nothing more than an electronic looseleaf folder --
take a bunch of smaller files, gather them together into one big file, and
transfer the one file.  Once received, you run another program to unpack the
library into the original dozen files.

     A program called "LAR" -- the Library Utility -- was quite popular and
handled both the packing and unpacking functions.  Library files can be
identified by the file extension LBR.
          Example:  xxxxxx.LBR


                       How about a "COMPRESSED LIBRARY"?
                       =================================

     Sure!  LAR a bunch of files into a single library file.  Take the
resulting file and SQueeze it to reduce transmission time.  Of course it's a
two-step operation prior to transmission, and another two-step operation
after reception.  Not something for the novice user, but it does indeed
work.

     A SQueezed Library file is identified by its LQR file extension.
          Example: xxxxxx.LQR


                               Along comes "ARC"
                               =================

     ARC -- the ARChive utility -- combines both the file compression and
the library operations into a single operation.  The sender ARChives the
file(s) prior to transmission, while the recipient de-ARChives the files
after downloading.

     ARChive also is much more intelligent in its file compression 
techniques.  File compression of 50% is typical -- while I have seen 
85% savings in certain situations.

     An ARChived file is identified by the file extension ARC.
          Example:  xxxxxx.ARC

     ARC has been adapted for many popular microcomputers.  It has also been
enhanced and improved, giving rise to several versions.  As of June 1986
version .011 is current.  

     The one program handles BOTH compression and de-compression.  



                              Putting ARC to work
                              ===================

     o You have downloaded an ARChived file.  Let's call it TEST.ARC.
       It now resides on the same disc as your ARC program ARC.COM or 
       ARC.EXE.

     o You wish to Extract (de-compress & unpack) all the original files
       packed into TEST.ARC. To accomplish this, two identical ARC commands
       are available -- E (Extract) or X (eXtract).

     o At the CLI prompt you simply type:
          ARC E TEST *.*   or   ARC X TEST *.*

     That's all there is to it.  You invoked ARC, commanded it into eXtract
mode, told it that it was to eXtract from TEST.ARC (the .ARC extension is
assumed), and that you wanted all the files (*.*) contained therein eXtracted
and place back in their original form on your disc.

     Sure there are many, many more features contained in the ARC system.  
Take a look at the documentation file for all the particulars, but this will
certainly get you started.

     I'm certain you will love what the authors of ARC have done.  I hope you
remember to support the Shareware concept.  No, I have no affiliation with
the authors of ARC.  Shareware benefits everyone, and will vanish without 
your support.

(This help file courtesy of Alan Bose of AVSIG)
