ARC (file format)
Encyclopedia
ARC is a lossless data compression
and archival
format
by System Enhancement Associates (SEA). It was very popular during the early days of networked dial-up BBS
. The file format and the program were both called ARC. The ARC program made obsolete the previous use of a combination of the SQ program
to compress files and the LU program to create .LBR archives
, by combining both compression and archiving functions into a single program. Unlike ZIP
, ARC is incapable of compressing entire directory trees. The format was subject to controversy in the 1980s—an important event in debates over what would later be known as open format
s.
The .arc file extension is often used for several file archive-like file types. For example, the Internet Archive
uses its own ARC format to store multiple web resources into a single file http://crawler.archive.org/articles/developer_manual/arcs.htmlhttp://www.archive.org/web/researcher/ArcFileFormat.php. The FreeArc
archiver also uses .arc extension, but uses a completely different file format.
Nintendo uses its own version of ARC for resources, such as MIDI and voice samples, in GameCube and Wii games. Several unofficial extractors exist for this type of ARC file.
, 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 sometimes called "arc files" as a result.
The source code for ARC was released by SEA in 1986 and subsequently ported to Unix
and the Atari ST
in 1987 by Howard Chu. This more portable code base 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 performing a Huffman Squeeze
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 among 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. This version included a full-screen user interface, with the last known version being 7.12. SEA was eventually sold to a Japanese company in 1992.
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.
of ARC, pointing out that comments in both programs were often identical, including spelling errors.
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 an undisclosed payment. 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. The Wisconsin court order showed defendants was ordered to pay damages to plaintiff for defendants' acts of infringing Plaintiff's copyrights, trademark, and acts of unfair trade practices and unfair competition.
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.
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. 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. The US 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.
The SEA vs. PKWARE dispute quickly expanded into one of the largest controversies the BBS
world ever saw. 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.
Data compression
In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....
and archival
File archiver
A file archiver is a computer program that combines a number of files together into one archive file, or a series of archive files, for easier transportation or storage...
format
File format
A file format is a particular way that information is encoded for storage in a computer file.Since a disk drive, or indeed any computer storage, can store only bits, the computer must have some way of converting information to 0s and 1s and vice-versa. There are different kinds of formats for...
by System Enhancement Associates (SEA). It was very popular during the early days of networked dial-up BBS
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...
. The file format and the program were both called ARC. The ARC program made obsolete the previous use of a combination of the SQ program
SQ (program)
SQ was a program used in the early 1980s on both DOS and CP/M computer systems to compress files so they use less space. Files compressed by SQ are identified by changing the middle initial of the extension to "Q", so that text files ended with the extension .TQT, executable files ended with the...
to compress files and the LU program to create .LBR archives
LBR (file format)
The .LBR file format was an archive file format used on CP/M and DOS operating systems during the early 1980s. .LBR files were created by the LU program; later programs like NULU arrived for .LBR creation, and many tools such as LT and QL were capable of extracting from .LBR archives...
, by combining both compression and archiving functions into a single program. Unlike ZIP
Zip
Zip or ZIP most commonly refers to:*Zipper or zip, a device for temporarily joining two edges of fabric together*ZIP code, the USPS Zone Improvement Plan used in postal addresses in the USA*Zip drive, a removable data storage format...
, ARC is incapable of compressing entire directory trees. The format was subject to controversy in the 1980s—an important event in debates over what would later be known as open format
Open format
An open file format is a published specification for storing digital data, usually maintained by a standards organization, which can therefore be used and implemented by anyone. For example, an open format can be implementable by both proprietary and free and open source software, using the typical...
s.
The .arc file extension is often used for several file archive-like file types. For example, the Internet Archive
Internet Archive
The Internet Archive is a non-profit digital library with the stated mission of "universal access to all knowledge". It offers permanent storage and access to collections of digitized materials, including websites, music, moving images, and nearly 3 million public domain books. The Internet Archive...
uses its own ARC format to store multiple web resources into a single file http://crawler.archive.org/articles/developer_manual/arcs.htmlhttp://www.archive.org/web/researcher/ArcFileFormat.php. The FreeArc
FreeArc
FreeArc is a free and open source file archiver developed by Bulat Ziganshin.-Algorithms:FreeArc uses LZMA, PPMD, TrueAudio, Tornado and GRzip algorithms with automatic switching by file type, and also uses set of filters—for instance it can remove repetitions from text.-Archive size:In Tom's...
archiver also uses .arc extension, but uses a completely different file format.
Nintendo uses its own version of ARC for resources, such as MIDI and voice samples, in GameCube and Wii games. Several unofficial extractors exist for this type of ARC file.
History
In 1985, Thom Henderson of System Enhancement Associates wrote a program called ARC, based on earlier programs such as arAr (Unix)
The archiver is a Unix utility that maintains groups of files as a single archive file. Today, ar is generally used only to create and update static library files that the link editor or linker uses; it can be used to create archives for any purpose, but has been largely replaced by tar for...
, 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 sometimes called "arc files" as a result.
The source code for ARC was released by SEA in 1986 and subsequently ported to Unix
Unix
Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
and the Atari ST
Atari ST
The Atari ST is a home/personal computer that was released by Atari Corporation in 1985 and commercially available from that summer into the early 1990s. The "ST" officially stands for "Sixteen/Thirty-two", which referred to the Motorola 68000's 16-bit external bus and 32-bit internals...
in 1987 by Howard Chu. This more portable code base was subsequently ported to other platforms including VAX/VMS
OpenVMS
OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase...
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 performing a Huffman Squeeze
Huffman coding
In computer science and information theory, Huffman coding is an entropy encoding algorithm used for lossless data compression. The term refers to the use of a variable-length code table for encoding a source symbol where the variable-length code table has been derived in a particular way based on...
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
Phil Katz
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 which ran under DOS.- Career :...
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 among 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. This version included a full-screen user interface, with the last known version being 7.12. SEA was eventually sold to a Japanese company in 1992.
The ARC format is no longer common on PC desktops but most antivirus
Antivirus software
Antivirus or anti-virus software is used to prevent, detect, and remove malware, including but not limited to computer viruses, computer worm, trojan horses, spyware and adware...
scanners can still uncompress any ARC archives found in order to detect viruses within the compressed files.
Lawsuits
In the late 1980s a dispute arose between SEA, maker of the ARC program, and PKWARE (Phil Katz Software). SEA sued Katz for trademark and copyright infringement. The most substantial evidence at trial was from an independent software expert appointed by the court to compare the two programs. He stated that PKARC was a derivative workDerivative work
In United States copyright law, a derivative work is an expressive creation that includes major, copyright-protected elements of an original, previously created first work .-Definition:...
of ARC, pointing out that comments in both programs were often identical, including spelling errors.
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 an undisclosed payment. 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. The Wisconsin court order showed defendants was ordered to pay damages to plaintiff for defendants' acts of infringing Plaintiff's copyrights, trademark, and acts of unfair trade practices and unfair competition.
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.
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. 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. The US 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.
The SEA vs. PKWARE dispute quickly expanded into one of the largest controversies the BBS
Bulletin board system
A Bulletin Board System, or BBS, is a computer system running software that allows users to connect and log in to the system using a terminal program. Once logged in, a user can perform functions such as uploading and downloading software and data, reading news and bulletins, and exchanging...
world ever saw. 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.
Filename extension
- .arc (all systems)
- .ark (adopted by some bulletin boards as a naming convention indicating that the file contained software for CP/MCP/MCP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
rather than DOSDOSDOS, short for "Disk Operating System", is an acronym for several closely related operating systems that dominated the IBM PC compatible market between 1981 and 1995, or until about 2000 if one includes the partially DOS-based Microsoft Windows versions 95, 98, and Millennium Edition.Related...
). - .sue (due to all the legal issues)
External links
- ARC file format description
- ARC - free software Linux/Unix port of the .arc compression program
- nomarch - another free software .arc compression program for Linux/Unix
- The BBS Documentary: Compression - A documentary that discusses ARC history, in the context of BBS
- CONTROVERSY: LAWSUITS: SEA vs. PKWARE