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Originally Posted by Steve Jordan
I did not know this. ePub makes even more sense, in that case!
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Back in the MS-DOS days, Phil Katz came to prominence in the PC community creating archive and compression utilities. The dominant one back then was a program called ARC by an outfit called Seaware. Phil reverse engineered their format, and created PKARC and PKXARC, which created and extracted ARC format archives. His programs were smaller, faster, more efficient, and had better compression, and rapidly took over. In those days, users called BBS systems over dial up phone lines, and size mattered. When your access to the outside world was a 2400 baud modem, you wanted the files you downloaded to be as small as possible.
Seaware sued for infringement, claiming copyright on their archive format. Phil developed a new format called Zip, and explicitly published the specs for it and dedicated it to the public domain. He also created PKZip and PKUnzip to create and extract zip files. Zip took over, and I'm not sure how many people even remember Seaware now.
Nico Mak was the first one to really develop a Windows zip archiver, and WinZip dominates the market on Windows. Phil's company, PKWare, still exists, and offers versions of zip for things like IBM mainframes. Phil, alas, does not. He drank himself to death a few years ago.
Compression was a topic of considerable interest and research, and everyone was trying to create ever smaller archive files. It was always a trade-off: the higher the compression you achieved, the longer it took to do it, and the more memory was required to perform the task.
There are a number of other archive formats out there with archivers that create them.
In Japan, for example, the dominant one is LHA, which creates LZH archives. That one encountered legal problems here, as well. It uses a compression algorithm known as Lev-Zempel-Welch. Lev and Zempel first devised it, and Terry Welch developed a simpler version that was much easier to implement. Terry was working for what is now Unisys at the time he published his work, and the terms of his contract made stuff he developed their property. Unisys belatedly awoke, realized they had rights to it, and started asking for money. The LZW compression method was the one used in GIF graphics, so web sites posting GIFs suddenly founds themselves being dunned. The PNG (Portable Network Graphics) image format was created specifically to have a format unencumbered by intellectual property considerations so the problem wouldn't recur.
Another relatively popular one is RAR, created by Eugene Rorshal. RAR files provide slightly better compression than zip, and have an assortment of features like multi-media support, user definable part size, and enhanced recovery features that make them a popular choice for people doing things like posting to binary newsgroups. Eugene released public domain code to
open RAR achives, but only his RAR and WinRAR programs can
create them.
On Macintoshes, the dominant archiver is Stuffit, producing SIT files.
Unix systems treat archiving and compression as separate operations. Archives are normally created by "tar" (tape archiver), and then compressed by pack, compress, or gzip
There are many others, and I have four different archivers installed here to cover all the bases. In practice, I normally only create Zip files, but I want to be able to extract any archive.
But as mentioned, there's nothing proprietary about zip files. Lots of things can create and extract them, and the tools exist for every platform I'm aware of. I even have a utility on my Palm OS PDA that can extract from zip files.
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Dennis