1.
Software developer
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A software developer is a person concerned with facets of the software development process, including the research, design, programming, and testing of computer software. Other job titles which are used with similar meanings are programmer, software analyst. According to developer Eric Sink, the differences between system design, software development, and programming are more apparent, even more so that developers become systems architects, those who design the multi-leveled architecture or component interactions of a large software system. In a large company, there may be employees whose sole responsibility consists of one of the phases above. In smaller development environments, a few people or even an individual might handle the complete process. The word software was coined as a prank as early as 1953, before this time, computers were programmed either by customers, or the few commercial computer vendors of the time, such as UNIVAC and IBM. The first company founded to provide products and services was Computer Usage Company in 1955. The software industry expanded in the early 1960s, almost immediately after computers were first sold in mass-produced quantities, universities, government, and business customers created a demand for software. Many of these programs were written in-house by full-time staff programmers, some were distributed freely between users of a particular machine for no charge. Others were done on a basis, and other firms such as Computer Sciences Corporation started to grow. The computer/hardware makers started bundling operating systems, systems software and programming environments with their machines, new software was built for microcomputers, so other manufacturers including IBM, followed DECs example quickly, resulting in the IBM AS/400 amongst others. The industry expanded greatly with the rise of the computer in the mid-1970s. In the following years, it created a growing market for games, applications. DOS, Microsofts first operating system product, was the dominant operating system at the time, by 2014 the role of cloud developer had been defined, in this context, one definition of a developer in general was published, Developers make software for the world to use. The job of a developer is to crank out code -- fresh code for new products, code fixes for maintenance, code for business logic, bus factor Software Developer description from the US Department of Labor
2.
Phil Katz
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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. A copyright lawsuit between System Enhancement Associates and Katzs company, PKWARE, Inc. was widely publicized in the BBS community in the late 1980s, Phil Katzs software business was very successful, but he struggled with social isolation and chronic alcoholism in the last years of his life. Phil Katz 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-Bradleys customers, Katz left Allen-Bradley in 1986 to work for Graysoft, a Milwaukee-based software company. At the time, he had worked on an alternative to Thom Hendersons ARC, ARC was written in C, with the source code available on System Enhancement Associates bulletin board system. PKARC, written partially in assembly language, was much faster, Katz had a special flair for optimizing code. He first publicly released only PKXARC, a program, as freeware. Its much greater speed caused it to very quickly throughout the BBS community. Strong positive feedback and encouragement prompted Katz to release his compression program, PKARC, Katz founded PKWARE, Inc. in 1986, with the companys operations located in his home in Glendale, Wisconsin, but he remained at Graysoft until 1987. Steve Burg, a former Graysoft programmer, joined PKWARE in 1988, in the late 1980s, a dispute arose between System Enhancement Associates, maker of the ARC program, and PKWARE. SEA sued Katz for trademark and copyright infringement, the most substantial evidence at trial was from an independent software expert, John Navas, who was appointed by the court to compare the two programs. He stated that PKARC was a work 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, in exchange, PKWARE licensed SEA to use its source code for PKWAREs ARC-compatible programs. PKWARE also agreed to any use of SEAs trademark ARC. 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 the defendants were ordered to pay damages to the plaintiff for the defendants acts, namely, the defendants were found to be infringing the plaintiffs copyrights, infringing trademark, as well as performing acts of unfair trade practices and unfair competition. The leaked agreement document revealed that under the settlement terms, the defendants had paid the plaintiff $22,500 for past royalty payments and $40,000 for expense reimbursements. In addition, the defendants would pay the plaintiff a royalty fee of 6. 5% of all revenue received for ARC compatible programs on all orders received after the date of the agreement
3.
Computer program
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A computer program is a collection of instructions that performs a specific task when executed by a computer. A computer requires programs to function, and typically executes the programs instructions in a processing unit. A computer program is written by a computer programmer in a programming language. From the program in its form of source code, a compiler can derive machine code—a form consisting of instructions that the computer can directly execute. Alternatively, a program may be executed with the aid of an interpreter. A part of a program that performs a well-defined task is known as an algorithm. A collection of programs, libraries and related data are referred to as software. Computer programs may be categorized along functional lines, such as software or system software. The earliest programmable machines preceded the invention of the digital computer, in 1801, Joseph-Marie Jacquard devised a loom that would weave a pattern by following a series of perforated cards. Patterns could be weaved and repeated by arranging the cards, in 1837, Charles Babbage was inspired by Jacquards loom to attempt to build the Analytical Engine. The names of the components of the device were borrowed from the textile industry. In the textile industry, yarn was brought from the store to be milled, the device would have had a store—memory to hold 1,000 numbers of 40 decimal digits each. Numbers from the store would then have then transferred to the mill. It was programmed using two sets of perforated cards—one to direct the operation and the other for the input variables, however, after more than 17,000 pounds of the British governments money, the thousands of cogged wheels and gears never fully worked together. During a nine-month period in 1842–43, Ada Lovelace translated the memoir of Italian mathematician Luigi Menabrea, the memoir covered the Analytical Engine. The translation contained Note G which completely detailed a method for calculating Bernoulli numbers using the Analytical Engine and this note is recognized by some historians as the worlds first written computer program. In 1936, Alan Turing introduced the Universal Turing machine—a theoretical device that can model every computation that can be performed on a Turing complete computing machine and it is a finite-state machine that has an infinitely long read/write tape. The machine can move the back and forth, changing its contents as it performs an algorithm
4.
Zip (file format)
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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 created in 1989 by Phil Katz, and was first implemented in PKWARE, Inc. s PKZIP utility. The. ZIP format is now supported by many software utilities other than PKZIP, Microsoft has included built-in. ZIP support in versions of Microsoft Windows since 1998. Apple has included built-in. ZIP support in Mac OS X10.3 and later. Most free operating systems have built in support for. ZIP in similar manners to Windows and Mac OS X. ZIP files generally use the file extensions. zip or. ZIP, ZIP is used as a base file format by many programs, usually under a different name. When navigating a file system via an interface, graphical icons representing. ZIP files often appear as a document or other object prominently featuring a zipper. The. ZIP file format was created by Phil Katz of PKWARE and they created the format after PKWARE had a lawsuits filed against them by Systems Enhancement Associates claiming that his archiving products were derivatives of SEAs ARC archiving system. The name zip was suggested by Katzs friend, Robert Mahoney and they wanted to imply that their product would be faster than ARC and other compression formats of the time. The earliest known version of. ZIP File Format Specification was first published as part of PKZIP0.9 package under the file APPNOTE. TXT in 1989, the. ZIP file format was released into the public domain. The. ZIP File Format Specification has its own version number, other companies or organizations support the PKWARE specifications at their own pace. The. ZIP file format specification is formally named APPNOTE -. ZIP File Format Specification, several versions of the specification were not published. Specifications of some such as BZIP2 compression, strong encryption specification. The URL of the specification was changed several times on the PKWARE website. A summary of key advances in various versions of the PKWARE specification,2.0, File entries can be compressed with DEFLATE,2.1, Deflate64 compression 4.5, Documented 64-bit zip format. 4.6, BZIP2 compression 5.0, DES, Triple DES, RC2, RC4 supported for encryption 5.2, AES encryption support, expanded list of supported hash, compression, encryption algorithms. 6.3.1, Corrected standard hash values for SHA-256/384/512,6.3.4, Updates the PKWARE, Inc. office address. WinZip, starting with version 12.1, uses the extension. zipx for. ZIP files that use compression methods newer than DEFLATE, specifically, methods BZip, LZMA, PPMd, Jpeg and Wavpack
5.
MS-DOS
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MS-DOS is a discontinued operating system for x86-based personal computers mostly developed by Microsoft. MS-DOS resulted from a request in 1981 by IBM for a system to use in its IBM PC range of personal computers. Microsoft quickly bought the rights to 86-DOS from Seattle Computer Products, IBM licensed and released it in August 1981 as PC DOS1.0 for use in their PCs. During its life, several competing products were released for the x86 platform and it was also the underlying basic operating system on which early versions of Windows ran as a GUI. It is a operating system, and consumes negligible installation space. MS-DOS was a form of 86-DOS – owned by Seattle Computer Products. This first version was shipped in August 1980, Microsoft, which needed an operating system for the IBM Personal Computer hired Tim Paterson in May 1981 and bought 86-DOS1.10 for $75,000 in July of the same year. Microsoft kept the number, but renamed it MS-DOS. They also licensed MS-DOS1. 10/1.14 to IBM, within a year Microsoft licensed MS-DOS to over 70 other companies. It was designed to be an OS that could run on any 8086-family computer, thus, there were many different versions of MS-DOS for different hardware, and there is a major distinction between an IBM-compatible machine and an MS-DOS machine. This design would have worked well for compatibility, if application programs had only used MS-DOS services to perform device I/O, Microsoft omitted multi-user support from MS-DOS because Microsofts Unix-based operating system, Xenix, was fully multi-user. After the breakup of the Bell System, however, AT&T Computer Systems started selling UNIX System V, believing that it could not compete with AT&T in the Unix market, Microsoft abandoned Xenix, and in 1987 transferred ownership of Xenix to the Santa Cruz Operation. On 25 March 2014, Microsoft made the code to SCP MS-DOS1.25, as an April Fools joke in 2015, Microsoft Mobile launched a Windows Phone application called MS-DOS Mobile which was presented as a new mobile operating system and worked similar to MS-DOS. Version 3.1 – Support for Microsoft Networks Version 3.2 – First version to support 3.5 inch,720 kB floppy drives and diskettes. Version 3.21 Version 3.22 – Version 3.25 Version 3.3 – First version to support 3.5 inch,1.44 MB floppy drives and diskettes, Version 3. 3a Version 3.31 – supports FAT16B and larger drives. MS-DOS4.0 and MS-DOS4.1 – A separate branch of development with additional multitasking features and it is unrelated to any later versions, including versions 4.00 and 4.01 listed below MS-DOS4. x – includes a graphical/mouse interface. It had many bugs and compatibility issues. Version 4.00 – First version to support a hard disk partition that is greater than 32 MiB. Version 4.01 – Microsoft rewritten Version 4.00 released under MS-DOS label, First version to introduce volume serial number when formatting hard disks and floppy disks
6.
IBM PC compatible
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IBM PC compatible computers are those similar to the original IBM PC, XT, and AT, able to run the same software and support the same expansion cards as those. Such computers used to be referred to as PC clones, or IBM clones, Columbia Data Products built the first clone of the IBM personal computer by a clean room implementation of its BIOS. Early IBM PC compatibles used the computer bus as the original PC. The IBM AT compatible bus was named the Industry Standard Architecture bus by manufacturers of compatible computers. The term IBM PC compatible is now a historical description only, only the Apple Macintosh classic Mac OS and macOS kept significant market share without compatibility with the IBM personal computer, so consumers are typically identified as being a PC or Mac user. IBM decided in 1980 to market a low-cost single-user computer as quickly as possible in response to Apple Computers success in the microcomputer market. On 12 August 1981, the first IBM PC went on sale, there were three operating systems available for it. The least expensive and most popular was PC DOS made by Microsoft, in a crucial concession, IBMs agreement allowed Microsoft to sell its own version, MS-DOS, for non-IBM computers. The only component of the original PC architecture exclusive to IBM was the BIOS and this software would run on any machine using MS-DOS or PC-DOS. Software that directly addressed the hardware instead of making standard calls was faster, however, software addressing IBM PC hardware in this way would not run on MS-DOS machines with different hardware. The 808x computer marketplace rapidly excluded all machines which were not hardware-, the 640 KB barrier on conventional system memory available to MS-DOS is a legacy of that period, other non-clone machines, while subject to a limit, could exceed 640 kB. Rumors of lookalike, compatible computers, created without IBMs approval, by June 1983 PC Magazine defined PC clone as a computer accommodate the user who takes a disk home from an IBM PC, walks across the room, and plugs it into the foreign machine. Because of a shortage of IBM PCs that year, many customers purchased clones instead, Columbia Data Products produced the first computer more or less compatible to the IBM PC standard during June 1982, soon followed by Eagle Computer. Compaq announced its first IBM PC compatible in November 1982, the Compaq Portable, the Compaq was the first sewing machine-sized portable computer that was essentially 100% PC-compatible. The company could not copy the BIOS directly as a result of the decision in Apple v. Franklin. Each computer would have its own Original Equipment Manufacturer version of MS-DOS, any software written for MS-DOS would operate on any MS-DOS computer, despite variations in hardware design. This expectation seemed reasonable in the marketplace of the time. Until then Microsoft was based primarily on computer languages such as BASIC, the established small system operating software was CP/M from Digital Research which was in use both at the hobbyist level and by the more professional of those using microcomputers
7.
Tar (computing)
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In computing, tar is a computer software utility for collecting many files into one archive file, often referred to as a tarball, for distribution or backup purposes. The name is derived from ape chive, as it was developed to write data to sequential I/O devices with no file system of their own. The archive data sets created by tar contain various file system parameters, such as name, time stamps, ownership, file access permissions, the command line utility was first introduced in the seventh edition of unix in January 1979, replacing the tp program. The file structure to store information was later standardized in POSIX. 1-1988 and later POSIX. 1-2001. Many historic tape drives read and write variable-length data blocks, leaving significant wasted space on the tape between blocks, some tape drives only support fixed-length data blocks. Also, when writing to any medium such as a filesystem or network, therefore, the tar command writes data in blocks of many 512 byte records. The user can specify a blocking factor, which is the number of records per block, a tar archive consists of a series of file objects, hence the popular term tarball, referencing how a tarball collects objects of all kinds that stick to its surface. Each file object includes any data, and is preceded by a 512-byte header record. The file data is written unaltered except that its length is rounded up to a multiple of 512 bytes. The original tar implementation did not care about the contents of the padding bytes, and left the buffer data unaltered, the end of an archive is marked by at least two consecutive zero-filled records. The final block of an archive is padded out to length with zeros. The file header record contains metadata about a file, to ensure portability across different architectures with different byte orderings, the information in the header record is encoded in ASCII. Thus if all the files in an archive are ASCII text files, the fields defined by the original Unix tar format are listed in the table below. The link indicator/file type table includes some modern extensions, when a field is unused it is filled with NUL bytes. The header uses 257 bytes, then is padded with NUL bytes to make it fill a 512 byte record, there is no magic number in the header, for file identification. Numeric values are encoded in octal numbers using ASCII digits, with leading zeroes, for historical reasons, a final NUL or space character should also be used. Thus although there are 12 bytes reserved for storing the file size and this gives a maximum file size of 8 gigabytes on archived files. To overcome this limitation, star in 2001 introduced a base-256 coding that is indicated by setting the bit of the leftmost byte of a numeric field
8.
Zoo (file format)
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Zoo is a data compression program and format developed by Rahul Dhesi in the mid-1980s. The format is based on the LZW compression algorithm and compressed files are identified by the. zoo file extension and it is no longer widely used. Program source code was published on the comp. sources. misc Usenet newsgroup. Binaries were also published for the MS-DOS and AmigaOS user communities, a small companion program was also developed, entitled booz, that provides only decompression functionality. The. ZOO file format was popular with Digital VAX computers running the OpenVMS operating system. This allows files that are modified to be backed up in such a way as to allow access to previous versions from one archive. Zoo 2.10 source unzoo - zoo archive extractor, source included
9.
ARJ
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ARJ is a software tool designed by Robert K. Jung for creating high-efficiency compressed file archives. ARJ is currently on version 2.86 for DOS and 3.20 for Windows, ARJ was one of two mainstream archivers for DOS and Windows during the early and mid-1990s, with PKZIP being its competition. Parts of ARJ were covered by U. S, generally ARJ was less popular than PKZIP, but it did enjoy a niche market during the BBS era and in the warez scene. This was largely due to ARJs creation and handling of multi-volume archives being more robust than PKZIPs, ARJ compressed files with the Filename extension. arj can be unpacked with various tools other than the ARJ software. There exists a free software re-implement of the tool, the software 7-Zip and Zipeg can also unpack. arj files. For Mac there exists a standalone utility UnArjMac, JAR, an archiver by the same author List of archive formats List of file archivers Comparison of file archivers ARJ Software Inc. Open Source version of the ARJ archiver
10.
Bulletin board system
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A bulletin board system, or BBS, is a computer server running software that allows users to connect to the system using a terminal program. Many BBSes also offer on-line games, in users can compete with each other. Bulletin board systems were in many ways a precursor to the form of the World Wide Web, social networks. Low-cost, high-performance modems drove the use of services and BBSes through the early 1990s. Infoworld estimated there were 60,000 BBSes serving 17 million users in the United States alone in 1994, over the next year, many of the leading BBS software providers went bankrupt and tens of thousands of BBSes disappeared. Today, BBSing survives largely as a hobby in most parts of the world. Most BBSes are now accessible over Telnet and typically offer free email accounts, FTP services, IRC, some offer access through packet switched networks, or packet radio connections. A precursor to the bulletin board system was Community Memory, started in August 1973 in Berkeley. Useful microcomputers did not exist at that time, and modems were both expensive and slow, Community Memory therefore ran on a mainframe computer and was accessed through terminals located in several San Francisco Bay Area neighborhoods. The poor quality of the original modem connecting the terminals to the mainframe prompted a user to invent the Pennywhistle modem, Community Memory allowed the user to type messages into a computer terminal after inserting a coin, and offered a pure bulletin board experience with public messages only. It did offer the ability to tag messages with keywords, which the user could use in searches, the system acted primarily in the form of a buy and sell system with the tags taking the place of the more traditional classifications. But users found ways to express themselves outside these bounds, unfortunately, the system was expensive to operate, and when their host machine became unavailable and a new one could not be found, the system closed in January 1975. Similar functionality was available to most mainframe users, which might be considered a sort of ultra-local BBS when used in this fashion. Commercial systems, expressly intended to offer features to the public, became available in the late 1970s. Early modems were very simple devices using acoustic couplers to handle telephone operation. The user would first pick up the phone, dial a number, disconnecting at the end of a call required the user to pick up the handset and return it to the phone. With the introduction of microcomputers with expansion slots, like the S-100 bus machines and Apple II, it possible for the modem to communicate instructions. A number of modems of this sort were available by the late 1970s
11.
DOS
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None of these systems were officially named DOS, and indeed DOS is a general term for disk operating system. MS-DOS dominated the IBM PC compatible market between 1981 and 1995, and Microsoft Windows, still ran on top of it until about 2001, dozens of other operating systems also use the acronym DOS, including DOS/360 from 1966. Others are Apple DOS, Apple ProDOS, Atari DOS, Commodore DOS, TRSDOS, see List of DOS operating systems § Other operating systems. IBM PC DOS and its predecessor, 86-DOS, resembled Digital Researchs CP/M—the dominant disk operating system for 8-bit Intel 8080, DOS instead ran on Intel 8086 16-bit processors. Starting with MS-DOS1.28 and PC DOS2.0 the operating system incorporated various features inspired by Xenix, when IBM introduced the IBM PC, built with the Intel 8088 microprocessor, they needed an operating system. Seeking an 8088-compatible build of CP/M, IBM initially approached Microsoft CEO Bill Gates, IBM was sent to Digital Research, and a meeting was set up. However, the negotiations for the use of CP/M broke down, Digital Research wished to sell CP/M on a royalty basis, while IBM sought a single license. Digital Research founder Gary Kildall refused, and IBM withdrew, Gates in turn approached Seattle Computer Products. There, programmer Tim Paterson had developed a variant of CP/M-80, the system was initially named QDOS, before being made commercially available as 86-DOS. Microsoft purchased 86-DOS, allegedly for $50,000 and this became Microsoft Disk Operating System, MS-DOS, introduced in 1981. Within a year Microsoft licensed MS-DOS to over 70 other companies, Microsoft later required the use of the MS-DOS name, with the exception of the IBM variant. IBM continued to develop their version, PC DOS, for the IBM PC, Digital Research became aware that an operating system similar to CP/M was being sold by IBM, and threatened legal action. IBM responded by offering an agreement, they would give PC consumers a choice of PC DOS or CP/M-86, side-by-side, CP/M cost almost $200 more than PC DOS, and sales were low. CP/M faded, with MS-DOS and PC DOS becoming the operating system for PCs. Microsoft originally sold MS-DOS only to original equipment manufacturers, one major reason for this was that not all early PCs were 100% IBM PC compatible. DOS was structured such that there was a separation between the specific device driver code and the DOS kernel. Microsoft provided an OEM Adaptation Kit which allowed OEMs to customize the device driver code to their particular system, by the early 1990s, most PCs adhered to IBM PC standards so Microsoft began selling MS-DOS in retail with MS-DOS5.0. In the mid-1980s Microsoft developed a version of DOS
12.
Microsoft Windows
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Microsoft Windows is a metafamily of graphical operating systems developed, marketed, and sold by Microsoft. It consists of families of operating systems, each of which cater to a certain sector of the computing industry with the OS typically associated with IBM PC compatible architecture. Active Windows families include Windows NT, Windows Embedded and Windows Phone, defunct Windows families include Windows 9x, Windows 10 Mobile is an active product, unrelated to the defunct family Windows Mobile. Microsoft introduced an operating environment named Windows on November 20,1985, Microsoft Windows came to dominate the worlds personal computer market with over 90% market share, overtaking Mac OS, which had been introduced in 1984. Apple came to see Windows as an encroachment on their innovation in GUI development as implemented on products such as the Lisa. On PCs, Windows is still the most popular operating system, however, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones. In 2014, the number of Windows devices sold was less than 25% that of Android devices sold and this comparison however may not be fully relevant, as the two operating systems traditionally target different platforms. As of September 2016, the most recent version of Windows for PCs, tablets, smartphones, the most recent versions for server computers is Windows Server 2016. A specialized version of Windows runs on the Xbox One game console, Microsoft, the developer of Windows, has registered several trademarks each of which denote a family of Windows operating systems that target a specific sector of the computing industry. It now consists of three operating system subfamilies that are released almost at the time and share the same kernel. Windows, The operating system for personal computers, tablets. The latest version is Windows 10, the main competitor of this family is macOS by Apple Inc. for personal computers and Android for mobile devices. Windows Server, The operating system for server computers, the latest version is Windows Server 2016. Unlike its clients sibling, it has adopted a strong naming scheme, the main competitor of this family is Linux. Windows PE, A lightweight version of its Windows sibling meant to operate as an operating system, used for installing Windows on bare-metal computers. The latest version is Windows PE10.0.10586.0, Windows Embedded, Initially, Microsoft developed Windows CE as a general-purpose operating system for every device that was too resource-limited to be called a full-fledged computer. The following Windows families are no longer being developed, Windows 9x, Microsoft now caters to the consumers market with Windows NT. Windows Mobile, The predecessor to Windows Phone, it was a mobile operating system
13.
Internet
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The Internet is the global system of interconnected computer networks that use the Internet protocol suite to link devices worldwide. The origins of the Internet date back to research commissioned by the United States federal government in the 1960s to build robust, the primary precursor network, the ARPANET, initially served as a backbone for interconnection of regional academic and military networks in the 1980s. Although the Internet was widely used by academia since the 1980s, Internet use grew rapidly in the West from the mid-1990s and from the late 1990s in the developing world. In the two decades since then, Internet use has grown 100-times, measured for the period of one year, newspaper, book, and other print publishing are adapting to website technology, or are reshaped into blogging, web feeds and online news aggregators. The entertainment industry was initially the fastest growing segment on the Internet, the Internet has enabled and accelerated new forms of personal interactions through instant messaging, Internet forums, and social networking. Business-to-business and financial services on the Internet affect supply chains across entire industries, the Internet has no centralized governance in either technological implementation or policies for access and usage, each constituent network sets its own policies. The term Internet, when used to refer to the global system of interconnected Internet Protocol networks, is a proper noun. In common use and the media, it is not capitalized. Some guides specify that the word should be capitalized when used as a noun, the Internet is also often referred to as the Net, as a short form of network. Historically, as early as 1849, the word internetted was used uncapitalized as an adjective, the designers of early computer networks used internet both as a noun and as a verb in shorthand form of internetwork or internetworking, meaning interconnecting computer networks. The terms Internet and World Wide Web are often used interchangeably in everyday speech, however, the World Wide Web or the Web is only one of a large number of Internet services. The Web is a collection of interconnected documents and other web resources, linked by hyperlinks, the term Interweb is a portmanteau of Internet and World Wide Web typically used sarcastically to parody a technically unsavvy user. The ARPANET project led to the development of protocols for internetworking, the third site was the Culler-Fried Interactive Mathematics Center at the University of California, Santa Barbara, followed by the University of Utah Graphics Department. In an early sign of growth, fifteen sites were connected to the young ARPANET by the end of 1971. These early years were documented in the 1972 film Computer Networks, early international collaborations on the ARPANET were rare. European developers were concerned with developing the X.25 networks, in December 1974, RFC675, by Vinton Cerf, Yogen Dalal, and Carl Sunshine, used the term internet as a shorthand for internetworking and later RFCs repeated this use. Access to the ARPANET was expanded in 1981 when the National Science Foundation funded the Computer Science Network, in 1982, the Internet Protocol Suite was standardized, which permitted worldwide proliferation of interconnected networks.5 Mbit/s and 45 Mbit/s. Commercial Internet service providers emerged in the late 1980s and early 1990s, the ARPANET was decommissioned in 1990
14.
DEC Alpha
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Alpha was implemented in microprocessors originally developed and fabricated by DEC. These microprocessors were most prominently used in a variety of DEC workstations and servers, several third-party vendors also produced Alpha systems, including PC form factor motherboards. Operating systems that supported Alpha included OpenVMS, Tru64 UNIX, Windows NT, Linux, BSD UNIX, Plan 9 from Bell Labs, as well as the L4Ka, the Alpha architecture was sold, along with most parts of DEC, to Compaq in 1998. Alpha was born out of an earlier RISC project named PRISM, PRISM was intended to be a flexible design, supporting both Unix-like applications, as well as Digitals existing VMS programs from the VAX after minor conversion. A new Unix-like operating system known as Mica would run applications natively, during development, the Palo Alto design team were working on a Unix-only workstation that originally included the PRISM. DEC management doubted the need to produce a new architecture to replace their existing VAX and DECstation lines. By the time of cancellation, however, second-generation RISC chips were offering much better price/performance ratios than the VAX lineup and it was clear a third generation would completely outperform the VAX in all ways, not just on cost. Another study was started to see if a new RISC architecture could be defined that could support the VMS operating system. The new design used most of the basic PRISM concepts, but was re-tuned to allow VMS and VMS programs to run at speed with no conversion at all. The decision was made to upgrade the design to a full 64-bit implementation from PRISMs 32-bit. Eventually that new architecture became Alpha, the primary Alpha instruction set architects were Richard L. Sites and Richard T. Witek. The PRISMs Epicode was developed into the Alphas PALcode, providing an interface to platform-. The main contribution of Alpha to the industry, and the main reason for its performance, was not so much the architecture. At that time, the industry was dominated by automated design. The chip designers at Digital continued pursuing sophisticated manual circuit design in order to deal with the overly complex VAX architecture and these chips caused a renaissance of custom circuit design within the microprocessor design community. Originally, the Alpha processors were designated the DECchip 21x64 series, the first two digits,21 signifies the 21st century, and the last two digits,64 signifies 64 bits. The Alpha was designed as 64-bit from the start and there is no 32-bit version, the middle digit corresponded to the generation of the Alpha architecture. The first few generations of the Alpha chips were some of the most innovative of their time, the first version, the Alpha 21064 or EV4, was the first CMOS microprocessor whose operating frequency rivalled higher-powered ECL minicomputers and mainframes
15.
PowerPC
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PowerPC is a RISC instruction set architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. PowerPC was the cornerstone of AIMs PReP and Common Hardware Reference Platform initiatives in the 1990s and it has since become niche in personal computers, but remain popular as embedded and high-performance processors. Its use in game consoles and embedded applications provided an array of uses. In addition, PowerPC CPUs are still used in AmigaOne and third party AmigaOS4 personal computers, the history of RISC began with IBMs 801 research project, on which John Cocke was the lead developer, where he developed the concepts of RISC in 1975–78. 801-based microprocessors were used in a number of IBM embedded products, the RT was a rapid design implementing the RISC architecture. The result was the POWER instruction set architecture, introduced with the RISC System/6000 in early 1990, the original POWER microprocessor, one of the first superscalar RISC implementations, was a high performance, multi-chip design. IBM soon realized that a microprocessor was needed in order to scale its RS/6000 line from lower-end to high-end machines. Work on a one-chip POWER microprocessor, designated the RSC began, in early 1991, IBM realized its design could potentially become a high-volume microprocessor used across the industry. IBM approached Apple with the goal of collaborating on the development of a family of single-chip microprocessors based on the POWER architecture and this three-way collaboration became known as AIM alliance, for Apple, IBM, Motorola. In 1991, the PowerPC was just one facet of an alliance among these three companies. The PowerPC chip was one of joint ventures involving the three, in their efforts to counter the growing Microsoft-Intel dominance of personal computing. For Motorola, POWER looked like an unbelievable deal and it allowed them to sell a widely tested and powerful RISC CPU for little design cash on their own part. It also maintained ties with an important customer, Apple, and seemed to offer the possibility of adding IBM too, at this point Motorola already had its own RISC design in the form of the 88000 which was doing poorly in the market. Motorola was doing well with their 68000 family and the majority of the funding was focused on this, the 88000 effort was somewhat starved for resources. However, the 88000 was already in production, Data General was shipping 88000 machines, the 88000 had also achieved a number of embedded design wins in telecom applications. The result of various requirements was the PowerPC specification. The differences between the earlier POWER instruction set and PowerPC is outlined in Appendix E of the manual for PowerPC ISA v.2.02, when the first PowerPC products reached the market, they were met with enthusiasm. In addition to Apple, both IBM and the Motorola Computer Group offered systems built around the processors, Microsoft released Windows NT3.51 for the architecture, which was used in Motorolas PowerPC servers, and Sun Microsystems offered a version of its Solaris OS
16.
Encryption
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In cryptography, encryption is the process of encoding a message or information in such a way that only authorized parties can access it. Encryption does not of itself prevent interference, but denies the intelligible content to a would-be interceptor, in an encryption scheme, the intended information or message, referred to as plaintext, is encrypted using an encryption algorithm, generating ciphertext that can only be read if decrypted. For technical reasons, an encryption scheme usually uses an encryption key generated by an algorithm. It is in possible to decrypt the message without possessing the key. An authorized recipient can decrypt the message with the key provided by the originator to recipients. In symmetric-key schemes, the encryption and decryption keys are the same, communicating parties must have the same key before they can achieve secure communication. In public-key encryption schemes, the key is published for anyone to use. However, only the party has access to the decryption key that enables messages to be read. Public-key encryption was first described in a document in 1973. Encryption has long used by militaries and governments to facilitate secret communication. It is now used in protecting information within many kinds of civilian systems. Encryption can be used to protect data at rest, such as stored on computers. In recent years, there have been reports of confidential data, such as customers personal records. Encrypting such files at rest helps protect them should physical security measures fail, in response to encryption of data at rest, cyber-adversaries have developed new types of attacks. There have been reports of data in transit being intercepted in recent years. Data should also be encrypted when transmitted across networks in order to protect against eavesdropping of network traffic by unauthorized users, standards for cryptographic software and hardware to perform encryption are widely available, but successfully using encryption to ensure security may be a challenging problem. A single error in design or execution can allow successful attacks. Sometimes an adversary can obtain unencrypted information without directly undoing the encryption, see, e. g. traffic analysis, TEMPEST, or Trojan horse
17.
Bzip2
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Bzip2 is a free and open-source file compression program that uses the Burrows–Wheeler algorithm. It only compresses single files and is not a file archiver and it is developed and maintained by Julian Seward. Seward made the first public release of bzip2, version 0.15, the compressors stability and popularity grew over the next several years, and Seward released version 1.0 in late 2000. Bzip2 compresses most files more effectively than the older LZW and Deflate compression algorithms, LZMA is generally more space-efficient than bzip2 at the expense of even slower compression speed, while having much faster decompression. Bzip2 compresses data in blocks of size between 100 and 900 kB and uses the Burrows–Wheeler transform to convert frequently-recurring character sequences into strings of identical letters and it then applies move-to-front transform and Huffman coding. Bzip2s ancestor bzip used arithmetic coding instead of Huffman, the change was made because of a software patent restriction. Bzip2 performance is asymmetric, as decompression is relatively fast, as of May 2010, this functionality has not been incorporated into the main project. Like gzip, bzip2 is only a data compressor, thus the sequence AAAAAAABBBBCCCD is replaced with AAAA\3BBBB\0CCCD, where \3 and \0 represent byte values 3 and 0 respectively. Runs of symbols are always transformed after four consecutive symbols, even if the run-length is set to zero, in the worst case, it can cause an expansion of 1.25 and best case a reduction to <0.02. While the specification allows for runs of length 256–259 to be encoded. The author of bzip2 has stated that the RLE step was a mistake and was only intended to protect the original BWT implementation from pathological cases. This is the reversible block-sort that is at the core of bzip2, the block is entirely self-contained, with input and output buffers remaining the same size—in bzip2, the operating limit for this stage is 900 kB. For the block-sort, a matrix is created in which row i contains the whole of the buffer, following rotation, the rows of the matrix are sorted into alphabetic order. A 24-bit pointer is stored marking the position for when the block is untransformed. In practice, it is not necessary to construct the matrix, rather. The output buffer is the last column of the matrix, this contains the whole buffer, again, this transform does not alter the size of the processed block. Each of the symbols in use in the document is placed in an array, when a symbol is processed, it is replaced by its location in the array and that symbol is shuffled to the front of the array. The effect is that immediately recurring symbols are replaced by zero symbols, much natural data contains identical symbols that recur within a limited range
18.
Advanced Encryption Standard
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AES is a subset of the Rijndael cipher developed by two Belgian cryptographers, Vincent Rijmen and Joan Daemen, who submitted a proposal to NIST during the AES selection process. Rijndael is a family of ciphers with different key and block sizes, for AES, NIST selected three members of the Rijndael family, each with a block size of 128 bits, but three different key lengths,128,192 and 256 bits. AES has been adopted by the U. S. government and is now used worldwide and it supersedes the Data Encryption Standard, which was published in 1977. The algorithm described by AES is an algorithm, meaning the same key is used for both encrypting and decrypting the data. In the United States, AES was announced by the NIST as U. S. FIPS PUB197 on November 26,2001. This announcement followed a five-year standardization process in which fifteen competing designs were presented and evaluated, AES became effective as a federal government standard on May 26,2002 after approval by the Secretary of Commerce. AES is included in the ISO/IEC 18033-3 standard, unlike its predecessor DES, AES does not use a Feistel network. AES is a variant of Rijndael which has a block size of 128 bits. By contrast, the Rijndael specification per se is specified with block and key sizes that may be any multiple of 32 bits, both with a minimum of 128 and a maximum of 256 bits. AES operates on a 4 ×4 column-major order matrix of bytes, termed the state, most AES calculations are done in a particular finite field. For instance, if there are 16 bytes, b 0, b 1, the number of cycles of repetition are as follows,10 cycles of repetition for 128-bit keys. 12 cycles of repetition for 192-bit keys,14 cycles of repetition for 256-bit keys. Each round consists of processing steps, each containing four similar but different stages. A set of rounds are applied to transform ciphertext back into the original plaintext using the same encryption key. KeyExpansions—round keys are derived from the key using Rijndaels key schedule. AES requires a separate 128-bit round key block for each round plus one more, initialRound AddRoundKey—each byte of the state is combined with a block of the round key using bitwise xor. Rounds SubBytes—a non-linear substitution step where each byte is replaced with another according to a lookup table, shiftRows—a transposition step where the last three rows of the state are shifted cyclically a certain number of steps. MixColumns—a mixing operation which operates on the columns of the state, AddRoundKey Final Round SubBytes ShiftRows AddRoundKey
19.
Optimal asymmetric encryption padding
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In cryptography, Optimal Asymmetric Encryption Padding is a padding scheme often used together with RSA encryption. OAEP was introduced by Bellare and Rogaway, and subsequently standardized in PKCS#1 v2, the OAEP algorithm is a form of Feistel network which uses a pair of random oracles G and H to process the plaintext prior to asymmetric encryption. When implemented with certain trapdoor permutations, OAEP is also proved secure against chosen ciphertext attack, OAEP can be used to build an all-or-nothing transform. OAEP satisfies the two goals, Add an element of randomness which can be used to convert a deterministic encryption scheme into a probabilistic scheme. Prevent partial decryption of ciphertexts by ensuring that an adversary cannot recover any portion of the plaintext without being able to invert the trapdoor one-way permutation f. The original version of OAEP showed a form of awareness in the random oracle model when OAEP is used with any trapdoor permutation. Subsequent results contradicted this claim, showing that OAEP was only IND-CCA1 secure, however, the original scheme was proved in the random oracle model to be IND-CCA2 secure when OAEP is used with the RSA permutation using standard encryption exponents, as in the case of RSA-OAEP. An improved scheme that works with any trapdoor one-way permutation was offered by Victor Shoup to solve this problem, more recent work has shown that in the standard model it is impossible to prove the IND-CCA2 security of RSA-OAEP under the assumed hardness of the RSA problem. In the diagram, n is the number of bits in the RSA modulus, k0 and k1 are integers fixed by the protocol. M is the message, an -bit string G and H are typically some cryptographic hash functions fixed by the protocol. ⊕ is an xor operation. To encode, messages are padded with k1 zeros to be n − k0 bits in length, R is a randomly generated k0-bit string G expands the k0 bits of r to n − k0 bits. X = m00.0 ⊕ G H reduces the n − k0 bits of X to k0 bits, Y = r ⊕ H The output is X || Y where X is shown in the diagram as the leftmost block and Y as the rightmost block. Since any changed bit of a cryptographic hash completely changes the result, the entire X, and the entire Y must both be completely recovered
20.
Smart card
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A smart card, chip card, or integrated circuit card is any pocket-sized card that has embedded integrated circuits. Smart cards are made of plastic, generally polyvinyl chloride, but sometimes polyethylene terephthalate based polyesters, since April 2009, a Japanese company has manufactured reusable financial smart cards made from paper. Smart cards can be either contact or contactless smart card, Smart cards can provide personal identification, authentication, data storage, and application processing. Smart cards may provide strong security authentication for single sign-on within large organizations, in 1968 and 1969 Helmut Gröttrup and Jürgen Dethloff jointly filed patents for the automated chip card. Roland Moreno patented the memory card concept in 1974, an important patent for smart cards with a microprocessor and memory as used today was filed by Jürgen Dethloff in 1976 and granted as USP4105156 in 1978. Three years later, Motorola used this patent in its CP8, at that time, Bull had 1,200 patents related to smart cards. In 2001, Bull sold its CP8 division together with its patents to Schlumberger, in 2006, Axalto and Gemplus, at the time the worlds top two smart card manufacturers, merged and became Gemalto. The first mass use of the cards was as a card for payment in French pay phones. After the Télécarte, microchips were integrated into all French Carte Bleue debit cards in 1992, customers inserted the card into the merchants point of sale terminal, then typed the personal identification number, before the transaction was accepted. Only very limited transactions are processed without a PIN, smart-card-based electronic purse systems store funds on the card so that readers do not need network connectivity. They entered European service in the mid-1990s and they have been common in Germany, Austria, Belgium, France, the Netherlands, Switzerland, Norway, Sweden, Finland, UK, Denmark and Portugal. Since the 1990s, smart-cards have been the Subscriber Identity Modules used in European GSM mobile phone equipment, Mobile phones are widely used in Europe, so smart cards have become very common. Europay MasterCard Visa -compliant cards and equipment are widespread, the United States started using the EMV technology in 2014. Historically, in 1993 several international payment companies agreed to develop specifications for debit and credit cards. The original brands were MasterCard, Visa, and Europay, the first version of the EMV system was released in 1994. In 1998 the specifications became stable, eMVcos purpose is to assure the various financial institutions and retailers that the specifications retain backward compatibility with the 1998 version. EMVco upgraded the specifications in 2000 and 2004, EMV compliant cards were first accepted into Malaysia in 2005 and later into United States in 2014. MasterCard was the first company that was allowed to use the technology in the United States, the United States has felt pushed to use the technology because of the increase in identity theft
21.
IBM i
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IBM i is an operating system that runs on IBM Power Systems and on IBM PureSystems. It is one of the operating systems supported on IBM Power Systems alongside AIX and Linux as well as on IBM PureSystems alongside AIX, Linux, IBM i programs, like System/38 programs before them, contain both processor-independent virtual binary code and processor-dependent executable binary code. Notably, when migrating from a processor, the only effect that most organizations notice is that the program runs somewhat longer when it runs for the first time on the new computer. Migration consists of taking a backup from the old computer, IBM designed IBM i as a turnkey operating system, requiring little or no on-site attention from IT staff during normal operation. For example, IBM i has a built-in DB2 database which does not require separate installation, disks are multiply redundant, and can be replaced on line without interrupting work. Hardware and software maintenance tasks are integrated, system administration has been wizard-driven for years, even before that term was defined. This automatic self-care policy goes so far as to automatically schedule all common system maintenance, detect many failures and even order spare parts, organizations using i sometimes have sticker shock when confronting the cost of system maintenance on other systems. Another peculiar feature is that this system was one of the earliest to be object-based, unlike traditional OSes like UNIX and Windows NT there are no files, only objects of different types. It implemented one of the systems for persistent objects. Further, the objects persist in very large, flat virtual memory, called a single-level store. IBM Systems Director Navigator for i now can be used to manage target servers running IBM i 5.4,6.1 or 7.1 from a single browser environment with the IBM i 7.1. In 1999, IBM introduced logical partitioning with i5/OS to support multiple virtual systems on a single hardware footprint, in 2011, IBM and Zend Technologies announced Zend DBi as replacement for the MySQL on IBM i support with a first General availability release in 2012. In 2013, IBM and PowerRuby Inc. announced PowerRuby as a commercially supported port of the Ruby programming language, PowerRuby will be offered as a free download to be installed on customer machines. In 2014, IBM ported Node. js to IBM i, the latest version of IBM i is 7.3, announced on April 12,2016 and released on April 15,2016. With 7.1, IBM started delivering new updates to the system via Technology Refreshes. Version 7.2 was released in May 2014, version 7.3 was released in April 2016. Auxiliary storage pool Multics for an earlier system which provided persistent objects User groups have played a major part in the evolution of the IBM i. The largest such group is COMMON, the Large User Group, whos membership consists of major corporations, is a major influence for current and future development of IBM i
22.
SHA-2
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SHA-2 is a set of cryptographic hash functions designed by the United States National Security Agency. Cryptographic hash functions are mathematical operations run on digital data, by comparing the computed hash to a known and expected hash value, a person can determine the datas integrity. For example, computing the hash of a file and comparing the result to a previously published hash result can show whether the download has been modified or tampered with. A key aspect of cryptographic hash functions is their collision resistance, SHA-2 includes significant changes from its predecessor, SHA-1. The SHA-2 family consists of six hash functions with digests that are 224,256,384 or 512 bits, SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, SHA-256 and SHA-512 are novel hash functions computed with 32-bit and 64-bit words, respectively. They use different shift amounts and additive constants, but their structures are virtually identical. SHA-224 and SHA-384 are simply truncated versions of the first two, computed with different initial values, SHA-512/224 and SHA-512/256 are also truncated versions of SHA-512, but the initial values are generated using the method described in Federal Information Processing Standards PUB 180-4. SHA-2 was published in 2001 by the National Institute of Standards, the SHA-2 family of algorithms are patented in US patent 6829355. The United States has released the patent under a royalty-free license, in 2005, an algorithm emerged for finding SHA-1 collisions in about 2,000 times fewer steps than was previously thought possible. In 2017, an example of a SHA-1 collision was published, the security margin left by SHA-1 is weaker than intended, and its use is therefore no longer recommended for applications that depend on collision resistance, such as digital signatures. Although SHA-2 bears some similarity to the SHA-1 algorithm, these attacks have not been extended to SHA-2. With the publication of FIPS PUB 180-2, NIST added three additional functions in the SHA family. The algorithms are known as SHA-2, named after their digest lengths, SHA-256, SHA-384. The algorithms were first published in 2001 in the draft FIPS PUB 180-2, at which time public review, in August 2002, FIPS PUB 180-2 became the new Secure Hash Standard, replacing FIPS PUB 180-1, which was released in April 1995. The updated standard included the original SHA-1 algorithm, with updated technical notation consistent with that describing the workings of the SHA-2 family. In February 2004, a notice was published for FIPS PUB 180-2, specifying an additional variant, SHA-224. In October 2008, the standard was updated in FIPS PUB 180-3, including SHA-224 from the change notice, the primary motivation for updating the standard was relocating security information about the hash algorithms and recommendations for their use to Special Publications 800-107 and 800-57. Detailed test data and example message digests were also removed from the standard, padding the final data block must still occur prior to hash output
23.
Comodo Group
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Comodo Group, Inc. is a privately held group of companies providing computer software and SSL digital certificates, based in Clifton, New Jersey in the United States. It has offices in the United Kingdom, Ukraine, Romania, China, India, Turkey and Clifton, as of 3 February 2017, Comodo is the largest issuer of SSL certificates with a 44% market share on 13. 9% of all web domains. The company was founded in 1998 in the United Kingdom, by Melih Abdulhayoğlu, the company relocated to the United States in 2004. Its product line is focused on computer and internet security, Comodo CA Limited, Based in City of Salford, Greater Manchester, UK, is a digital certificate authority that issues SSL and other digital certificates. According to W3Techs. com, Comodo is the largest digital certificate provider, Comodo Security Solutions, Inc, Based in Clifton, NJ, develops and markets security software for commercial and consumer use. This includes web site vulnerability and penetration scannng, corporate and consumer pc security systems, Comodo AntiVirus Labs support all versions of their security systems. DNS. com, Based in Louisville, Kentucky, the company provides managed DNS services, Comodo Internet Security is a suite of security products for the desktop, provided free, with additional features available for a fee. It includes a firewall, Host-based intrusion detection system and antivirus program. Comodo Antivirus- A free Antivirus product that supports all major OS including Mac, Linux, Comodo Mobile Security - A free Android application that protects mobile devices against viruses, worms and scripts. In addition, it also features SMS & Call Blocking, a software & process manager, data and apps backup, Comodo email certificate - S/MIME-enabling certificates, free for personal use, per-year fee for corporate use. Comodo SSL - Comodo was founded as a Certificate Authority selling Comodo SSL and its primary source of revenue comes from related products to business and enterprises. Related E-Commerce products include PCI Compliance Scanning and Web Site Vulnerability Scanning, Comodo Certificate Manager is a cloud-based digital certificate management product allowing enterprises to manage certificates. Comodo Advanced Endpoint Protection provides next-generation endpoint protection, combining Comodo Client Security, ITSM, Valkyrie Cloud File Analysis Platform - The Valkyrie cloud-based file analysis platform uses multiple techniques to provide a verdict of good or bad on unknown files. Comodo Client Security is the client application used by AEP to provide endpoint security and it allows for the configuration of security policies and visibility into the security posture and health of enterprise endpoints. Comodo Dome - a family of products providing a secure web platform providing various security functions including web security, anti spam, secure VPN. In May 2014, the Comodo Group acquired MyDLP, a source data loss prevention system. Using this tool they can manage and at the same time ensure the security of a number of mobile devices. Comodo cWatch a breach prevention and threat detection managed SaaS offering hosted by Comodo, SurGate Labs - In 2014 Comodo acquired SurGate Labs, a Turkish Software company that specializes in secure email an messaging systems
24.
Wayback Machine
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The Internet Archive launched the Wayback Machine in October 2001. It was set up by Brewster Kahle and Bruce Gilliat, and is maintained with content from Alexa Internet, the service enables users to see archived versions of web pages across time, which the archive calls a three dimensional index. Since 1996, the Wayback Machine has been archiving cached pages of websites onto its large cluster of Linux nodes and it revisits sites every few weeks or months and archives a new version. Sites can also be captured on the fly by visitors who enter the sites URL into a search box, the intent is to capture and archive content that otherwise would be lost whenever a site is changed or closed down. The overall vision of the machines creators is to archive the entire Internet, the name Wayback Machine was chosen as a reference to the WABAC machine, a time-traveling device used by the characters Mr. Peabody and Sherman in The Rocky and Bullwinkle Show, an animated cartoon. These crawlers also respect the robots exclusion standard for websites whose owners opt for them not to appear in search results or be cached, to overcome inconsistencies in partially cached websites, Archive-It. Information had been kept on digital tape for five years, with Kahle occasionally allowing researchers, when the archive reached its fifth anniversary, it was unveiled and opened to the public in a ceremony at the University of California, Berkeley. Snapshots usually become more than six months after they are archived or, in some cases, even later. The frequency of snapshots is variable, so not all tracked website updates are recorded, Sometimes there are intervals of several weeks or years between snapshots. After August 2008 sites had to be listed on the Open Directory in order to be included. As of 2009, the Wayback Machine contained approximately three petabytes of data and was growing at a rate of 100 terabytes each month, the growth rate reported in 2003 was 12 terabytes/month, the data is stored on PetaBox rack systems manufactured by Capricorn Technologies. In 2009, the Internet Archive migrated its customized storage architecture to Sun Open Storage, in 2011 a new, improved version of the Wayback Machine, with an updated interface and fresher index of archived content, was made available for public testing. The index driving the classic Wayback Machine only has a bit of material past 2008. In January 2013, the company announced a ground-breaking milestone of 240 billion URLs, in October 2013, the company announced the Save a Page feature which allows any Internet user to archive the contents of a URL. This became a threat of abuse by the service for hosting malicious binaries, as of December 2014, the Wayback Machine contained almost nine petabytes of data and was growing at a rate of about 20 terabytes each week. Between October 2013 and March 2015 the websites global Alexa rank changed from 162 to 208, in a 2009 case, Netbula, LLC v. Chordiant Software Inc. defendant Chordiant filed a motion to compel Netbula to disable the robots. Netbula objected to the motion on the ground that defendants were asking to alter Netbulas website, in an October 2004 case, Telewizja Polska USA, Inc. v. Echostar Satellite, No.02 C3293,65 Fed. 673, a litigant attempted to use the Wayback Machine archives as a source of admissible evidence, Telewizja Polska is the provider of TVP Polonia and EchoStar operates the Dish Network
25.
Data compression
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In signal processing, data compression, source coding, or bit-rate reduction involves encoding information using fewer bits than the original representation. Compression can be lossy or lossless. Lossless compression reduces bits by identifying and eliminating statistical redundancy, no information is lost in lossless compression. Lossy compression reduces bits by removing unnecessary or less important information, the process of reducing the size of a data file is referred to as data compression. In the context of data transmission, it is called coding in opposition to channel coding. Compression is useful because it reduces resources required to store and transmit data, computational resources are consumed in the compression process and, usually, in the reversal of the process. Data compression is subject to a space–time complexity trade-off, Lossless data compression algorithms usually exploit statistical redundancy to represent data without losing any information, so that the process is reversible. Lossless compression is possible because most real-world data exhibits statistical redundancy, for example, an image may have areas of color that do not change over several pixels, instead of coding red pixel, red pixel. The data may be encoded as 279 red pixels and this is a basic example of run-length encoding, there are many schemes to reduce file size by eliminating redundancy. The Lempel–Ziv compression methods are among the most popular algorithms for lossless storage, DEFLATE is a variation on LZ optimized for decompression speed and compression ratio, but compression can be slow. DEFLATE is used in PKZIP, Gzip, and PNG, LZW is used in GIF images. LZ methods use a table-based compression model where table entries are substituted for repeated strings of data, for most LZ methods, this table is generated dynamically from earlier data in the input. The table itself is often Huffman encoded, current LZ-based coding schemes that perform well are Brotli and LZX. LZX is used in Microsofts CAB format, the best modern lossless compressors use probabilistic models, such as prediction by partial matching. The Burrows–Wheeler transform can also be viewed as a form of statistical modelling. The basic task of grammar-based codes is constructing a context-free grammar deriving a single string, sequitur and Re-Pair are practical grammar compression algorithms for which software is publicly available. In a further refinement of the use of probabilistic modelling. Arithmetic coding is a more modern coding technique that uses the mathematical calculations of a machine to produce a string of encoded bits from a series of input data symbols
26.
Free software
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The right to study and modify software entails availability of the software source code to its users. This right is conditional on the person actually having a copy of the software. Richard Stallman used the existing term free software when he launched the GNU Project—a collaborative effort to create a freedom-respecting operating system—and the Free Software Foundation. The FSFs Free Software Definition states that users of software are free because they do not need to ask for permission to use the software. Free software thus differs from proprietary software, such as Microsoft Office, Google Docs, Sheets, and Slides or iWork from Apple, which users cannot study, change, freeware, which is a category of freedom-restricting proprietary software that does not require payment for use. For computer programs that are covered by law, software freedom is achieved with a software license. Software that is not covered by law, such as software in the public domain, is free if the source code is in the public domain. Proprietary software, including freeware, use restrictive software licences or EULAs, Users are thus prevented from changing the software, and this results in the user relying on the publisher to provide updates, help, and support. This situation is called vendor lock-in, Users often may not reverse engineer, modify, or redistribute proprietary software. Other legal and technical aspects, such as patents and digital rights management may restrict users in exercising their rights. Free software may be developed collaboratively by volunteer computer programmers or by corporations, as part of a commercial, from the 1950s up until the early 1970s, it was normal for computer users to have the software freedoms associated with free software, which was typically public domain software. Software was commonly shared by individuals who used computers and by manufacturers who welcomed the fact that people were making software that made their hardware useful. Organizations of users and suppliers, for example, SHARE, were formed to exchange of software. As software was written in an interpreted language such as BASIC. Software was also shared and distributed as printed source code in computer magazines and books, in United States vs. IBM, filed January 17,1969, the government charged that bundled software was anti-competitive. While some software might always be free, there would henceforth be an amount of software produced primarily for sale. In the 1970s and early 1980s, the industry began using technical measures to prevent computer users from being able to study or adapt the software as they saw fit. In 1980, copyright law was extended to computer programs, Software development for the GNU operating system began in January 1984, and the Free Software Foundation was founded in October 1985
27.
7-Zip
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7-Zip is an open-source file archiver, an application used primarily to compress files. 7-Zip uses its own 7z archive format, but can read, the program can be used from a command-line interface as the command p7zip, as a graphical user interface, or with a window-based shell integration. 7-Zip began in 1999 and is developed by Igor Pavlov, most of the source code is under the GNU LGPL license. The unRAR code is under the GNU LGPL with an unRAR restriction, by default, 7-Zip creates 7z-format archives with a. 7z file extension. Each archive can contain multiple directories and files, as a container format, security or size reduction are achieved using a stacked combination of filters. These can consist of pre-processors, compression algorithms, and encryption filters, the core 7z compression uses a variety of algorithms, the most common of which are bzip2, PPMd, LZMA2, and LZMA. Developed by Pavlov, LZMA is a new system, making its debut as part of the 7z format. LZMA uses an LZ-based sliding dictionary of up to 4 GB in size, the native 7z file format is open and modular. All filenames are stored as Unicode, the 7z file format specification is distributed with the programs source code, in the doc subdirectory. 7-Zip supports a number of compression and non-compression archive formats, including ZIP, Gzip, bzip2, xz, tar. 7-Zip supports the ZIPX format for unpacking only and it has had this support since at least version 9.20, which was released in late 2010. 7-Zip can open some MSI files, allowing access to the meta-files within along with the main contents, some Microsoft CAB and NSIS installer formats can be opened. Similarly, some Microsoft executable programs that are self-extracting archives or otherwise contain archived content may be opened as archives. When compressing ZIP or gzip files, 7-Zip uses its own DEFLATE encoder, which may achieve higher compression, the 7-Zip deflate encoder implementation is available separately as part of the AdvanceCOMP suite of tools. The decompression engine for RAR archives was developed using source code of the unRAR program, 7-Zip v15.06 and later support the RAR5 file format. It can also unpack a few types of backup created by Android stock recovery image, 7-Zip comes with a file manager along with the standard archiver tools. The file manager, by default, displays hidden files because it not follow Windows Explorers policies. The tabs show name, modification time, original and compressed sizes, attributes, when going up one directory on the root, all drives, removable or internal appear
28.
Archive Manager
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Archive Manager is the archive manager of the GNOME desktop environment. Archive Manager can, Create and modify archives, view the content of an archive. View a file contained in the archive, backend programs are needed to use Archive Manager as a frontend. This can be set however using gconf-editor, Comparison of archive formats Comparison of file archivers Official website Manuals Source code
29.
Ark (software)
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Ark is a file archiver and compressor developed by KDE and included in the KDE Applications software bundle. It supports various common archive and compression formats including zip, 7z, rar, lha, Ark uses libarchive and karchive to support tar-based archives, and is also a frontend for several command-line archivers. Ark can be integrated into Konqueror, through KParts technology, after installing it, files can be added or extracted in/from the archives using Konquerors context menus. Support for editing files in archive with external programs, files can also be deleted from the archive. Archive creation with drag and drop from file manager, comparison of file archivers KDE Utilities / Ark
