1.
Difference engine
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A difference engine is an automatic mechanical calculator designed to tabulate polynomial functions. The name derives from the method of divided differences, a way to interpolate or tabulate functions by using a set of polynomial coefficients. The historical difficulty in producing error-free tables by teams of mathematicians, J. H. Müller, an engineer in the Hessian army, conceived of the idea of a difference machine. This was described in a book published in 1786, but Müller was unable to obtain funding to progress with the idea and this machine used the decimal number system and was powered by cranking a handle. The British government was interested, since producing tables was time-consuming and expensive, in 1823, the British government gave Babbage £1700 to start work on the project. Although Babbages design was feasible, the techniques of the era could not economically make parts in the precision. Thus the implementation proved to be more expensive and doubtful of success than the governments initial estimate. By the time the government abandoned the project in 1842, Babbage had received and spent over £17,000 on development, the government valued only the machines output, not the development of the machine itself. Babbage did not, or was unwilling to, recognize that predicament, meanwhile, Babbages attention had moved on to developing an analytical engine, further undermining the government’s confidence in the eventual success of the difference engine. By improving the concept as an engine, Babbage had made the difference engine concept obsolete. Babbage went on to design his much more general analytical engine, Babbage was able to take advantage of ideas developed for the analytical engine to make the new difference engine calculate more quickly while using fewer parts. Inspired by Babbages difference engine plans, Per Georg Scheutz built several difference engines from 1855 onwards, martin Wiberg improved Scheutzs construction but used his device only for producing and publishing printed logarithmic tables. This work led the Science Museum to construct a working difference engine No.2 from 1989 to 1991, under Doron Swade and this was to celebrate the 200th anniversary of Babbages birth in 2001. In 2000, the printer which Babbage originally designed for the engine was also completed. The conversion of the design drawings into drawings suitable for engineering manufacturers use revealed some minor errors in Babbages design. Once completed, both the engine and its printer worked flawlessly, and still do, the difference engine and printer were constructed to tolerances achievable with 19th-century technology, resolving a long-standing debate as to whether Babbages design would actually have worked. The printers primary purpose is to produce plates for use in printing presses. The printers paper output is mainly a means of checking the Engines performance, in addition to funding the construction of the output mechanism for the Science Museums Difference Engine No
2.
Polynomial
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In mathematics, a polynomial is an expression consisting of variables and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents. An example of a polynomial of a single indeterminate x is x2 − 4x +7, an example in three variables is x3 + 2xyz2 − yz +1. Polynomials appear in a variety of areas of mathematics and science. In advanced mathematics, polynomials are used to construct polynomial rings and algebraic varieties, central concepts in algebra, the word polynomial joins two diverse roots, the Greek poly, meaning many, and the Latin nomen, or name. It was derived from the binomial by replacing the Latin root bi- with the Greek poly-. The word polynomial was first used in the 17th century, the x occurring in a polynomial is commonly called either a variable or an indeterminate. When the polynomial is considered as an expression, x is a symbol which does not have any value. It is thus correct to call it an indeterminate. However, when one considers the function defined by the polynomial, then x represents the argument of the function, many authors use these two words interchangeably. It is a convention to use uppercase letters for the indeterminates. However one may use it over any domain where addition and multiplication are defined, in particular, when a is the indeterminate x, then the image of x by this function is the polynomial P itself. This equality allows writing let P be a polynomial as a shorthand for let P be a polynomial in the indeterminate x. A polynomial is an expression that can be built from constants, the word indeterminate means that x represents no particular value, although any value may be substituted for it. The mapping that associates the result of substitution to the substituted value is a function. This can be expressed concisely by using summation notation, ∑ k =0 n a k x k That is. Each term consists of the product of a number—called the coefficient of the term—and a finite number of indeterminates, because x = x1, the degree of an indeterminate without a written exponent is one. A term and a polynomial with no indeterminates are called, respectively, a constant term, the degree of a constant term and of a nonzero constant polynomial is 0. The degree of the polynomial,0, is generally treated as not defined
3.
Computer lab
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A computer lab is a space which provides computer services to a defined community. Users typically must follow a certain user policy to retain access to the computers and this generally consists of the user not engaging in illegal activities or attempting to circumvent any security or content-control software while using the computers. Computers in computer labs are equipped with internet access, while scanners and printers may augment the lab setup. These specialized purposes include but may not be limited to editing, stock trading, 3-D design. In some cases, these purposes are the main purposes for the existence of traditional desktop-style computer labs. In some settings, traditional desktop computer labs are impractical due to the requirement of a dedicated space, because of this, some labs use laptop carts instead of desktop setups, in order to both save space and give the lab some degree of mobility. A media lab is a used for interdisciplinary organizations, collectives or spaces with the main focus on new media, digital culture. The MIT Media Lab is an example of a media lab. An Internet café differs from a lab in that usage of a computer lab is generally free for those with access. Computer science Kiosk software Public computer
4.
Server (computing)
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In computing, a server is a computer program or a device that provides functionality for other programs or devices, called clients. This architecture is called the model, and a single overall computation is distributed across multiple processes or devices. Servers can provide various functionalities, often called services, such as sharing data or resources among multiple clients, a single server can serve multiple clients, and a single client can use multiple servers. A client process may run on the device or may connect over a network to a server on a different device. Typical servers are database servers, file servers, mail servers, print servers, web servers, game servers, designating a computer as server-class hardware implies that it is specialized for running servers on it. The use of the server in computing comes from queueing theory, where it dates to the mid 20th century, being notably used in Kendall. In earlier papers, such as the Erlang, more terms such as operators are used. In computing, server dates at least to RFC5, one of the earliest documents describing ARPANET, the use of serving also dates to early documents, such as RFC4, contrasting serving-host with using-host. The Jargon File defines server in the sense of a process performing service for requests, usually remote, with the 1981 version reading. A kind of DAEMON which performs a service for the requester, strictly speaking, the term server refers to a computer program or process. Through metonymy, it refers to a used to running one or several server programs. On a network, such a device is called a host, in addition to server, the words serve and service are frequently used, though servicer and servant are not. The word service may refer to either the form of functionality. Alternatively, it may refer to a program that turns a computer into a server. Originally used as servers serve users, in the sense of obey, today one says that servers serve data. For instance, web servers serve web pages to users or service their requests, the server is part of the client–server model, in this model, a server serves data for clients. The nature of communication between a client and server is request and response and this is in contrast with peer-to-peer model in which the relationship is on-demand reciprocation. In principle, any computerized process that can be used or called by another process is a server, thus any general purpose computer connected to a network can host servers
5.
Computer
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A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically. The ability of computers to follow a sequence of operations, called a program, such computers are used as control systems for a very wide variety of industrial and consumer devices. The Internet is run on computers and it millions of other computers. Since ancient times, simple manual devices like the abacus aided people in doing calculations, early in the Industrial Revolution, some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms. More sophisticated electrical machines did specialized analog calculations in the early 20th century, the first digital electronic calculating machines were developed during World War II. The speed, power, and versatility of computers has increased continuously and dramatically since then, conventionally, a modern computer consists of at least one processing element, typically a central processing unit, and some form of memory. The processing element carries out arithmetic and logical operations, and a sequencing, peripheral devices include input devices, output devices, and input/output devices that perform both functions. Peripheral devices allow information to be retrieved from an external source and this usage of the term referred to a person who carried out calculations or computations. The word continued with the same meaning until the middle of the 20th century, from the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations. The Online Etymology Dictionary gives the first attested use of computer in the 1640s, one who calculates, the Online Etymology Dictionary states that the use of the term to mean calculating machine is from 1897. The Online Etymology Dictionary indicates that the use of the term. 1945 under this name, theoretical from 1937, as Turing machine, devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers. The earliest counting device was probably a form of tally stick, later record keeping aids throughout the Fertile Crescent included calculi which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one example, the abacus was initially used for arithmetic tasks. The Roman abacus was developed from used in Babylonia as early as 2400 BC. Since then, many forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, the Antikythera mechanism is believed to be the earliest mechanical analog computer, according to Derek J. de Solla Price. It was designed to calculate astronomical positions and it was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC
6.
Computer hardware
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Computer hardware is the collection of physical components that constitute a computer system. By contrast, software is instructions that can be stored and run by hardware, hardware is directed by the software to execute any command or instruction. A combination of hardware and software forms a usable computing system, the template for all modern computers is the Von Neumann architecture, detailed in a 1945 paper by Hungarian mathematician John von Neumann. The meaning of the term has evolved to mean a stored-program computer in which an instruction fetch and this is referred to as the Von Neumann bottleneck and often limits the performance of the system. For the third year, U. S. business-to-business channel sales increased. The impressive growth was the fastest sales increase since the end of the recession, sales growth accelerated in the second half of the year peaking in fourth quarter with a 6.9 percent increase over the fourth quarter of 2012. There are a number of different types of system in use today. The personal computer, also known as the PC, is one of the most common types of computer due to its versatility, laptops are generally very similar, although they may use lower-power or reduced size components, thus lower performance. The computer case is a plastic or metal enclosure that houses most of the components, a case can be either big or small, but the form factor of motherboard for which it is designed matters more. A power supply unit converts alternating current electric power to low-voltage DC power for the components of the computer. Laptops are capable of running from a battery, normally for a period of hours. The motherboard is the component of a computer. It is usually cooled by a heatsink and fan, or water-cooling system, most newer CPUs include an on-die Graphics Processing Unit. The clock speed of CPUs governs how fast it executes instructions, many modern computers have the option to overclock the CPU which enhances performance at the expense of greater thermal output and thus a need for improved cooling. The chipset, which includes the bridge, mediates communication between the CPU and the other components of the system, including main memory. Random-Access Memory, which stores the code and data that are being accessed by the CPU. For example, when a web browser is opened on the computer it takes up memory, RAM usually comes on DIMMs in the sizes 2GB, 4GB, and 8GB, but can be much larger. Read-Only Memory, which stores the BIOS that runs when the computer is powered on or otherwise begins execution, the BIOS includes boot firmware and power management firmware
7.
Software
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Computer software, or simply software, is that part of a computer system that consists of data or computer instructions, in contrast to the physical hardware from which the system is built. In computer science and software engineering, computer software is all information processed by computer systems, programs, computer software includes computer programs, libraries and related non-executable data, such as online documentation or digital media. Computer hardware and software require each other and neither can be used on its own. At the lowest level, executable code consists of machine language instructions specific to an individual processor—typically a central processing unit, a machine language consists of groups of binary values signifying processor instructions that change the state of the computer from its preceding state. For example, an instruction may change the value stored in a storage location in the computer—an effect that is not directly observable to the user. An instruction may also cause something to appear on a display of the computer system—a state change which should be visible to the user. The processor carries out the instructions in the order they are provided, unless it is instructed to jump to a different instruction, the majority of software is written in high-level programming languages that are easier and more efficient for programmers, meaning closer to a natural language. High-level languages are translated into machine language using a compiler or an interpreter or a combination of the two, an outline for what would have been the first piece of software was written by Ada Lovelace in the 19th century, for the planned Analytical Engine. However, neither the Analytical Engine nor any software for it were ever created, the first theory about software—prior to creation of computers as we know them today—was proposed by Alan Turing in his 1935 essay Computable numbers with an application to the Entscheidungsproblem. This eventually led to the creation of the academic fields of computer science and software engineering. Computer science is more theoretical, whereas software engineering focuses on practical concerns. However, prior to 1946, software as we now understand it—programs stored in the memory of stored-program digital computers—did not yet exist, the first electronic computing devices were instead rewired in order to reprogram them. On virtually all platforms, software can be grouped into a few broad categories. There are many different types of software, because the range of tasks that can be performed with a modern computer is so large—see list of software. System software includes, Operating systems, which are collections of software that manage resources and provides common services for other software that runs on top of them. Supervisory programs, boot loaders, shells and window systems are parts of operating systems. In practice, an operating system bundled with additional software so that a user can potentially do some work with a computer that only has an operating system. Device drivers, which operate or control a particular type of device that is attached to a computer, utilities, which are computer programs designed to assist users in the maintenance and care of their computers
8.
Computer engineering
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Computer engineering is a discipline that integrates several fields of electrical engineering and computer science required to develop computer hardware and software. Computer engineers usually have training in engineering, software design. This field of engineering not only focuses on how computer systems themselves work, Computer engineers are also suited for robotics research, which relies heavily on using digital systems to control and monitor electrical systems like motors, communications, and sensors. Other institutions may require engineering students to one or two years of General Engineering before declaring computer engineering as their primary focus. The first computer engineering program in the United States was established at Case Western Reserve University in 1972. As of 2015, there were 238 ABET-accredited computer engineering programs in the US, in Europe, accreditation of computer engineering schools is done by a variety of agencies part of the EQANIE network. Both computer engineering and electronic engineering programs include analog and digital circuit design in their curriculum, as with most engineering disciplines, having a sound knowledge of mathematics and science is necessary for computer engineers. There are two major specialties in computer engineering, software and hardware, Computer software engineers develop, design, and test software. They construct, and maintain computer programs, as well as set up such as intranets for companies. Software engineers can design or code new applications to meet the needs of a business or individual. Some software engineers work independently as freelancers and sell their software products/applications to an enterprise or individual, most computer hardware engineers research, develop, design, and test various computer equipment. This can range from circuit boards and microprocessors to routers, some update existing computer equipment to be more efficient and work with newer software. Most computer hardware engineers work in laboratories and high-tech manufacturing firms. Some also work for the federal government, according to BLS, 95% of computer hardware engineers work in metropolitan areas. Approximately 33% of their work more than 40 hours a week. The median salary for employed qualified computer hardware engineers was $100,920 per year or $48.52 per hour, Computer hardware engineers held 83,300 jobs in 2012 in the USA. There are many specialty areas in the field of computer engineering, examples include work on wireless communications, multi-antenna systems, optical transmission, and digital watermarking. Those focusing on communications and wireless networks, work advancements in telecommunications systems and networks, modulation and error-control coding, high-speed network design, interference suppression and modulation, design and analysis of fault-tolerant system, and storage and transmission schemes are all a part of this specialty
9.
Software engineering
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Software engineering is the application of engineering to the development of software in a systematic method. Practitioners quickly realized that this design was not flexible and came up with the stored program architecture or von Neumann architecture, thus the division between hardware and software began with abstraction being used to deal with the complexity of computing. Programming languages started to appear in the early 1950s and this was another major step in abstraction. Major languages such as Fortran, ALGOL, and COBOL were released in the late 1950s to deal with scientific, algorithmic, the conference was attended by international experts on software who agreed on defining best practices for software grounded in the application of engineering. The result of the conference is a report that defines how software should be developed, the original report is publicly available. Engineering already addresses all issues, hence the same principles used in engineering can be applied to software. The widespread lack of best practices for software at the time was perceived as a software crisis, barry W. Boehm documented several key advances to the field in his 1981 book, Software Engineering Economics. These include his Constructive Cost Model, which relates software development effort for a program, in man-years T, T = k ∗ The book analyzes sixty-three software projects and concludes the cost of fixing errors escalates as the project moves toward field use. The book also asserts that the key driver of software cost is the capability of the development team. Watts Humphrey founded the SEI Software Process Program, aimed at understanding and managing the software engineering process and his 1989 book, Managing the Software Process, asserts that the Software Development Process can and should be controlled, measured, and improved. Modern, generally accepted best-practices for software engineering have been collected by the ISO/IEC JTC 1/SC7 subcommittee, Software engineering can be divided into 15 sub-disciplines. They are, Software requirements, The elicitation, analysis, specification, Software design, The process of defining the architecture, components, interfaces, and other characteristics of a system or component. It is also defined as the result of that process, Software construction, The detailed creation of working, meaningful software through a combination of coding, verification, unit testing, integration testing, and debugging. Software testing, An empirical, technical investigation conducted to provide stakeholders with information about the quality of the product or service under test, Software maintenance, The totality of activities required to provide cost-effective support to software. Software development process, The definition, implementation, assessment, measurement, management, change, many software engineers enter the profession by obtaining a university degree or training at a vocational school. One standard international curriculum for undergraduate software engineering degrees was defined by the CCSE, in addition to university education, many companies sponsor internships for students wishing to pursue careers in information technology. These internships can introduce the student to interesting real-world tasks that typical software engineers encounter every day, similar experience can be gained through military service in software engineering. Legal requirements for the licensing or certification of professional software engineers vary around the World, in Canada, there is a legal requirement to have P. Eng when one wants to use the title engineer or practice software engineering
10.
Computer science
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Computer science is the study of the theory, experimentation, and engineering that form the basis for the design and use of computers. An alternate, more succinct definition of science is the study of automating algorithmic processes that scale. A computer scientist specializes in the theory of computation and the design of computational systems and its fields can be divided into a variety of theoretical and practical disciplines. Some fields, such as computational complexity theory, are highly abstract, other fields still focus on challenges in implementing computation. Human–computer interaction considers the challenges in making computers and computations useful, usable, the earliest foundations of what would become computer science predate the invention of the modern digital computer. Machines for calculating fixed numerical tasks such as the abacus have existed since antiquity, further, algorithms for performing computations have existed since antiquity, even before the development of sophisticated computing equipment. Wilhelm Schickard designed and constructed the first working mechanical calculator in 1623, in 1673, Gottfried Leibniz demonstrated a digital mechanical calculator, called the Stepped Reckoner. He may be considered the first computer scientist and information theorist, for, among other reasons and he started developing this machine in 1834, and in less than two years, he had sketched out many of the salient features of the modern computer. A crucial step was the adoption of a card system derived from the Jacquard loom making it infinitely programmable. Around 1885, Herman Hollerith invented the tabulator, which used punched cards to process statistical information, when the machine was finished, some hailed it as Babbages dream come true. During the 1940s, as new and more powerful computing machines were developed, as it became clear that computers could be used for more than just mathematical calculations, the field of computer science broadened to study computation in general. Computer science began to be established as an academic discipline in the 1950s. The worlds first computer science program, the Cambridge Diploma in Computer Science. The first computer science program in the United States was formed at Purdue University in 1962. Since practical computers became available, many applications of computing have become distinct areas of study in their own rights and it is the now well-known IBM brand that formed part of the computer science revolution during this time. IBM released the IBM704 and later the IBM709 computers, still, working with the IBM was frustrating if you had misplaced as much as one letter in one instruction, the program would crash, and you would have to start the whole process over again. During the late 1950s, the science discipline was very much in its developmental stages. Time has seen significant improvements in the usability and effectiveness of computing technology, modern society has seen a significant shift in the users of computer technology, from usage only by experts and professionals, to a near-ubiquitous user base
11.
Information system
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An information system is any organized system for the collection, organization, storage and communication of information. More specifically, it is the study of networks that people and organizations use to collect, filter, process. An information system is a group of components that interact to produce information, a computer information system is a system composed of people and computers that processes or interprets information. The term is sometimes used in more restricted senses to refer to only the software used to run a computerized database or to refer to only a computer system. An emphasis is placed on a system having a definitive boundary, users, processors, storage, inputs, outputs. Any specific information system aims to support operations, management and decision-making, an information system is the information and communication technology that an organization uses, and also the way in which people interact with this technology in support of business processes. Some authors make a distinction between information systems, computer systems, and business processes. Information systems typically include an ICT component but are not purely concerned with ICT, Information systems are also different from business processes. Information systems help to control the performance of business processes, alter argues for advantages of viewing an information system as a special type of work system. A work system is a system in humans or machines perform processes and activities using resources to produce specific products or services for customers. An information system is a system whose activities are devoted to capturing, transmitting, storing, retrieving, manipulating and displaying information. As such, information systems inter-relate with data systems on the one hand, an information system is a form of communication system in which data represent and are processed as a form of social memory. An information system can also be considered a language which supports human decision making. Information systems are the focus of study for organizational informatics. Silver et al. provided two views on IS that includes software, hardware, data, people, and procedures, zheng provided another system view of information system which also adds processes and essential system elements like environment, boundary, purpose, and interactions. Information technologies are a important and malleable resource available to executives. The CTO may also serve as CIO, and vice versa, the chief information security officer focuses on information security management. The six components that must come together in order to produce a system are, Hardware
12.
Information technology
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Information technology is the application of computers to store, study, retrieve, transmit, and manipulate data, or information, often in the context of a business or other enterprise. IT is considered a subset of information and communications technology, the term is commonly used as a synonym for computers and computer networks, but it also encompasses other information distribution technologies such as television and telephones. Several industries are associated with technology, including computer hardware, software, electronics, semiconductors, internet, telecom equipment. Leavitt and Thomas L. Whisler commented that the new technology not yet have a single established name. We shall call it information technology, based on the storage and processing technologies employed, it is possible to distinguish four distinct phases of IT development, pre-mechanical, mechanical, electromechanical, electronic. This article focuses on the most recent period, which began in about 1940, devices have been used to aid computation for thousands of years, probably initially in the form of a tally stick. Electronic computers, using either relays or valves, began to appear in the early 1940s, the electromechanical Zuse Z3, completed in 1941, was the worlds first programmable computer, and by modern standards one of the first machines that could be considered a complete computing machine. Colossus, developed during the Second World War to decrypt German messages was the first electronic digital computer, although it was programmable, it was not general-purpose, being designed to perform only a single task. It also lacked the ability to store its program in memory, programming was carried out using plugs, the first recognisably modern electronic digital stored-program computer was the Manchester Small-Scale Experimental Machine, which ran its first program on 21 June 1948. The development of transistors in the late 1940s at Bell Laboratories allowed a new generation of computers to be designed with reduced power consumption. The first commercially available stored-program computer, the Ferranti Mark I, by comparison the first transistorised computer, developed at the University of Manchester and operational by November 1953, consumed only 150 watts in its final version. Early electronic computers such as Colossus made use of punched tape, a strip of paper on which data was represented by a series of holes. IBM introduced the first hard drive in 1956, as a component of their 305 RAMAC computer system. Most digital data today is stored magnetically on hard disks. Until 2002 most information was stored on analog devices, but that year digital storage capacity exceeded analog for the first time. As of 2007 almost 94% of the data stored worldwide was held digitally, 52% on hard disks, 28% on optical devices and 11% on digital magnetic tape. It has been estimated that the capacity to store information on electronic devices grew from less than 3 exabytes in 1986 to 295 exabytes in 2007. Database management systems emerged in the 1960s to address the problem of storing and retrieving large amounts of data accurately and quickly, one of the earliest such systems was IBMs Information Management System, which is still widely deployed more than 50 years later
13.
Association for Computing Machinery
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The Association for Computing Machinery is an international learned society for computing. It was founded in 1947 and is the worlds largest scientific and it is a not-for-profit professional membership group. Its membership is more than 100,000 as of 2011 and its headquarters are in New York City. The ACM is an organization for academic and scholarly interests in computer science. Its motto is Advancing Computing as a Science & Profession, ACM is organized into over 171 local chapters and 37 Special Interest Groups, through which it conducts most of its activities. Additionally, there are over 500 college and university chapters, the first student chapter was founded in 1961 at the University of Louisiana at Lafayette. Many of the SIGs, such as SIGGRAPH, SIGPLAN, SIGCSE and SIGCOMM, sponsor regular conferences, the groups also publish a large number of specialized journals, magazines, and newsletters. ACM publishes over 50 journals including the prestigious Journal of the ACM, other publications of the ACM include, ACM XRDS, formerly Crossroads, was redesigned in 2010 and is the most popular student computing magazine in the US. ACM Interactions, an interdisciplinary HCI publication focused on the connections between experiences, people and technology, and the third largest ACM publication, ACM Computing Surveys ACM Computers in Entertainment A number of journals, specific to subfields of computer science, titled ACM Transactions. ACM has made almost all of its publications available to subscribers online at its Digital Library. Individual members additionally have access to Safari Books Online and Books24x7, ACM also offers insurance, online courses, and other services to its members. In 1997, ACM Press published Wizards and Their Wonders, Portraits in Computing, written by Christopher Morgan, the book is a collection of historic and current portrait photographs of figures from the computer industry. The ACM Portal is a service of the ACM. Its core are two sections, ACM Digital Library and the ACM Guide to Computing Literature. The ACM Digital Library is the collection of all articles published by the ACM in its articles, magazines. The Guide is a bibliography in computing with over one million entries, the ACM Digital Library contains a comprehensive archive starting in the 1950s of the organizations journals, magazines, newsletters and conference proceedings. Online services include a forum called Ubiquity and Tech News digest, there is an extensive underlying bibliographic database containing key works of all genres from all major publishers of computing literature. This secondary database is a rich discovery service known as The ACM Guide to Computing Literature, ACM adopted a hybrid Open Access publishing model in 2013
14.
Synonym
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A synonym is a word or phrase that means exactly or nearly the same as another word or phrase in the same language. Words that are synonyms are said to be synonymous, and the state of being a synonym is called synonymy, the word comes from Ancient Greek sýn and ónoma. An example of synonyms are the words begin, start, commence, words can be synonymous when meant in certain senses, even if they are not synonymous in all of their senses. For example, if one talks about a time or an extended time, long. Some academics call the former type cognitive synonyms to distinguish them from the latter type, some lexicographers claim that no synonyms have exactly the same meaning because etymology, orthography, phonic qualities, ambiguous meanings, usage, etc. make them unique. Different words that are similar in meaning usually differ for a reason, feline is more formal than cat, long and extended are only synonyms in one usage, synonyms are also a source of euphemisms. In the figurative sense, two words are said to be synonymous if they have the same connotation. a widespread impression that. Metonymy can sometimes be a form of synonymy, as when, for example, thus a metonym is a type of synonym, and the word metonym is a hyponym of the word synonym. The analysis of synonymy, polysemy, hyponymy, and hypernymy is inherent to taxonomy and it has applications in pedagogy and machine learning, because they rely on word-sense disambiguation and schema. Synonyms can be any part of speech, as long as both words belong to the part of speech. Such like, he expired means the same as he died, in English, many synonyms emerged in the Middle Ages, after the Norman conquest of England. While Englands new ruling class spoke Norman French, the lower classes continued to speak Old English, thus, today we have synonyms like the Norman-derived people, liberty and archer, and the Saxon-derived folk, freedom and bowman. For more examples, see the list of Germanic and Latinate equivalents in English, the purpose of a thesaurus is to offer the user a listing of similar or related words, these are often, but not always, synonyms. The word poecilonym is a synonym of the word synonym. It is not entered in most major dictionaries and is a curiosity or piece of trivia for being a word because of its meta quality as a synonym of synonym. Antonyms are words with opposite or nearly opposite meanings, for example, hot ↔ cold, large ↔ small, thick ↔ thin, synonym ↔ antonym Hypernyms and hyponyms are words that refer to, respectively, a general category and a specific instance of that category. For example, vehicle is a hypernym of car, and car is a hyponym of vehicle, homophones are words that have the same pronunciation, but different meanings. For example, witch and which are homophones in most accents, homographs are words that have the same spelling, but have different pronunciations
15.
Mechanical computer
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A mechanical computer is built from mechanical components such as levers and gears, rather than electronic components. The most common examples are adding machines and mechanical counters, which use the turning of gears to increment output displays, more complex examples could carry out multiplication and division—Friden used a moving head which paused at each column—and even differential analysis. One model sold in the 1960s calculated square roots, mechanical computers can be either analog, using smooth mechanisms such as curved plates or slide rules for computations, or digital, which use gears. Noteworthy are mechanical flight instruments for spacecraft, which provided their computed output not in the form of digits. Mechanical computers continued to be used into the 1960s, but were replaced by electronic calculators. The evolution culminated in the 1970s with the introduction of handheld electronic calculators. Mechanical computers were ailing in the 1970s and dead by the 1980s, stepped Reckoner,1672 – Gottfried Wilhelm Leibnizs mechanical calculator that could add, subtract, multiply, and divide. Difference Engine,1822 – Charles Babbages mechanical device to calculate polynomials, analytical Engine,1837 – A later Charles Babbage device that could be said to encapsulate most of the elements of modern computers. Ball-and-disk integrator,1886 - William Thomson used it in his Harmonic Analyser to measure tide heights by calculating coefficients of a Fourier series, marchant Calculator,1918 – Most advanced of the mechanical calculators. The key design was by Carl Friden, kerrison Predictor Z1,1938 by Konrad Zuse Curta calculator,1948 Moniac,1949 – An analog computer used to model or simulate the UK economy. Examples include, Z2,1939 Z3,1941 – Designed by Konrad Zuse, harvard Mark I,1944 – Built by IBM
16.
Human computer
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The term computer, in use from the early 17th century, meant one who computes, a person performing mathematical calculations, before electronic computers became commercially available. The human computer is supposed to be following fixed rules, he has no authority to deviate from them in any detail, teams of people were frequently used to undertake long and often tedious calculations, the work was divided so that this could be done in parallel. Since the end of the 20th century, the human computer has also been applied to individuals with prodigious powers of mental arithmetic. The approach was taken for astronomical and other complex calculations, for some men, being a computer was a temporary position until they moved on to greater advancements. This changed in the nineteenth century with Edward Charles Pickering. His group was at times termed Harvard Computers, many of the women astronomers from this era were computers with possibly the best known being Henrietta Swan Leavitt, who worked with Pickering from 1893. Florence Cushman was another of the Harvard University computers from 1888 onward, among her best known works was A Catalogue of 16,300 Stars Observed with the 12-inch Meridian Photometer. She also worked with Annie Jump Cannon, the Indian mathematician Radhanath Sikdar was employed as a computer for the Great Trigonometrical Survey of India in 1840. It was he who first identified and calculated the height of the worlds highest mountain, Human computers were used to compile 18th and 19th century Western European mathematical tables, for example those for trigonometry and logarithms. Although these tables were most often known by the names of the principal mathematician involved in the project, such tables were often in fact the work of an army of unknown, ever more accurate tables to a high degree of precision were needed for navigation and engineering. Approaches differred, but one was to break up the project into a form of long distance work from home piece work. The computers, often educated middle class women who society deemed it unseemly to engage in the professions or go out to work, would receive, Human computers were used to predict the effects of building the Afsluitdijk in the Zuiderzee. The computer simulation was set up by Hendrik Lorentz, around 1910 he had already used human computers to calculate the stresses inside a masonry dam. In the Manhattan Project, human computers, working with a variety of mechanical aids, Margot Lee Shetterlys biographical book, Hidden Figures, documents the contributions of African American woman who served as human computers at NASA. One such computer was Dorothy Vaughan who began her work in 1943 with the Langley Research Center as a special hire to aid the WWII effort and this usage is questionable for the following reason. HBC is a technique where a machine outsources certain tasks to humans. In fact, most of the humans in the context of HBC are not provided with a sequence of exact steps that needs to be executed to yield an answer. HBC is agnostic about how humans solve the problem and this is why the term outsourcing is used in the definition
17.
History of computing
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The timeline of computing presents a summary list of major developments in computing by date. Digital computing is intimately tied to the representation of numbers, but long before abstractions like the number arose, there were mathematical concepts to serve the purposes of civilization. Eventually, the concept of numbers became concrete and familiar enough for counting to arise, all known languages have words for at least one and two, and even some animals like the blackbird can distinguish a surprising number of items. Eventually the operations were formalized, and concepts about the operations became understood well enough to be stated formally, see, for example, Euclids algorithm for finding the greatest common divisor of two numbers. By the High Middle Ages, the positional Hindu–Arabic numeral system had reached Europe, even into the period of programmable calculators, Richard Feynman would unhesitatingly compute any steps which overflowed the memory of the calculators, by hand, just to learn the answer. The earliest known tool for use in computation was the abacus and its original style of usage was by lines drawn in sand with pebbles. Abaci, of a modern design, are still used as calculation tools today. This was the first known computer and most advanced system of calculation known to date - preceding Greek methods by 2,000 years, in 1110 BC, the south-pointing chariot was invented in ancient China. It was the first known geared mechanism to use a differential gear, the Chinese also invented a more sophisticated abacus from around the 2nd century BC known as the Chinese abacus. In the 5th century BC in ancient India, the grammarian Pāṇini formulated the grammar of Sanskrit in 3959 rules known as the Ashtadhyayi which was highly systematized, panini used metarules, transformations and recursions. The Antikythera mechanism is believed to be the earliest known analog computer. It was designed to calculate astronomical positions and it was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC. According to Simon Singh, Muslim mathematicians also made important advances in cryptography, such as the development of cryptanalysis, during the Middle Ages, several European philosophers made attempts to produce analog computer devices. Moreover, they lacked a versatile architecture, each machine serving only very concrete purposes, in spite of this, Llulls work had a strong influence on Gottfried Leibniz, who developed his ideas further, and built several calculating tools using them. The apex of this era of formal computing can be seen in the difference engine and its successor the analytical engine. The analytical engine combined concepts from his work and that of others to create a device that if constructed as designed would have possessed many properties of an electronic computer. This was a shift in thought, previous computational devices served only a single purpose. Babbages devices could be reprogramed to solve new problems by the entry of new data, ada Lovelace took this concept one step further, by creating a program for the analytical engine to calculate Bernoulli numbers, a complex calculation requiring a recursive algorithm
18.
History of computing hardware
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The history of computing hardware covers the developments from early simple devices to aid calculation to modern day computers. Before the 20th century, most calculations were done by humans, early mechanical tools to help humans with digital calculations, such as the abacus, were called calculating machines, by proprietary names, or even as they are now, calculators. The machine operator was called the computer, later, computers represented numbers in a continuous form, for instance distance along a scale, rotation of a shaft, or a voltage. Numbers could also be represented in the form of digits, automatically manipulated by a mechanical mechanism, although this approach generally required more complex mechanisms, it greatly increased the precision of results. A series of breakthroughs, such as miniaturized transistor computers, the cost of computers gradually became so low that by the 1990s, personal computers, and then, in the 2000s, mobile computers, became ubiquitous in industrialized countries. Devices have been used to aid computation for thousands of years, the earliest counting device was probably a form of tally stick. Later record keeping throughout the Fertile Crescent included calculi which represented counts of items, probably livestock or grains. The use of counting rods is one example, the abacus was early used for arithmetic tasks. What we now call the Roman abacus was used in Babylonia as early as 2400 BC, since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, several analog computers were constructed in ancient and medieval times to perform astronomical calculations. These include the Antikythera mechanism and the astrolabe from ancient Greece, hero of Alexandria made many complex mechanical devices including automata and a programmable cart. Ramon Llull invented the Lullian Circle, a machine for calculating answers to philosophical questions via logical combinatorics. This idea was taken up by Leibniz centuries later, and is one of the founding elements in computing. While producing the first logarithmic tables, Napier needed to perform many tedious multiplications and it was at this point that he designed his Napiers bones, an abacus-like device that greatly simplified calculations that involved multiplication and division. Edmund Gunter built a device with a single logarithmic scale at the University of Oxford. His device greatly simplified arithmetic calculations, including multiplication and division, William Oughtred greatly improved this in 1630 with his circular slide rule. He followed this up with the slide rule in 1632. Slide rules were used by generations of engineers and other mathematically involved professional workers, Wilhelm Schickard, a German polymath, designed a calculating machine in 1623 which combined a mechanised form of Napiers rods with the worlds first mechanical adding machine built into the base
19.
Number
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Numbers that answer the question How many. Are 0,1,2,3 and so on, when used to indicate position in a sequence they are ordinal numbers. To the Pythagoreans and Greek mathematician Euclid, the numbers were 2,3,4,5, Euclid did not consider 1 to be a number. Numbers like 3 +17 =227, expressible as fractions in which the numerator and denominator are whole numbers, are rational numbers and these make it possible to measure such quantities as two and a quarter gallons and six and a half miles. What we today would consider a proof that a number is irrational Euclid called a proof that two lengths arising in geometry have no common measure, or are incommensurable, Euclid included proofs of incommensurability of lengths arising in geometry in his Elements. In the Rhind Mathematical Papyrus, a pair of walking forward marked addition. They were the first known civilization to use negative numbers, negative numbers came into widespread use as a result of their utility in accounting. They were used by late medieval Italian bankers, by 1740 BC, the Egyptians had a symbol for zero in accounting texts. In Maya civilization zero was a numeral with a shape as a symbol. The ancient Egyptians represented all fractions in terms of sums of fractions with numerator 1, for example, 2/5 = 1/3 + 1/15. Such representations are known as Egyptian Fractions or Unit Fractions. The earliest written approximations of π are found in Egypt and Babylon, in Babylon, a clay tablet dated 1900–1600 BC has a geometrical statement that, by implication, treats π as 25/8 =3.1250. In Egypt, the Rhind Papyrus, dated around 1650 BC, astronomical calculations in the Shatapatha Brahmana use a fractional approximation of 339/108 ≈3.139. Other Indian sources by about 150 BC treat π as √10 ≈3.1622 The first references to the constant e were published in 1618 in the table of an appendix of a work on logarithms by John Napier. However, this did not contain the constant itself, but simply a list of logarithms calculated from the constant and it is assumed that the table was written by William Oughtred. The discovery of the constant itself is credited to Jacob Bernoulli, the first known use of the constant, represented by the letter b, was in correspondence from Gottfried Leibniz to Christiaan Huygens in 1690 and 1691. Leonhard Euler introduced the letter e as the base for natural logarithms, Euler started to use the letter e for the constant in 1727 or 1728, in an unpublished paper on explosive forces in cannons, and the first appearance of e in a publication was Eulers Mechanica. While in the subsequent years some researchers used the letter c, e was more common, the first numeral system known is Babylonian numeric system, that has a 60 base, it was introduced in 3100 B. C. and is the first Positional numeral system known
20.
Abstraction
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An abstraction is the product of this process — a concept that acts as a super-categorical noun for all subordinate concepts, and connects any related concepts as a group, field, or category. Conceptual abstractions may be formed by filtering the information content of a concept or an observable phenomenon, in a type–token distinction, a type is more abstract than its tokens. Abstraction in its use is a material process, discussed in the themes below. Its development is likely to have been connected with the development of human language. Abstraction involves induction of ideas or the synthesis of particular facts into one theory about something. It is the opposite of specification, which is the analysis or breaking-down of an idea or abstraction into concrete facts. Thales believed that everything in the universe comes from one main substance and he deduced or specified from a general idea, everything is water, to the specific forms of water such as ice, snow, fog, and rivers. Modern scientists can use the opposite approach of abstraction, or going from particular facts collected into one general idea. This conceptual scheme emphasizes the inherent equality of both constituent and abstract data, thus avoiding problems arising from the distinction between abstract and concrete, in this sense the process of abstraction entails the identification of similarities between objects, and the process of associating these objects with an abstraction. For example, picture 1 below illustrates the concrete relationship Cat sits on Mat, for example, graph 1 below expresses the abstraction agent sits on location. This conceptual scheme entails no specific hierarchical taxonomy, only a progressive exclusion of detail, things that do not exist at any particular place and time are often considered abstract. By contrast, instances, or members, of such a thing might exist in many different places and times. Those abstract things are said to be multiply instantiated, in the sense of picture 1, picture 2. It is not sufficient, however, to abstract ideas as those that can be instantiated. Although the concepts cat and telephone are abstractions, they are not abstract in the sense of the objects in graph 1 below, perhaps confusingly, some philosophies refer to tropes as abstract particulars — e. g. the particular redness of a particular apple is an abstract particular. This is similar to qualia and sumbebekos, karl Marxs writing on the commodity abstraction recognizes a parallel process. The state as both concept and material practice exemplifies the two sides of this process of abstraction, conceptually, the current concept of the state is an abstraction from the much more concrete early-modern use as the standing or status of the prince, his visible estates. At the same time, materially, the practice of statehood is now constitutively and materially more abstract than at the time when princes ruled as the embodiment of extended power and that difference accounts for the ontological usefulness of the word abstract
21.
One-to-one correspondence
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In mathematical terms, a bijective function f, X → Y is a one-to-one and onto mapping of a set X to a set Y. A bijection from the set X to the set Y has a function from Y to X. If X and Y are finite sets, then the existence of a means they have the same number of elements. For infinite sets the picture is complicated, leading to the concept of cardinal number. A bijective function from a set to itself is called a permutation. Bijective functions are essential to many areas of including the definitions of isomorphism, homeomorphism, diffeomorphism, permutation group. Satisfying properties and means that a bijection is a function with domain X and it is more common to see properties and written as a single statement, Every element of X is paired with exactly one element of Y. Functions which satisfy property are said to be onto Y and are called surjections, Functions which satisfy property are said to be one-to-one functions and are called injections. With this terminology, a bijection is a function which is both a surjection and an injection, or using words, a bijection is a function which is both one-to-one and onto. Consider the batting line-up of a baseball or cricket team, the set X will be the players on the team and the set Y will be the positions in the batting order The pairing is given by which player is in what position in this order. Property is satisfied since each player is somewhere in the list, property is satisfied since no player bats in two positions in the order. Property says that for each position in the order, there is some player batting in that position, in a classroom there are a certain number of seats. A bunch of students enter the room and the instructor asks them all to be seated. After a quick look around the room, the instructor declares that there is a bijection between the set of students and the set of seats, where each student is paired with the seat they are sitting in. The instructor was able to conclude there were just as many seats as there were students. For any set X, the identity function 1X, X → X, the function f, R → R, f = 2x +1 is bijective, since for each y there is a unique x = /2 such that f = y. In more generality, any linear function over the reals, f, R → R, f = ax + b is a bijection, each real number y is obtained from the real number x = /a. The function f, R →, given by f = arctan is bijective since each real x is paired with exactly one angle y in the interval so that tan = x
22.
Abacus
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The exact origin of the abacus is still unknown. Today, abaci are often constructed as a frame with beads sliding on wires. The use of the word abacus dates before 1387 AD, when a Middle English work borrowed the word from Latin to describe a sandboard abacus, the Latin word came from Greek ἄβαξ abax which means something without base, and improperly, any piece of rectangular board or plank. Alternatively, without reference to ancient texts on etymology, it has suggested that it means a square tablet strewn with dust. Whereas the table strewn with dust definition is popular, there are those that do not place credence in this at all, Greek ἄβαξ itself is probably a borrowing of a Northwest Semitic, perhaps Phoenician, word akin to Hebrew ʾābāq, dust. The preferred plural of abacus is a subject of disagreement, with both abacuses and abaci in use, the user of an abacus is called an abacist. The period 2700–2300 BC saw the first appearance of the Sumerian abacus, some scholars point to a character from the Babylonian cuneiform which may have been derived from a representation of the abacus. Archaeologists have found ancient disks of various sizes that are thought to have used as counters. However, wall depictions of this instrument have not been discovered, during the Achaemenid Empire, around 600 BC the Persians first began to use the abacus. The earliest archaeological evidence for the use of the Greek abacus dates to the 5th century BC, also Demosthenes talked of the need to use pebbles for calculations too difficult for your head. The Greek abacus was a table of wood or marble, pre-set with small counters in wood or metal for mathematical calculations and this Greek abacus saw use in Achaemenid Persia, the Etruscan civilization, Ancient Rome and, until the French Revolution, the Western Christian world. A tablet found on the Greek island Salamis in 1846 AD, dates back to 300 BC and it is a slab of white marble 149 cm long,75 cm wide, and 4.5 cm thick, on which are 5 groups of markings. Below these lines is a space with a horizontal crack dividing it. Also from this frame the Darius Vase was unearthed in 1851. It was covered with pictures including a holding a wax tablet in one hand while manipulating counters on a table with the other. The earliest known documentation of the Chinese abacus dates to the 2nd century BC. The Chinese abacus, known as the suanpan, is typically 20 cm tall and it usually has more than seven rods. There are two beads on each rod in the deck and five beads each in the bottom for both decimal and hexadecimal computation
23.
Babylon
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Babylon was a major city of ancient Mesopotamia in the fertile plain between the Tigris and Euphrates rivers. The city was built upon the Euphrates and divided in parts along its left and right banks. Babylon was originally a small Semitic Akkadian city dating from the period of the Akkadian Empire c.2300 BC, the town attained independence as part of a small city-state with the rise of the First Amorite Babylonian Dynasty in 1894 BC. Babylon grew and South Mesopotamia came to be known as Babylonia, the empire quickly dissolved after Hammurabis death and Babylon spent long periods under Assyrian, Kassite and Elamite domination. After being destroyed and then rebuilt by the Assyrians, Babylon became the capital of the Neo-Babylonian Empire from 609 to 539 BC, the Hanging Gardens of Babylon was one of the Seven Wonders of the Ancient World. After the fall of the Neo-Babylonian Empire, the city came under the rule of the Achaemenid, Seleucid, Parthian, Roman, and Sassanid empires. It has been estimated that Babylon was the largest city in the world from c.1770 to 1670 BC and it was perhaps the first city to reach a population above 200,000. Estimates for the extent of its area range from 890 to 900 hectares. The remains of the city are in present-day Hillah, Babil Governorate, Iraq, about 85 kilometres south of Baghdad, comprising a large tell of broken mud-brick buildings, the English Babylon comes from Greek Babylṓn, a transliteration of the Akkadian Babili. The Babylonian name in the early 2nd millennium BC had been Babilli or Babilla, by the 1st millennium BC, it had changed to Babili under the influence of the folk etymology which traced it to bāb-ili. The Gate of God or Gate of El being from the Aramaic Hebrew Bab for Gate and El for God and this being similar to the Hebrew word for confusion Balal. In the Bible, the name appears as Babel, interpreted in the Hebrew Scriptures Book of Genesis to mean confusion, the modern English verb, to babble, or to speak meaningless words, is popularly thought to derive from this name, but there is no direct connection. The remains of the city are in present-day Hillah, Babil Governorate, Iraq, about 85 kilometers south of Baghdad, comprising a large tell of broken mud-brick buildings and debris. The site at Babylon consists of a number of mounds covering an area of about 2 by 1 kilometer, oriented north to south, along the Euphrates to the west. Originally, the river roughly bisected the city, but the course of the river has since shifted so that most of the remains of the western part of the city are now inundated. Some portions of the city wall to the west of the river also remain, remains of the city include, Kasr—also called Palace or Castle, it is the location of the Neo-Babylonian ziggurat Etemenanki and lies in the center of the site. Amran Ibn Ali—the highest of the mounds at 25 meters, to the south and it is the site of Esagila, a temple of Marduk which also contained shrines to Ea and Nabu. Homera—a reddish colored mound on the west side, most of the Hellenistic remains are here
24.
C. E. Wynn-Williams
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Charles Eryl Wynn-Williams, was a Welsh physicist, noted for his research on electronic instrumentation for use in nuclear physics. His work on the scale-of-two counter contributed to the development of the modern computer, Wynn-Williams was born at Glasfryn in Swansea, Glamorganshire, Wales, on 5 March 1903. His education was at Grove Park School in Wrexham, and, from 1920, at Bangor University and he stayed on University to undertake research work on electrical instrumentation, and gained the degree of MSc from the University of Wales in 1924. He was known as C. E. Wynn-Williams from his time at University onwards, Wynn-Williams was Liberal in politics and was a Welsh-speaker. On 12 August 1943 he married in London Annie Eiluned James, in October 1925 he entered Trinity College, Cambridge, having been awarded a University of Wales open fellowship. Initially he continued research into short electric waves at the Cavendish Laboratory under the supervision of Sir Ernest Rutherford, Wynn-Williams most significant work in this period, however, was in the development of electronic instrumentation for use in radioactivity and nuclear physics. Like many scientists at that time he was a wireless enthusiast, in 1926 he employed his electronics skills to construct an amplifier using thermionic valves for very small electrical currents. There followed a series of brilliant contributions to the armamentarium of nuclear physics, in 1929–30, with H. M. Cave and F. A. B. Ward he designed and constructed a counting device using thyratrons in conjunction with a mechanical counter. By 1931 a valve amplifier and thyratron-based automatic counting system were in use in the Cavendish Laboratory. Wynn-Williams amplifier played an important part in James Chadwicks discovery of the neutron in 1932, in 1932 Wynn-Williams published details of his thyratron-based scale-of-two counter, which allowed particles to be counted at much higher rates than previously. His devices became crucial unifying elements in the hardware of the emergent discipline of nuclear physics and they were widely copied in laboratories in Europe and the United States of America, often with advice from Wynn-Williams. In 1935 Wynn-Williams was appointed assistant lecturer in physics at Imperial College, continuing his work on electronic instrumentation he contributed to the development of nuclear physics at Imperial under G. P. Thomson. On 1 February 1942, the Allied success in breaking Nazi German naval Enigma messages suffered a serious setback and this was due to the adoption, for the North Atlantic U-boat traffic, of an Enigma machine with an additional rotor — the four-wheel Enigma. This increased the time required of the Turing-designed Bombe machines by a factor of 26, higher speed bombes were therefore needed and Wynn-Williams was called in to contribute to one of the streams of development of high-speed Bombes. The Post Office team developed a Bombe attachment for a standard three-wheel Bombe containing high speed wheels and it was attached to the Bombe by a very thick cable and was dubbed the Cobra Bombe. Both machines were subsequently overshadowed by the success of the US Navy Bombes. The one using the Lorenz SZ 40/42, code-named Tunny at the Government Code & Cypher School at Bletchley Park, was used for traffic between German High Command and field commanders. A young chemistry graduate, Bill Tutte worked out how it could in theory be broken and he took the idea to his boss, the mathematician Max Newman, who realised that the only feasible way to apply the method, was by automating it
25.
Claude Shannon
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Claude Elwood Shannon was an American mathematician, electrical engineer, and cryptographer known as the father of information theory. Shannon is noted for having founded information theory with a paper, A Mathematical Theory of Communication. Shannon contributed to the field of cryptanalysis for national defense during World War II, including his work on codebreaking. Shannon was born in Petoskey, Michigan and grew up in Gaylord and his father, Claude, Sr. a descendant of early settlers of New Jersey, was a self-made businessman, and for a while, a Judge of Probate. Shannons mother, Mabel Wolf Shannon, was a language teacher, most of the first 16 years of Shannons life were spent in Gaylord, where he attended public school, graduating from Gaylord High School in 1932. Shannon showed an inclination towards mechanical and electrical things and his best subjects were science and mathematics. At home he constructed such devices as models of planes, a model boat. While growing up, he worked under Andrew Coltrey as a messenger for the Western Union company. His childhood hero was Thomas Edison, who he learned was a distant cousin. Both were descendants of John Ogden, a leader and an ancestor of many distinguished people. Shannon was apolitical and an atheist, in 1932, Shannon entered the University of Michigan, where he was introduced to the work of George Boole. He graduated in 1936 with two degrees, one in electrical engineering and the other in mathematics. In 1936, Shannon began his studies in electrical engineering at MIT, where he worked on Vannevar Bushs differential analyzer. While studying the complicated ad hoc circuits of this analyzer, Shannon designed switching circuits based on Booles concepts, in 1937, he wrote his masters degree thesis, A Symbolic Analysis of Relay and Switching Circuits, A paper from this thesis was published in 1938. In this work, Shannon proved that his switching circuits could be used to simplify the arrangement of the electromechanical relays that were used then in telephone call routing switches, next, he expanded this concept, proving that these circuits could solve all problems that Boolean algebra could solve. In the last chapter, he presents diagrams of several circuits, using this property of electrical switches to implement logic is the fundamental concept that underlies all electronic digital computers. Shannons work became the foundation of digital design, as it became widely known in the electrical engineering community during. The theoretical rigor of Shannons work superseded the ad hoc methods that had prevailed previously, howard Gardner called Shannons thesis possibly the most important, and also the most noted, masters thesis of the century
26.
Boolean algebra
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In mathematics and mathematical logic, Boolean algebra is the branch of algebra in which the values of the variables are the truth values true and false, usually denoted 1 and 0 respectively. It is thus a formalism for describing logical relations in the way that ordinary algebra describes numeric relations. Boolean algebra was introduced by George Boole in his first book The Mathematical Analysis of Logic, according to Huntington, the term Boolean algebra was first suggested by Sheffer in 1913. Boolean algebra has been fundamental in the development of digital electronics and it is also used in set theory and statistics. Booles algebra predated the modern developments in algebra and mathematical logic. In an abstract setting, Boolean algebra was perfected in the late 19th century by Jevons, Schröder, Huntington, in fact, M. H. Stone proved in 1936 that every Boolean algebra is isomorphic to a field of sets. Shannon already had at his disposal the abstract mathematical apparatus, thus he cast his switching algebra as the two-element Boolean algebra, in circuit engineering settings today, there is little need to consider other Boolean algebras, thus switching algebra and Boolean algebra are often used interchangeably. Efficient implementation of Boolean functions is a problem in the design of combinational logic circuits. Logic sentences that can be expressed in classical propositional calculus have an equivalent expression in Boolean algebra, thus, Boolean logic is sometimes used to denote propositional calculus performed in this way. Boolean algebra is not sufficient to capture logic formulas using quantifiers, the closely related model of computation known as a Boolean circuit relates time complexity to circuit complexity. Whereas in elementary algebra expressions denote mainly numbers, in Boolean algebra they denote the truth values false and these values are represented with the bits, namely 0 and 1. Addition and multiplication then play the Boolean roles of XOR and AND respectively, Boolean algebra also deals with functions which have their values in the set. A sequence of bits is a commonly used such function, another common example is the subsets of a set E, to a subset F of E is associated the indicator function that takes the value 1 on F and 0 outside F. The most general example is the elements of a Boolean algebra, as with elementary algebra, the purely equational part of the theory may be developed without considering explicit values for the variables. The basic operations of Boolean calculus are as follows, AND, denoted x∧y, satisfies x∧y =1 if x = y =1 and x∧y =0 otherwise. OR, denoted x∨y, satisfies x∨y =0 if x = y =0, NOT, denoted ¬x, satisfies ¬x =0 if x =1 and ¬x =1 if x =0. Alternatively the values of x∧y, x∨y, and ¬x can be expressed by tabulating their values with truth tables as follows, the first operation, x → y, or Cxy, is called material implication. If x is then the value of x → y is taken to be that of y
27.
Machine
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A machine is a tool containing one or more parts that uses energy to perform an intended action. Machines are usually powered by chemical, thermal, or electrical means, historically, a power tool also required moving parts to classify as a machine. However, the advent of electronics has led to the development of power tools without moving parts that are considered machines, a simple machine is a device that simply transforms the direction or magnitude of a force, but a large number of more complex machines exist. Examples include vehicles, electronic systems, molecular machines, computers, television, the word machine derives from the Latin word machina, which in turn derives from the Greek. The word mechanical comes from the same Greek roots, however, the Ancient Greeks probably have borrowed the word mekhane from the ancient Hebrews. The ancient Greeks were familiar with the Hebrew Scriptures and language, a wider meaning of fabric, structure is found in classical Latin, but not in Greek usage. This meaning is found in late medieval French, and is adopted from the French into English in the mid-16th century, in the 17th century, the word could also mean a scheme or plot, a meaning now expressed by the derived machination. The modern meaning develops out of specialized application of the term to stage engines used in theater and to siege engines. Simple Machines are commonly reckoned to be Six in Number, viz. the Ballance, Leaver, Pulley, Wheel, Wedge, compound Machines, or Engines, are innumerable. The word engine used as a synonym both by Harris and in later language derives ultimately from Latin ingenium ingenuity, an invention, perhaps the first example of a human made device designed to manage power is the hand axe, made by chipping flint to form a wedge. A wedge is a machine that transforms lateral force and movement of the tool into a transverse splitting force. The idea of a simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines, lever, pulley and he discovered the principle of mechanical advantage in the lever. Later Greek philosophers defined the five simple machines and were able to roughly calculate their mechanical advantage. Heron of Alexandria in his work Mechanics lists five mechanisms that can set a load in motion, lever, windlass, pulley, wedge, and screw, however the Greeks understanding was limited to statics and did not include dynamics or the concept of work. In 1586 Flemish engineer Simon Stevin derived the mechanical advantage of the inclined plane, the complete dynamic theory of simple machines was worked out by Italian scientist Galileo Galilei in 1600 in Le Meccaniche. He was the first to understand that simple machines do not create energy, the classic rules of sliding friction in machines were discovered by Leonardo da Vinci, but remained unpublished in his notebooks. They were rediscovered by Guillaume Amontons and were developed by Charles-Augustin de Coulomb. The word mechanical refers to the work that has produced by machines or the machinery
28.
Source code
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In computing, source code is any collection of computer instructions, possibly with comments, written using a human-readable programming language, usually as ordinary text. The source code of a program is designed to facilitate the work of computer programmers. The source code is often transformed by an assembler or compiler into binary machine code understood by the computer, the machine code might then be stored for execution at a later time. Alternatively, source code may be interpreted and thus immediately executed, most application software is distributed in a form that includes only executable files. If the source code were included it would be useful to a user, programmer or a system administrator, the Linux Information Project defines source code as, Source code is the version of software as it is originally written by a human in plain text. The notion of source code may also be more broadly, to include machine code and notations in graphical languages. It is therefore so construed as to include code, very high level languages. Often there are several steps of program translation or minification between the source code typed by a human and an executable program. The earliest programs for stored-program computers were entered in binary through the front panel switches of the computer and this first-generation programming language had no distinction between source code and machine code. When IBM first offered software to work with its machine, the code was provided at no additional charge. At that time, the cost of developing and supporting software was included in the price of the hardware, for decades, IBM distributed source code with its software product licenses, until 1983. Most early computer magazines published source code as type-in programs, Source code can also be stored in a database or elsewhere. The source code for a piece of software may be contained in a single file or many files. Though the practice is uncommon, a source code can be written in different programming languages. For example, a program written primarily in the C programming language, in some languages, such as Java, this can be done at run time. The code base of a programming project is the larger collection of all the source code of all the computer programs which make up the project. It has become practice to maintain code bases in version control systems. Moderately complex software customarily requires the compilation or assembly of several, sometimes dozens or even hundreds, in these cases, instructions for compilations, such as a Makefile, are included with the source code
29.
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
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Programmer
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A programmer, computer programmer, developer, dev, coder, or software engineer is a person who writes computer software. The term computer programmer can refer to a specialist in one area of programming or to a generalist who writes code for many kinds of software. One who practices or professes a formal approach to programming may also be known as a programmer analyst, a programmers primary computer language is often prefixed to these titles, and those who work in a web environment often prefix their titles with web. The use of the term programmer for these positions is sometimes considered an insulting or derogatory oversimplification. Because Babbages machine was never completed to a standard in her time. The first person to run a program on a functioning modern electronically based computer was computer scientist Konrad Zuse, the ENIAC programming team, consisting of Kay McNulty, Betty Jennings, Betty Snyder, Marlyn Wescoff, Fran Bilas and Ruth Lichterman were the first regularly working programmers. International Programmers Day is celebrated annually on 7 January, in 2009, the government of Russia decreed a professional annual holiday known as Programmers Day to be celebrated on 13 September. It had also been an international holiday before that. Some of this section is from the Occupational Outlook Handbook, 2006–07 Edition, Computer programmers write, test, debug, and maintain the detailed instructions, called computer programs, that computers must follow to perform their functions. Programmers also conceive, design, and test logical structures for solving problems by computer, job titles and descriptions may vary, depending on the organization. Programmers work in many settings, including corporate information technology departments, big companies, small service firms. Many professional programmers also work for consulting companies at client sites as contractors, licensing is not typically required to work as a programmer, although professional certifications are commonly held by programmers. Programming is widely considered a profession, Programmers work varies widely depending on the type of business for which they are writing programs. For example, the involved in updating financial records are very different from those required to duplicate conditions on an aircraft for pilots training in a flight simulator. In most cases, several work together as a team under a senior programmer’s supervision. Programmers write programs according to the specifications determined primarily by more senior programmers, after the design process is complete, it is the job of the programmer to convert that design into a logical series of instructions that the computer can follow. The programmer codes these instructions in one of many programming languages, different programming languages are used depending on the purpose of the program. COBOL, for example, is used for business applications that typically run on mainframe and midrange computers, whereas Fortran is used in science
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Algorithm
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In mathematics and computer science, an algorithm is a self-contained sequence of actions to be performed. Algorithms can perform calculation, data processing and automated reasoning tasks, an algorithm is an effective method that can be expressed within a finite amount of space and time and in a well-defined formal language for calculating a function. The transition from one state to the next is not necessarily deterministic, some algorithms, known as randomized algorithms, giving a formal definition of algorithms, corresponding to the intuitive notion, remains a challenging problem. In English, it was first used in about 1230 and then by Chaucer in 1391, English adopted the French term, but it wasnt until the late 19th century that algorithm took on the meaning that it has in modern English. Another early use of the word is from 1240, in a manual titled Carmen de Algorismo composed by Alexandre de Villedieu and it begins thus, Haec algorismus ars praesens dicitur, in qua / Talibus Indorum fruimur bis quinque figuris. Which translates as, Algorism is the art by which at present we use those Indian figures, the poem is a few hundred lines long and summarizes the art of calculating with the new style of Indian dice, or Talibus Indorum, or Hindu numerals. An informal definition could be a set of rules that precisely defines a sequence of operations, which would include all computer programs, including programs that do not perform numeric calculations. Generally, a program is only an algorithm if it stops eventually, but humans can do something equally useful, in the case of certain enumerably infinite sets, They can give explicit instructions for determining the nth member of the set, for arbitrary finite n. An enumerably infinite set is one whose elements can be put into one-to-one correspondence with the integers, the concept of algorithm is also used to define the notion of decidability. That notion is central for explaining how formal systems come into being starting from a set of axioms. In logic, the time that an algorithm requires to complete cannot be measured, from such uncertainties, that characterize ongoing work, stems the unavailability of a definition of algorithm that suits both concrete and abstract usage of the term. Algorithms are essential to the way computers process data, thus, an algorithm can be considered to be any sequence of operations that can be simulated by a Turing-complete system. Although this may seem extreme, the arguments, in its favor are hard to refute. Gurevich. Turings informal argument in favor of his thesis justifies a stronger thesis, according to Savage, an algorithm is a computational process defined by a Turing machine. Typically, when an algorithm is associated with processing information, data can be read from a source, written to an output device. Stored data are regarded as part of the state of the entity performing the algorithm. In practice, the state is stored in one or more data structures, for some such computational process, the algorithm must be rigorously defined, specified in the way it applies in all possible circumstances that could arise. That is, any conditional steps must be dealt with, case-by-case
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Central processing unit
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The computer industry has used the term central processing unit at least since the early 1960s. The form, design and implementation of CPUs have changed over the course of their history, most modern CPUs are microprocessors, meaning they are contained on a single integrated circuit chip. An IC that contains a CPU may also contain memory, peripheral interfaces, some computers employ a multi-core processor, which is a single chip containing two or more CPUs called cores, in that context, one can speak of such single chips as sockets. Array processors or vector processors have multiple processors that operate in parallel, there also exists the concept of virtual CPUs which are an abstraction of dynamical aggregated computational resources. Early computers such as the ENIAC had to be rewired to perform different tasks. Since the term CPU is generally defined as a device for software execution, the idea of a stored-program computer was already present in the design of J. Presper Eckert and John William Mauchlys ENIAC, but was initially omitted so that it could be finished sooner. On June 30,1945, before ENIAC was made, mathematician John von Neumann distributed the paper entitled First Draft of a Report on the EDVAC and it was the outline of a stored-program computer that would eventually be completed in August 1949. EDVAC was designed to perform a number of instructions of various types. Significantly, the programs written for EDVAC were to be stored in high-speed computer memory rather than specified by the wiring of the computer. This overcame a severe limitation of ENIAC, which was the considerable time, with von Neumanns design, the program that EDVAC ran could be changed simply by changing the contents of the memory. Early CPUs were custom designs used as part of a larger, however, this method of designing custom CPUs for a particular application has largely given way to the development of multi-purpose processors produced in large quantities. This standardization began in the era of discrete transistor mainframes and minicomputers and has accelerated with the popularization of the integrated circuit. The IC has allowed increasingly complex CPUs to be designed and manufactured to tolerances on the order of nanometers, both the miniaturization and standardization of CPUs have increased the presence of digital devices in modern life far beyond the limited application of dedicated computing machines. Modern microprocessors appear in electronic devices ranging from automobiles to cellphones, the so-called Harvard architecture of the Harvard Mark I, which was completed before EDVAC, also utilized a stored-program design using punched paper tape rather than electronic memory. Relays and vacuum tubes were used as switching elements, a useful computer requires thousands or tens of thousands of switching devices. The overall speed of a system is dependent on the speed of the switches, tube computers like EDVAC tended to average eight hours between failures, whereas relay computers like the Harvard Mark I failed very rarely. In the end, tube-based CPUs became dominant because the significant speed advantages afforded generally outweighed the reliability problems, most of these early synchronous CPUs ran at low clock rates compared to modern microelectronic designs. Clock signal frequencies ranging from 100 kHz to 4 MHz were very common at this time, the design complexity of CPUs increased as various technologies facilitated building smaller and more reliable electronic devices
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Process (computing)
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In computing, a process is an instance of a computer program that is being executed. It contains the code and its current activity. Depending on the system, a process may be made up of multiple threads of execution that execute instructions concurrently. A computer program is a collection of instructions, while a process is the actual execution of those instructions. Several processes may be associated with the program, for example. Multitasking is a method to allow processes to share processors. Each CPU executes a task at a time. However, multitasking allows each processor to switch between tasks that are being executed without having to wait for each task to finish. Depending on the system implementation, switches could be performed when tasks perform input/output operations. A common form of multitasking is time-sharing, time-sharing is a method to allow fast response for interactive user applications. In time-sharing systems, context switches are performed rapidly, which makes it seem like multiple processes are being executed simultaneously on the same processor and this seeming execution of multiple processes simultaneously is called concurrency. In general, a system process consists of the following resources. Memory, which includes the code, process-specific data, a call stack. Operating system descriptors of resources that are allocated to the process, such as file descriptors or handles, security attributes, such as the process owner and the process set of permissions. Processor state, such as the content of registers and physical memory addressing, the state is typically stored in computer registers when the process is executing, and in memory otherwise. The operating system holds most of this information about processes in data structures called process control blocks. Any subset of the resources, typically at least the processor state, the operating system keeps its processes separate and allocates the resources they need, so that they are less likely to interfere with each other and cause system failures. The operating system may also provide mechanisms for communication to enable processes to interact in safe
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Instruction set architecture
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An ISA includes a specification of the set of opcodes, and the native commands implemented by a particular processor. An instruction set architecture is distinguished from a microarchitecture, which is the set of design techniques used, in a particular processor. Processors with different microarchitectures can share a common instruction set, for example, the Intel Pentium and the AMD Athlon implement nearly identical versions of the x86 instruction set, but have radically different internal designs. The concept of an architecture, distinct from the design of a machine, was developed by Fred Brooks at IBM during the design phase of System/360. Prior to NPL, the companys computer designers had been free to honor cost objectives not only by selecting technologies, the SPREAD compatibility objective, in contrast, postulated a single architecture for a series of five processors spanning a wide range of cost and performance. In addition, these virtual machines execute less frequently used code paths by interpretation, transmeta implemented the x86 instruction set atop VLIW processors in this fashion. A complex instruction set computer has many specialized instructions, some of which may only be used in practical programs. Theoretically important types are the instruction set computer and the one instruction set computer. Another variation is the very long instruction word where the processor receives many instructions encoded and retrieved in one instruction word, machine language is built up from discrete statements or instructions. Examples of operations common to many instruction sets include, Set a register to a constant value. Copy data from a location to a register, or vice versa. Used to store the contents of a register, result of a computation, often called load and store operations. Read and write data from hardware devices, add, subtract, multiply, or divide the values of two registers, placing the result in a register, possibly setting one or more condition codes in a status register. Increment, decrement in some ISAs, saving operand fetch in trivial cases, perform bitwise operations, e. g. taking the conjunction and disjunction of corresponding bits in a pair of registers, taking the negation of each bit in a register. Floating-point instructions for arithmetic on floating-point numbers, branch to another location in the program and execute instructions there. Conditionally branch to another if a certain condition holds. Call another block of code, while saving the location of the instruction as a point to return to. Load/store data to and from a coprocessor, or exchanging with CPU registers, processors may include complex instructions in their instruction set
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Application software
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An application program is a computer program designed to perform a group of coordinated functions, tasks, or activities for the benefit of the user. Examples of an application include a processor, a spreadsheet, an accounting application, a web browser, a media player, an aeronautical flight simulator. The collective noun application software refers to all applications collectively and this contrasts with system software, which is mainly involved with running the computer. Applications may be bundled with the computer and its software or published separately. Apps built for mobile platforms are called mobile apps, in information technology, an application is a computer program designed to help people perform an activity. An application thus differs from a system, a utility. Depending on the activity for which it was designed, an application can manipulate text, numbers, graphics, some application packages focus on a single task, such as word processing, others, called integrated software include several applications. User-written software tailors systems to meet the specific needs. User-written software includes templates, word processor macros, scientific simulations, graphics. Even email filters are a kind of user software, users create this software themselves and often overlook how important it is. The delineation between system software such as operating systems and application software is not exact, however, and is occasionally the object of controversy. As another example, the GNU/Linux naming controversy is, in part, the above definitions may exclude some applications that may exist on some computers in large organizations. For an alternative definition of an app, see Application Portfolio Management, the word application, once used as an adjective, is not restricted to the of or pertaining to application software meaning. Sometimes a new and popular application arises which only runs on one platform and this is called a killer application or killer app. There are many different ways to divide up different types of application software, web apps have indeed greatly increased in popularity for some uses, but the advantages of applications make them unlikely to disappear soon, if ever. Furthermore, the two can be complementary, and even integrated, Application software can also be seen as being either horizontal or vertical. Horizontal applications are more popular and widespread, because they are general purpose, vertical applications are niche products, designed for a particular type of industry or business, or department within an organization. Integrated suites of software will try to handle every aspect possible of, for example, manufacturing or banking systems, or accounting
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