This article is missing information about the file format specifications and its byte signature.(February 2019) |
Filename extension | .arc, .ark |
---|---|
Internet media type | application/octet-stream |
Uniform Type Identifier (UTI) | public.archive.arc |
Developed by | System Enhancement Associates |
Type of format | Data compression |
ARC is a lossless data compression and archival format by System Enhancement Associates (SEA). The file format and the program were both called ARC. The format is known as the subject of controversy in the 1980s, part of important debates over what would later be known as open formats.
ARC was extremely popular during the early days of the dial-up BBS. ARC was convenient as it combined the functions of the SQ program to compress files and the LU program to create .LBR archives of multiple files. The format was later replaced by the ZIP format, which offered better compression ratios and the ability to retain directory structures through the compression/decompression process.
The .arc filename extension is often used for several unrelated file archive-like file types. For example, the Internet Archive used its own ARC format to store multiple web resources into a single file. [1] [2] The FreeArc archiver also uses a .arc extension, but uses a completely different file format. Nintendo uses an unrelated "ARC" format for resources, such as MIDI, voice samples, or text, in GameCube and Wii games. Several unofficial extractors exist for this type of ARC file.[ which? ][ citation needed ]
In 1985, Thom Henderson of System Enhancement Associates wrote a program called ARC, [3] based on earlier programs such as ar, that not only grouped files into a single archive file but also compressed them to save disk space, a feature of great importance on early personal computers, where space was very limited and modem transmission speeds were very slow. The archive files produced by ARC had file names ending in ".ARC" and were thus sometimes called "arc files".
The source code for ARC was released by SEA in 1986 and subsequently ported to Unix and Atari ST in 1987 by Howard Chu. This more portable codebase was subsequently ported to other platforms, including VAX/VMS and IBM System/370 mainframes. Howard's work was also the first to disprove the prevalent belief that Lempel-Ziv encoded files could not be further compressed. Additional compression could be achieved by using Huffman coding on the LZW data, and Howard's version of ARC was the first program to demonstrate this property. This hybrid technique was later used in several other compression schemes by Phil Katz and others.
Later, Phil Katz developed his own shareware utilities, PKARC and PKXARC, to create archive files and extract their contents. These files worked with the archive file format used by ARC and were significantly faster than ARC on the IBM-PC platform due to selective assembly-language coding. Unlike SEA, which combined archive creation and archive file extraction in a single program, Katz divided these functions between two separate utilities, reducing the amount of memory needed to run them. PKARC also allowed the creation of self-extracting archives, which could unpack themselves without requiring an external file extraction utility.
Following the System Enhancement Associates, Inc. vs PKWARE Inc. and Phillip W. Katz lawsuit, SEA withdrew from the shareware market and developed ARC+Plus. [4] This version included a full-screen user interface, with the last known version being 7.12. [5] SEA was eventually sold to an unspecified Japanese company in 1992. [6]
The ARC format is no longer common on PC desktops, but most antivirus scanners can still uncompress any ARC archives found in order to detect viruses within the compressed files.
In the late 1980s a dispute arose between SEA, maker of the ARC program, and PKWARE, Inc. (Phil Katz Software). SEA sued Katz for trademark and copyright infringement. An independent software expert, John Navas, was appointed by the court to compare the two programs, and stated that PKARC was a derivative work of ARC, pointing out that comments in both programs were often identical, including spelling errors. [7]
On August 2, 1988, the plaintiff and defendants announced a settlement of the lawsuit, which included a Confidential Cross-License Agreement under which SEA licensed PKWARE for all the ARC-compatible programs published by PKWARE during the period beginning with the first release of PKXARC in late 1985 through July 31, 1988, in return for $62,500, which at the time was an undisclosed payment amount. In the agreement, PKWARE paid SEA to obtain a license that allowed the distribution of PKWARE's ARC-compatible programs until January 31, 1989, after which PKWARE would not license, publish or distribute any ARC compatible programs or utilities that process ARC compatible files. In exchange, PKWARE licensed SEA to use its source code for PKWARE's ARC-compatible programs. PKWARE also agreed to cease any use of SEA's trademark "ARC" and to change the names or marks used with PKWARE's programs to non-confusing designations. The remaining details of the agreement were sealed. In reaching the settlement, the defendants did not admit any fault or wrongdoing. [8] The Wisconsin court order showed defendants were ordered to pay damages to plaintiff for defendants' acts of infringing Plaintiff's copyrights, trademark, and acts of unfair trade practices and unfair competition. [9]
The leaked agreement document revealed under the settlement terms, the defendants had paid plaintiff $22,500 for past royalty payments, and $40,000 for expense reimbursements. In addition, defendants would pay plaintiff a royalty fee of 6.5% of all revenue received for ARC compatible programs on all orders received after the effective date of this Agreement, such revenue including any license fees or shareware registrations received after the expiration of the license, for ARC compatible programs. In exchange, plaintiff would also pay a commission in the amount of 6.5% of any license fees received by plaintiff from any licensee referred to plaintiff by defendants, whether before or after the license termination date. [10]
After the lawsuit, PKWARE released one last version of his PKARC and PKXARC utilities under the new names "PKPAK" and "PKUNPAK", and from then on concentrated on developing the separate programs PKZIP and PKUNZIP, which were based on new and different file compression techniques and archive file formats. However, following the renaming, SEA filed a lawsuit against PKWARE for contempt, for continually using plaintiff's protected mark ARC, by turning ARC from noun into verb in the PKPAK manual. [11] The U.S. district court of the East District of Wisconsin ruled SEA's motion was denied, and the defendant was entitled to recover the legal cost of $500. [12]
The SEA vs. PKWARE dispute quickly expanded into one of the largest controversies the BBS world ever saw. [13] The suit by SEA angered many shareware users who perceived that SEA was a "large, faceless corporation" and Katz was "the little guy". In fact, at the time, both SEA and PKWARE were small home-based companies. However, the community largely sided with Katz, due to the fact that SEA was attempting to retroactively declare the ARC file format to be closed and proprietary. Katz received positive publicity by releasing the APPNOTE.TXT specification documenting the ZIP file format, and declaring that the ZIP file format would always be free for competing software to implement. The net result was that the ARC format quickly dropped out of common use as the predominant compression format that PC-BBSs used for their file archives, and after a brief period of competing formats, the ZIP format was adopted as the predominant standard.
In an interview, Thom Henderson of SEA said that the main reason he dropped out of software development was because of his inability to emotionally cope with what he claimed was the hate-mail campaign launched against him by Katz. [14]
Phillip Walter Katz was a computer programmer best known as the co-creator of the ZIP file format for data compression, and the author of PKZIP, a program for creating zip files that ran under DOS.
In computing, Deflate is a lossless data compression file format that uses a combination of LZ77 and Huffman coding. It was designed by Phil Katz, for version 2 of his PKZIP archiving tool. Deflate was later specified in RFC 1951 (1996).
PKZIP is a file archiving computer program, notable for introducing the popular ZIP file format. PKZIP was first introduced for MS-DOS on the IBM-PC compatible platform in 1989. Since then versions have been released for a number of other architectures and operating systems. PKZIP was originally written by Phil Katz and marketed by his company PKWARE, Inc starting in 1986. The company bears his initials: "PK".
ZIP is an archive file format that supports lossless data compression. A ZIP file may contain one or more files or directories that may have been compressed. The ZIP file format permits a number of compression algorithms, though DEFLATE is the most common. This format was originally created in 1989 and was first implemented in PKWARE, Inc.'s PKZIP utility, as a replacement for the previous ARC compression format by Thom Henderson. The ZIP format was then quickly supported by many software utilities other than PKZIP. Microsoft has included built-in ZIP support in versions of Microsoft Windows since 1998 via the "Plus! 98" addon for Windows 98. Native support was added as of the year 2000 in Windows ME. Apple has included built-in ZIP support in Mac OS X 10.3 and later. Most free operating systems have built in support for ZIP in similar manners to Windows and macOS.
RAR is a proprietary archive file format that supports data compression, error correction and file spanning. It was developed in 1993 by Russian software engineer Eugene Roshal and the software is licensed by win.rar GmbH. The name RAR stands for Roshal Archive.
7-Zip is a free and open-source file archiver, a utility used to place groups of files within compressed containers known as "archives". It is developed by Igor Pavlov and was first released in 1999. 7-Zip has its own archive format called 7z, but can read and write several others.
7z is a compressed archive file format that supports several different data compression, encryption and pre-processing algorithms. The 7z format initially appeared as implemented by the 7-Zip archiver. The 7-Zip program is publicly available under the terms of the GNU Lesser General Public License. The LZMA SDK 4.62 was placed in the public domain in December 2008. The latest stable version of 7-Zip and LZMA SDK is version 24.05.
StuffIt is a discontinued family of computer software utilities for archiving and compressing files. Originally produced for Macintosh, versions for Microsoft Windows, Linux (x86), and Sun Solaris were later created. The proprietary compression format used by the StuffIt utilities is also termed StuffIt.
StuffIt Expander is a proprietary, freeware, closed source, decompression software utility developed by Allume Systems. It runs on the classic Mac OS, macOS, and Microsoft Windows. Prior to 2011, a Linux version had also been available for download.
WavPack is a free and open-source lossless audio compression format and application implementing the format. It is unique in the way that it supports hybrid audio compression alongside normal compression which is similar to how FLAC works. It also supports compressing a wide variety of lossless formats, including various variants of PCM and also DSD as used in SACDs, together with its support for surround audio.
The following tables compare general and technical information for a number of file archivers. Please see the individual products' articles for further information. They are neither all-inclusive nor are some entries necessarily up to date. Unless otherwise specified in the footnotes section, comparisons are based on the stable versions—without add-ons, extensions or external programs.
PowerArchiver is a proprietary file archiver for Microsoft Windows and MacOS, developed by ConeXware Inc. It supports creating and reading ZIP, 7z, and Tar archive formats, as well as various disk image formats. Additionally, it can read RAR and ACE files. The evaluation version of the program remains functional for 40 days. Personal licenses are currently permitted free lifetime updates to all future versions of the software, while the business license is valid through two major versions.
In computing, an archive file is a computer file that is composed of one or more files along with metadata. Many archive formats also support compression of member files. Archive files are used to collect multiple data files together into a single file for easier portability and storage, or simply to compress files to use less storage space. Archive files often store directory structures, error detection and correction information, comments, and some use built-in encryption.
Compact Pro is a software data compression utility for archiving and compressing files on the Apple Macintosh platform. It was a major competitor to StuffIt in the early 1990s, producing smaller archives in less time, able to create self-extracting archives without the use of an external program, as well as being distributed via shareware which greatly helped its popularity. A PC version was also available, ExtractorPC. Neither program is actively supported.
ALZip is an archive and compression utility software application from ESTsoft for Microsoft Windows that can unzip 40 different zip file archives. ALZip can zip files into eight different archive formats such as ZIP, EGG, TAR, and others. Introduced in ALZip version 8, the EGG archive format can be used, which supports Unicode and other features.
PeaZip is a free and open-source file manager and file archiver for Microsoft Windows, ReactOS, Linux, MacOS and BSD by Giorgio Tani. It supports its native PEA archive format and other mainstream formats, with special focus on handling open formats. Version 9.4.0 supported 234 file extensions.
XZ Utils is a set of free software command-line lossless data compressors, including the programs lzma and xz, for Unix-like operating systems and, from version 5.0 onwards, Microsoft Windows. For compression/decompression the Lempel–Ziv–Markov chain algorithm (LZMA) is used. XZ Utils started as a Unix port of Igor Pavlov's LZMA-SDK that has been adapted to fit seamlessly into Unix environments and their usual structure and behavior.
PKWARE, Inc. is an enterprise data protection software company that provides discovery, classification, masking and encryption software, along with data compression software. It is used by organizations in a range of industries including financial services, manufacturing, military, healthcare and government. The company's products are intended to assist other companies in complying with various data protection regulations such as GDPR and CCPA. The company is headquartered in Milwaukee, Wisconsin with additional offices in the US, UK, and India.
lzip is a free, command-line tool for the compression of data; it employs the Lempel–Ziv–Markov chain algorithm (LZMA) with a user interface that is familiar to users of usual Unix compression tools, such as gzip and bzip2.
AppleDisk Image is a disk image format commonly used by the macOS operating system. When opened, an Apple Disk Image is mounted as a volume within the Finder.
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