FACTOID # 14: North Carolina has a larger Native American population than North Dakota, South Dakota and Montana combined.
 
 Home   Encyclopedia   Statistics   States A-Z   Flags   Maps   FAQ   About 
 
WHAT'S NEW
RELATED ARTICLES
People who viewed "Computer" also viewed:
 

SEARCH ALL

FACTS & STATISTICS    Advanced view

Search encyclopedia, statistics and forums:

 

 

(* = Graphable)

 

 


Encyclopedia > Computer
A computer in a wristwatch.

A computer is a machine which manipulates data according to a list of instructions which makes it an ideal example of a data processing system. Computer is an IEEE Computer Society practitioner-oriented magazine issued to all members of the society. ... Image File history File links Download high-resolution version (2100x1524, 3508 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Supercomputer NASA Advanced Supercomputing facility Computer/Temp ... Image File history File links Download high-resolution version (2100x1524, 3508 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Supercomputer NASA Advanced Supercomputing facility Computer/Temp ... This article is about the American space agency. ... NASAs 10,240-processor Columbia supercomputer is built from 20 SGI Altix systems, each powered by 512 Itanium 2 processors. ... Download high resolution version (1024x1539, 87 KB)wristwatch computer from http://wearcam. ... Download high resolution version (1024x1539, 87 KB)wristwatch computer from http://wearcam. ... A watch is a timepiece or portable clock that displays the time and sometimes the day, date, month and year. ... This article is about devices that perform tasks. ... In Computer Science, data is often distinguished from code, though both are represented in modern computers as binary strings. ... In computer programming, the word code refers to instructions to a computer in a programming language. ... In data processing, a Data Processor or Data Processing System is a system which processes information after it has been encoded into data. ...


Computers take numerous physical forms. The first devices that resemble modern computers date to the mid-20th century (around 1940 - 1941), although the computer concept and various machines similar to computers existed prior. Early electronic computers were the size of a large room, consuming as much power as several hundred modern personal computers.[1] Modern computers are based on comparatively tiny integrated circuits and are millions to billions of times more capable while occupying a fraction of the space. [2] Today, simple computers may be made small enough to fit into a wrist watch and be powered from a watch battery. Personal computers in various forms are icons of the information age and are what most people think of as "a computer". However, the most common form of computer in use today is by far the embedded computer. Embedded computers are small, simple devices that are often used to control other devices — for example, they may be found in machines ranging from fighter aircraft to industrial robots, digital cameras, and even children's toys. (19th century - 20th century - 21st century - more centuries) Decades: 1900s 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s As a means of recording the passage of time, the 20th century was that century which lasted from 1901–2000 in the sense of the Gregorian calendar (1900–1999... Year 1940 (MCMXL) was a leap year starting on Monday (link will display the full 1940 calendar) of the Gregorian calendar. ... For other uses, see 1941 (disambiguation). ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... A watch is a timepiece or portable clock that displays the time and sometimes the day, date, month and year. ... Type CR2032 watch battery (lithium anode, 3 V, 20. ... A university computer lab containing many desktop PCs The transition of communication technology: Oral Culture, Manuscript Culture, Print Culture, and Information Age Information Age is a name given to a period after the industrial age and before the Knowledge Economy. ... An embedded system is a special-purpose computer system, which is completely encapsulated by the device it controls. ... An A-10 Thunderbolt II, F-86 Sabre, P-38 Lightning and P-51 Mustang fly in formation during an air show at Langley Air Force Base, Virginia. ... An industrial robot is officially defined by ISO[1] as an automatically controlled, reprogrammable, multipurpose manipulator programmable in three or more axes. ... A SiPix digital camera next to a matchbox to show scale Nikon D200 SLR with Nikon film scanner, which converts film images to digital A Hasselblad 503CW with a digital camera back A digital camera is an electronic device used to capture and store photographs digitally, instead of using photographic... A teddy bear A toy is an object used in play. ...


The ability to store and execute lists of instructions called programs makes computers extremely versatile and distinguishes them from calculators. The Church – Turing thesis is a mathematical statement of this versatility: Any computer with a certain minimum capability is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, computers with capability and complexity ranging from that of a personal digital assistant to a supercomputer are all able to perform the same computational tasks given enough time and storage capacity. For other uses, see Calculator (disambiguation). ... In computability theory the Church–Turing thesis (also known as Churchs thesis, Churchs conjecture and Turings thesis) is a combined hypothesis about the nature of effectively calculable (computable) functions by recursion (Churchs Thesis), by mechanical device equivalent to a Turing machine (Turings Thesis) or by... Look up Personal digital assistant in Wiktionary, the free dictionary. ... A supercomputer is a computer that led the world (or was close to doing so) in terms of processing capacity, particularly speed of calculation, at the time of its introduction. ...

Contents

History of computing

Main article: History of computing
The Jacquard loom was one of the first programmable devices.
The Jacquard loom was one of the first programmable devices.

It is difficult to identify any one device as the earliest computer, partly because the term "computer" has been subject to varying interpretations over time. The history of computing is longer than the history of computing hardware and modern computing technology and includes the history of methods intended for pen and paper or for chalk and slate, with or without the aid of tables. ... Jacquard loom on display at the museum of science and industry. ... Jacquard loom on display at the museum of science and industry. ... Jacquard loom on display at Museum of Science and Industry in Manchester, England The Jacquard Loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, which utilized holes punched in pasteboard, each row of which corresponded to one row of the design. ...


Originally, the term "computer" referred to a person who performed numerical calculations (a human computer), often with the aid of a mechanical calculating device. Examples of early mechanical computing devices included the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism (which dates from about 150-100 BC). The end of the Middle Ages saw a re-invigoration of European mathematics and engineering, and Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers. Before mechanical and electronic computers, the term computer, in use from the mid 17th century, meant a human undertaking mathematical calculations. ... A basic arithmetic calculator. ... It has been suggested that Abax be merged into this article or section. ... A typical 10 inch student slide rule (Pickett N902-T simplex trig). ... A 16th century astrolabe. ... The Antikythera mechanism (main fragment). ... The Middle Ages formed the middle period in a traditional schematic division of European history into three ages: the classical civilization of Antiquity, the Middle Ages, and modern times, beginning with the Renaissance. ... Wilhelm Schickard Wilhelm Schickard (April 22, 1592 – October 23, 1635) was a German polymath who built the first computer in 1623. ...


However, none of those devices fit the modern definition of a computer because they could not be programmed. In 1801, Joseph Marie Jacquard made an improvement to the textile loom that used a series of punched paper cards as a template to allow his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability. This does not adequately cite its references or sources. ... For other uses, see Loom (disambiguation). ... Punched cards (or Hollerith cards, or IBM cards), are pieces of stiff paper that contain digital information represented by the presence or absence of holes in predefined positions. ...


In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer that he called "The Analytical Engine".[3] Due to limited finance, and an inability to resist tinkering with the design, Babbage never actually built his Analytical Engine. Babbage redirects here. ... The analytical engine, an important step in the history of computers, was the design of a mechanical general-purpose computer by the British professor of mathematics Charles Babbage. ...


Large-scale automated data processing of punched cards was performed for the U.S. Census in 1890 by tabulating machines designed by Herman Hollerith and manufactured by the Computing Tabulating Recording Corporation, which later became IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter. The Eleventh United States Census was taken June 1, 1890. ... Tabulating machine constructed by Hollerith The tabulating machine was a machine designed to assist in tabulations. ... Herman Hollerith (February 29, 1860 – November 17, 1929) was an German-American statistician who developed a mechanical tabulator based on punched cards in order to rapidly tabulate statistics from millions of pieces of data. ... The Computing Tabulating Recording Corporation (CTR)[1] was incorporated on June 15, 1911 in Endicott, New York a few miles west of Binghamton. ... For other uses, see IBM (disambiguation) and Big Blue. ... Punched cards (or Hollerith cards, or IBM cards), are pieces of stiff paper that contain digital information represented by the presence or absence of holes in predefined positions. ... Boolean algebra is the finitary algebra of two values. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ...


During the first half of the 20th century, many scientific computing needs were met by increasingly sophisticated analog computers, which used a direct mechanical or electrical model of the problem as a basis for computation. However, these were not programmable and generally lacked the versatility and accuracy of modern digital computers. A page from the Bombardiers Information File (BIF) that describes the components and controls of the Norden bombsight. ... Electric redirects here. ... Look up computation in Wiktionary, the free dictionary. ...

Defining characteristics of five first operative digital computers
Computer Shown working Binary Electronic Programmable Turing complete
Zuse Z3 May 1941 Yes No By punched film stock Yes (1998)
Atanasoff–Berry Computer Summer 1941 Yes Yes No No
Colossus December 1943 / January 1944 Yes Yes Partially, by rewiring No
Harvard Mark I – IBM ASCC 1944 No No By punched paper tape Yes (1998)
ENIAC 1944 No Yes Partially, by rewiring Yes
1948 No Yes By Function Table ROM Yes

A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult (Shannon 1940). Notable achievements include: The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... This article is about the engineering discipline. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... For the usage of this term in Turing reductions, see Turing complete set. ... Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 Berlin - December 18, 1995 Hünfeld) was a German engineer and computer pioneer. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Film stock is the term for photographic film on which films are recorded. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... Atanasoff–Berry Computer replica at 1st floor of Durham Center, Iowa State University The Atanasoff–Berry Computer (ABC) was the first electronic digital computing device. ... A Colossus Mark II computer. ... Portion of the Harvard-IBM Mark 1, left side. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... Claude Shannon Claude Elwood Shannon (April 30, 1916 – February 24, 2001), an American electrical engineer and mathematician, has been called the father of information theory,[1] and was the founder of practical digital circuit design theory. ...

EDSAC was one of the first computers to implement the stored program (von Neumann) architecture.
EDSAC was one of the first computers to implement the stored program (von Neumann) architecture.
  • Konrad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.
  • The non-programmable Atanasoff – Berry Computer (1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory.
  • The secret British Colossus computer (1944), which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.
  • The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.
  • The U.S. Army's Ballistics Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an inflexible architecture which essentially required rewiring to change its programming.

Several developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the stored program architecture or von Neumann architecture. This design was first formally described by John von Neumann in the paper "First Draft of a Report on the EDVAC", published in 1945. A number of projects to develop computers based on the stored program architecture commenced around this time, the first of these being completed in Great Britain. The first to be demonstrated working was the Manchester Small-Scale Experimental Machine (SSEM) or "Baby". However, the EDSAC, completed a year after SSEM, was perhaps the first practical implementation of the stored program design. Shortly thereafter, the machine originally described by von Neumann's paper — EDVAC — was completed but did not see full-time use for an additional two years. Image File history File links EDSAC_(10). ... Image File history File links EDSAC_(10). ... EDSAC EDSAC (Electronic Delay Storage Automatic Calculator) was an early British computer (one of the first computers to be created). ... Design of the Von Neumann architecture For the robotic architecture also named after Von Neumann, see Von Neumann machine The von Neumann architecture is a computer design model that uses a single storage structure to hold both instructions and data. ... Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 Berlin - December 18, 1995 Hünfeld) was a German engineer and computer pioneer. ... In engineering, electromechanics combines the sciences of electromagnetism of electrical engineering and mechanics. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... The binary numeral system, or base-2 number system, is a numeral system that represents numeric values using two symbols, usually 0 and 1. ... For the usage of this term in Turing reductions, see Turing complete set. ... Look up computation in Wiktionary, the free dictionary. ... Regenerative capacitor memory is a type of computer memory that uses the electrical property of capacitance to store the data. ... A Colossus Mark II computer. ... Cryptanalysis (from the Greek kryptós, hidden, and analýein, to loosen or to untie) is the study of methods for obtaining the meaning of encrypted information, without access to the secret information which is normally required to do so. ... Portion of the Harvard-IBM Mark 1, left side. ... The US Army Ballistics Research Labatory is at Aberdeen Proving Ground, Aberdeen, Maryland. ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... For other uses, see Decimal (disambiguation). ... This article is about the engineering discipline. ... Statue in Bad Hersfeld Konrad Zuse (June 22, 1910 Berlin - December 18, 1995 Hünfeld) was a German engineer and computer pioneer. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... An electromagnet is a type of magnet in which the magnetic field is induced by a flow of electric current. ... This article is about the engineering discipline. ... Design of the Von Neumann architecture For the robotic architecture also named after Von Neumann, see Von Neumann machine The von Neumann architecture is a computer design model that uses a single storage structure to hold both instructions and data. ... For other persons named John Neumann, see John Neumann (disambiguation). ... The First Draft of a Report on the EDVAC (or First Draft) was an incomplete 101-page document written by John von Neumann and distributed on June 30, 1945 by Herman Goldstine, security officer on the classified ENIAC project. ... Replica of the SSEM The Manchester Small-Scale Experimental Machine (SSEM), nicknamed Baby, was the first stored-program computer to run a program, on June 21, 1948. ... EDSAC EDSAC (Electronic Delay Storage Automatic Calculator) was an early British computer (one of the first computers to be created). ... The EDVAC as installed in Building 328 at the Ballistics Research Laboratory. ...


Nearly all modern computers implement some form of the stored program architecture, making it the single trait by which the word "computer" is now defined. By this standard, many earlier devices would no longer be called computers by today's definition, but are usually referred to as such in their historical context. While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the von Neumann architecture. The design made the universal computer a practical reality. Design of the Von Neumann architecture For the robotic architecture also named after Von Neumann, see Von Neumann machine The von Neumann architecture is a computer design model that uses a single storage structure to hold both instructions and data. ...

Microprocessors are miniaturized devices that often implement stored program CPUs.
Microprocessors are miniaturized devices that often implement stored program CPUs.

Vacuum tube-based computers were in use throughout the 1950s, but were largely replaced in the 1960s by transistor-based devices, which were smaller, faster, cheaper, used less power and were more reliable. These factors allowed computers to be produced on an unprecedented commercial scale. By the 1970s, the adoption of integrated circuit technology and the subsequent creation of microprocessors such as the Intel 4004 caused another leap in size, speed, cost and reliability. By the 1980s, computers had become sufficiently small and cheap to replace simple mechanical controls in domestic appliances such as washing machines. Around the same time, computers became widely accessible for personal use by individuals in the form of home computers and the now ubiquitous personal computer. In conjunction with the widespread growth of the Internet since the 1990s, personal computers are becoming as common as the television and the telephone and almost all modern electronic devices contain a computer of some kind.
Image File history File links Download high resolution version (1341x1002, 803 KB) Summary Macro shot of an Intel 80486DX2 die in its packaging. ... Image File history File links Download high resolution version (1341x1002, 803 KB) Summary Macro shot of an Intel 80486DX2 die in its packaging. ... Microprocessors, including an Intel 80486DX2 and an Intel 80386 A microprocessor (abbreviated as µP or uP) is an electronic computer central processing unit (CPU) made from miniaturized transistors and other circuit elements on a single semiconductor integrated circuit (IC) (aka microchip or just chip). ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... Structure of a vacuum tube diode Structure of a vacuum tube triode In electronics, a vacuum tube, electron tube, or (outside North America) thermionic valve or just valve, is a device used to amplify, switch or modify a signal by controlling the movement of electrons in an evacuated space. ... Assorted discrete transistors A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... The Intel 4004, a 4-bit central processing unit (CPU) released by Intel Corp. ... Front-loading washing machine. ... Children playing on a Amstrad CPC 464 in the 1980s. ... For other uses, see Telephone (disambiguation). ...


Stored program architecture

The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that a list of instructions (the program) can be given to the computer and it will store them and carry them out at some time in the future. A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... “Programming” redirects here. ... “Programming” redirects here. ... In computer science, an instruction typically refers to a single operation of a processor within a computer architecture. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ...


In most cases, computer instructions are simple: add one number to another, move some data from one location to another, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to that point. This article does not cite any references or sources. ... In computer science, conditional statements are a vital part of a programming language. ... In computer science, a subroutine (function, method, procedure, or subprogram) is a portion of code within a larger program, which performs a specific task and can be relatively independent of the remaining code. ...


Program execution might be likened to reading a book. While a person will normally read each word and line in sequence, they may at times jump back to an earlier place in the text or skip sections that are not of interest. Similarly, a computer may sometimes go back and repeat the instructions in some section of the program over and over again until some internal condition is met. This is called the flow of control within the program and it is what allows the computer to perform tasks repeatedly without human intervention. In computer science control flow (or alternatively, flow of control) refers to the order in which the individual statements, instructions or function calls of an imperative or functional program are executed or evaluated. ...


Comparatively, a person using a pocket calculator can perform a basic arithmetic operation such as adding two numbers with just a few button presses. But to add together all of the numbers from 1 to 1,000 would take thousands of button presses and a lot of time — with a near certainty of making a mistake. On the other hand, a computer may be programmed to do this with just a few simple instructions. For example: For other uses, see Calculator (disambiguation). ...

 sum ← 0 ; set sum to 0 num ← 1 ; set num to 1 loop: ; define the beginning of the loop sum ← (num + sum) ; add num to sum and store new result num ← (num + 1) ; add 1 to num if num ≤ 1000 loop ; continue to loop while num ≤ 1000, if not continue below halt ; end of program, stop running 

Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in about a millionth of a second.[4]


However, computers cannot "think" for themselves in the sense that they only solve problems in exactly the way they are programmed to. An intelligent human faced with the above addition task might soon realize that instead of actually adding up all the numbers one can simply use the equation

1+2+3+...+n = {{n(n+1)} over 2}

and arrive at the correct answer (500,500) with little work.[5] In other words, a computer programmed to add up the numbers one by one as in the example above would do exactly that without regard to efficiency or alternative solutions.


Programs

A 1970s punched card containing one line from a FORTRAN program. The card reads: "Z(1) = Y + W(1)" and is labelled "PROJ039" for identification purposes.
A 1970s punched card containing one line from a FORTRAN program. The card reads: "Z(1) = Y + W(1)" and is labelled "PROJ039" for identification purposes.

In practical terms, a computer program might include anywhere from a dozen instructions to many millions of instructions for something like a word processor or a web browser. A typical modern computer can execute billions of instructions every second and nearly never make a mistake over years of operation. Image File history File links Download high-resolution version (1687x809, 475 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Punch card ... Image File history File links Download high-resolution version (1687x809, 475 KB) Summary Licensing File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Punch card ... A CTR census machine, utilizing a punched card system. ... Fortran (previously FORTRAN[1]) is a general-purpose[2], procedural,[3] imperative programming language that is especially suited to numeric computation and scientific computing. ... A computer program is a collection of instructions that describe a task, or set of tasks, to be carried out by a computer. ... A word processor (also more formally known as a document preparation system) is a computer application used for the production (including composition, editing, formatting, and possibly printing) of any sort of viewable or printed material. ... An example of a Web browser (Mozilla Firefox) A web browser is a software application that enables a user to display and interact with text, images, videos, music and other information typically located on a Web page at a website on the World Wide Web or a local area network. ...


Large computer programs may take teams of computer programmers years to write and the probability of the entire program having been written completely in the manner intended is unlikely. Errors in computer programs are called bugs. Sometimes bugs are benign and do not affect the usefulness of the program, in other cases they might cause the program to completely fail (crash), in yet other cases there may be subtle problems. Sometimes otherwise benign bugs may be used for malicious intent, creating a security exploit. Bugs are usually not the fault of the computer. Since computers merely execute the instructions they are given, bugs are nearly always the result of programmer error or an oversight made in the program's design.[6] In computing, a programmer is someone who does computer programming and develops computer software. ... A software bug is an error, flaw, mistake, failure, or fault in a computer program that prevents it from behaving as intended (e. ... A crash in computing is a condition where a program (either an application or part of the operating system) stops performing its expected function and also stops responding to other parts of the system. ... An exploit is a piece of software, a chunk of data, or sequence of commands that take advantage of a bug, glitch or vulnerability in order to cause unintended or unanticipated behavior to occur on computer software, hardware, or something electronic (usually computerized). ...


In most computers, individual instructions are stored as machine code with each instruction being given a unique number (its operation code or opcode for short). The command to add two numbers together would have one opcode, the command to multiply them would have a different opcode and so on. The simplest computers are able to perform any of a handful of different instructions, the more complex computers have several hundred to choose from — each with a unique numerical code. Since the computer's memory is able to store numbers, it can also store the instruction codes. This leads to the important fact that entire programs (which are just lists of instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer just as if they were numeric data. The fundamental concept of storing programs in the computer's memory alongside the data they operate on is the crux of the von Neumann, or stored program, architecture. In some cases, a computer might store some or all of its program in memory that is kept separate from the data it operates on. This is called the Harvard architecture after the Harvard Mark I computer. Modern von Neumann computers display some traits of the Harvard architecture in their designs, such as in CPU caches. Machine code or machine language is a system of instructions and data directly understandable by a computers central processing unit. ... Microprocessors perform operations using binary bits (on/off/1or0). ... The term Harvard architecture originally referred to computer architectures that used physically separate storage and signal pathways for their instructions and data (in contrast to the von Neumann architecture). ... Portion of the Harvard-IBM Mark 1, left side. ... Diagram of a CPU memory cache A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. ...


While it is possible to write computer programs as long lists of numbers (machine language) and this technique was used with many early computers,[7] it is extremely tedious to do so in practice, especially for complicated programs. Instead, each basic instruction can be given a short name that is indicative of its function and easy to remember — a mnemonic such as ADD, SUB, MULT or JUMP. These mnemonics are collectively known as a computer's assembly language. Converting programs written in assembly language into something the computer can actually understand (machine language) is usually done by a computer program called an assembler. Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) tend to be unique to a particular type of computer. For instance, an ARM architecture computer (such as may be found in a PDA or a hand-held videogame) cannot understand the machine language of an Intel Pentium or the AMD Athlon 64 computer that might be in a PC.[8] A system of codes directly understandable by a computers CPU is termed this CPUs native or machine language. ... For other uses, see Mnemonic (disambiguation). ... See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ... This article does not cite any references or sources. ... The ARM architecture (previously, the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture developed by ARM Limited that is widely used in a number of embedded designs. ... Look up Personal digital assistant in Wiktionary, the free dictionary. ... A handheld video game is a video game designed primarily for handheld game consoles such as Nintendos Game Boy line. ... This article does not cite any references or sources. ... The Athlon 64 is an eighth-generation, AMD64 architecture microprocessor produced by AMD, released on September 23, 2003. ... A personal computer (PC) is a computer whose price, size, and capabilities make it useful for individuals. ...


Though considerably easier than in machine language, writing long programs in assembly language is often difficult and error prone. Therefore, most complicated programs are written in more abstract high-level programming languages that are able to express the needs of the computer programmer more conveniently (and thereby help reduce programmer error). High level languages are usually "compiled" into machine language (or sometimes into assembly language and then into machine language) using another computer program called a compiler.[9] Since high level languages are more abstract than assembly language, it is possible to use different compilers to translate the same high level language program into the machine language of many different types of computer. This is part of the means by which software like video games may be made available for different computer architectures such as personal computers and various video game consoles. A high-level programming language is a programming language that, in comparison to low-level programming languages, may be more abstract, easier to use, or more portable across platforms. ... In computing, a programmer is someone who does computer programming and develops computer software. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... “Game console” redirects here. ...


The task of developing large software systems is an immense intellectual effort. It has proven, historically, to be very difficult to produce software with an acceptably high reliability, on a predictable schedule and budget. The academic and professional discipline of software engineering concentrates specifically on this problem. Computer software (or simply software) refers to one or more computer programs and data held in the storage of a computer for some purpose. ... Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software. ...


Example

A traffic light showing red.

Suppose a computer is being employed to drive a traffic light. A simple stored program might say: Image File history File linksMetadata Download high-resolution version (2048x1536, 1138 KB)y bib y invntea the trafic File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Image File history File linksMetadata Download high-resolution version (2048x1536, 1138 KB)y bib y invntea the trafic File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... “Traffic Signal” redirects here. ...

  1. Turn off all of the lights
  2. Turn on the red light
  3. Wait for sixty seconds
  4. Turn off the red light
  5. Turn on the green light
  6. Wait for sixty seconds
  7. Turn off the green light
  8. Turn on the yellow light
  9. Wait for two seconds
  10. Turn off the yellow light
  11. Jump to instruction number (2)

With this set of instructions, the computer would cycle the light continually through red, green, yellow and back to red again until told to stop running the program.


However, suppose there is a simple on/off switch connected to the computer that is intended be used to make the light flash red while some maintenance operation is being performed. The program might then instruct the computer to: Electrical switches. ...

  1. Turn off all of the lights
  2. Turn on the red light
  3. Wait for sixty seconds
  4. Turn off the red light
  5. Turn on the green light
  6. Wait for sixty seconds
  7. Turn off the green light
  8. Turn on the yellow light
  9. Wait for two seconds
  10. Turn off the yellow light
  11. If the maintenance switch is NOT turned on then jump to instruction number 2
  12. Turn on the red light
  13. Wait for one second
  14. Turn off the red light
  15. Wait for one second
  16. Jump to instruction number 11

In this manner, the computer is either running the instructions from number (2) to (11) over and over or its running the instructions from (11) down to (16) over and over, depending on the position of the switch.[10]


How computers work

A general purpose computer has four main sections: the arithmetic and logic unit (ALU), the control unit, the memory, and the input and output devices (collectively termed I/O). These parts are interconnected by busses, often made of groups of wires. “CPU” redirects here. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... ALU redirects here. ... A control unit is the part of a CPU or other device that directs its operation. ... This article does not cite any references or sources. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... A wire is a single, usually cylindrical, elongated strand of drawn metal. ...


The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor. “CPU” redirects here. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ...


Control unit

Main articles: CPU design and Control unit

The control unit (often called a control system or central controller) directs the various components of a computer. It reads and interprets (decodes) instructions in the program one by one. The control system decodes each instruction and turns it into a series of control signals that operate the other parts of the computer.[11] Control systems in advanced computers may change the order of some instructions so as to improve performance. CPU design is the hardware design of a central processing unit. ... A control unit is the part of a CPU or other device that directs its operation. ...


A key component common to all CPUs is the program counter, a special memory cell (a register) that keeps track of which location in memory the next instruction is to be read from.[12] The program counter (also called the instruction pointer in some computers) is a register in a computer processor which indicates where the computer is in its instruction sequence. ... In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to frequently used values—typically, these values are involved in multiple expression evaluations occurring within a small region on the program. ...

Diagram showing how a particular MIPS architecture instruction would be decoded by the control system.

The control system's function is as follows — note that this is a simplified description and some of these steps may be performed concurrently or in a different order depending on the type of CPU: Image File history File links Mips32_addi. ... Image File history File links Mips32_addi. ... A MIPS R4400 microprocessor made by Toshiba. ...

  1. Read the code for the next instruction from the cell indicated by the program counter.
  2. Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.
  3. Increment the program counter so it points to the next instruction.
  4. Read whatever data the instruction requires from cells in memory (or perhaps from an input device). The location of this required data is typically stored within the instruction code.
  5. Provide the necessary data to an ALU or register.
  6. If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.
  7. Write the result from the ALU back to a memory location or to a register or perhaps an output device.
  8. Jump back to step (1).

Since the program counter is (conceptually) just another set of memory cells, it can be changed by calculations done in the ALU. Adding 100 to the program counter would cause the next instruction to be read from a place 100 locations further down the program. Instructions that modify the program counter are often known as "jumps" and allow for loops (instructions that are repeated by the computer) and often conditional instruction execution (both examples of control flow). In computer science control flow (or alternatively, flow of control) refers to the order in which the individual statements, instructions or function calls of an imperative or functional program are executed or evaluated. ...


It is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program - and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer that runs a microcode program that causes all of these events to happen. In the field of computer architecture and engineering, a sequencer or microsequencer, is a part of a control unit of a CPU. It generates the addresses used to step through the microprogram of a control store. ... A microprogram is a program consisting of microcode that controls the different parts of a computers central processing unit (CPU). ...


Arithmetic/logic unit (ALU)

Main article: Arithmetic logic unit

The ALU is capable of performing two classes of operations: arithmetic and logic. A typical schematic symbol for an ALU: A & B are operands; R is the output; F is the input from the Control Unit; D is an output status In computing, an arithmetic logic unit (ALU) is a digital circuit that performs arithmetic and logical operations. ...


The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers — albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation — although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?"). Wikibooks has a book on the topic of Trigonometry All of the trigonometric functions of an angle θ can be constructed geometrically in terms of a unit circle centered at O. Trigonometry (from Greek trigōnon triangle + metron measure[1]), informally called trig, is a branch of mathematics that deals with... In mathematics, a square root of a number x is a number r such that , or in words, a number r whose square (the result of multiplying the number by itself) is x. ... The integers are commonly denoted by the above symbol. ... A floating-point number is a digital representation for a number in a certain subset of the rational numbers, and is often used to approximate an arbitrary real number on a computer. ... In mathematics, the real numbers may be described informally as numbers that can be given by an infinite decimal representation, such as 2. ... In logic and mathematics, a logical value, also called a truth value, is a value indicating to what extent a proposition is true. ...


Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic. Boolean logic is a complete system for logical operations. ... AND Logic Gate In logic and mathematics, logical conjunction (usual symbol and) is a two-place logical operation that results in a value of true if both of its operands are true, otherwise a value of false. ... OR logic gate. ... Exclusive disjunction, also known as exclusive or and symbolized by XOR or EOR, is a logical operation on two operands that results in a logical value of true if and only if one of the operands, but not both, has a value of true. ... Negation, in its most basic sense, changes the truth value of a statement to its opposite. ... In computer science, conditional statements are a vital part of a programming language. ... Boolean logic is a complete system for logical operations. ...


Superscalar computers contain multiple ALUs so that they can process several instructions at the same time. Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices. Simple superscalar pipeline. ... “GPU” redirects here. ... -1... Multiple Instruction Multiple Data (MIMD) is a type of parallel computing architecture where many functional units perform different operations on different data. ... A vector going from A to B. In physics and in vector calculus, a spatial vector, or simply vector, is a concept characterized by a magnitude and a direction. ... In mathematics, a matrix (plural matrices) is a rectangular table of elements (or entries), which may be numbers or, more generally, any abstract quantities that can be added and multiplied. ...


Memory

Main article: Computer storage
Magnetic core memory was popular main memory for computers through the 1960s until it was completely replaced by semiconductor memory.
Magnetic core memory was popular main memory for computers through the 1960s until it was completely replaced by semiconductor memory.

A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595". The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is up to the software to give significance to what the memory sees as nothing but a series of numbers. This article does not cite any references or sources. ... Image File history File linksMetadata Download high-resolution version (1280x960, 259 KB) This is a 50x photograph of magnetic core random access memory from a 4 KiB memory plane. ... Image File history File linksMetadata Download high-resolution version (1280x960, 259 KB) This is a 50x photograph of magnetic core random access memory from a 4 KiB memory plane. ... A 16×16 cm area core memory plane of 128×128 bits, i. ...


In almost all modern computers, each memory cell is set up to store binary numbers in groups of eight bits (called a byte). Each byte is able to represent 256 different numbers; either from 0 to 255 or -128 to +127. To store larger numbers, several consecutive bytes may be used (typically, two, four or eight). When negative numbers are required, they are usually stored in two's complement notation. Other arrangements are possible, but are usually not seen outside of specialized applications or historical contexts. A computer can store any kind of information in memory as long as it can be somehow represented in numerical form. Modern computers have billions or even trillions of bytes of memory. The binary or base-two numeral system is a system for representing numbers in which a radix of two is used; that is, each digit in a binary numeral may have either of two different values. ... This article is about the unit of information. ... In computer science a byte (pronounced bite) is a unit of measurement of information storage, most often consisting of eight bits. ... The twos complement of a binary number is the value obtained by subtracting the number from a large power of two (specifically, from 2N for an N-bit twos complement). ...


The CPU contains a special set of memory cells called registers that can be read and written to much more rapidly than the main memory area. There are typically between two and one hundred registers depending on the type of CPU. Registers are used for the most frequently needed data items to avoid having to access main memory every time data is needed. Since data is constantly being worked on, reducing the need to access main memory (which is often slow compared to the ALU and control units) greatly increases the computer's speed. In computer architecture, a processor register is a small amount of very fast computer memory used to speed the execution of computer programs by providing quick access to frequently used values—typically, these values are involved in multiple expression evaluations occurring within a small region on the program. ...


Computer main memory comes in two principal varieties: random access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM is erased when the power to the computer is turned off while ROM retains its data indefinitely. In a PC, the ROM contains a specialized program called the BIOS that orchestrates loading the computer's operating system from the hard disk drive into RAM whenever the computer is turned on or reset. In embedded computers, which frequently do not have disk drives, all of the software required to perform the task may be stored in ROM. Software that is stored in ROM is often called firmware because it is notionally more like hardware than software. Flash memory blurs the distinction between ROM and RAM by retaining data when turned off but being rewritable like RAM. However, flash memory is typically much slower than conventional ROM and RAM so its use is restricted to applications where high speeds are not required.[13] “RAM” redirects here. ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... For other uses, see Bios. ... // An operating system (OS) is the software that manages the sharing of the resources of a computer. ... An embedded system is a special-purpose computer system, which is completely encapsulated by the device it controls. ... A microcontroller, like this PIC18F8720 is controlled by firmware stored inside on FLASH memory In computing, firmware is a computer program that is embedded in a hardware device, for example a microcontroller. ... A USB flash drive. ...


In more sophisticated computers there may be one or more RAM cache memories which are slower than registers but faster than main memory. Generally computers with this sort of cache are designed to move frequently needed data into the cache automatically, often without the need for any intervention on the programmer's part. Diagram of a CPU memory cache A CPU cache is a cache used by the central processing unit of a computer to reduce the average time to access memory. ...


Input/output (I/O)

Main article: Input/output
Hard disks are common I/O devices used with computers.
Hard disks are common I/O devices used with computers.

I/O is the means by which a computer receives information from the outside world and sends results back. Devices that provide input or output to the computer are called peripherals. On a typical personal computer, peripherals include input devices like the keyboard and mouse, and output devices such as the display and printer. Hard disk drives, floppy disk drives and optical disc drives serve as both input and output devices. Computer networking is another form of I/O. Energy Input: The energy placed into a reaction. ... Image File history File links Download high resolution version (1024x683, 323 KB) Summary Alpha six, http://www. ... Image File history File links Download high resolution version (1024x683, 323 KB) Summary Alpha six, http://www. ... Typical hard drives of the mid-1990s. ... It has been suggested that this article or section be merged into Computer hardware. ... Operating a mechanical 1: Pulling the mouse turns the ball. ... Nineteen inch (48 cm) CRT computer monitor A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper transparencies]]. Many printers are primarily used as computer peripherals, and are attached by a printer cable to... A hard disk drive (HDD), commonly referred to as a hard drive, hard disk or fixed disk drive,[1] is a non-volatile storage device which stores digitally encoded data on rapidly rotating platters with magnetic surfaces. ... A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ... In computing, sound reproduction, and video, an optical disc is flat, circular, usually polycarbonate disc whereon data is stored. ... This article or section is in need of attention from an expert on the subject. ...


Often, I/O devices are complex computers in their own right with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O. “GPU” redirects here. ... 3D computer graphics (in contrast to 2D computer graphics) are graphics that utilize a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images. ... Desktop computer with several common peripherals (Monitor, keyboard, mouse, speakers, microphone and a printer) A desktop computer is a computer made for use on a desk in an office or home and is distinguished from portable computers such as laptops or PDAs. ...


Multitasking

Main article: Computer multitasking

While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by having the computer switch rapidly between running each program in turn. One means by which this is done is with a special signal called an interrupt which can periodically cause the computer to stop executing instructions where it was and do something else instead. By remembering where it was executing prior to the interrupt, the computer can return to that task later. If several programs are running "at the same time", then the interrupt generator might be causing several hundred interrupts per second, causing a program switch each time. Since modern computers typically execute instructions several orders of magnitude faster than human perception, it may appear that many programs are running at the same time even though only one is ever executing in any given instant. This method of multitasking is sometimes termed "time-sharing" since each program is allocated a "slice" of time in turn. In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... In computing, an interrupt is an asynchronous signal from hardware or software indicating the need for attention. ...


Before the era of cheap computers, the principle use for multitasking was to allow many people to share the same computer.


Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly - in direct proportion to the number of programs it is running. However, most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run at the same time without unacceptable speed loss.


Multiprocessing

Main article: Multiprocessing
Cray designed many supercomputers that used multiprocessing heavily.
Cray designed many supercomputers that used multiprocessing heavily.

Some computers may divide their work between one or more separate CPUs, creating a multiprocessing configuration. Traditionally, this technique was utilized only in large and powerful computers such as supercomputers, mainframe computers and servers. However, multiprocessor and multi-core (multiple CPUs on a single integrated circuit) personal and laptop computers have become widely available and are beginning to see increased usage in lower-end markets as a result. Multiprocessing is traditionally known as the use of multiple concurrent processes in a system as opposed to a single process at any one instant. ... ImageMetadata File history File links Download high resolution version (2592x1944, 2110 KB) File links The following pages link to this file: Supercomputer Cray-2 ... ImageMetadata File history File links Download high resolution version (2592x1944, 2110 KB) File links The following pages link to this file: Supercomputer Cray-2 ... For alternate meanings, see Cray (disambiguation). ... A supercomputer is a computer that led the world (or was close to doing so) in terms of processing capacity, particularly speed of calculation, at the time of its introduction. ... For other uses, see Mainframe. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... Diagram of an Intel Core 2 dual core processor, with CPU-local Level 1 caches, and a shared, on-die Level 2 cache. ...


Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general purpose computers.[14] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of a the available resources at once. Supercomputers usually see usage in large-scale simulation, graphics rendering, and cryptography applications, as well as with other so-called "embarrassingly parallel" tasks. It has been suggested that simulation software be merged into this article or section. ... This article does not cite any references or sources. ... The German Lorenz cipher machine, used in World War II for encryption of very high-level general staff messages Cryptography (or cryptology; derived from Greek κρυπτός kryptós hidden, and the verb γράφω gráfo write or λεγειν legein to speak) is the study of message secrecy. ... In the jargon of parallel computing, an embarrassingly parallel workload (or embarrassingly parallel problem) is one for which no particular effort is needed to segment the problem into a very large number of parallel tasks, and there is no essential dependency (or communication) between those parallel tasks. ...


Networking and the Internet

Main articles: Computer networking and Internet
Visualization of a portion of the routes on the Internet.

Computers have been used to coordinate information in multiple locations since the 1950s, with the U.S. military's SAGE system the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre. This article or section is in need of attention from an expert on the subject. ... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (1280 × 1280 pixel, file size: 1. ... Image File history File links Size of this preview: 600 × 600 pixelsFull resolution (1280 × 1280 pixel, file size: 1. ... This article is about routing (or routeing) in computer networks. ... SAGE Sector Control Room. ... Sabre Logo Sabre is a computer reservations system/global distribution system (GDS) used by airlines, railways, hotels, travel agents and other travel companies. ...


In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET. The technologies that made the Arpanet possible spread and evolved. In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments. The Defense Advanced Research Projects Agency (DARPA) is an agency of the United States Department of Defense responsible for the development of new technology for use by the military. ... For the scientific and engineering discipline studying computer networks, see Computer networking. ... ARPANET logical map, March 1977. ... Wikipedia does not yet have an article with this exact name. ... WWWs historical logo designed by Robert Cailliau The World Wide Web (commonly shortened to the Web) is a system of interlinked, hypertext documents accessed via the Internet. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... Asymmetric Digital Subscriber Line (ADSL) is a form of DSL, a data communications technology that enables faster data transmission over copper telephone lines than a conventional modem can provide. ...


Further topics

Hardware

Main article: Computer hardware

The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware. It has been suggested that Peripheral be merged into this article or section. ...

History of computing hardware
First Generation (Mechanical/Electromechanical) Calculators Antikythera mechanism, Difference Engine, Norden bombsight
Programmable Devices Jacquard loom, Analytical Engine, Harvard Mark I, Z3
Second Generation (Vacuum Tubes) Calculators Atanasoff – Berry Computer, IBM 604, UNIVAC 60, UNIVAC 120
Programmable Devices ENIAC, EDSAC, EDVAC, UNIVAC I, IBM 701, IBM 702, IBM 650, Z22
Third Generation (Discrete transistors and SSI, MSI, LSI Integrated circuits) Mainframes IBM 7090, IBM 7080, System/360, BUNCH
Minicomputer PDP-8, PDP-11, System/32, System/36
Fourth Generation (VLSI integrated circuits) Minicomputer VAX, AS/400
4-bit microcomputer Intel 4004, Intel 4040
8-bit microcomputer Intel 8008, Intel 8080, Motorola 6800, Motorola 6809, MOS Technology 6502, Zilog Z80
16-bit microcomputer 8088, Zilog Z8000, WDC 65816/65802
32-bit microcomputer 80386, Pentium, 68000, ARM architecture
64-bit microcomputer[15] x86-64, PowerPC, MIPS, SPARC
Embedded computer 8048, 8051
Personal computer Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet computer, Wearable computer
Theoretical/experimental Quantum computer, Chemical computer, DNA computing, Optical computer, Spintronics based computer
Other Hardware Topics
Peripheral device (Input/output) Input Mouse, Keyboard, Joystick, Image scanner
Output Monitor, Printer
Both Floppy disk drive, Hard disk, Optical disc drive, Teleprinter
Computer busses Short range RS-232, SCSI, PCI, USB
Long range (Computer networking) Ethernet, ATM, FDDI

Computing hardware has been an important component of the process of calculation and data storage since it became useful for numerical values to be processed and shared. ... The Antikythera mechanism (main fragment). ... Part of Babbages Difference engine, assembled after his death by Babbages son, using parts found in his laboratory. ... The Norden bombsight A page from the Bombardiers Information File (BIF) that describes the components and controls of the Norden Bombsight. ... Jacquard loom on display at Museum of Science and Industry in Manchester, England The Jacquard Loom is a mechanical loom, invented by Joseph Marie Jacquard in 1801, which utilized holes punched in pasteboard, each row of which corresponded to one row of the design. ... The analytical engine, an important step in the history of computers, was the design of a mechanical general-purpose computer by the British professor of mathematics Charles Babbage. ... Portion of the Harvard-IBM Mark 1, left side. ... Konrad Zuses Z3 was the first working programmable, fully automatic machine, whose attributes, with the addition of conditional branching, have often been the ones used as criteria in defining a computer. ... The IBM 604 was a plug-board programmable Electronic Calculating Punch introduced in 1948, and was a machine on which considerable expectations for the future of IBM were pinned and in which a corresponding amount of planning talent was invested. ... UNIVAC 120 The Remington Rand 409 plugboard programmed punch card calculator, designed in 1949, was sold in two models: the UNIVAC 60 (1952) and the UNIVAC 120 (1953). ... UNIVAC 120 The Remington Rand 409 plugboard programmed punch card calculator, designed in 1949, was sold in two models: the UNIVAC 60 (1952) and the UNIVAC 120 (1953). ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... EDSAC EDSAC (Electronic Delay Storage Automatic Calculator) was an early British computer (one of the first computers to be created). ... The EDVAC as installed in Building 328 at the Ballistics Research Laboratory. ... UNIVAC I Central Complex, containing the central processor and main memory unit. ... The IBM 701, known as the Defense Calculator while in development, was announced to the public on April 29, 1952, and was IBM’s first commercial scientific computer. ... The IBM 700/7000 series was a series of incompatible large scale (mainframe) computer systems made by IBM through the 1950s and early 1960s. ... IBM 650 front panel, showing bi-quinary indicators IBM 650 front panel, rear view The IBM 650 was one of IBM’s early computers, and the world’s first mass-produced computer. ... After the Z1, Z2, Z3, Z4, Z5 and Z11, the Z22 was the seventh computer model Konrad Zuse developed. ... An integrated circuit (IC) is a thin chip consisting of at least two interconnected semiconductor devices, mainly transistors, as well as passive components like resistors. ... For other uses, see Mainframe. ... IBM 7090 console The IBM 7090 was a second-generation transistorized version of the earlier IBM 709 vacuum tube mainframe computers and was designed for large-scale scientific and technological applications. The 7090 was the third member of the IBM 700/7000 series scientific computers. ... The IBM 7080 was a transistorized variable word length BCD computer in the IBM 700/7000 series commercial architecture line, introduced in August 1961, that provided an upgrade path from the vacuum tube IBM 705 computer. ... System/360 Model 65 operators console, with register value lamps and toggle switches (middle of picture) and emergency pull switch (upper right). ... The group of competitors (mainframe computer manufacturers) to IBM in the 1960s became known as the BUNCH: Burroughs, UNIVAC, NCR, Control Data Corporation, and Honeywell. ... Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (traditionally, mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ... A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ... The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... The System/32 (IBM 5320) is a single user minicomputer marketed by IBM in the mid- to late 1970s. ... The System/36 was a minicomputer marketed by IBM from 1983 to 2000. ... VAX is a 32-bit computing architecture that supports an orthogonal instruction set (machine language) and virtual addressing (i. ... i5 Model 570 (2006) The IBM System i (formerly known as iSeries, AS/400, and Application System/400) is a minicomputer platform produced by IBM. It was officially introduced as the AS/400 in 1988. ... In computer science, 4-bit is an adjective used to describe integers, memory addresses or other data units that are at most 4 bits wide, or to describe CPU and ALU architectures based on registers, address buses, or data buses of that size. ... The Intel 4004, a 4-bit central processing unit (CPU) released by Intel Corp. ... Intel D4040 Microprocessor The Intel 4040 microprocessor was the successor to the Intel 4004. ... 8-bit refers to the number of bits used in the data bus of a computer. ... Intel 8008 The Intel 8008 was an early microprocessor designed and manufactured by Intel and introduced in April, 1972. ... AMD clone NEC 8080AF (2nd-source). ... Motorola 6800 Microprocessor The 6800 is a microprocessor produced by Motorola and released shortly after the Intel 8080 in 1975. ... 1 MHz Motorola 6809E processor, manufactured in 1983. ... The MOS Technology 6502 is an 8-bit microprocessor that was designed by Chuck Peddle for MOS Technology in 1975. ... One of the first Z80 microprocessors manufactured; the date stamp is from June 1976. ... In computer science, 16-bit is an adjective used to describe integers that are at most two bytes wide, or to describe CPU architectures based on registers, address buses, or data buses of that size. ... The Intel 8088 is an Intel microprocessor based on the 8086, with 16-bit registers and an 8-bit external data bus. ... The Z8000 was a 16-bit microprocessor introduced by ZiLOG in 1979. ... W65C816S microprocessor in a DIP40 package. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... The Intel 80386 is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 1994 and later. ... This article does not cite any references or sources. ... The Motorola 68000 is a CISC microprocessor, the first member of a successful family of microprocessors from Motorola, which were all mostly software compatible. ... The ARM architecture (previously, the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture developed by ARM Limited that is widely used in a number of embedded designs. ... In computing, a 64-bit component is one in which data are processed or stored in 64-bit units (words). ... The AMD64 or x86-64 is a 64-bit processor architecture invented by AMD. It is a superset of the x86 architecture, which it natively supports. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... A MIPS R4400 microprocessor made by Toshiba. ... Sun UltraSPARC II Microprocessor Sun UltraSPARC T1 (Niagara 8 Core) SPARC (Scalable Processor Architecture) is a RISC microprocessor instruction set architecture originally designed in 1985 by Sun Microsystems. ... A router, an example of an embedded system. ... The Intel 8048 microcontroller, Intels first µC, was used in the Magnavox Odyssey² video game console and (in its 8042 variant) in the original IBM PC keyboard. ... The Intel 8051 is a microcontroller developed by Intel in 1980 for use in embedded products and still (2003) one of the most popular microcontrollers. ... Desktop computer with several common peripherals (Monitor, keyboard, mouse, speakers, microphone and a printer) A desktop computer is a computer made for use on a desk in an office or home and is distinguished from portable computers such as laptops or PDAs. ... Children playing on a Amstrad CPC 464 in the 1980s. ... Laptop with touchpad. ... Look up Personal digital assistant in Wiktionary, the free dictionary. ... A Portable computer is a computer that is designed to be moved from one place to another (in other words, it is a computer that is portable). ... Toshiba Portege 3500 tablet PC, in tablet configuration. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... The Bloch sphere is a representation of a qubit, the fundamental building block of quantum computers. ... A chemical computer, also called reaction-diffusion computer, BZ computer or gooware computer is an unconventional computer based on a semi-solid chemical soup where data is represented by varying concentrations of chemicals. ... DNA computing is a form of computing which uses DNA and molecular biology, instead of the traditional silicon-based computer technologies. ... An optical computer is a computer that uses light instead of electricity (i. ... Unsolved problems in physics: Is it possible to construct a practical electronic device that operates on the spin of the electron, rather than its charge? Spintronics (a neologism for spin-based electronics), also known as magnetoelectronics, is an emergent technology which exploits the quantum spin states of electrons as well... It has been suggested that this article or section be merged into Computer hardware. ... Energy Input: The energy placed into a reaction. ... A contemporary computer mouse, with the most common standard features: two buttons and a scroll wheel. ... A 104-key PC US English QWERTY keyboard layout The Dvorak Simplified Keyboard layout A standard Hebrew keyboard showing both Hebrew and QWERTY. A computer keyboard is a peripheral partially modelled after the typewriter keyboard. ... For other uses, see Joystick (disambiguation). ... In computing, a scanner is a device that analyzes images, printed text, or handwriting, or an object (such as an ornament) and converts it to a digital image. ... Nineteen inch (48 cm) CRT computer monitor A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. ... A computer printer, or more commonly a printer, produces a hard copy (permanent human-readable text and/or graphics) of documents stored in electronic form, usually on physical print media such as paper transparencies]]. Many printers are primarily used as computer peripherals, and are attached by a printer cable to... A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ... Typical hard drives of the mid-1990s. ... “Optical media” redirects here. ... Teletype machines in World War II A teleprinter (teletypewriter, teletype or TTY for TeleTYpe/TeleTYpewriter) is a now largely obsolete electro-mechanical typewriter which can be used to communicate typed messages from point to point through a simple electrical communications channel, often just a pair of wires. ... In computer architecture, a bus is a subsystem that transfers data or power between computer components inside a computer or between computers and typically is controlled by device driver software. ... RS-232 (also referred to as EIA RS-232C or V.24) is a standard for serial binary data interchange between a DTE (Data terminal equipment) and a DCE (Data communication equipment). ... This article or section does not cite any references or sources. ... 64-bit PCI expansion slots inside a Power Macintosh G4 The Peripheral Component Interconnect, or PCI Standard (in practice almost always shortened to PCI), specifies a computer bus for attaching peripheral devices to a computer motherboard. ... Note: USB may also mean upper sideband in radio. ... This article or section is in need of attention from an expert on the subject. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operate at many speeds for local area networks (LANs). ... Asynchronous Transfer Mode (ATM) is a cell relay, packet switching network and data link layer protocol which encodes data traffic into small (53 bytes; 48 bytes of data and 5 bytes of header information) fixed-sized cells. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ...

Software

Main article: Computer software

Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called "firmware" to indicate that it falls into an uncertain area somewhere between hardware and software. It has been suggested that this article or section be merged with Computer program. ... For other uses, see Bios. ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... The Columbia MPC was one of the many IBM PC compatibles offered on the US market. ...

Computer software
Operating system Unix/BSD UNIX System V, AIX, HP-UX, Solaris (SunOS), FreeBSD, OpenBSD, NetBSD, IRIX
GNU/Linux List of Linux distributions, Comparison of Linux distributions
Microsoft Windows Windows 9x, Windows NT, Windows XP, Windows Vista, Windows CE
DOS 86-DOS (QDOS), PC-DOS, MS-DOS, FreeDOS
Mac OS Mac OS classic, Mac OS X
Embedded and real-time List of embedded operating systems
Experimental Amoeba, Oberon/Bluebottle, Plan 9 from Bell Labs
Library Multimedia DirectX, OpenGL, OpenAL
Programming library C standard library, Standard template library
Data Protocol TCP/IP, Kermit, FTP, HTTP, SMTP
File format HTML, XML, JPEG, MPEG, PNG
User interface Graphical user interface (WIMP) Microsoft Windows, GNOME, QNX Photon, CDE, GEM
Text user interface Command line interface, shells
Other
Application Office suite Word processing, Desktop publishing, Presentation program, Database management system, Scheduling & Time management, Spreadsheet, Accounting software
Internet Access Browser, E-mail client, Web server, Mail transfer agent, Instant messaging
Design and manufacturing Computer-aided design, Computer-aided manufacturing, Plant management, Robotic manufacturing, Supply chain management
Graphics Raster graphics editor, Vector graphics editor, 3D modeler, Animation editor, 3D computer graphics, Video editing, Image processing
Audio Digital audio editor, Audio playback, Mixing, Audio synthesis, Computer music
Software Engineering Compiler, Assembler, Interpreter, Debugger, Text Editor, Integrated development environment, Performance analysis, Revision control, Software configuration management
Educational Edutainment, Educational game, Serious game, Flight simulator
Games Strategy, Arcade, Puzzle, Simulation, First-person shooter, Platform, Massively multiplayer, Interactive fiction
Misc Artificial intelligence, Antivirus software, Malware scanner, Installer/Package management systems, File manager

It has been suggested that this article or section be merged with Computer program. ... // An operating system (OS) is the software that manages the sharing of the resources of a computer. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... “BSD” redirects here. ... It has been suggested that Traditional Unix be merged into this article or section. ... AIX (Advanced Interactive eXecutive) is a proprietary operating system developed by IBM based on UNIX System V. Before the product was ever marketed, the acronym AIX originally stood for Advanced IBM UNIX. AIX has pioneered numerous network operating system enhancements, introducing new innovations later adopted by Unix-like operating systems... HP-UX (Hewlett Packard UniX) is Hewlett-Packards proprietary implementation of the Unix operating system, based on System V (initially System III). ... Solaris is a computer operating system developed by Sun Microsystems. ... SunOS was the version of the UNIX operating system developed by Sun Microsystems for their workstations and server systems until the early 1990s. ... FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through the 386BSD and 4. ... OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution (BSD), a Unix derivative developed at the University of California, Berkeley. ... NetBSD is a freely redistributable, open source version of the Unix-like BSD computer operating system. ... IRIX is a computer operating system developed by Silicon Graphics, Inc. ... GNU (pronounced ) is a computer operating system composed entirely of free software. ... This article is about operating systems that use the Linux kernel. ... This page provides general information about each of the notable Linux distributions in the form of a categorized list. ... Technical variations include support for different hardware devices and systems or software package configurations. ... “Windows” redirects here. ... Windows 9x is a term used to describe the DOS-based operating systems Windows 95 and Windows 98, similar versions of Microsoft Windows which were produced in the 1990s. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Windows XP is a line of operating systems developed by Microsoft for use on general-purpose computer systems, including home and business desktops, notebook computers, and media centers. ... Windows Vista is a line of graphical operating systems used on personal computers, including home and business desktops, notebook computers, Tablet PCs, and media centers. ... Windows CE (sometimes abbreviated WinCE) is a variation of Microsofts Windows operating system for minimalistic computers and embedded systems. ... This article is about the family of closely related operating systems for the IBM PC compatible platform. ... 86-DOS was an operating system developed and marketed by Seattle Computer Products for its Intel 8086-based computer kit. ... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... FreeDOS (formerly Free-DOS and PD-DOS) is an operating system for IBM PC compatible computers. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... Mac OS X (IPA: ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... An embedded operating system is an operating system for embedded computer systems. ... A real-time operating system (RTOS) is a multitasking operating system intended for real-time applications. ... Operating systems can be categorized by technology, ownership, licensing, working state, usage, and by many other characteristics. ... The Amoeba distributed operating system is a microkernel-based research operating system written by Andrew S. Tanenbaum at Vrije Universiteit. ... Tiled window arrangement of Oberon Oberon is an operating system, originally developed as part of the NS32032-based Ceres workstation project; it is written entirely in the Oberon programming language. ... Bluebottle, also known as AOS, is the name of the next generation Native Oberon, the Oberon operating system for bare PC hardware. ... Plan 9 from Bell Labs is a distributed operating system, primarily used as a research vehicle. ... Illustration of an application which may use libvorbisfile. ... Look up Multimedia in Wiktionary, the free dictionary. ... Microsoft DirectX is a collection of application programming interfaces for handling tasks related to multimedia, especially game programming and video, on Microsoft platforms. ... OpenGL (Open Graphics Library) is a standard specification defining a cross-language cross-platform API for writing applications that produce 2D and 3D computer graphics. ... OpenAL (Open Audio Library) is a cross-platform audio API. It is designed for efficient rendering of multichannel three dimensional positional audio. ... The C standard library is a now-standardised collection of header files and library routines used to implement common operations, such as input/output and string handling, in the C programming language. ... [[Im[[Image:Example. ... In Computer Science, data is often distinguished from code, though both are represented in modern computers as binary strings. ... For other senses of this word, see protocol. ... The Internet protocol suite is the set of communications protocols that implement the protocol stack on which the Internet runs. ... Kermit is a computer file transfer/management protocol and a set of communications software tools; it provides a consistent approach to file transfer, terminal emulation, script programming, and character set conversion across many different computer hardware and OS platforms. ... The abbreviation FTP can refer to: The File Transfer Protocol used on the Internet. ... HTTP (for HyperText Transfer Protocol) is the primary method used to convey information on the World Wide Web. ... Simple Mail Transfer Protocol (SMTP) is the de facto standard for email transmission across the Internet. ... A file format is a particular way to encode information for storage in a computer file. ... HTML, short for Hypertext Markup Language, is the predominant markup language for web pages. ... The Extensible Markup Language (XML) is a general-purpose markup language. ... JPG redirects here. ... The Moving Picture Experts Group or MPEG is a working group of ISO/IEC charged with the development of video and audio encoding standards. ... PNG (Portable Network Graphics), sometimes pronounced as ping, is a relatively new bitmap image format that is becoming popular on the World Wide Web and elsewhere. ... The user interface is the part of a system exposed to users. ... “GUI” redirects here. ... In human–computer interaction, WIMP stands for window, icon, menu, pointing device, denoting a style of interaction using these elements. ... “Windows” redirects here. ... This article is about the mythical creature. ... QNX (pronounced either Q-N-X or Q-nix) is a commercial POSIX-compliant Unix-like real-time operating system, aimed primarily at the embedded systems market. ... CDE on Unix (Solaris 8) DECwindows CDE on OpenVMS 7. ... GEM (Graphical Environment Manager) was a windowing system created by Digital Research, Inc. ... TUI (Text User Interface) is a retronym that was coined sometime after the invention of graphical user interfaces, to distinguish them from text based user interfaces. ... This article or section does not adequately cite its references or sources. ... In computing, a shell is a piece of software that provides an interface for users (command line interpreter). ... This article does not cite any references or sources. ... In computing, an office suite, sometimes called an office application suite or productivity suite is a software suite intended to be used by typical clerical and knowledge workers. ... Word processing, in its now-usual meaning, is the use of a word processor to create documents using computers. ... Adobe InDesign CS2, one of many popular desktop publishing applications. ... A presentation using PowerPoint. ... A database management system (DBMS) is computer software designed for the purpose of managing databases. ... A spreadsheet is a rectangular table (or grid) of information, often financial information. ... This article does not cite any references or sources. ... An example of a Web browser (Mozilla Firefox) A web browser is a software application that enables a user to display and interact with text, images, videos, music and other information typically located on a Web page at a website on the World Wide Web or a local area network. ... This article does not cite any references or sources. ... The inside/front of a Dell PowerEdge web server The term Web server can mean one of two things: A computer program that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are... A mail transfer agent or MTA (also called a mail transport agent, mail server, or a mail exchanger in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ... Instant messaging (IM) is a form of real-time communication between two or more people based on typed text. ... CADD and CAD redirect here. ... Computer-aided manufacturing (CAM) is the use of a wide range of computer-based software tools that assist engineers and CNC machinists in the manufacture or prototyping of product components. ... This article is about the scientific discipline of computer graphics. ... A screenshot from the KDE raster graphics editor KolourPaint A screenshot from the GIMP raster graphics editor A raster graphics editor is a computer program that allows users to paint and edit pictures interactively on the computer screen and save them in one of many popular bitmap or raster formats... A screenshot of the xfig vector graphics editor A screenshot of the modern vector graphics editor Xara Xtreme A vector graphics editor is a computer program that allows users to compose and edit vector graphics images interactively on the computer screen (compare with MetaPost) and save them in one of... It has been suggested that this article or section be merged into 3D computer graphics software. ... Animation software is software that is used either for computer animation or to assist animators with the considerable work needed to create more traditional pieces of animation. ... 3D computer graphics (in contrast to 2D computer graphics) are graphics that utilize a three-dimensional representation of geometric data that is stored in the computer for the purposes of performing calculations and rendering 2D images. ... The term video editing can refer to: non-linear editing system, using computers with video editing software linear video editing, using videotape Video editing is the process of re-arranging or modifying segments of video to form another piece of video. ... UPIICSA IPN - Binary image Image processing is any form of information processing for which the input is an image, such as photographs or frames of video; the output is not necessarily an image, but can be for instance a set of features of the image. ... Digital audio comprises audio signals stored in a digital format. ... A digital audio editor is a computer application for audio editing, i. ... An audio player is a kind of media player for playing back digital audio, including optical discs such as CDs, SACDs, DVD-Audio, HDCD, and audio files. ... A software synthesizer, also known as a softsynth or virtual instrument is a computer program for digital audio generation. ... Computer music is music generated with, or composed with the aid of, computers. ... Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ... In computer science, an interpreter is a computer program that executes, or performs, instructions written in a computer programming language. ... A debugger is a computer program that is used to test and debug other programs. ... Notepad is the standard text editor for Microsoft Windows A text editor is a piece of computer software for editing plain text. ... An integrated development environment (IDE), also known as integrated design environment and integrated debugging environment, is a programming environment that has been packaged as an application program,that assists computer programmers in developing software. ... In software engineering, performance analysis (a field of dynamic program analysis) is the investigation of a programs behavior using information gathered as the program runs, as opposed to static code analysis. ... Revision control (also known as version control, source control or (source) code management (SCM)) is the management of multiple revisions of the same unit of information. ... Software Configuration Management (SCM) is part of configuration management (CM). ... Edutainment (also educational entertainment or entertainment-education) is a form of entertainment designed to educate as well as to amuse. ... Educational games are games; board and card games, including video games that are designed to teach people, typically children, about a certain subject, expand concepts, reinforce development, understand an historical event or culture, or assit them in learning a skill as they play. ... A serious game is a software application developed with game technology and game design principles for a primary purpose other than pure entertainment. ... For flight simulator software from Microsoft, see Microsoft Flight Simulator. ... This article is about the British magazine covering computer and video games. ... Chess is one of the most well-known and played strategy games of all time. ... Minesweeper, a popular computer puzzle game found on many machines. ... This article is about video games. ... A simple platform sequence from the game Wonder Boy Platform game, or platformer, is a video game genre characterized by jumping to and from suspended platforms or over obstacles. ... “MMO” redirects here. ... Zork I is one of the first interactive fiction games, as well as being one of the first commercially sold. ... Bold text[[Link title]] “AI” redirects here. ... “Antivirus” redirects here. ... A malware scanner is a program, akin to virus scanners, which detects malicious software in a computers RAM or hard drive. ... An installation program or installer is a computer program that installs files, such as applications, drivers, or other software, onto a computer. ... Illustration of a package management system being used to download new software. ... A screenshot of File Manager displaying a folder and the contents of the C drive. ...

Programming languages

Programming languages provide various ways of specifying programs for computers to run. Unlike natural languages, programming languages are designed to permit no ambiguity and to be concise. They are purely written languages and are often difficult to read aloud. They are generally either translated into machine language by a compiler or an assembler before being run, or translated directly at run time by an interpreter. Sometimes programs are executed by a hybrid method of the two techniques. There are thousands of different programming languages — some intended to be general purpose, others useful only for highly specialized applications. The term natural language is used to distinguish languages spoken and signed (by hand signals and facial expressions) by humans for general-purpose communication from constructs such as writing, computer-programming languages or the languages used in the study of formal logic, especially mathematical logic. ... A system of codes directly understandable by a computers CPU is termed this CPUs native or machine language. ... A diagram of the operation of a typical multi-language, multi-target compiler. ... See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ... In computer science, an interpreter is a computer program that executes, or performs, instructions written in a computer programming language. ...

Programming Languages
Lists of programming languages Timeline of programming languages, Categorical list of programming languages, Generational list of programming languages, Alphabetical list of programming languages, Non-English-based programming languages
Commonly used Assembly languages ARM, MIPS, x86
Commonly used High level languages BASIC, C, C++, C#, COBOL, Fortran, Java, Lisp, Pascal
Commonly used Scripting languages Bourne script, JavaScript, Python, Ruby, PHP, Perl

Other listings of programming languages are: Categorical list of programming languages Generational list of programming languages Chronological list of programming languages Note: Esoteric programming languages have been moved to the separate List of esoteric programming languages. ... This is a timeline, i. ... This is a list of programming languages grouped by category. ... Here, a genealogy of programming languages is shown. ... The list of programming languages consists of all notable programming languages in existence, currently or since the dawn of computing, in alphabetical order. ... Non-English-based programming languages are computer programming languages that, unlike most well-known programming languages, do not use keywords taken from, or inspired by, the English vocabulary. ... See the terminology section, below, regarding inconsistent use of the terms assembly and assembler. ... The ARM architecture (previously, the Advanced RISC Machine, and prior to that Acorn RISC Machine) is a 32-bit RISC processor architecture developed by ARM Limited that is widely used in a number of embedded designs. ... A MIPS R4400 microprocessor made by Toshiba. ... The correct title of this article is . ... A high-level programming language is a programming language that is more user-friendly, to some extent platform-independent, and abstract from low-level computer processor operations such as memory accesses. ... This article is about the programming language. ... C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... C++ (pronounced see plus plus, IPA: ) is a general-purpose programming language with high-level and low-level capabilities. ... The title given to this article is incorrect due to technical limitations. ... COBOL (pronounced //) is a third-generation programming language, and one of the oldest programming languages still in active use. ... Fortran (previously FORTRAN[1]) is a general-purpose[2], procedural,[3] imperative programming language that is especially suited to numeric computation and scientific computing. ... “Java language” redirects here. ... “LISP” redirects here. ... Pascal is a structured imperative computer programming language, developed in 1970 by Niklaus Wirth as a language particularly suitable for structured programming. ... Scripting languages (commonly called scripting programming languages or script languages) are computer programming languages that are typically interpreted and can be typed directly from a keyboard. ... The Bourne shell, or sh, was the default Unix shell of Unix Version 7, and replaced the Thompson shell, whose executable file had the same name, sh. ... It has been suggested that Client-side JavaScript be merged into this article or section. ... Python is a high-level programming language first released by Guido van Rossum in 1991. ... Ruby is a reflective, dynamic, object-oriented programming language. ... For other uses, see PHP (disambiguation). ... Wikibooks has a book on the topic of Perl Programming Perl is a dynamic programming language created by Larry Wall and first released in 1987. ...

Professions and organizations

As the use of computers has spread throughout society, there are an increasing number of careers involving computers. Following the theme of hardware, software and firmware, the brains of people who work in the industry are sometimes known irreverently as wetware or "meatware".

Computer-related professions
Hardware-related Electrical engineering, Electronics engineering, Computer engineering, Telecommunications engineering, Optical engineering, Nanoscale engineering
Software-related Human-computer interaction, Information technology, Software engineering, Scientific computing, Web design, Desktop publishing

The need for computers to work well together and to be able to exchange information has spawned the need for many standards organizations, clubs and societies of both a formal and informal nature. Electrical Engineers design power systems… … and complex electronic circuits. ... It has been suggested that this article or section be merged with electrical and electronics engineering. ... Computer engineering (also called electronic and computer engineering) is a discipline that combines elements of both electrical engineering and computer science. ... Telecommunications engineering focuses on the transmission of information across a channel such as a coax cable, optical fibre or free space. ... Optical engineering is the field of study which focuses on applications of optics. ... Nanoengineering is the practice of engineering on the nanoscale. ... // Human–computer interaction (HCI), alternatively man–machine interaction (MMI) or computer–human interaction (CHI)This interactive computer allows the user to intergrate a reaction towards oneself and the primary source that is the http server, the port and Ip address show as the user connects to the imb harddrive , is... Information and communication technology spending in 2005 Information technology (IT), as defined by the Information Technology Association of America (ITAA), is the study, design, development, implementation, support or management of computer-based information systems, particularly software applications and computer hardware. ... Software engineering is the application of a systematic, disciplined, quantifiable approach to the development, operation, and maintenance of software. ... Scientific computing (or computational science) is the field of study concerned with constructing mathematical models and numerical solution techniques and using computers to analyze and solve scientific and engineering problems. ... Web design is a process of conceptualization, planning, modeling, and execution of electronic media delivery via Internet in the form of Markup language suitable for interpretation by Web browser and display as Graphical user interface (GUI). ... Adobe InDesign CS2, one of many popular desktop publishing applications. ...

Organizations
Standards groups ANSI, IEC, IEEE, IETF, ISO, W3C
Professional Societies ACM, ACM Special Interest Groups, IET, IFIP
Free/Open source software groups Free Software Foundation, Mozilla Foundation, Apache Software Foundation

The American National Standards Institute or ANSI (pronounced an-see) is a nonprofit organization that oversees the development of standards for products, services, processes and systems in the United States. ... The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... Not to be confused with the Institution of Electrical Engineers (IEE). ... The Internet Engineering Task Force (IETF) develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standard bodies; and dealing in particular with standards of the TCP/IP and Internet protocol suite. ... “ISO” redirects here. ... It has been suggested that W3C Markup Validation Service be merged into this article or section. ... The Association for Computing Machinery, or ACM, was founded in 1947 as the worlds first scientific and educational computing society. ... IET logo The Institution of Engineering and Technology (IET) is the professional institution for engineering and technology in the United Kingdom. ... The International Federation for Information Processing, usually known as IFIP, is an umbrella organization for national societies working in the field of information technology. ... This article is about free software as used in the sociopolitical free software movement; for non-free software distributed without charge, see freeware. ... Open source software is computer software which source code is available under a license (or arrangement such as the public domain) that meets the Open_source_definition. ... The Free Software Foundation (FSF) is a non-profit corporation founded in October 1985 by Richard Stallman to support the free software movement (free as in freedom), and in particular the GNU project. ... The Mountain View office shared by the Mozilla Foundation and the Mozilla Corporation The Mozilla Foundation (abbreviated MF or MoFo) is a non-profit organization that exists to support and provide leadership for the open source Mozilla project. ... Apache Software Foundation Logo The Apache Software Foundation (ASF) is a non-profit corporation (classified as 501(c)(3) in the United States) to support Apache software projects, including the Apache HTTP Server. ...

See also

Look up Computer in
Wiktionary, the free dictionary.
Wikiquote has a collection of quotations related to:
Wikimedia Commons has media related to:


Wikipedia does not have an article with this exact name. ... Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 150 languages. ... Image File history File links This is a lossless scalable vector image. ... Wikiquote is one of a family of wiki-based projects run by the Wikimedia Foundation, running on MediaWiki software. ... Image File history File links Commons-logo. ... In computer science, computability theory is the branch of the theory of computation that studies which problems are computationally solvable using different models of computation. ... Computer science, or computing science, is the study of the theoretical foundations of information and computation and their implementation and application in computer systems. ... RAM (Random Access Memory) Look up computing in Wiktionary, the free dictionary. ... This page is intended to be a list of computers in fiction and science fiction. ... This article describes how security can be achieved through design and engineering. ... Many current computer systems have only limited security precautions in place. ... This is a list of the origins of computer-related terms (i. ... In computing, virtualization is a broad term that refers to the abstraction of computer resources. ...


Notes

  1. ^ In 1946, ENIAC consumed an estimated 174 kW. By comparison, a typical personal computer may use around 400 W; over four hundred times less. (Kempf 1961)
  2. ^ Early computers such as Colossus and ENIAC were able to process between 5 and 100 operations per second. A modern "commodity" microprocessor (as of 2007) can process billions of operations per second, and many of these operations are more complicated and useful than early computer operations.
  3. ^ The Analytical Engine should not be confused with Babbage's difference engine which was a non-programmable mechanical calculator.
  4. ^ This program was written similarly to those for the PDP-11 minicomputer and shows some typical things a computer can do. All the text after the semicolons are comments for the benefit of human readers. These have no significance to the computer and are ignored. (Digital Equipment Corporation 1972)
  5. ^ Attempts are often made to create programs that can overcome this fundamental limitation of computers. Software that mimics learning and adaptation is part of artificial intelligence.
  6. ^ It is not universally true that bugs are solely due to programmer oversight. Computer hardware may fail or may itself have a fundamental problem that produces unexpected results in certain situations. For instance, the Pentium FDIV bug caused some Intel microprocessors in the early 1990s to produce inaccurate results for certain floating point division operations. This was caused by a flaw in the microprocessor design and resulted in a partial recall of the affected devices.
  7. ^ Even some later computers were commonly programmed directly in machine code. Some minicomputers like the DEC PDP-8 could be programmed directly from a panel of switches. However, this method was usually used only as part of the booting process. Most modern computers boot entirely automatically by reading a boot program from some non-volatile memory.
  8. ^ However, there is sometimes some form of machine language compatibility between different computers. An x86-64 compatible microprocessor like the AMD Athlon 64 is able to run most of the same programs that an Intel Core 2 microprocessor can, as well as programs designed for earlier microprocessors like the Intel Pentiums and Intel 80486. This contrasts with very early commercial computers, which were often one-of-a-kind and totally incompatible with other computers.
  9. ^ High level languages are also often interpreted rather than compiled. Interpreted languages are translated into machine code on the fly by another program called an interpreter.
  10. ^ Although this is a simple program, it contains a software bug. If the traffic signal is showing red when someone switches the "flash red" switch, it will cycle through green once more before starting to flash red as instructed. This bug is quite easy to fix by changing the program to repeatedly test the switch throughout each "wait" period — but writing large programs that have no bugs is exceedingly difficult.
  11. ^ The control unit's rule in interpreting instructions has varied somewhat in the past. While the control unit is solely responsible for instruction interpretation in most modern computers, this is not always the case. Many computers include some instructions that may only be partially interpreted by the control system and partially interpreted by another device. This is especially the case with specialized computing hardware that may be partially self-contained. For example, EDVAC, the first modern stored program computer to be designed, used a central control unit that only interpreted four instructions. All of the arithmetic-related instructions were passed on to its arithmetic unit and further decoded there.
  12. ^ Instructions often occupy more than one memory address, so the program counters usually increases by the number of memory locations required to store one instruction.
  13. ^ Flash memory also may only be rewritten a limited number of times before wearing out, making it less useful for heavy random access usage. (Verma 1988)
  14. ^ However, it is also very common to construct supercomputers out of many pieces of cheap commodity hardware; usually individual computers connected by networks. These so-called computer clusters can often provide supercomputer performance at a much lower cost than customized designs. While custom architectures are still used for most of the most powerful supercomputers, there has been a proliferation of cluster computers in recent years. (TOP500 2006)
  15. ^ Most major 64-bit instruction set architectures are extensions of earlier designs. All of the architectures listed in this table existed in 32-bit forms before their 64-bit incarnations were introduced.

ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... A Colossus Mark II computer. ... ENIAC ENIAC, short for Electronic Numerical Integrator And Computer,[1] was the first large-scale, electronic, digital computer capable of being reprogrammed to solve a full range of computing problems,[2] although earlier computers had been built with some of these properties. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era in the 21st Century. ... Part of Babbages Difference engine, assembled after his death by Babbages son, using parts found in his laboratory. ... The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (traditionally, mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ... An illustration of Java source code with prologue comments indicated in red and inline comments in green. ... Bold text[[Link title]] “AI” redirects here. ... On October 30, 1994, Professor Thomas Nicely who was then at Lynchburg College reported a bug in the Pentium floating point unit. ... Intel Corporation (NASDAQ: INTC, SEHK: 4335), founded in 1968 as Integrated Electronics Corporation, is an American multinational corporation that is best known for designing and manufacturing microprocessors and specialized integrated circuits. ... A microprocessor is a programmable digital electronic component that incorporates the functions of a central processing unit (CPU) on a single semiconducting integrated circuit (IC). ... A floating-point number is a digital representation for a number in a certain subset of the rational numbers, and is often used to approximate an arbitrary real number on a computer. ... Minicomputer (colloquially, mini) is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (traditionally, mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ... A PDP-8 on display at the Smithsonians National Museum of American History in Washington, D.C.. This example is from the first generation of PDP-8s, built with discrete transistors and later known as the Straight 8. ... In computing, booting (booting up) is a bootstrapping process that starts operating systems when the user turns on a computer system. ... It has been suggested that this article or section be merged with NVRAM. (Discuss) Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, is computer memory that can retain the stored information even when not powered. ... The AMD64 or x86-64 is a 64-bit processor architecture invented by AMD. It is a superset of the x86 architecture, which it natively supports. ... “AMD” redirects here. ... The Athlon 64 is an eighth-generation, AMD64 architecture microprocessor produced by AMD, released on September 23, 2003. ... The Core 2 brand refers to a range of Intels consumer dual-core and quad-core (2x2) 64-bit x86-64 CPUs based on the Intel Core microarchitecture, which derived from the 32-bit dual-core Yonah laptop processor. ... This article does not cite any references or sources. ... The Intel486[1] brand refers to Intels family of i486 (incl. ... In computer programming, an interpreted language is a programming language whose programs may be executed from source form, by an interpreter. ... In computer science, an interpreter is a computer program that executes, or performs, instructions written in a computer programming language. ... A software bug is an error, flaw, mistake, failure, or fault in a computer program that prevents it from behaving as intended (e. ... The EDVAC as installed in Building 328 at the Ballistics Research Laboratory. ... An example of a Computer cluster A computer cluster is a group of tightly coupled computers that work together closely so that in many respects they can be viewed as though they are a single computer. ... An instruction set, or instruction set architecture (ISA), describes the aspects of a computer architecture visible to a programmer, including the native datatypes, instructions, registers, addressing modes, memory architecture, interrupt and exception handling, and external I/O (if any). ...

References

Aberdeen Proving Ground is a United States Army facility located at Aberdeen, Maryland (in Harford county). ... The United States Army is the largest and oldest branch of the armed forces of the United States. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 95th day of the year (96th in leap years) in the Gregorian calendar. ... The DEC logo Digital Equipment Corporation was a pioneering American company in the computer industry. ...   Maynard is a town in Middlesex County, Massachusetts, United States. ... Hans Meuer is a Professor of Computer Science at the University of Mannheim, general manager of Prometeus GmbH and general chairman of the International Supercomputing Conference[1]. In 1986, he became co-founder and organizer of the first Mannheim Supercomputer Conference[2], which has been held annually ever since. ... Jack Dongarra is a University Distinguished Professor of Computer Science in the Computer Science Department [1] at the University of Tennessee. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 317th day of the year (318th in leap years) in the Gregorian calendar. ... The TOP500 project ranks and details the 500 most powerful publicly-known computer systems in the world. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 331st day of the year (332nd in leap years) in the Gregorian calendar. ...


  Results from FactBites:
 
SCHOOL OF COMPUTER SCIENCE/Carnegie Mellon University (492 words)
A paper detailing the algorithm, developed by Tuomas Sandholm, Avrim Blum (professors of computer science), and graduate assistant David J. Abraham, will be presented at the Association for Computing Machinery’s Conference on Electronic Commerce in San Diego.
Computational Thinking: By coining the term “computational thinking,” Jeannette Wing, Head CSD, encapsulated both the answer to the question, “What is computer science?”; and a viewpoint on how computer science is revolutionizing not only all the sciences, but impacting every aspect of our lives in the 21st century.
You can also download a copy of the Computer Science poster which displays many of the diverse and exciting areas of Computer Science.
Home Computer Security (12040 words)
While intruders also attack home computers connected to the Internet through dial-in connections, high-speed connections (cable modems and DSL modems) are a favorite target.
Instead, it goes from your computer to another computer to still another computer and so on, eventually reaching his or her computer.
For a computer, the repair cycle might have to be repeated until a patch completely fixes a problem.
  More results at FactBites »

 
 

COMMENTARY     


Share your thoughts, questions and commentary here
Your name
Your comments

Want to know more?
Search encyclopedia, statistics and forums:

 


Press Releases |  Feeds | Contact
The Wikipedia article included on this page is licensed under the GFDL.
Images may be subject to relevant owners' copyright.
All other elements are (c) copyright NationMaster.com 2003-5. All Rights Reserved.
Usage implies agreement with terms, 1022, m