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I test DOS archivers, and tell you how they work

technofile  by al fasoldt

Columns and commentaries in a life-long dance with technology
 

Simple gray rule



I test DOS archivers, and tell you how they work 


By Al Fasoldt

Copyright © 1990, The Syracuse Newspapers

Computer users are able to get something for nothing these days.

This is done through the amazing process of file compression. A special software program looks at the bytes in a file and then tosses out everything that's repetitive. It works on text files and graphics as well as programs.

Then, any time you need to have the file back in its normal shape, you just uncompress it with the same program. It's like buying 20 pounds of groceries at the supermarket, compressing them to 10 pounds for the trip home, and then unsqueezing them back to normal in the kitchen.

The most famous of these data-compression programs is called "ARC." The word stands for "archive," and comes from the praiseworthy goal of squeezing files down to the smallest possible size so they won't take up much space when they are put away for long-term storage—for ARChival storage, in other words.

The ARC program belongs to a company called System Enhancement Associates. In a one of the smartest moves in all of computing, SEA decided to issue its ARC program as shareware some years ago. Because shareware is passed around freely, ARC became popular quickly, and it also became the standard way of shrinking files in the world of IBM compatibles.

This led to imitation. Software writers created ARC-like programs for such computers as the Apple II, the Commodore 64 and Amiga, and all the Atari line. In the PC domain, meanwhile, self-styled improvements on ARC began to appear, and when it seemed that some of the actual software code used in ARC was being copied, SEA went to court to assert its rights.

Shareware programs, as SEA pointed out, may be freely copyable, but they're still copyrighted, and the copyrights are just as valid as those for commercial software programs.

The court case led PKWARE, the main rival of SEA, to change the way its compression program worked. Computer users benefited from the change, because a new race began to create file squeezers that performed better than ARC without infringing on SEA's copyright.

One of the best came from PKWARE itself, with its "zip" program. Another company created a compression program called "zoo" (which has a companion decompression program called, appropriately, "ooz"). And then a new champ was proclaimed in a Japanese import called "lhARC."

In the best Hollywood tradition, SEA has brought out its big guns. It has come up with a new version of ARC that just might knock all the other programs out of the ring.

The new ARC is fast and foolproof, and squeezes the dickens out of files. The figures are impressive, and I'll get to them next week in a close look at the new ARC and its main rivals. Don't go away.

When we were kids, my friends and I spent a lot of rainy nights one summer making up word-o-grams. That was the name we gave to such shorthand sentences as this: "O I C U R M T"—"Oh, I see you are empty."

That's data compression at its best—seven letters that say the same thing as 17 letters, not counting the spaces in between the words.

I'm sure some of the girls would have been happier if I'd stuck to data compression. But they'll be pleased to know I'm a full-fledged compactor now, spending quite a bit of time each week squeezing and squishing files.

I don't have any choice. Like nearly every other computer user, I have too many files and too little space. I have no intention of getting rid of my files, so that means I have to do something else.

The obvious choice would be to add more space for storage—in other words, a larger hard-disc drive. But that costs money.

The alternative: Free (or almost free) file-compression programs that make everything that my computer stores smaller.

Here are five of them, all MS-DOS programs designed to run on IBM-compatible PCs. Most of them are also available in versions for other computers, too.

They're all fine, and they each have different strengths. All of them are shareware except for one. (Shareware is software that you share with others freely but are expected to pay for; the fee is always small.)

The best is the original, called ARC. The current version is called ARC602. In my tests, ARC602 squeezed a group of 299 files totaling 3 megabytes in size down to 2.17 megabytes. The compression time was two minutes and 23 seconds—very fast.

Very close to ARC602 is a newcomer called LHARC. The version I tested is 1.3. It squeezed the same files down to 1.80 megabytes, but took a lot longer—a time of 12:25. LHARC is the only one in this group that is not shareware; it's free.

PKZIP did an excellent job, compacting the files to 1.84 megabytes. It took six seconds under six minutes.

ZOO did reasonably well, giving me a squeezed file of 2.08 megabytes in a time of 6:13.

Finally, PAK produced a file of 1.82 megabytes in a time of 9:15.

1997 epilogue: ARC is no longer popular in the PC world. In fact, you'll probably never find an ARCed file unless you delve into files that were Archived more than five years ago. Phil Katz turned the world of PC file ARChiving into a ZIP universe. We all owe him a debt.


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