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computer
A computer is a device that can be instructed to carry out an arbitrary set of arithmetic or logical operations automatically.
The ability of computers to follow a sequence of operations, called a program,
make computers very flexible and useful. Such computers are used as control systems for a very wide variety of industrial and consumer devices.
This includes simple special purpose devices like microwave ovens and remote controls,
factory devices such as industrial robots and computer assisted design,
but also in general purpose devices like personal computers and mobile devices such as smartphones.
The Internet is run on computers and it connects millions of other computers.
Since ancient times, simple manual devices like the abacus aided people in doing calculations. Early in the Industrial Revolution,
some mechanical devices were built to automate long tedious tasks, such as guiding patterns for looms.
More sophisticated electrical machines did specialized analog calculations in the early 20th century.
The first digital electronic calculating machines were developed during World War II. The speed, power,
and versatility of computers increased continuously and dramatically since then,
to the point that artificial intelligence may become possible in the future.
Conventionally, a modern computer consists of at least one processing element,
typically a central processing unit (CPU), and some form of memory.
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.
Etymology
Pre-twentieth century
The Ishango bone
Devices have been used to aid computation for thousands of years, mostly using one-to-one correspondence with fingers.
The earliest counting device was probably a form of tally stick. Later record keeping aids throughout the Fertile Crescent included calculi (clay spheres, cones, etc.) which represented counts of items, probably livestock or grains, sealed in hollow unbaked clay containers.[3][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 BC. Since then, many other forms of reckoning boards or tables have been invented. In a medieval European counting house, a checkered cloth would be placed on a table, and markers moved around on it according to certain rules, as an aid to calculating sums of money.
The ancient Greek-designed Antikythera mechanism, dating between 150 and 100 BC, is the world's oldest analog computer.
The Antikythera mechanism is believed to be the earliest mechanical analog "computer", according to Derek J. de Solla Price.[5] It was designed to calculate astronomical positions. It was discovered in 1901 in the Antikythera wreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to circa 100 BC. Devices of a level of complexity comparable to that of the Antikythera mechanism would not reappear until a thousand years later.
Many mechanical aids to calculation and measurement were constructed for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī in the early 11th century.[6] The astrolabe was invented in the Hellenistic world in either the 1st or 2nd centuries BC and is often attributed to Hipparchus. A combination of the planisphere and dioptra, the astrolabe was effectively an analog computer capable of working out several different kinds of problems in spherical astronomy. An astrolabe incorporating a mechanical calendar computer[7][8] and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235.[9] Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe,[10] an early fixed-wired knowledge processing machine[11] with a gear train and gear-wheels,[12] circa 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, 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. Aviation is one of the few fields where slide rules are still in widespread use, particularly for solving time–distance problems in light aircraft. To save space and for ease of reading, these are typically circular devices rather than the classic linear slide rule shape. A popular example is the E6B.
In the 1770s Pierre Jaquet-Droz, a Swiss watchmaker, built a mechanical doll (automata) 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.[13]
The tide-predicting machine invented by 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 Lord Kelvin 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.[14] 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.
Supercomputer
Supercomputers were introduced in the 1960s, made initially, and for decades primarily, by Seymour Cray at Control Data Corporation (CDC), Cray Research and subsequent companies bearing his name or monogram. While the supercomputers of the 1970s used only a few processors, in the 1990s, machines with thousands of processors began to appear and, by the end of the 20th century, massively parallel supercomputers with tens of thousands of off-the-shelf processors were the norm.[3][4]
As of June 2016, the fastest supercomputer in the world is the Sunway TaihuLight, in mainland China, with a Linpack benchmark of 93 PFLOPS, exceeding the previous record holder, Tianhe-2, by around 59 PFLOPS. It tops the rankings in the TOP500 supercomputer list. Sunway TaihuLight's emergence is also notable for its use of indigenous chips, and is the first Chinese computer to enter the TOP500 list without using hardware from the United States. As of June 2016, the Chinese, for the first time, had more computers (167) on the TOP500 list than the United States (165). However, U.S. built computers held ten of the top 20 positions.[5][6]
PC games, also known as computer games or personal computer games, are video games played on a personal computer rather than a dedicated video game console or arcade machine. Their defining characteristics include a lack of any centralized controlling authority, a greater degree of user control over the video-gaming hardware and software used and a generally greater capacity in input, processing, and output.
Home computer games became popular following the video game crash of 1983 leading to the era of the "bedroom coder". In the 1990s, PC games lost mass-market traction to console games before enjoying a resurgence in the mid-2000s through digital distribution.[1][2]
Newzoo, reports that gaming (on all platforms) is a US$99.6 billion dollar industry, and that as of 2016, "mobile gaming will take a larger share than PC with $36.9 billion, up 21.3% globally."[3] PC is considered synonymous (by them and others) with IBM PC compatible systems; while mobile computers – smartphones and tablets, such as those running Android or iOS – are also personal computers. The "APAC" region is estimated to generate $46.6 billion in 2016, or 47% of total global game revenues (note, not only "PC" games). China alone accounts for half of APAC's revenues, reaching $24.4 billion, cementing its place as the largest games market in the world, ahead of the US's anticipated market size of $23.5 billion.
The uncoordinated nature of the PC game market and its lack of physical media make precisely assessing its size difficult.
PC game
PC games, also known as computer games or personal computer games, are video games played on a personal computer rather than a dedicated video game console or arcade machine. Their defining characteristics include a lack of any centralized controlling authority, a greater degree of user control over the video-gaming hardware and software used and a generally greater capacity in input, processing, and output.
Home computer games became popular following the video game crash of 1983 leading to the era of the "bedroom coder". In the 1990s, PC games lost mass-market traction to console games before enjoying a resurgence in the mid-2000s through digital distribution.[1][2]
Newzoo, reports that gaming (on all platforms) is a US$99.6 billion dollar industry, and that as of 2016, "mobile gaming will take a larger share than PC with $36.9 billion, up 21.3% globally."[3] PC is considered synonymous (by them and others) with IBM PC compatible systems; while mobile computers – smartphones and tablets, such as those running Android or iOS – are also personal computers. The "APAC" region is estimated to generate $46.6 billion in 2016, or 47% of total global game revenues (note, not only "PC" games). China alone accounts for half of APAC's revenues, reaching $24.4 billion, cementing its place as the largest games market in the world, ahead of the US's anticipated market size of $23.5 billion.
The uncoordinated nature of the PC game market and its lack of physical media make precisely assessing its size difficult.
Computer network
Network computer devices that originate, route and terminate the data are called network nodes.[1] Nodes can include hosts such as personal computers, phones, servers as well as networking hardware. Two such devices can be said to be networked together when one device is able to exchange information with the other device, whether or not they have a direct connection to each other.
Computer networks differ in the transmission medium used to carry their signals, communications protocols to organize network traffic, the network's size, topology and organizational intent.
Computer networks support an enormous number of applications and services such as access to the World Wide Web, digital video, digital audio, shared use of application and storage servers, printers, and fax machines, and use of email and instant messaging applications as well as many others. In most cases, application-specific communications protocols are layered (i.e. carried as payload) over other more general communications protocols.
A role in IT, computer operators oversee the running of computer systems, ensuring that the machines and computers are running properly.[1][2][3]
The former role of a computer operator was to work with mainframe computers which required a great deal of management day-to-day, however nowadays they often work with a variety of different systems and applications. The computer operator normally works in a server room or a data center, but can also work remotely so that they can operate systems across multiple sites. Most of their duties are taught on the job, as their job description will vary according to the systems and set-up they help manage.
The role also includes maintaining records and logging events, listing each backup that is run, each machine malfunction and program abnormal termination. Operators assist system administrators and programmers in testing and debugging of new systems and programs prior to their becoming production environments.
Modern-day computing has led to a greater proliferation of personal computers, with a rapid change from older mainframe systems to newer self-managing systems. This is reflected in the operator's role. Tasks may include managing the backup systems, cycling tapes or other media, filling and maintaining printers. Overall the operator fills in as a lower level system administrator or operations analyst. Most operations departments will work 24x7.
A computer operator also has knowledge of disaster recovery and business continuity procedures. Formerly this would have meant sending physical data tapes offsite, but now the data is more than likely transmitted over computer networks.
A computer operator can work inside the home on the network editing domains and nets or they can work on the road or as part of a company.[citation needed]
See also[edit]
