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)