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A computer is a

digital electronic computers can perform generic sets of operations known as programs. These programs enable computers to perform a wide range of tasks. A computer system is a nominally complete computer that includes the hardware, operating system (main software), and peripheral equipment needed and used for full operation. This term may also refer to a group of computers that are linked and function together, such as a computer network or computer cluster

A broad range of industrial and consumer products use computers as control systems. Simple special-purpose devices like microwave ovens and remote controls are included, as are factory devices like industrial robots and computer-aided design, as well as general-purpose devices like personal computers and mobile devices like smartphones. Computers power the Internet, which links billions of other computers and users.

Early computers were meant to be used only for calculations. Simple manual instruments like the

microcomputer revolution in the 1970s. The speed, power and versatility of computers have been increasing dramatically ever since then, with transistor counts increasing at a rapid pace (as predicted by Moore's law), leading to the Digital Revolution
during the late 20th to early 21st centuries.

Conventionally, a modern computer consists of at least one

processing element, typically a central processing unit (CPU) in the form of a microprocessor, along with some type of computer memory, typically semiconductor memory chips. The processing element carries out arithmetic and logical operations, and a sequencing and control unit can change the order of operations in response to stored information. Peripheral devices include input devices (keyboards, mice, joystick, etc.), output devices (monitor screens, printers, etc.), and input/output devices that perform both functions (e.g., the 2000s-era touchscreen
). Peripheral devices allow information to be retrieved from an external source and they enable the result of operations to be saved and retrieved.


A human computer.
A human computer, with microscope and calculator, 1952

According to the

human computer, a person who carried out calculations or computations. The word continued with the same meaning until the middle of the 20th century. During the latter part of this period women were often hired as computers because they could be paid less than their male counterparts.[1] By 1943, most human computers were women.[2]

The Online Etymology Dictionary gives the first attested use of computer in the 1640s, meaning 'one who calculates'; this is an "agent noun from compute (v.)". The Online Etymology Dictionary states that the use of the term to mean "'calculating machine' (of any type) is from 1897." The Online Etymology Dictionary indicates that the "modern use" of the term, to mean 'programmable digital electronic computer' dates from "1945 under this name; [in a] theoretical [sense] from 1937, as Turing machine".[3]


Pre-20th century

The Ishango bone, a bone tool dating back to prehistoric Africa

Devices have been used to aid computation for thousands of years, mostly using

fingers. The earliest counting device was most likely a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, likely livestock or grains, sealed in hollow unbaked clay containers.[a][4] The use of counting rods
is one example.

The Chinese suanpan (算盘). The number represented on this abacus is 6,302,715,408.

The abacus was initially used for arithmetic tasks. The Roman abacus was developed from devices used in Babylonia as early as 2400 BCE. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money.[5]

analog computing


Kythera and Crete, and has been dated to approximately c. 100 BCE. Devices of comparable complexity to the Antikythera mechanism would not reappear until the fourteenth century.[7]

Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The

Persia in 1235.[11] Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe,[12] an early fixed-wired knowledge processing machine[13] with a gear train and gear-wheels,[14]
c. 1000 AD.

The sector, a calculating instrument used for solving problems in proportion, trigonometry, multiplication and division, and for various functions, such as squares and cube roots, was developed in the late 16th century and found application in gunnery, surveying and navigation.

The planimeter was a manual instrument to calculate the area of a closed figure by tracing over it with a mechanical linkage.

A slide rule

The slide rule was invented around 1620–1630 by the English clergyman William Oughtred, shortly after the publication of the concept of the logarithm. It is a hand-operated analog computer for doing multiplication and division. As slide rule development progressed, added scales provided reciprocals, squares and square roots, cubes and cube roots, as well as transcendental functions such as logarithms and exponentials, circular and hyperbolic trigonometry and other functions. Slide rules with special scales are still used for quick performance of routine calculations, such as the E6B circular slide rule used for time and distance calculations on light aircraft.

In the 1770s,

automaton) that could write holding a quill pen. By switching the number and order of its internal wheels different letters, and hence different messages, could be produced. In effect, it could be mechanically "programmed" to read instructions. Along with two other complex machines, the doll is at the Musée d'Art et d'Histoire of Neuchâtel, Switzerland, and still operates.[15]

In 1831–1835, mathematician and engineer

Sir William Thomson
in 1872 was of great utility to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for a set period at a particular location.

The differential analyser, a mechanical analog computer designed to solve differential equations by integration, used wheel-and-disc mechanisms to perform the integration. In 1876, Sir William Thomson had already discussed the possible construction of such calculators, but he had been stymied by the limited output torque of the ball-and-disk integrators.[16] In a differential analyzer, the output of one integrator drove the input of the next integrator, or a graphing output. The torque amplifier was the advance that allowed these machines to work. Starting in the 1920s, Vannevar Bush and others developed mechanical differential analyzers.

In the 1890s, the Spanish engineer Leonardo Torres Quevedo began to develop a series of advanced analog machines that could solve real and complex roots of polynomials,[17][18][19][20] which were published in 1901 by the Paris Academy of Sciences.[21]

First computer

Charles Babbage c. 1850
A diagram of a portion of Babbage's Difference engine
The Difference Engine Number 2 at the Intellectual Ventures laboratory in Seattle

father of the computer",[22] he conceptualized and invented the first mechanical computer
in the early 19th century.

After working on his

The machine was about a century ahead of its time. All the parts for his machine had to be made by hand – this was a major problem for a device with thousands of parts. Eventually, the project was dissolved with the decision of the

Henry Babbage
, completed a simplified version of the analytical engine's computing unit (the mill) in 1888. He gave a successful demonstration of its use in computing tables in 1906.

Electromechanical calculating machine

Electro-mechanical calculator (1920) by Leonardo Torres Quevedo.

In his work Essays on Automatics published in 1914, Leonardo Torres Quevedo wrote a brief history of Babbage's efforts at constructing a mechanical Difference Engine and Analytical Engine. He described the Analytical Engine as exemplifying his theories about the potential power of machines, and takes the problem of designing such an engine as a challenge to his skills as an inventor of electromechanical devices. The paper contains a design of a machine capable of calculating completely automatically the value of the formula , for a sequence of sets of values of the variables involved. The whole machine was to be controlled by a

Electromechanical Arithmometer, which consisted of an arithmetic unit connected to a (possibly remote) typewriter, on which commands could be typed and the results printed automatically,[29][30][31] demonstrating the feasibility of an electromechanical analytical engine.[32]

Analog computers

Sir William Thomson
's third tide-predicting machine design, 1879–81

During the first half of the 20th century, many scientific

Sir William Thomson (later to become Lord Kelvin) in 1872. The differential analyser, a mechanical analog computer designed to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized in 1876 by James Thomson, the elder brother of the more famous Sir William Thomson.[16]

The art of mechanical analog computing reached its zenith with the

differential analyzer, built by H. L. Hazen and Vannevar Bush at MIT starting in 1927. This built on the mechanical integrators of James Thomson and the torque amplifiers invented by H. W. Nieman. A dozen of these devices were built before their obsolescence became obvious. By the 1950s, the success of digital electronic computers had spelled the end for most analog computing machines, but analog computers remained in use during the 1950s in some specialized applications such as education (slide rule) and aircraft (control systems

Digital computers


By 1938, the United States Navy had developed an electromechanical analog computer small enough to use aboard a submarine. This was the Torpedo Data Computer, which used trigonometry to solve the problem of firing a torpedo at a moving target. During World War II similar devices were developed in other countries as well.

Replica of Konrad Zuse's Z3, the first fully automatic, digital (electromechanical) computer

Early digital computers were electromechanical; electric switches drove mechanical relays to perform the calculation. These devices had a low operating speed and were eventually superseded by much faster all-electric computers, originally using vacuum tubes. The Z2, created by German engineer Konrad Zuse in 1939 in Berlin, was one of the earliest examples of an electromechanical relay computer.[34]

Konrad Zuse, inventor of the modern computer[35][36]

In 1941, Zuse followed his earlier machine up with the

floating-point numbers. Rather than the harder-to-implement decimal system (used in Charles Babbage's earlier design), using a binary system meant that Zuse's machines were easier to build and potentially more reliable, given the technologies available at that time.[40] The Z3 was not itself a universal computer but could be extended to be Turing complete.[41][42]

Zuse's next computer, the

Zuse KG [de], which was founded in 1941 as the first company with the sole purpose of developing computers in Berlin.[43]

Vacuum tubes and digital electronic circuits


Atanasoff–Berry Computer (ABC) in 1942,[44] the first "automatic electronic digital computer".[45] This design was also all-electronic and used about 300 vacuum tubes, with capacitors fixed in a mechanically rotating drum for memory.[46]

Two women are seen by the Colossus computer.
Colossus, the first electronic digital programmable computing device, was used to break German ciphers during World War II. It is seen here in use at Bletchley Park in 1943.

During World War II, the British code-breakers at

Lorenz SZ 40/42 machine, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to build the Colossus.[46] He spent eleven months from early February 1943 designing and building the first Colossus.[49] After a functional test in December 1943, Colossus was shipped to Bletchley Park, where it was delivered on 18 January 1944[50] and attacked its first message on 5 February.[46]

Colossus was the world's first

boolean logical operations on its data, but it was not Turing-complete. Nine Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines in total). Colossus Mark I contained 1,500 thermionic valves (tubes), but Mark II with 2,400 valves, was both five times faster and simpler to operate than Mark I, greatly speeding the decoding process.[51][52]

ENIAC was the first electronic, Turing-complete device, and performed ballistics trajectory calculations for the United States Army.


stored program electronic machines that came later. Once a program was written, it had to be mechanically set into the machine with manual resetting of plugs and switches. The programmers of the ENIAC were six women, often known collectively as the "ENIAC girls".[54][55]

It combined the high speed of electronics with the ability to be programmed for many complex problems. It could add or subtract 5000 times a second, a thousand times faster than any other machine. It also had modules to multiply, divide, and square root. High speed memory was limited to 20 words (about 80 bytes). Built under the direction of John Mauchly and J. Presper Eckert at the University of Pennsylvania, ENIAC's development and construction lasted from 1943 to full operation at the end of 1945. The machine was huge, weighing 30 tons, using 200 kilowatts of electric power and contained over 18,000 vacuum tubes, 1,500 relays, and hundreds of thousands of resistors, capacitors, and inductors.[56]

Modern computers

Concept of modern computer

The principle of the modern computer was proposed by

stored program, where all the instructions for computing are stored in memory. Von Neumann acknowledged that the central concept of the modern computer was due to this paper.[58] Turing machines are to this day a central object of study in theory of computation. Except for the limitations imposed by their finite memory stores, modern computers are said to be Turing-complete, which is to say, they have algorithm
execution capability equivalent to a universal Turing machine.

Stored programs

Three tall racks containing electronic circuit boards
A section of the reconstructed Manchester Baby, the first electronic stored-program computer

Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring of the machine.

instruction set and can store in memory a set of instructions (a program) that details the computation. The theoretical basis for the stored-program computer was laid out by Alan Turing in his 1936 paper. In 1945, Turing joined the National Physical Laboratory and began work on developing an electronic stored-program digital computer. His 1945 report "Proposed Electronic Calculator" was the first specification for such a device. John von Neumann at the University of Pennsylvania also circulated his First Draft of a Report on the EDVAC in 1945.[33]


Frederic C. Williams, Tom Kilburn and Geoff Tootill, and ran its first program on 21 June 1948.[59] It was designed as a testbed for the Williams tube, the first random-access digital storage device.[60] Although the computer was described as "small and primitive" by a 1998 retrospective, it was the first working machine to contain all of the elements essential to a modern electronic computer.[61] As soon as the Baby had demonstrated the feasibility of its design, a project began at the university to develop it into a practically useful computer, the Manchester Mark 1

The Mark 1 in turn quickly became the prototype for the


Grace Hopper was the first to develop a compiler for a programming language.[2]


Bipolar junction transistor (BJT)

The concept of a

mass-production basis, which limited them to a number of specialized applications.[67]

At the University of Manchester, a team under the leadership of Tom Kilburn designed and built a machine using the newly developed transistors instead of valves.[68] Their first transistorized computer and the first in the world, was operational by 1953, and a second version was completed there in April 1955. However, the machine did make use of valves to generate its 125 kHz clock waveforms and in the circuitry to read and write on its magnetic drum memory, so it was not the first completely transistorized computer. That distinction goes to the Harwell CADET of 1955,[69] built by the electronics division of the Atomic Energy Research Establishment at Harwell.[69][70]

MOSFET (MOS transistor), showing gate (G), body (B), source (S) and drain (D) terminals. The gate is separated from the body by an insulating layer (pink).


computer revolution.[77][78] The MOSFET is the most widely used transistor in computers,[79][80] and is the fundamental building block of digital electronics.[81]

Integrated circuits

MOS 6502 computer chip die photograph
Die photograph of a MOS 6502, an early 1970s microprocessor integrating 3500 transistors on a single chip
MOS 6502 computer chip in 'DIP' package
Integrated circuits are typically packaged in plastic, metal, or ceramic cases to protect the IC from damage and for ease of assembly.

The next great advance in computing power came with the advent of the integrated circuit (IC). The idea of the integrated circuit was first conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence, Geoffrey W.A. Dummer. Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Quality Electronic Components in Washington, D.C., on 7 May 1952.[82]

The first working ICs were invented by

monolithic integrated circuit (IC) chip.[87] Kilby's IC had external wire connections, which made it difficult to mass-produce.[88]

Noyce also came up with his own idea of an integrated circuit half a year later than Kilby.[89] Noyce's invention was the first true monolithic IC chip.[90][88] His chip solved many practical problems that Kilby's had not. Produced at Fairchild Semiconductor, it was made of silicon, whereas Kilby's chip was made of germanium. Noyce's monolithic IC was fabricated using the planar process, developed by his colleague Jean Hoerni in early 1959. In turn, the planar process was based on Mohamed M. Atalla's work on semiconductor surface passivation by silicon dioxide in the late 1950s.[91][92][93]

Modern monolithic ICs are predominantly MOS (

silicon-gate MOS IC with self-aligned gates was developed by Federico Faggin at Fairchild Semiconductor in 1968.[97] The MOSFET has since become the most critical device component in modern ICs.[94]

The development of the MOS integrated circuit led to the invention of the

integration of more than 10,000 transistors on a single chip.[75]

circuit board
) the SoC, and the flash memory is usually placed right next to the SoC, this all done to improve data transfer speeds, as the data signals do not have to travel long distances. Since ENIAC in 1945, computers have advanced enormously, with modern SoCs (Such as the Snapdragon 865) being the size of a coin while also being hundreds of thousands of times more powerful than ENIAC, integrating billions of transistors, and consuming only a few watts of power.

Mobile computers

The first mobile computers were heavy and ran from mains power. The 50 lb (23 kg) IBM 5100 was an early example. Later portables such as the Osborne 1 and Compaq Portable were considerably lighter but still needed to be plugged in. The first laptops, such as the Grid Compass, removed this requirement by incorporating batteries – and with the continued miniaturization of computing resources and advancements in portable battery life, portable computers grew in popularity in the 2000s.[104] The same developments allowed manufacturers to integrate computing resources into cellular mobile phones by the early 2000s.


System on a Chip (SoCs), which are complete computers on a microchip the size of a coin.[103]


Computers can be classified in a number of different ways, including:

By architecture

By size, form-factor and purpose


Video demonstrating the standard components of a "slimline" computer

The term hardware covers all of those parts of a computer that are tangible physical objects. Circuits, computer chips, graphic cards, sound cards, memory (RAM), motherboard, displays, power supplies, cables, keyboards, printers and "mice" input devices are all hardware.

History of computing hardware

First generation
Quevedo's analytical machines
Programmable devices
Second generation
(vacuum tubes)
Atanasoff–Berry Computer, IBM 604, UNIVAC 60, UNIVAC 120
Programmable devices Colossus, ENIAC, Manchester Baby, EDSAC, Manchester Mark 1, Ferranti Pegasus, Ferranti Mercury, CSIRAC, 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, IBM System/360, BUNCH
Minicomputer HP 2116A, IBM System/32, IBM System/36, LINC, PDP-8, PDP-11
Desktop Computer
HP 9100
Fourth generation
integrated circuits)
Minicomputer VAX, IBM 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
WDC 65816/65802
32-bit microcomputer
64-bit microcomputer[c]
Embedded computer
Intel 8048, Intel 8051
Personal computer Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet PC, Wearable computer
Quantum computer
IBM Q System One
Chemical computer
DNA computing
Optical computer
Spintronics-based computer
Wetware/Organic computer

Other hardware topics

Peripheral device (input/output) Input Mouse, keyboard, joystick, image scanner, webcam, graphics tablet, microphone
Output Monitor, printer, loudspeaker
Both Floppy disk drive, hard disk drive, optical disc drive, teleprinter
Computer buses Short range RS-232, SCSI, PCI, USB
Long range (computer networking) Ethernet, ATM, FDDI

A general-purpose computer has four main components: the

input and output devices (collectively termed I/O). These parts are interconnected by buses, often made of groups of wires. Inside each of these parts are thousands to trillions of small electrical circuits which can be turned off or on by means of an electronic switch. Each circuit represents a bit (binary digit) of information so that when the circuit is on it represents a "1", and when off it represents a "0" (in positive logic representation). The circuits are arranged in logic gates
so that one or more of the circuits may control the state of one or more of the other circuits.

Input devices

When unprocessed data is sent to the computer with the help of input devices, the data is processed and sent to output devices. The input devices may be hand-operated or automated. The act of processing is mainly regulated by the CPU. Some examples of input devices are:

Output devices

The means through which computer gives output are known as output devices. Some examples of output devices are:

Control unit

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

The control unit (often called a control system or central controller) manages the computer's various components; it reads and interprets (decodes) the program instructions, transforming them into control signals that activate other parts of the computer.[d] Control systems in advanced computers may change the order of execution of some instructions to improve performance.

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.[e]

The control system's function is as follows— 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:

  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).

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, which runs a microcode program that causes all of these events to happen.

Central processing unit (CPU)

The control unit, ALU, and registers are collectively known as a

MOS integrated circuit chip called a microprocessor

Arithmetic logic unit (ALU)

The ALU is capable of performing two classes of operations: arithmetic and logic.

Boolean logic

Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously.[111] Graphics processors and computers with SIMD and MIMD features often contain ALUs that can perform arithmetic on vectors and matrices


magnetic cores) was the computer memory of choice in the 1960s, until it was replaced by semiconductor memory (using MOS memory cells

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 the software's responsibility to give significance to what the memory sees as nothing but a series of numbers.

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 (28 = 256); 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 if it can be represented numerically. Modern computers have billions or even trillions of bytes of memory.

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. As 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.

Computer main memory comes in two principal varieties:

RAM can be read and written to anytime the CPU commands it, but ROM is preloaded with data and software that never changes, therefore 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 are erased when the power to the computer is turned off, but 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 required software may be stored in ROM. Software 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, as it retains its data when turned off but is also rewritable. It is typically much slower than conventional ROM and RAM however, so its use is restricted to applications where high speed is unnecessary.[f]

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.

Input/output (I/O)

Hard disk drives are common storage devices used with computers.

I/O is the means by which a computer exchanges information with the outside world.[113] Devices that provide input or output to the computer are called peripherals.[114] 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. I/O devices are often 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.[citation needed] Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O. A 2016-era flat screen display contains its own computer circuitry.


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 multitasking i.e. having the computer switch rapidly between running each program in turn.[115] 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.[116]

Before the era of inexpensive computers, the principal 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, but 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 simultaneously without unacceptable speed loss.


Cray designed many supercomputers that used multiprocessing heavily.

Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed in only large and powerful machines such as

(multiple CPUs on a single integrated circuit) personal and laptop computers are now widely available, and are being increasingly used in lower-end markets as a result.

Supercomputers in particular often have highly unique architectures that differ significantly from the basic stored-program architecture and from general-purpose computers.[g] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful for only specialized tasks due to the large scale of program organization required to use most of 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.


Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. Software is that part of a computer system that consists of encoded information or computer instructions, in contrast to the physical

data, such as online documentation or digital media. It is often divided into system software and application software. Computer hardware and software require each other and neither can be realistically used on its own. When software is stored in hardware that cannot easily be modified, such as with BIOS ROM in an IBM PC compatible
computer, it is sometimes called "firmware".

Operating system /System Software Unix and BSD
Linux List of Linux distributions, Comparison of Linux distributions
Microsoft Windows
Macintosh operating systems
Classic Mac OS, macOS (previously OS X and Mac OS X)
Embedded and real-time List of embedded operating systems
Experimental Amoeba, OberonAOS, Bluebottle, A2, Plan 9 from Bell Labs
Library Multimedia DirectX, OpenGL, OpenAL, Vulkan (API)
Programming library C standard library, Standard Template Library
File format
User interface Graphical user interface (WIMP) Microsoft Windows, GNOME, KDE, QNX Photon, CDE, GEM, Aqua
Text-based user interface
Text user interface
Application Software
Office suite
Database management system, Scheduling & Time management, Spreadsheet, Accounting software
Internet Access
Mail transfer agent, Instant messaging
Design and manufacturing Computer-aided design, Computer-aided manufacturing, Plant management, Robotic manufacturing, Supply chain management
Image processing
Software engineering
Package management systems, File manager


There are thousands of different programming languages—some intended for general purpose, others useful for only highly specialized applications.

Programming languages
Lists of programming languages
Commonly used assembly languages
ARM, MIPS, x86
Commonly used high-level programming languages
Commonly used scripting languages Bourne script, JavaScript, Python, Ruby, PHP, Perl


The defining feature of modern computers which distinguishes them from all other machines is that they can be

imperative programming language. In practical terms, a computer program may be just a few instructions or extend to many millions of instructions, as do the programs for word processors and web browsers for example. A typical modern computer can execute billions of instructions per second (gigaflops) and rarely makes a mistake over many years of operation. Large computer programs consisting of several million instructions may take teams of programmers
years to write, and due to the complexity of the task almost certainly contain errors.

Stored program architecture

Museum of Science and Industry
in Manchester, England

This section applies to most common

RAM machine
–based computers.

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

by providing a type of jump that "remembers" the location it jumped from and another instruction to return to the instruction following that jump instruction.

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.

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. The following example is written in the MIPS assembly language:

  addi $8, $0, 0           # initialize sum to 0
  addi $9, $0, 1           # set first number to add = 1
  slti $10, $9, 1000       # check if the number is less than 1000
  beq $10, $0, finish      # if odd number is greater than n then exit
  add $8, $8, $9           # update sum
  addi $9, $9, 1           # get next number
  j loop                   # repeat the summing process
  add $2, $8, $0           # put sum in output register

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 a fraction of a second.

Machine code

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 these instructions) can be represented as lists of numbers and can themselves be manipulated inside the computer in the same way as 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.[118][119] 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.

While it is possible to write computer programs as long lists of numbers (machine language) and while this technique was used with many early computers,[h] it is extremely tedious and potentially error-prone 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.

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

Programming language

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 code 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.

Low-level languages

Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) are generally unique to the particular architecture of a computer's central processing unit (

hand-held videogame) cannot understand the machine language of an x86 CPU that might be in a PC.[i]
Historically a significant number of other cpu architectures were created and saw extensive use, notably including the MOS Technology 6502 and 6510 in addition to the Zilog Z80.

High-level languages

Although considerably easier than in machine language, writing long programs in assembly language is often difficult and is also error prone. Therefore, most practical programs are written in more abstract high-level programming languages that are able to express the needs of the 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.[j] High level languages are less related to the workings of the target computer than assembly language, and more related to the language and structure of the problem(s) to be solved by the final program. It is therefore often 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.

Program design

Program design of small programs is relatively simple and involves the analysis of the problem, collection of inputs, using the programming constructs within languages, devising or using established procedures and algorithms, providing data for output devices and solutions to the problem as applicable.

software systems presents a significant intellectual challenge.[123] Producing software with an acceptably high reliability within a predictable schedule and budget has historically been difficult;[124] the academic and professional discipline of software engineering concentrates specifically on this challenge.[125]


The actual first computer bug, a moth found trapped on a relay of the Harvard Mark II computer

Errors in computer programs are called "bugs". They may be benign and not affect the usefulness of the program, or have only subtle effects. However, in some cases they may cause the program or the entire system to "hang", becoming unresponsive to input such as mouse clicks or keystrokes, to completely fail, or to crash.[126] Otherwise benign bugs may sometimes be harnessed for malicious intent by an unscrupulous user writing an exploit, code designed to take advantage of a bug and disrupt a computer's proper execution. 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.[k] Admiral Grace Hopper, an American computer scientist and developer of the first compiler, is credited for having first used the term "bugs" in computing after a dead moth was found shorting a relay in the Harvard Mark II computer in September 1947.[127]

Networking and the Internet

Visualization of a portion of the routes on the Internet

Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's

Sabre.[128] In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. The effort was funded by ARPA (now DARPA), and the computer network that resulted was called the ARPANET.[129]
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

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.

Unconventional computers

A computer does not need to be

hard disk. While popular usage of the word "computer" is synonymous with a personal electronic computer,[l] a typical modern definition of a computer is: "A device that computes, especially a programmable [usually] electronic machine that performs high-speed mathematical or logical operations or that assembles, stores, correlates, or otherwise processes information."[130]
According to this definition, any device that processes information qualifies as a computer.


There is active research to make non-classical computers out of many promising new types of technology, such as optical computers, DNA computers, neural computers, and quantum computers. Most computers are universal, and are able to calculate any computable function, and are limited only by their memory capacity and operating speed. However different designs of computers can give very different performance for particular problems; for example quantum computers can potentially break some modern encryption algorithms (by quantum factoring) very quickly.

Computer architecture paradigms

There are many types of computer architectures:

Of all these

minimum capability (being Turing-complete) is, in principle, capable of performing the same tasks that any other computer can perform. Therefore, any type of computer (netbook, supercomputer, cellular automaton
, etc.) is able to perform the same computational tasks, given enough time and storage capacity.

Artificial intelligence

A computer will solve problems in exactly the way it is programmed to, without regard to efficiency, alternative solutions, possible shortcuts, or possible errors in the code. Computer programs that learn and adapt are part of the emerging field of artificial intelligence and machine learning. Artificial intelligence based products generally fall into two major categories: rule-based systems and pattern recognition systems. Rule-based systems attempt to represent the rules used by human experts and tend to be expensive to develop. Pattern-based systems use data about a problem to generate conclusions. Examples of pattern-based systems include voice recognition, font recognition, translation and the emerging field of on-line marketing.

Professions and organizations

As the use of computers has spread throughout society, there are an increasing number of careers involving computers.

Computer-related professions
Hardware-related Electrical engineering, Electronic engineering, Computer engineering, Telecommunications engineering, Optical engineering, Nanoengineering

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.

Standards groups ANSI, IEC, IEEE, IETF, ISO, W3C
Professional societies ACM, AIS, IET, IFIP, BCS
open source software
Apache Software Foundation

See also


  1. ^ According to Schmandt-Besserat 1981, these clay containers contained tokens, the total of which were the count of objects being transferred. The containers thus served as something of a bill of lading or an accounts book. In order to avoid breaking open the containers, first, clay impressions of the tokens were placed on the outside of the containers, for the count; the shapes of the impressions were abstracted into stylized marks; finally, the abstract marks were systematically used as numerals; these numerals were finally formalized as numbers.
    Eventually the marks on the outside of the containers were all that were needed to convey the count, and the clay containers evolved into clay tablets with marks for the count. Schmandt-Besserat 1999 estimates it took 4000 years.
  2. ^ The Intel 4004 (1971) die was 12 mm2, composed of 2300 transistors; by comparison, the Pentium Pro was 306 mm2, composed of 5.5 million transistors.[101]
  3. instruction set
    architectures are extensions of earlier designs. All of the architectures listed in this table, except for Alpha, existed in 32-bit forms before their 64-bit incarnations were introduced.
  4. ^ The control unit's role in interpreting instructions has varied somewhat in the past. Although the control unit is solely responsible for instruction interpretation in most modern computers, this is not always the case. Some computers have instructions that are partially interpreted by the control unit with further interpretation performed by another device. For example, EDVAC, one of the earliest stored-program computers, used a central control unit that interpreted only four instructions. All of the arithmetic-related instructions were passed on to its arithmetic unit and further decoded there.
  5. ^ Instructions often occupy more than one memory address, therefore the program counter usually increases by the number of memory locations required to store one instruction.
  6. ^ Flash memory also may only be rewritten a limited number of times before wearing out, making it less useful for heavy random access usage.[112]
  7. ^ 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.[117]
  8. ^ 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.
  9. Intel 80486
    . This contrasts with very early commercial computers, which were often one-of-a-kind and totally incompatible with other computers.
  10. interpreted rather than compiled. Interpreted languages are translated into machine code on the fly, while running, by another program called an interpreter
  11. floating point
    division operations. This was caused by a flaw in the microprocessor design and resulted in a partial recall of the affected devices.
  12. ^ According to the Shorter Oxford English Dictionary (6th ed, 2007), the word computer dates back to the mid 17th century, when it referred to "A person who makes calculations; specifically a person employed for this in an observatory etc."


  1. ^ Evans 2018, p. 23.
  2. ^ a b Smith 2013, p. 6.
  3. ^ "computer (n.)". Online Etymology Dictionary. Archived from the original on 16 November 2016. Retrieved 19 August 2021.
  4. sexagesimal number system
    was in use 2350–2000 BCE.
  5. OCLC 24660570
  6. ^ The Antikythera Mechanism Research Project Archived 28 April 2008 at the Wayback Machine, The Antikythera Mechanism Research Project. Retrieved 1 July 2007.
  7. S2CID 4305761
  8. ^ G. Wiet, V. Elisseeff, P. Wolff, J. Naudu (1975). History of Mankind, Vol 3: The Great medieval Civilisations, p. 649. George Allen & Unwin Ltd, UNESCO.
  9. ^ Fuat Sezgin "Catalogue of the Exhibition of the Institute for the History of Arabic-Islamic Science (at the Johann Wolfgang Goethe University", Frankfurt, Germany) Frankfurt Book Fair 2004, pp. 35 & 38.
  10. S2CID 33513516
  11. .
  12. .
  13. (PDF) from the original on 15 September 2009. Retrieved 21 April 2016.
  14. Donald Routledge Hill
    (1985). "Al-Biruni's mechanical calendar", Annals of Science 42, pp. 139–163.
  15. ^ "The Writer Automaton, Switzerland". 11 July 2013. Archived from the original on 20 February 2015. Retrieved 28 January 2015.
  16. ^ a b Ray Girvan, "The revealed grace of the mechanism: computing after Babbage" Archived 3 November 2012 at the Wayback Machine, Scientific Computing World, May/June 2003
  17. ^ Torres, Leonardo (10 October 1895). "Memória sobre las Máquinas Algébricas" (PDF). Revista de Obras Públicas (in Spanish) (28): 217–222.
  18. ^ Leonardo Torres. Memoria sobre las máquinas algébricas: con un informe de la Real academia de ciencias exactas, fisicas y naturales, Misericordia, 1895.
  19. ISSN 0094-114X
  20. .
  21. ^ Torres Quevedo, Leonardo (1901). "Machines á calculer". Mémoires Présentés par Divers Savants à l'Académie des Scienes de l'Institut de France (in French). Impr. nationale (París). XXXII.
  22. .
  23. ^ O'Connor, John J.; Robertson, Edmund F. (1998). "Charles Babbage". MacTutor History of Mathematics archive. School of Mathematics and Statistics, University of St Andrews, Scotland. Archived from the original on 16 June 2006. Retrieved 14 June 2006.
  24. ^ "Babbage". Online stuff. Science Museum. 19 January 2007. Archived from the original on 7 August 2012. Retrieved 1 August 2012.
  25. ^ Graham-Cumming, John (23 December 2010). "Let's build Babbage's ultimate mechanical computer". opinion. New Scientist. Archived from the original on 5 August 2012. Retrieved 1 August 2012.
  26. ^ L. Torres Quevedo. Ensayos sobre Automática – Su definicion. Extension teórica de sus aplicaciones, Revista de la Academia de Ciencias Exacta, Revista 12, pp. 391–418, 1914.
  27. ^ Torres Quevedo, Leonardo. Automática: Complemento de la Teoría de las Máquinas, (pdf), pp. 575-583, Revista de Obras Públicas, 19 November 1914.
  28. ^ Randell 1982, p. 6, 11–13.
  29. ^ B. Randell. Electromechanical Calculating Machine, The Origins of Digital Computers, pp.109-120, 1982.
  30. ^ Bromley 1990.
  31. ^ Randell, Brian. Digital Computers, History of Origins, (pdf), p. 545, Digital Computers: Origins, Encyclopedia of Computer Science, January 2003.
  32. ^ a b c d The Modern History of Computing. Stanford Encyclopedia of Philosophy. 2017. Archived from the original on 12 July 2010. Retrieved 7 January 2014.
  33. ^ Zuse, Horst. "Part 4: Konrad Zuse's Z1 and Z3 Computers". The Life and Work of Konrad Zuse. EPE Online. Archived from the original on 1 June 2008. Retrieved 17 June 2008.
  34. ^ Bellis, Mary (15 May 2019) [First published 2006 at]. "Biography of Konrad Zuse, Inventor and Programmer of Early Computers". Dotdash Meredith. Archived from the original on 13 December 2020. Retrieved 3 February 2021. Konrad Zuse earned the semiofficial title of 'inventor of the modern computer'[who?]
  35. ^ "Who is the Father of the Computer?".
  36. .
  37. ^ Salz Trautman, Peggy (20 April 1994). "A Computer Pioneer Rediscovered, 50 Years On". The New York Times. Archived from the original on 4 November 2016. Retrieved 15 February 2017.
  38. .
  39. ^ "Crash! The Story of IT: Zuse". Archived from the original on 18 September 2016. Retrieved 1 June 2016.
  40. S2CID 14606587
  41. ^ Rojas, Raúl. "How to Make Zuse's Z3 a Universal Computer" (PDF). Archived (PDF) from the original on 9 August 2017. Retrieved 28 September 2015.
  42. ^ .
  43. ^ "notice". Des Moines Register. 15 January 1941.
  44. . Retrieved 1 June 2019.
  45. ^ .
  46. ^ Miller, Joe (10 November 2014). "The woman who cracked Enigma cyphers". BBC News. Archived from the original on 10 November 2014. Retrieved 14 October 2018.
  47. ^ Bearne, Suzanne (24 July 2018). "Meet the female codebreakers of Bletchley Park". The Guardian. Archived from the original on 7 February 2019. Retrieved 14 October 2018.
  48. ^ "Bletchley's code-cracking Colossus". BBC. Archived from the original on 4 February 2010. Retrieved 24 November 2021.
  49. ^ "Colossus – The Rebuild Story". The National Museum of Computing. Archived from the original on 18 April 2015. Retrieved 7 January 2014.
  50. ^ Randell, Brian; Fensom, Harry; Milne, Frank A. (15 March 1995). "Obituary: Allen Coombs". The Independent. Archived from the original on 3 February 2012. Retrieved 18 October 2012.
  51. ^ Fensom, Jim (8 November 2010). "Harry Fensom obituary". The Guardian. Archived from the original on 17 September 2013. Retrieved 17 October 2012.
  52. Honeywell v. Sperry Rand
  53. ^ Evans 2018, p. 39.
  54. ^ Light 1999, p. 459.
  55. ^ "Generations of Computer". Archived from the original on 2 July 2015. Retrieved 7 January 2014.
  56. S2CID 73712
  57. , 1972.
  58. ISSN 0958-7403. Archived from the original
    on 9 January 2012. Retrieved 19 April 2008.
  59. ISSN 0958-7403. Archived from the original
    on 28 August 2017. Retrieved 7 July 2010.
  60. ^ "Early Electronic Computers (1946–51)". University of Manchester. Archived from the original on 5 January 2009. Retrieved 16 November 2008.
  61. ^ Napper, R. B. E. "Introduction to the Mark 1". The University of Manchester. Archived from the original on 26 October 2008. Retrieved 4 November 2008.
  62. ^ "Our Computer Heritage Pilot Study: Deliveries of Ferranti Mark I and Mark I Star computers". Computer Conservation Society. Archived from the original on 11 December 2016. Retrieved 9 January 2010.
  63. ^ Lavington, Simon. "A brief history of British computers: the first 25 years (1948–1973)". British Computer Society. Archived from the original on 5 July 2010. Retrieved 10 January 2010.
  64. ISBN 978-1139643771. Archived from the original
    (PDF) on 9 December 2019. Retrieved 31 July 2019.
  65. . Retrieved 31 July 2019.
  66. ^ . Retrieved 28 August 2019.
  67. ^ Lavington 1998, pp. 34–35.
  68. ^ from the original on 8 November 2020. Retrieved 7 June 2009. (subscription required)
  69. ^ Cooke-Yarborough, E.H. (1957). Introduction to Transistor Circuits. Edinburgh: Oliver and Boyd. p. 139.
  70. ^ "1960: Metal Oxide Semiconductor (MOS) Transistor Demonstrated". The Silicon Engine: A Timeline of Semiconductors in Computers. Computer History Museum. Archived from the original on 27 October 2019. Retrieved 31 August 2019.
  71. S2CID 29105721
  72. from the original on 24 September 2019. Retrieved 18 July 2019.
  73. ^ Laws, David (4 December 2013). "Who Invented the Transistor?". Computer History Museum. Archived from the original on 13 December 2013. Retrieved 20 July 2019.
  74. ^
    JSTOR 24923169
  75. . Retrieved 28 August 2019. The relative simplicity and low power requirements of MOSFETs have fostered today's microcomputer revolution.
  76. . Retrieved 28 August 2019.
  77. ^ Marriott, J.W. (10 June 2019). "Remarks by Director Iancu at the 2019 International Intellectual Property Conference". United States Patent and Trademark Office. Archived from the original on 17 December 2019. Retrieved 20 July 2019.
  78. ^ "Dawon Kahng". National Inventors Hall of Fame. Archived from the original on 27 October 2019. Retrieved 27 June 2019.
  79. ^ "Martin Atalla in Inventors Hall of Fame, 2009". Archived from the original on 19 September 2019. Retrieved 21 June 2013.
  80. ^ Triumph of the MOS Transistor. Computer History Museum. 6 August 2010. Archived from the original on 18 August 2021. Retrieved 21 July 2019 – via YouTube.
  81. ^ "The Hapless Tale of Geoffrey Dummer" Archived 11 May 2013 at the Wayback Machine, (n.d.), (HTML), Electronic Product News, accessed 8 July 2008.
  82. ^ Kilby, Jack (2000). "Nobel lecture" (PDF). Stockholm: Nobel Foundation. Archived (PDF) from the original on 29 May 2008. Retrieved 15 May 2008.
  83. ^ The Chip that Jack Built Archived 1 May 2015 at the Wayback Machine, (c. 2008), (HTML), Texas Instruments, Retrieved 29 May 2008.
  84. ^ Jack S. Kilby, Miniaturized Electronic Circuits, United States Patent Office, US Patent 3,138,743, filed 6 February 1959, issued 23 June 1964.
  85. . Retrieved 6 June 2020.
  86. . Retrieved 28 August 2019.
  87. ^ a b "Integrated circuits". NASA. Archived from the original on 21 July 2019. Retrieved 13 August 2019.
  88. Fairchild Semiconductor Corporation
  89. ^ "1959: Practical Monolithic Integrated Circuit Concept Patented". Computer History Museum. Archived from the original on 24 October 2019. Retrieved 13 August 2019.
  90. .
  91. . Retrieved 31 July 2019.
  92. . Retrieved 28 August 2019.
  93. ^ (PDF) from the original on 29 August 2017. Retrieved 31 July 2019.
  94. ^ a b "Tortoise of Transistors Wins the Race – CHM Revolution". Computer History Museum. Archived from the original on 10 March 2020. Retrieved 22 July 2019.
  95. ^ "1964 – First Commercial MOS IC Introduced". Computer History Museum. Archived from the original on 22 December 2015. Retrieved 31 July 2019.
  96. ^ "1968: Silicon Gate Technology Developed for ICs". Computer History Museum. Archived from the original on 29 July 2020. Retrieved 22 July 2019.
  97. ^ a b "1971: Microprocessor Integrates CPU Function onto a Single Chip". Computer History Museum. Archived from the original on 12 August 2021. Retrieved 22 July 2019.
  98. . Retrieved 31 July 2019.
  99. ^ "Intel's First Microprocessor—the Intel 4004". Intel Corp. November 1971. Archived from the original on 13 May 2008. Retrieved 17 May 2008.
  100. .
  101. ^ Federico Faggin, The Making of the First Microprocessor Archived 27 October 2019 at the Wayback Machine, IEEE Solid-State Circuits Magazine, Winter 2009, IEEE Xplore
  102. ^ a b "7 dazzling smartphone improvements with Qualcomm's Snapdragon 835 chip". 3 January 2017. Archived from the original on 30 September 2019. Retrieved 5 April 2019.
  103. ^ Chartier, David (23 December 2008). "Global notebook shipments finally overtake desktops". Ars Technica. Archived from the original on 4 July 2017. Retrieved 14 June 2017.
  104. ^ IDC (25 July 2013). "Growth Accelerates in the Worldwide Mobile Phone and Smartphone Markets in the Second Quarter, According to IDC". Archived from the original on 26 June 2014.
  105. ^ "Google Books Ngram Viewer".
  106. ^ "Google Books Ngram Viewer".
  107. ^ "Google Books Ngram Viewer".
  108. ^ "Google Books Ngram Viewer".
  109. .
  110. .
  111. ^ Verma & Mielke 1988.
  112. ^ Donald Eadie (1968). Introduction to the Basic Computer. Prentice-Hall. p. 12.
  113. .
  114. .
  115. .
  116. ^ TOP500 2006, p. [page needed].
  117. from the original on 30 July 2022. Retrieved 10 June 2022.
  118. from the original on 30 July 2022. Retrieved 10 June 2022. It is called the stored program architecture or stored program model, also known as the von Neumann architecture. We will use these terms interchangeably.
  119. . Retrieved 26 November 2022.
  120. . Retrieved 26 November 2022.
  121. . Retrieved 26 November 2022.
  122. . Retrieved 26 November 2022.
  123. . Retrieved 26 November 2022.
  124. . Retrieved 26 November 2022.
  125. ^ "Why do computers crash?". Scientific American. Archived from the original on 1 May 2018. Retrieved 3 March 2022.
  126. ^ Taylor, Alexander L., III (16 April 1984). "The Wizard Inside the Machine". Time. Archived from the original on 16 March 2007. Retrieved 17 February 2007.{{cite magazine}}: CS1 maint: multiple names: authors list (link)
  127. . The experience of SAGE helped make possible the first truly large-scale commercial real-time network: the SABRE computerized airline reservations system
  128. .
  129. ^ "Definition of computer". Archived from the original on 26 December 2009. Retrieved 29 January 2012.
  130. . Retrieved 9 November 2020.


External links