A computer is a programmable machine A machine is a device that uses energy to perform some activity. In common usage, the meaning is that of a device having parts that perform or assist in performing any type of work. A simple machine is a device that transforms the direction or magnitude of a force without consuming any energy. The word "machine" is derived from the Latin that receives input, stores and manipulates data In computer science, data is anything in a form suitable for use with a computer. Data is often distinguished from programs. A program is a set of instructions that detail a task for the computer to perform. In this sense, data is thus everything that is not program code//information Information, in its most restricted technical sense, is an ordered sequence of symbols. As a concept, however, information has many meanings. Moreover, the concept of information is closely related to notions of constraint, communication, control, form, instruction, knowledge, meaning, mental stimulus, pattern, perception, and representation, and provides output in a useful format.

While a computer can, in theory, be made out of almost anything (see misconceptions section), and mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century (1940–1945). Originally, they were the size of a large room, consuming as much power as several hundred modern personal computers A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator. This is in contrast to the batch processing or time-sharing models which allowed large expensive mainframe (PCs).^[1] Modern computers based on integrated circuits In electronics, an integrated circuit is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material. Integrated circuits are used in almost all electronic equipment in use today and have revolutionized the are millions to billions of times more capable than the early machines, and occupy a fraction of the space.^[2] Simple computers are small enough to fit into mobile devices A mobile device is a pocket-sized computing device, typically having a display screen with touch input or a miniature keyboard. In the case of the personal digital assistant (PDA) the input and output are combined into a touch-screen interface. Smartphones and PDAs are popular amongst those who require the assistance and convenience of a, and can be powered by a small battery. Personal computers in their various forms are icons An icon is a religious work of art, most commonly a painting, from Eastern Orthodox Christianity and Catholicism. More broadly the term is used in a wide number of contexts for an image, picture, or representation; it is a sign or likeness that stands for an object by signifying or representing it either concretely or by analogy, as in semiotics; of the Information Age The Information Age, also commonly known as the Computer Age or Information Era, is an idea that the current age will be characterized by the ability of individuals to transfer information freely, and to have instant access to knowledge that would have been difficult or impossible to find previously. The idea is linked to the concept of a Digital and are what most people think of as "computers". However, the embedded computers An embedded system is a computer system designed to perform one or a few dedicated functions often with real-time computing constraints. It is embedded as part of a complete device often including hardware and mechanical parts. By contrast, a general-purpose computer, such as a personal computer , is designed to be flexible and to meet a wide found in many devices from MP3 players A digital audio player, or DAP, usually referred to as an MP3 player, is a consumer electronic device that has the primary function of storing, organizing and playing audio files. Some DAPs are also referred to as portable media players as they have image-viewing and/or video-playing support to fighter aircraft A fighter aircraft is a military aircraft designed primarily for air-to-air combat with other aircraft, as opposed to a bomber, which is designed primarily to attack ground targets by dropping bombs. Fighters are small, fast, and maneuverable. Many fighters have secondary ground-attack capabilities, and some are dual-roled as fighter-bombers; the and from toys A toy is any object that can be used for play. Toys are usually associated with children and pets, but it is not unusual for adults and some other animals to play with toys. An example of this is a dolphin being trained to nudge a ball through a hoop. Many items are designed to serve as toys, but goods produced for other purposes can also be used to industrial robots An industrial robot is officially defined by ISO as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes. The field of robotics may be more practically defined as the study, design and use of robot systems for manufacturing are the most numerous.

Misconceptions

A computer does not need to be electric Electricity is a general term that encompasses a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena, such as lightning and static electricity, but in addition, less familiar concepts, such as the electromagnetic field and electromagnetic induction, nor even have a processor, nor RAM Random-access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order (i.e., at random). "Random" refers to the idea that any piece of data can be returned in a constant time, regardless of its physical location and whether or not it is related to the, nor even hard disk Host adapter of system, in PCs typically integrated into motherboard. via one of:. The minimal definition of a computer is anything that transforms information Information, in its most restricted technical sense, is an ordered sequence of symbols. As a concept, however, information has many meanings. Moreover, the concept of information is closely related to notions of constraint, communication, control, form, instruction, knowledge, meaning, mental stimulus, pattern, perception, and representation in a purposeful way.

Required technology

Computational systems as flexible In computability theory, a collection of data-manipulation rules is said to be Turing complete if and only if such system can simulate any single-taped Turing machine. Classical Turing-complete systems include context-sensitive grammars, recursive functions and lambda calculus as a personal computer A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end user, with no intervening computer operator. This is in contrast to the batch processing or time-sharing models which allowed large expensive mainframe can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); this is an unintuitive and pedagogical example that a computer can be made out of almost anything. More realistically, modern computers are made out of transistors A transistor is a semiconductor device used to amplify and switch electronic signals. It is made of a solid piece of semiconductor material, with at least three terminals for connection to an external circuit. A voltage or current applied to one pair of the transistor's terminals changes the current flowing through another pair of terminals made of photolithographed Photolithography is a process used in microfabrication to selectively remove parts of a thin film or the bulk of a substrate. It uses light to transfer a geometric pattern from a photo mask to a light-sensitive chemical photo resist, or simply "resist," on the substrate. A series of chemical treatments then engraves the exposure pattern semiconductors A semiconductor is a material that has an electrical conductivity due to flowing electrons which is intermediate in magnitude between that of a conductor and an insulator. This means roughly in the range 103 to 10−8 siemens per centimeter. Devices made from semiconductor materials are the foundation of modern electronics, including radio,.

Historically, computers evolved from mechanical computers and eventually from vacuum tube In electronics, a vacuum tube, electron tube , or thermionic valve (elsewhere, especially in Britain) is a device used to amplify, switch, otherwise modify, or create an electrical signal by controlling the movement of electrons in a low-pressure space. Some special function vacuum tubes are filled with low-pressure gas: these are so-called soft transistors.

There is active research to make computers out of many promising new types of technology, such as optical computing Today's computers use the movement of electrons in-and-out of transistors to do logic. Photonic computing is intended to use photons or light particles, produced by lasers, in place of electrons. Compared to electrons, photons are much faster – light travels about 30 cm, or one foot, in a nanosecond – and have a higher bandwidth, DNA computers DNA computing is a form of computing which uses DNA, biochemistry and molecular biology, instead of the traditional silicon-based computer technologies. DNA computing, or, more generally, biomolecular computing, is a fast developing interdisciplinary area. Research and development in this area concerns theory, experiments and applications of DNA, neural computers A wetware computer is an organic computer built from living neurons. Professor Bill Ditto, at the Georgia Institute of Technology, is the primary researcher driving the creation of these artificially constructed, but still organic brains. One prototype is constructed from leech neurons, and is capable of performing simple arithmetic operations, and quantum computers A quantum computer is a device for computation that makes direct use of quantum mechanical phenomena, such as superposition and entanglement, to perform operations on data. Quantum computers are different from traditional computers based on transistors. The basic principle behind quantum computation is that quantum properties can be used to. Some of these can easily tackle problems that modern computers cannot (such as how quantum computers can break some modern encryption algorithms by quantum factoring).

Computer architecture paradigms

Some different paradigms The word paradigm refers to a field or "world" —either conceptual worlds or else of real phenomena— which is expansive in content and developing dynamically.[citation needed] The term has been used in linguistics and science to describe distinct "worlds" of scientific concepts. It comes from Greek "παράδειγμα& of how to build a computer from the ground-up:

RAM machines

These are the types of computers with a CPU The central processing unit or the processor is the portion of a computer system that carries out the instructions of a computer program, and is the primary element carrying out the computer's functions. It is the unit that reads and executes program instructions. The data in the instruction tells the processor what to do. The instructions are, computer memory Computer memory refers to devices that are used to store data or programs on a temporary or permanent basis for use in an electronic digital computer. Computers represent information in binary code, written as sequences of 0s and 1s. Each binary digit (or "bit") may be stored by any physical system that can be in either of two stable, etc., which understand basic instructions in a machine language Machine code or machine language is a system of instructions and data executed directly by a computer's central processing unit. Machine code may be regarded as a primitive programming language or as the lowest-level representation of a compiled and/or assembled computer program. Programs in interpreted languages are not represented by machine. The concept evolved from the Turing machine A Turing machine is a theoretical device that manipulates symbols according to a table of rules contained on a strip of tape. Despite its simplicity, a Turing machine can be adapted to simulate the logic of any computer algorithm, and is particularly useful in explaining the functions of a CPU inside a computer.

Brains

Brains are massively parallel processors made of neurons A neuron (pronounced /ˈnjʊərɒn/ NOOR-on, also known as a neurone or nerve cell) is an electrically excitable cell that processes and transmits information by electrical and chemical signaling. Chemical signaling occurs via synapses, specialized connections with other cells. Neurons connect to each other to form networks. Neurons are the core, wired in intricate patterns, that communicate via electricity and neurotransmitter Neurotransmitters are endogenous chemicals which transmit signals from a neuron to a target cell across a synapse. Neurotransmitters are packaged into synaptic vesicles clustered beneath the membrane on the presynaptic side of a synapse, and are released into the synaptic cleft, where they bind to receptors in the membrane on the postsynaptic side chemicals.

Programming languages A programming language is an artificial language designed to express computations that can be performed by a machine, particularly a computer. Programming languages can be used to create programs that control the behavior of a machine, to express algorithms precisely, or as a mode of human communication

Such as the lambda calculus In mathematical logic and computer science, lambda calculus, also written as λ-calculus, is a formal system for function definition, function application and recursion. It was introduced by Alonzo Church in the 1930s as part of an investigation into the foundations of mathematics. After the original system was shown to be logically inconsistent ,, or modern programming languages, are virtual computers built on top of other computers.

Cellular automata A cellular automaton is a discrete model studied in computability theory, mathematics, physics, theoretical biology and microstructure modeling. It consists of a regular grid of cells, each in one of a finite number of states, such as "On" and "Off". The grid can be in any finite number of dimensions. For each cell, a set of

For example, the game of Life can create "gliders" and "loops" and other constructs that transmit information; this paradigm can be applied to DNA computing DNA computing is a form of computing which uses DNA, biochemistry and molecular biology, instead of the traditional silicon-based computer technologies. DNA computing, or, more generally, biomolecular computing, is a fast developing interdisciplinary area. Research and development in this area concerns theory, experiments and applications of DNA, chemical computing, etc.

Groups and committees A committee is a type of small deliberative assembly that is usually intended to remain subordinate to another, larger deliberative assembly—which when organized so that action on committee requires a vote by all its entitled members, is called the "Committee of the Whole". Committees often serve several different functions:

The linking of multiple computers (brains) is itself a computer

Logic gates A logic gate performs a logical operation on one or more logic inputs and produces a single logic output. The logic normally performed is Boolean logic and is most commonly found in digital circuits. Logic gates are primarily implemented electronically using diodes or transistors, but can also be constructed using electromagnetic relays , fluidic are a common abstraction which can apply to most of the above digital A digital system is a data technology that uses discrete values. By contrast, non-digital (or analog) systems use a continuous range of values to represent information. Although digital representations are discrete, the information represented can be either discrete, such as numbers, letters or icons, or continuous, such as sounds, images, and or analog paradigms.

The ability to store and execute lists of instructions called programs A computer program is a sequence of instructions written to perform a specified task for a computer. A computer requires programs to function, typically executing the program's instructions in a central processor. The program has an executable form that the computer can use directly to execute the instructions. The same program in its human- makes computers extremely versatile, distinguishing them from calculators A calculator is a small , usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain Turing-complete is, in principle, capable of performing the same tasks that any other computer can perform. Therefore any type of computer (netbook Netbooks are a branch of subnotebooks, a rapidly evolving category of small, lightweight, and inexpensive laptop computers suited for general computing and accessing Web-based applications; they are often marketed as "companion devices", i.e., to augment a user's other computer access, supercomputer A supercomputer is a computer that is at the frontline of current processing capacity, particularly speed of calculation. Supercomputers were introduced in the 1960s and were designed primarily by Seymour Cray at Control Data Corporation , which led the market into the 1970s until Cray left to form his own company, Cray Research. He then took over, cellular automaton A cellular automaton is a discrete model studied in computability theory, mathematics, physics, complexity science, theoretical biology and microstructure modeling. It consists of a regular grid of cells, each in one of a finite number of states, such as "On" and "Off" (in contrast to a coupled map lattice). The grid can be in, etc.) is able to perform the same computational tasks, given enough time and storage capacity.

Limited-function computers

Conversely, a computer which is limited in function (one that is not "Turing-complete In computability theory, a collection of data-manipulation rules is said to be Turing complete if and only if such system can simulate any single-taped Turing machine. Classical Turing-complete systems include context-sensitive grammars, recursive functions and lambda calculus") cannot simulate arbitrary things. For example, a simple four-function calculators A calculator is a small , usually inexpensive electronic device used to perform the basic operations of arithmetic. Modern calculators are more portable than most computers, though most PDAs are comparable in size to handheld calculators cannot simulate a real computer without human intervention. As a more complicated example, without the ability to program Programme or program (American English) (from the Ancient Greek: πρόγραμμα, προ pro "before", γράμμα gramma "letter, writing") may refer to: a gaming console A video game console is an interactive entertainment computer or electronic device that produces a video display signal which can be used with a display device to display a video game. The term "video game console" is used to distinguish a machine designed for consumers to buy and use solely for playing video games from a personal, it can never accomplish what a programmable calculator from the 1990s could (given enough time); the system as a whole is not Turing-complete, even though it contains a Turing-complete component (the microprocessor). Living organisms (the body, not the brain) are also limited-function computers designed to make a copies of themselves; they cannot be reprogrammed without genetic engineering.

Virtual computers

A "computer" is commonly considered to be a physical device. However, one can create a computer program which describes how to run a different computer, i.e. "simulating a computer in a computer". Not only is this a constructive proof of the Church-Turing thesis, but is also extremely common in all modern computers. For example, some programming languages use something called an interpreter, which is a simulated computer built on top of the basic computer; this allows programmers to write code (computer input) in a different language than the one understood by the base computer (the alternative is to use a compiler). Additionally, virtual machines are simulated computers which virtually replicate a physical computer in software, and are very commonly used by IT. Virtual machines are also a common technique used to create emulators, such game console emulators.

History of computing

The first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued to be used in that sense until the middle of the 20th century. From the end of the 19th century onwards though, the word began to take on its more familiar meaning, describing a machine that carries out computations.^[3]

Limited-function ancient computers

The history of the modern computer begins with two separate technologies—automated calculation and programmability—but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. Examples of early mechanical calculating devices include the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150–100 BC). Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when.^[4] This is the essence of programmability.

The "castle clock", an astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer.^[5] It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour,^[6][7] and five robotic musicians who played music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed to compensate for the changing lengths of day and night throughout the year.^[5]

The Renaissance saw a re-invigoration of European mathematics and engineering. Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers, but none fit the modern definition of a computer, because they could not be programmed.

Show All>>

What Links Here:

Recently Viewed Pages:

• Health: Addictions: Internet: Directory
• Home
• Addiction: News
• Addiction: Encyclopedia
• Addiction: Answers
• Addiction: Images
• Compulsive Overeating: Encyclopedia
• Drug Addiction
• Developmental Delay: Blogs
• Drug Addiction: Encyclopedia

Most Popular Pages:

• Unpaired Electrons: Answers
• Computer Addiction: Encyclopedia
• Psychological Dependence: Encyclopedia
• Yimg
• Ktre: News
• Irritability: Answers
• Search Terms
• Ruyan: Blogs
• Dyslexia-Dysgraphia-Dyscalculia: Images
• Drug Addiction

Related 'Computers' Searches: