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I believe that the current description is completely wrong. "arc" was a very specific archiving format similar to zip and various others. It had pretty bad compression ratio so it died as soon as better alternatives showed up, primarily "lharc" (or "lha").

Are there any examples of other archiving programs using the extension "arc"?

Yes, FreeArc uses the extension ".arc" for all of its output files, no matter the compression. I checked that format for use with the old ARC compression program by SEA, and it didn't work. Obviously, those two arc-files are completely different. The console program of FreeArc uses similar command options as old DOS and CP/M archivers. It seems, as if the author of FreeArc tried to design a complete replacement for the old Arc. Polemon (talk) 09:32, 26 July 2010 (UTC)[reply]

Two different things. In the PC world, .ARC was almost exclusively used by SEA's (and PK's) compressors; but on other computer architectures, .ARC were used that had no relation to SEA.

some examples: http://sta.c64.org/stararcdoc.html

http://www.math.utah.edu/pub/arc/

There were several others, I could probably dig up more references if requested.

SEA's ARC had excellent compression, for the time it was released. The ongoing legal woes that Phil Katz and other suffered, spurred them to develop better, competing archive formats. The original ZIP algorithms, for that matter, were much less efficient than the algorithms ZIP uses today.

ARC was the first common format in wide use on the PC. ZIP, ZOO, then ARJ, ACE and others all stem from the lineage of products competing with ARC; and most were commercial or shareware in origin.

LZH/LHA was developed independently by computer scientists in Japan; if not for the SEA lawsuit, it might well have eventually spread to the US and pushed out ARC, but its timing seems incidental; LZH/LHA didn't enter into common use in the US/Europe until after PKZIP was established.

--Raduga 01:04, 15 February 2006 (UTC)[reply]

Didn't later versions of ARC support archiving directories? What exactly was the last version of ARC, 7.0?

BTW, don't forget to mention that: 1). ARC was (supposedly?) free for non-commercial use, and 2). SEA was a very small company that needed others to port ARC to non-DOS platforms, so that's why they released the source. Also, from what I've read, ARC replaced the LBR+SQ combo. I think Thom Henderson runs his own ISP nowadays, right? Armslurp 14:34, 26 June 2006 (UTC)[reply]

The Acorn Computer had a file archive type called ArcFS, which also used the "arc" extension. The only reference to the layout of the file that I've found is here (the file named "arcfsdata"): http://arcade.demon.co.uk/filepages/file46.htm

--05:27:21, 5 March 2010 (UTC)

The text here seems to contradict (or at least fails to mention important facts [?]) with the PKZIP article. The other article mentions SEA won the legal case and calls the code 'plagiarised', while in this article it is not mentioned SEA won the case, nor is it very clear that what PKWARE did was indeed considered illegal. A correction would be nice, the other article has some good references to sources on the case for exact details. 82.157.229.156 10:15, 22 August 2007 (UTC)[reply]

The phrase near the end "Henderson moved back to Virginia" seems very odd -- there's no previous mention of him being anywhere else, and in any case, his physical location seem irrelevant to the subject of the article. Snogglethorpe (talk) 23:14, 9 March 2008 (UTC)[reply]

Henderson?

Who is it? —Preceding unsigned comment added by 68.207.123.4 (talk) 20:44, 25 July 2008 (UTC)[reply]

There could be more said about SEA's decision to retroactively declare the ARC file format to be closed and proprietary. I doubt whether it was strictly necessary for SEA to win its court case, and it created a huge negative backlash among the user community and allowed Phil Katz to be the good guy by declaring that the APPNOTE.TXT specification was free for anyone to implement.

Also, the sentence which was recently added to the end oversimplifies the compression wars of the early 1990s. ZIP's status as the replacement to ARC wasn't really sealed until after Zip 1.93a (with the deflate algorithm) was released in 1991; before that time, Lharc, Arj, another (non-PKWare) Pak program etc. were competitors. AnonMoos (talk) 00:28, 30 January 2010 (UTC)[reply]

A point not made clear in the article.
If an archive was created in PKARC, could that archive be opened by SEA's ARC, or did it specifically *require* PKXARC ?
86.25.121.61 (talk) 08:26, 24 October 2011 (UTC)[reply]

I'm reasonably certain that there was file format compatibility... AnonMoos (talk) 15:26, 24 October 2011 (UTC)[reply]

I'm sure that Henderson perceives it that way, but many many other people viewed it as a mostly spontaneous BBS uprising sparked by revulsion against the attempt to retroactively declare the .ARC file format to be closed and proprietary (not too different from the later Burn all GIFs movement), so we must be careful with the wording here... AnonMoos (talk) 01:45, 18 August 2012 (UTC)[reply]

This page is currently based on file extension .arc which leads to awkward results: my own main interest is the .arc file format, also known as ARCs, developed by the Internet Archive and now deprecated in favour of the WARC format (the pair often known as (W)ARCs). These are mentioned at the end of the first paragraphs, embedded in a page describing a totally different format. The same problem with some other formats with the same extension mentioned below. Could this be handled better by a disambiguation page? Zosterae (talk) 16:56, 11 December 2015 (UTC)[reply]

Added hatnote to Web ARChive which is Internet Archive's ARC_IA format and has nothing to do with this article. -- œ^™ 05:15, 7 January 2021 (UTC)[reply]

Can anyone prove just what kind of archive the .arc and .ark files are in Wii and GameCube game discs? ILoveWikis (talk) 06:04, 16 March 2019 (UTC)[reply]

Almost certainly not this ancient compression format described in this article. -- œ^™ 05:16, 7 January 2021 (UTC)[reply]

I just want to point out that this article recapitulates the controversies and debates of the '80s, and not in a good way. To wit, Phil Katz is consistently referred to by his name (and not PKWARE, Inc), while Thom Henderson is almost always referred to as SEA, rather than by name - even though both companies seem to have been essentially small or even single-person shareware operations. This is exactly what happened then, leading to the idea we all had that SEA was a 'faceless corporation', when in fact, it was nearly identical to PKWARE. I don't have a suggestion to fix the article. Eaglizard (talk) 10:48, 14 August 2022 (UTC)[reply]

Some people probably semi-consciously got that idea when Henderson/SEA retroactively declared .ARC to be a closed and proprietary file format, which seemed like a "corporate" maneuver... AnonMoos (talk) 03:40, 15 August 2022 (UTC)[reply]