कंप्यूटर (Computer) एक छोटी सी लेेकिन पावरफुल मशीन, कई लोगों के लिये यह किसी जादू से कम नहीं, जो कई सारे काम एक साथ बिना थके कर सकती है, इसके कई लाभ (Labh) हैं लेकिन इससे होने वालेे नुकसान (nuksan) को भी अनदेेखा नहीं किया जा सकता है - computer advantages and disadvantages in hindi - कम्प्यूटर के लाभ और हानि
Benefits and Importance of Computer in Hindi - कम्प्यूटर के लाभ और महत्व
- आज हर जगह कंप्यूटर का उपयोग बडें पैमाने पर किया जा रहा है, इससे का सबसे बडा कारण यह है कि मनुष्य के मुकाबले बहुत तेजी सेे काम करता है, यह बहुत बडी गणना को कुछ सेकेण्ड में कर सकता हैै
- आज हर चीज कंप्यूटर पर उपलब्ध है, आप बहुत सारा डाटा कंप्यूूटर में स्टोर कर सकते हैं और उसे कभी भी उपयोग में ला सकते हैं और अगर आपके पास इंटरनेट की सुविधा भी है तो आप क्लाउड स्टोरेज का उपयोग कर इंटरनेट पर भी अपने डाटा काे सुरक्षित रख सकते हैं।
- आप कभी-भी और कहीं भी अपने दोस्तों के सम्पर्क में वीडियो कॉल, ईमेल, सोशल नेटवर्किंग जैसे सुविधाओं केे माध्यम सेे जुडें रह सकते हैं।
- आप इंटरनेट पर कोई भी जानकारी प्राप्त कर सकते हैं।
- बैंकिग जैसी सुविधाओं में कंंप्यूटर तकनीक का जबाब नहीं है, आप घर बैठे-बैठे अपने मोबाइल फोन से या कंंप्यूटर से किसी को भी रूपये ट्रांसफर कर सकते हैं।
- आज मोबाइल रीचार्ज, बिजली का बिल से जमा करने से लेकर ऑनलाइन शॉपिग यहॉ तक कि हवाई जहाज तक कंप्यूटर द्वारा उडाये जा रहेे हैं वह भी बिना कोई गलती किये।
- शिक्षा और चिकित्सा के क्षेत्र में कंप्यूटर ने दुुनियाॅॅ को बदल दिया है आप घर बैठे-बैठे ही बेस्ट टीचर्स/संस्थाओं से शिक्षा प्राप्त कर सकते हैं और चिकित्सा की बात करें तो दुनियॉ के बेहतरीन डाक्टर्स से इंटरनेट पर परामर्श ले सकते हैं और अब तो मैडीकल स्टोर जाने की भी जरूरत नहीं है आप घर बैठे ही दवाईयॉ भी आर्डर कर सकते हैं, चाहे वह आपके श्ाहर में मिलती हों या नहीं।
Disadvantages of Computer in Hindi - कंप्यूटर के नुकसान
- जहॉ एक और कंंप्यूूटर लोगों को स्मार्ट बना रहा है वहीं दूसरी और इसका जरूरत से ज्यादा प्रयोग बीमार भी बना रहा है
- कंप्यूटर और मोबाइल का अधिक प्रयोग स्वास्थ्य के लिए हानिकारक साबित हो रहा है
- मोबाइल और कंंप्यूटर स्क्रीन पर ज्यादा लगातार देखते रहने से सबसे ज्यादा नुकसान आंखों को होता है
- लोगों का मिलना जुलना बंद हो गया है, ज्यादा लोग किसी के घर जाकर मिलने से बेहतर उनसे सोशन नेटवर्किंग साइट जैसे फेसबुक और व्हाट्सएप चैट करना ज्यादा पंंसद करते हैं, यहॉ तक कि एक घर में रह रहे 4 व्यक्ति भी अपने-अपने मोबाइल फोन से ही चिपके रहते हैं।
- बडी-बडी कंंपनियों और फैट्रियों में कई-कई मजदूरों का काम कंप्यूटर और रोबोट करने लगे हैं, जिससे बेरोजगारी भी बढी है
- इंटरनेट बैंकिग का उपयोग सावधानी से न करने पर आपके पर्सनल डाटा चोरी रखने का खतरा रहता है, जिससे कई यूजर्स को आर्थिक नुकसान उठाना पडता है
- इसी प्रकार सोशन नेटवर्किंंग साइट पर भी सावधानी से काम न करने पर भी होता है
- इंटरनेट के माध्यम से ठगी बहुत बडे पैमाने पर बढ गयी है
Conclusion - निष्कर्ष
अगर हम सही तरीके से इस तकनीक का प्रयोग करें, तो हमारे भविष्य को बहुत बदल सकती हैै, लेकिन इसका गलत प्रयोग हमारे वर्तमान को भी खराब कर सकता है, आप तो जानते ही हैं कि हम कम्प्यूटर कंट्रोल में नहीं यह हमारे कंट्रोल में है, इसका सही और सुरक्षित प्रयोग कीजिये
advantages of computer in hindi language, merits and demerits of computer in hindi, essay on importance of computer in hindi, computer ka mahatva in hindi nibandh, hindi composition on computer, computer ka mahatva in hindi
Other Computer tips and tricks
- कम्प्यूटर सीखें हिन्दी में - Learn Computer In Hindi
- सीसीसी कंप्यूटर कोर्स क्या है - What is CCC Computer Course Hindi- New *
- सीसीसी कंप्यूटर कोर्स इन हिंदी- CCC Computer Course in Hindi
- 31 फ्री फुल एक्सेल वीडियो ट्यूटोरियल
- कंप्यूटर टिप्स और ट्रिक्स
- प्रमुख तकनीकी आविष्कार और आविष्कारक
- हमें यूट्यूब पर जॉइन करें और पायें फ्री डेली टेक अपडेट
- बेस्ट वेबसाइट सभी के लिये - Best Website For Allदेखना ना भूलें 👈
- A to Z कंप्यूटर टर्म्स, डिक्शनरी और शब्दावली - A to Z Computer Terms, Dictionary
- PDF Tricks and Tips - पीडीएफ ट्रिक्स और टिप्स
- Internet Tips and Tricks - इंटरनेट टिप्स अौर ट्रिक्स
- YouTube Tips and Tricks - यूट्यूब टिप्स और ट्रिक्स
- Printing Tips - प्रिंटिंग टिप्स
- Parental Control Tips - पेरेंटल कंट्रोल टिप्स
- How To Guide In Hindi - हाउ टू गाइड हिन्दी में
- Google Search Tips and Tricks -गूगल सर्च के टिप्स और ट्रिक्स
- Google Now Tips and Tricks गूगल नॉउ टिप्स और ट्रिक्स हिन्दी में
- Google Map Tricks and Tips - गूगल मैप के टिप्स अौर ट्रिक्स
- Google Drive Tips and Tricks- गूगल ड्राइव के टिप्स अौर ट्रिक्स
- Google Chrome Tips and Tricks - गूगल क्रोम के टिप्स और ट्रिक्स
- Gmail Tips and Tricks - जीमेल के टिप्स और ट्रिक्स
- Cloud computing tips and tricks - क्लाउड कंप्यूटिंग के टिप्स और ट्रिक्स
- Facebook Tips and Tricks - फेसबुक के टिप्स और ट्रिक्स
- Android tips and tricks - एड्राइड के टिप्स अौर ट्रिक्स
- Blogger Tips and Tricks - ब्लागर टिप्स और ट्रिक्स
हमें सोशल मीडिया पर फॉलों करें - Facebook, Twitter, Google+, Pinterest, Linkedin, Youtube
हमारा ग्रुप जॉइन करें - फेसबुक ग्रुप, गूगल ग्रुप अन्य FAQ पढें हमारी एड्राइड एप्प डाउनलोड करें
"Computer system" redirects here. For other uses, see Computer (disambiguation) and Computer system (disambiguation).
A computer is a device that can be instructed to carry out arbitrary sequences of arithmetic or logical operations automatically. The ability of computers to follow generalized sets of operations, called programs, enables them to perform an extremely wide range of tasks.
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 has increased continuously and dramatically since then.
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.
According to the Oxford English Dictionary, the first known use of the word "computer" was in 1613 in a book called The Yong Mans Gleanings by English writer Richard Braithwait: "I haue [sic] read the truest computer of Times, and the best Arithmetician that euer [sic] breathed, and he reduceth thy dayes into a short number." This usage of the term referred to a person who carried out calculations or computations. The word continued with the same meaning until the middle of the 20th century. From the end of the 19th century the word began to take on its more familiar meaning, a machine that carries out computations.
The Online Etymology Dictionary gives the first attested use of "computer" in the "1640s, [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".
Main article: History of computing hardware
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. The use of counting rods is one example.
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 Antikythera mechanism is believed to be the earliest mechanical analog "computer", according to Derek J. de Solla Price. It was designed to calculate astronomical positions. 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. 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 and gear-wheels was invented by Abi Bakr of Isfahan, Persia in 1235.Abū Rayhān al-Bīrūnī invented the first mechanical geared lunisolar calendar astrolabe, an early fixed-wired knowledge processing machine with a gear train and gear-wheels,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.
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 hyperbolictrigonometry 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 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.
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. 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.
First computing device
Charles Babbage, an English mechanical engineer and polymath, originated the concept of a programmable computer. Considered the "father of the computer", he conceptualized and invented the first mechanical computer in the early 19th century. After working on his revolutionary difference engine, designed to aid in navigational calculations, in 1833 he realized that a much more general design, an Analytical Engine, was possible. The input of programs and data was to be provided to the machine via punched cards, a method being used at the time to direct mechanical looms such as the Jacquard loom. For output, the machine would have a printer, a curve plotter and a bell. The machine would also be able to punch numbers onto cards to be read in later. The Engine incorporated an arithmetic logic unit, control flow in the form of conditional branching and loops, and integrated memory, making it the first design for a general-purpose computer that could be described in modern terms as Turing-complete.
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 British Government to cease funding. Babbage's failure to complete the analytical engine can be chiefly attributed to difficulties not only of politics and financing, but also to his desire to develop an increasingly sophisticated computer and to move ahead faster than anyone else could follow. Nevertheless, his son, 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.
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. The first modern analog computer was a tide-predicting machine, invented by Sir William Thomson 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 brother of the more famous Lord Kelvin.
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 (control systems) and aircraft (slide rule).
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.
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, was one of the earliest examples of an electromechanical relay computer.
In 1941, Zuse followed his earlier machine up with the Z3, the world's first working electromechanicalprogrammable, fully automatic digital computer. The Z3 was built with 2000 relays, implementing a 22 bitword length that operated at a clock frequency of about 5–10 Hz. Program code was supplied on punched film while data could be stored in 64 words of memory or supplied from the keyboard. It was quite similar to modern machines in some respects, pioneering numerous advances such as 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. The Z3 was Turing complete.
Vacuum tubes and digital electronic circuits
Purely electronic circuit elements soon replaced their mechanical and electromechanical equivalents, at the same time that digital calculation replaced analog. The engineer Tommy Flowers, working at the Post Office Research Station in London in the 1930s, began to explore the possible use of electronics for the telephone exchange. Experimental equipment that he built in 1934 went into operation five years later, converting a portion of the telephone exchange network into an electronic data processing system, using thousands of vacuum tubes. In the US, John Vincent Atanasoff and Clifford E. Berry of Iowa State University developed and tested the Atanasoff–Berry Computer (ABC) in 1942, the first "automatic electronic digital computer". This design was also all-electronic and used about 300 vacuum tubes, with capacitors fixed in a mechanically rotating drum for memory.
During World War II, the British at Bletchley Park achieved a number of successes at breaking encrypted German military communications. The German encryption machine, Enigma, was first attacked with the help of the electro-mechanical bombes. To crack the more sophisticated German Lorenz SZ 40/42 machine, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to build the Colossus. He spent eleven months from early February 1943 designing and building the first Colossus. After a functional test in December 1943, Colossus was shipped to Bletchley Park, where it was delivered on 18 January 1944 and attacked its first message on 5 February.
Colossus was the world's first electronicdigitalprogrammable computer. It used a large number of valves (vacuum tubes). It had paper-tape input and was capable of being configured to perform a variety of 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 5 times faster and simpler to operate than Mark I, greatly speeding the decoding process.
The U.S.-built ENIAC (Electronic Numerical Integrator and Computer) was the first electronic programmable computer built in the US. Although the ENIAC was similar to the Colossus, it was much faster, more flexible, and it was Turing-complete. Like the Colossus, a "program" on the ENIAC was defined by the states of its patch cables and switches, a far cry from the 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.
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.
Concept of modern computer
The principle of the modern computer was proposed by Alan Turing in his seminal 1936 paper,On Computable Numbers. Turing proposed a simple device that he called "Universal Computing machine" and that is now known as a universal Turing machine. He proved that such a machine is capable of computing anything that is computable by executing instructions (program) stored on tape, allowing the machine to be programmable. The fundamental concept of Turing's design is the 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. 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.
Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring of the machine. With the proposal of the stored-program computer this changed. A stored-program computer includes by design an 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 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.
The Manchester Small-Scale Experimental Machine, nicknamed Baby, was the world's first stored-program computer. It was built at the Victoria University of Manchester by Frederic C. Williams, Tom Kilburn and Geoff Tootill, and ran its first program on 21 June 1948. It was designed as a testbed for the Williams tube, the first random-access digital storage device. Although the computer was considered "small and primitive" by the standards of its time, it was the first working machine to contain all of the elements essential to a modern electronic computer. As soon as the SSEM had demonstrated the feasibility of its design, a project was initiated at the university to develop it into a more usable computer, the Manchester Mark 1.
The Mark 1 in turn quickly became the prototype for the Ferranti Mark 1, the world's first commercially available general-purpose computer. Built by Ferranti, it was delivered to the University of Manchester in February 1951. At least seven of these later machines were delivered between 1953 and 1957, one of them to Shell labs in Amsterdam. In October 1947, the directors of British catering company J. Lyons & Company decided to take an active role in promoting the commercial development of computers. The LEO I computer became operational in April 1951 and ran the world's first regular routine office computer job.
The bipolar transistor was invented in 1947. From 1955 onwards transistors replaced vacuum tubes in computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have many advantages: they are smaller, and require less power than vacuum tubes, so give off less heat. Silicon junction transistors were much more reliable than vacuum tubes and had longer, indefinite, service life. Transistorized computers could contain tens of thousands of binary logic circuits in a relatively compact space.
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. Their first transistorised 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, built by the electronics division of the Atomic Energy Research Establishment at Harwell.
The next great advance in computing power came with the advent of the integrated circuit. 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.
The first practical ICs were invented by Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor. Kilby recorded his initial ideas concerning the integrated circuit in July 1958, successfully demonstrating the first working integrated example on 12 September 1958. In his patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material ... wherein all the components of the electronic circuit are completely integrated". Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. 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.
This new development heralded an explosion in the commercial and personal use of computers and led to the invention of the microprocessor. While the subject of exactly which device was the first microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed that the first single-chip microprocessor was the Intel 4004, designed and realized by Ted Hoff, Federico Faggin, and Stanley Mazor at Intel.
Mobile computers become dominant
With the continued miniaturization of computing resources, and advancements in portable battery life, portable computers grew in popularity in the 2000s. The same developments that spurred the growth of laptop computers and other portable computers allowed manufacturers to integrate computing resources into cellular phones. These so-called smartphones and tablets run on a variety of operating systems and have become the dominant computing device on the market, with manufacturers reporting having shipped an estimated 237 million devices in 2Q 2013.
Computers are typically classified based on their uses:
Based on uses
Based on sizes
Main articles: Computer hardware, Personal computer hardware, Central processing unit, and Microprocessor
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
Main article: History of computing hardware
|First generation (mechanical/electromechanical)||Calculators||Pascal's calculator, Arithmometer, Difference engine, Quevedo's analytical machines|
|Programmable devices||Jacquard loom, Analytical engine, IBM ASCC/Harvard Mark I, Harvard Mark II, IBM SSEC, Z1, Z2, Z3|
|Second generation (vacuum tubes)||Calculators||Atanasoff–Berry Computer, IBM 604, UNIVAC 60, UNIVAC 120|
|Programmable devices||Colossus, ENIAC, Manchester Small-Scale Experimental Machine, 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||Programma 101, HP 9100|
|Fourth generation (VLSI integrated circuits)||Minicomputer||VAX, IBM System i|
|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||Intel 8088, Zilog Z8000, WDC 65816/65802|
|32-bit microcomputer||Intel 80386, Pentium, Motorola 68000, ARM|
|64-bit microcomputer||Alpha, MIPS, PA-RISC, PowerPC, SPARC, x86-64, ARMv8-A|
|Embedded computer||Intel 8048, Intel 8051|
|Personal computer||Desktop computer, Home computer, Laptop computer, Personal digital assistant (PDA), Portable computer, Tablet PC, 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, 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 arithmetic logic unit (ALU), the control unit, the memory, and 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.
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:
The means through which computer gives output are known as output devices. Some examples of output devices are:
Main articles: CPU design and Control unit
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. 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.
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:
- Read the code for the next instruction from the cell indicated by the program counter.
- Decode the numerical code for the instruction into a set of commands or signals for each of the other systems.
- Increment the program counter so it points to the next instruction.
- 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.
- Provide the necessary data to an ALU or register.
- If the instruction requires an ALU or specialized hardware to complete, instruct the hardware to perform the requested operation.
- Write the result from the ALU back to a memory location or to a register or perhaps an output device.
- 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 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.
Arithmetic logic unit (ALU)
Main article: Arithmetic logic unit
The ALU is capable of performing two classes of operations: arithmetic and logic. The set of arithmetic operations that a particular ALU supports may be limited to addition and subtraction, or might include multiplication, division, trigonometry functions such as 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?"). Logic operations involve Boolean logic: AND, OR, XOR, and NOT. These can be useful for creating complicated conditional statements and processing boolean logic.
Superscalar computers may contain multiple ALUs, allowing them to process several instructions simultaneously.Graphics processors and computers with SIMD and MIMD features often contain ALUs that can perform arithmetic on vectors and matrices.
Main article: Computer data storage
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