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ARC (file Format)
ARC is a Lossless compression, lossless data compression and file archiver, archival file format, 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 Bulletin board system, BBS. ARC was convenient as it combined the functions of the SQ (program), SQ program to compress files and the LU program to create LBR (file format), .LBR archives of multiple files. The format was later replaced by the Zip (file format), ZIP format, which offered better data compression ratio, 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 Heritrix#Arc_files, its own ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
System Enhancement Associates
A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. A system, surrounded and influenced by its open system (systems theory), environment, is described by its boundaries, structure and purpose and is expressed in its functioning. Systems are the subjects of study of systems theory and other systems sciences. Systems have several common properties and characteristics, including structure, function(s), behavior and interconnectivity. Etymology The term ''system'' comes from the Latin word ''systēma'', in turn from Greek language, Greek ''systēma'': "whole concept made of several parts or members, system", literary "composition"."σύστημα" , Henry George Liddell, Robert Scott, ''A Greek–English Lexicon'', on Pers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unix
Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and others. Initially intended for use inside the Bell System, AT&T licensed Unix to outside parties in the late 1970s, leading to a variety of both academic and commercial Unix variants from vendors including University of California, Berkeley ( BSD), Microsoft (Xenix), Sun Microsystems ( SunOS/ Solaris), HP/ HPE ( HP-UX), and IBM ( AIX). The early versions of Unix—which are retrospectively referred to as " Research Unix"—ran on computers such as the PDP-11 and VAX; Unix was commonly used on minicomputers and mainframes from the 1970s onwards. It distinguished itself from its predecessors as the first portable operating system: almost the entire operating system is written in the C programming language (in 1973), which allows U ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PKZIP
PKZIP is a file archiving computer program A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ..., 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". History By the 1970s, file archiving programs were distributed as standard utilities with operating systems. They include the Unix utilities ar, shar, and tar. These utilities were designed to gather a number of separate files into a single archive file for easier copying and distribution. These archives coul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Derivative Work
In copyright law, a derivative work is an expressive creation that includes major copyrightable elements of a first, previously created original work (the underlying work). The derivative work becomes a second, separate work independent from the first. The transformation, modification or adaptation of the work must be substantial and bear its author's personality sufficiently to be original and thus protected by copyright. Translations, cinematic adaptations and musical arrangements are common types of derivative works. Most countries' legal systems seek to protect both original and derivative works. They grant authors the right to impede or otherwise control their integrity and the author's commercial interests. Derivative works and their authors benefit in turn from the full protection of copyright without prejudicing the rights of the original work's author. Definition Berne The Berne Convention for the Protection of Literary and Artistic Works, an international copy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PKWare
PKWARE, Inc. is an American 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. PKWARE was founded in 1986 by Phil Katz, co-inventor of the ZIP standard. Thompson Street Capital Partners acquired PKWARE Inc. in 2020. History Compression software (1986–2000) PKWARE was founded in 1986 by Phil Katz, a software developer who had begun distributing a new file compression utility, called PKARC, as shareware. PKARC represented a radical improvement over existing compression software (including the ARC ut ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antivirus Software
Antivirus software (abbreviated to AV software), also known as anti-malware, is a computer program used to prevent, detect, and remove malware. Antivirus software was originally developed to detect and remove computer viruses, hence the name. However, with the proliferation of other malware, antivirus software started to protect against other computer threats. Some products also include protection from malicious URLs, spam, and phishing. History 1971–1980 period (pre-antivirus days) The first known computer virus appeared in 1971 and was dubbed the " Creeper virus". This computer virus infected Digital Equipment Corporation's ( DEC) PDP-10 mainframe computers running the TENEX operating system.From the first email to the first YouTube video: a d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Shopper (US Magazine)
''Computer Shopper'' is a monthly consumer computer magazine that was published by SX2 Media Labs. The magazine ceased print publication in April 2009. The website was closed and redirected to the PCMag website in late May 2018. History ''Computer Shopper'' magazine was established in 1979 in Titusville, Florida. It began as a tabloid-size publication on yellow newsprint that primarily contained classified advertising and ads for kit computers, parts, and software. The magazine was created by Glenn Patch, publisher of the photo-equipment magazine ''Shutterbug Ads'', in the hopes of applying its formula to a PC-technology magazine. The magazine expanded into prebuilt home computers and white box IBM PC compatibles through the 1980s. The magazine grew to several hundred pages, mostly of advertisements. It was during this time that the magazine was sold to Ziff Davis Publishing, first as a limited partnership, then solely owned. It was sold in 2000, along with Ziff-Davis' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phil Katz
Phillip Walter Katz (November 3, 1962 – April 14, 2000) 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. A copyright lawsuit between System Enhancement Associates (SEA) and Katz's company, PKWARE, was widely publicized in the BBS community in the late 1980s. Katz's software business was very successful, but he struggled with social isolation and chronic alcoholism in the last years of his life. Education and career Phil Katz was a graduate of Nicolet High School in Glendale, Wisconsin. He graduated from the Computer Science Engineering program at the University of Wisconsin–Milwaukee. After his graduation, he was hired by the Allen-Bradley company as a programmer. He wrote code to run programmable logic controllers, which operated manufacturing equipment on shop floors worldwide for Allen-Bradley's customers. PKARC and PKWARE Katz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lempel–Ziv–Welch
Lempel–Ziv–Welch (LZW) is a universal lossless data compression algorithm created by Abraham Lempel, Jacob Ziv, and Terry Welch. It was published by Welch in 1984 as an improved implementation of the LZ78 algorithm published by Lempel and Ziv in 1978. The algorithm is simple to implement and has the potential for very high throughput in hardware implementations. It is the algorithm of the Unix file compression utility compress and is used in the GIF image format. Algorithm The scenario described by Welch's 1984 paper encodes sequences of 8-bit data as fixed-length 12-bit codes. The codes from 0 to 255 represent 1-character sequences consisting of the corresponding 8-bit character, and the codes 256 through 4095 are created in a dictionary for sequences encountered in the data as it is encoded. At each stage in compression, input bytes are gathered into a sequence until the next character would make a sequence with no code yet in the dictionary. The code for th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huffman Coding
In computer science and information theory, a Huffman code is a particular type of optimal prefix code that is commonly used for lossless data compression. The process of finding or using such a code is Huffman coding, an algorithm developed by David A. Huffman while he was a Doctor of Science, Sc.D. student at Massachusetts Institute of Technology, MIT, and published in the 1952 paper "A Method for the Construction of Minimum-Redundancy Codes". The output from Huffman's algorithm can be viewed as a variable-length code table for encoding a source symbol (such as a character in a file). The algorithm derives this table from the estimated probability or frequency of occurrence (''weight'') for each possible value of the source symbol. As in other entropy encoding methods, more common symbols are generally represented using fewer bits than less common symbols. Huffman's method can be efficiently implemented, finding a code in time linear time, linear to the number of input weigh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LZ77 And LZ78
LZ77 and LZ78 are the two lossless data compression algorithms published in papers by Abraham Lempel and Jacob Ziv in 1977 and 1978. They are also known as Lempel-Ziv 1 (LZ1) and Lempel-Ziv 2 (LZ2) respectively. These two algorithms form the basis for many variations including LZW, LZSS, LZMA and others. Besides their academic influence, these algorithms formed the basis of several ubiquitous compression schemes, including GIF and the DEFLATE algorithm used in PNG and ZIP. They are both theoretically dictionary coders. LZ77 maintains a sliding window during compression. This was later shown to be equivalent to the ''explicit dictionary'' constructed by LZ78—however, they are only equivalent when the entire data is intended to be decompressed. Since LZ77 encodes and decodes from a sliding window over previously seen characters, decompression must always start at the beginning of the input. Conceptually, LZ78 decompression could allow random access to the input if the en ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IBM System/370
The IBM System/370 (S/370) is a range of IBM mainframe computers announced as the successors to the IBM System/360, System/360 family on June 30, 1970. The series mostly maintains backward compatibility with the S/360, allowing an easy migration path for customers; this, plus improved performance, were the dominant themes of the product announcement. Early 370 systems differed from the 360 largely in their internal circuitry, moving from the Solid Logic Technology hybrid integrated circuits containing separate transistors to more modern monolithic integrated circuits containing multiple transistors per integrated circuit, which IBM referred to as Monolithic System Technology, or MST. The higher density packaging allowed several formerly optional features from the 360 line to be included as standard features of the machines, floating-point support for instance. The 370 also added a small number of new instructions. At the time of its introduction, the development of virtual mem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
