Etymology

The primary known use of the word "computer" was in 1613 within a book called The Yong Mans Gleanings by English writer Richard Braithwait: "I haue read the truest computer of Times, along with the best Arithmetician that euer breathed, and he reduceth thy dayes in a short number. " It referred to a person who executed calculations, or computations. The word continued with the same meaning until center of the 20th century. From the end of the 19th century the word began to consider its more familiar meaning, a machine that carries out computations.

History

Pre-twentie

                                                                                                                                    Devices have been used to aid computation for many years, mostly using one-to-one correspondence with fingers . The earliest counting device was probably a variety of tally stick . Later record keeping aids throughout the Fertile Crescent bundled calculi (clay spheres, cones, etc. ) which represented numbers of items, probably livestock or grains, sealed in hollow unbaked clay containers. The use of counting rods is one case.                                                                                 

The abacus wasinitially used for arithmetic tasks. The Roman abacus was used in Babylonia as early as 2400 BC. Since then, many other forms of reckoning boards or tables are invented. In a medieval European counting house , a checkered cloth could well be placed on a table, and markers moved around on it in line with certain rules, as an aid to calculating sums of dollars.

The Antikythera mechanism is regarded as the earliest mechanical analog "computer", according to Derek J. de Solla Price tag . [6] It was designed to calculate astronomical roles. It was discovered in 1901 in the Antikythera wreck off your Greek island of Antikythera , between Kythera and Crete , and possesses been dated to circa 100 BC. Devices of a a higher level complexity comparable to that of the Antikythera mechanism would not reappear until lots of years later.
Many mechanical aids to calculation and measurement ended up constructed for astronomical and navigation use. The planisphere was a star chart invented by Abū Rayhān al-Bīrūnī inside early 11th century. [7] The astrolabe was invented inside Hellenistic world in either the 1st or 2nd centuries BC and is also often attributed to Hipparchus . A combination of the planisphere along with dioptra , the astrolabe was effectively an analog computer capable of working out several kinds of problems in spherical astronomy . An astrolabe incorporating a hardware calendar computer[8] [9] and gear -wheels was conceived by Abi Bakr of Isfahan , Persia in 1235. [10] Abū Rayhān al-Bīrūnī invented the 1st mechanical geared lunisolar calendar astrolabe, [11] an early fixed-wired knowledge processing machine [12] which has a gear train and gear-wheels, [13] circa 1000 ADVERTISING.
The sector , a calculating instrument used for solving problems equal in shape, trigonometry, multiplication and division, and for various functions, such while squares and cube roots, was developed in the late sixteenth century and found application in gunnery, surveying and navigation.

Your slide rule was invented around 1620-1630, shortly after the publication of the very idea of the logarithm . It is a hand-operated analog computer pertaining to doing multiplication and division. As slide rule development progressed, included scales provided reciprocals, squares and square roots, cubes and dice roots, as well as transcendental functions such as logarithms along with exponentials, circular and hyperbolic trigonometry and other functions . Aviation is just about the few fields where slide rules are still in widespread employ, particularly for solving time-distance problems in light aircraft. To save space and for easier reading, these are typically circular devices rather than the basic linear slide rule shape. A popular example is the E6B .
Inside 1770s Pierre Jaquet-Droz , a Swiss watchmaker , built a mechanical doll (automata ) that can write holding a quill pen. By switching the number along with order of its internal wheels different letters, and hence distinct messages, could be produced. In effect, it could be mechanically "programmed" you just read instructions. Along with two other complex machines, the doll is a the Musée d'Art et d'Histoire of Neuchâtel , Switzerland , nevertheless operates. [14]
The tide-predicting machine invented by Sir William Thomson in 1872 was of great utility for you to navigation in shallow waters. It used a system of pulleys and wires to automatically calculate predicted tide levels for the set period at a particular location.
The differential analyser , a mechanical analog computer meant to solve differential equations by integration , used wheel-and-disc mechanisms to complete the integration. In 1876 Lord Kelvin had already mentioned the possible construction of such calculators, but he had been stymied with the limited output torque of the ball-and-disk integrators . [15] In a very differential analyzer, the output of one integrator drove the input in the next integrator, or a graphing output. The torque amplifier was the advance that allowed these machines to function. Starting in the 1920s, Vannevar Bush and others designed mechanical differential analyzers.

First general-purpose computing device

Charles Babbage , an English mechanical engineer and polymath , originated the thought of a programmable computer. Considered the "father of the computer ", [16] he conceptualized and invented the initial mechanical computer in the early 19th century. After taking care of his revolutionary difference engine , designed to aid in navigational data, in 1833 he realized that a much more general layout, anAnalytical Engine , was possible. The input of programs and data was being provided to the machine via punched cards , a method being used during the time to direct mechanical looms such as the Jacquard loom . Regarding output, the machine would have a printer, a curve plotter plus a bell. The machine would also be able to punch numbers onto cards being read in later. The Engine incorporated an arithmetic logic product , control flow in the form of conditional branching and also loops , and integrated memory , making it the first design for a general-purpose computer that might be described in modern terms as Turing-complete . [17] [18]
The device was about a century ahead of its time. All the parts for his machine must be made by hand - this was a major problem to get a device with thousands of parts. Eventually, the project was dissolved with all the decision of the British Government to cease funding. Babbage's failure to perform the analytical engine can be chiefly attributed to difficulties not merely of politics and financing, but also to his desire to produce an increasingly sophisticated computer and to move ahead faster than someone else could follow. Nevertheless, his son, Henry Babbage, completed a simplified version with the analytical engine's computing unit (the mill) in 1888. He gave a prosperous demonstration of its use in computing tables in 1906.

Later analog computers

Later analog computers

In the first half of the 20th century, many scientific computing requires were met by increasingly sophisticated analog computers , which used a principal mechanical or electrical model of the problem as a time frame for computation . However, these were not programmable and normally lacked the versatility and accuracy of modern digital computers. [19]
The 1st modern analog computer was a tide-predicting machine , invented by simply Sir William Thomson in 1872. The differential analyser , a mechanical analog computer meant to solve differential equations by integration using wheel-and-disc mechanisms, was conceptualized throughout 1876 by James Thomson , the brother of the additional famous Lord Kelvin. [15]
The art of mechanical analog computing reached its zenith while using differential analyzer , built by H. L. Hazen and Vannevar Bush at MIT starting in 1927. This built on the mechanical integrators of James Thomson plus the torque amplifiers invented by H. W. Nieman. A dozen of such devices were built before their obsolescence became obvious.
By the 1950s the success of digital electronic computers had spelled the final for most analog computing machines, but analog computers remain available in some specialized applications such as education 

Digital computer development

Digital computer development

The principle in the modern computer was first described by mathematician and revolutionary computer scientist Alan Turing , who set out the thought in his seminal 1936 paper, [20] On Computable Figures. Turing reformulated Kurt Gödel 's 1931 results on the boundaries of proof and computation, replacing Gödel's universal arithmetic-based formal language while using formal and simple hypothetical devices that became known as Turing models . He proved that some such machine would be competent at performing any conceivable mathematical computation if it were representable just as one algorithm . He went on to prove that there was no strategy to the Entscheidungsproblem by first showing that the halting problem pertaining to Turing machines is undecidable : in general, it is impossible to decide algorithmically whether a given Turing machine will ever before halt.
He also introduced the notion of a 'Universal Machine' (now generally known as a Universal Turing machine ), with the idea that a real machine could perform the tasks of any other machine, or basically, it is provably capable of computing anything that is computable by executing a plan stored on tape, allowing the machine to be programmable. Von Neumann acknowledged that the central concept of the modern computer was just for this paper. Turing machines are to this day a central. object of study in theory of computation . Except for the limitations imposed by his or her finite memory stores, modern computers are said to be Turing-complete , and that is to say, they have algorithm execution capability equivalent to your universal Turing machine .

Electromechanical

Electromechanical

By 1938 the us Navy had developed an electromechanical analog computer small enough to work with aboard a submarine . This was the Torpedo Data Laptop or computer , which used trigonometry to solve the problem of firing a torpedo at the moving target. During World War II similar devices were developed far away as well.

Imitation of Zuse 's Z3 , the first fully automatic, a digital (electromechanical) computer.
Early digital computers were electromechanical; electric switches drove mechanical relays to accomplish the calculation. These devices had a low operating speed and were eventually superseded by much quicker all-electric computers, originally using vacuum tubes . The Z2 , put together by German engineer Konrad Zuse in 1939, was one on the earliest examples of an electromechanical relay computer. [22]
With 1941, Zuse followed his earlier machine up with the Z3 , this world's first working electromechanical programmable , fully automatic a digital computer. [23] [24] The Z3 was built with 2000 relays , implementing a 22 bit word length that operated for a clock frequency of about 5-10 Hz . [25] Program code was supplied on punched film while data may very well be stored in 64 words of memory or supplied from this keyboard. It was quite similar to modern machines in many respects, pioneering numerous advances such as floating point numbers . Replacement on the hard-to-implement decimal system (used in Charles Babbage 's earlier design) because of the simpler binary system meant that Zuse's machines were much better to build and potentially more reliable, given the technologies available during that time. The Z3 was Turing complete .

Vacuum tubes and digital electronic circuits

Simply electronic circuit elements soon replaced their mechanical and electromechanical equivalents, as well that digital calculation replaced analog. The engineerTommy Flowers , working with the Post Office Research Station in London in your 1930s, began to explore the possible use of electronics to the telephone exchange . Experimental equipment that he built in 1934 gone into operation 5 years later, converting a portion of phoning exchange network into an electronic data processing system, using a huge number of vacuum tubes . [19] In the US, John Vincent Atanasoff along with Clifford E. Berry of Iowa State University developed and screened the -AtanasoffBerry Computer (ABC) in 1942, [29] the 1st "automatic electronic digital computer". [30] This design was in addition all-electronic and used about 300 vacuum tubes, with capacitors fixed in a very mechanically rotating drum for memory.

Colossus was the 1st electronic digital programmable computing device, and was employed to break German ciphers during World War II.
During World Warfare II, the British at Bletchley Park achieved a amount of successes at breaking encrypted German military communications. The German encryption appliance, Enigma , was first attacked with the help of your electro-mechanical bombes . To crack the more sophisticated German Lorenz SZ 40/42 appliance, used for high-level Army communications, Max Newman and his colleagues commissioned Flowers to develop the Colossus . [31] He spent eleven months from early February 1943 designing and building the 1st Colossus. [32] After a functional test in December 1943, Colossus ended up being shipped to Bletchley Park, where it was delivered on 16 January 1944[33] and attacked its first message on 5 March. [31]
Colossus was the world's first electronic digital camera programmable computer. [19] It used a numerous valves (vacuum tubes). It had paper-tape input and was capable of being configured to perform various boolean logical operations on its data, but it has not been Turing-complete . Nine Mk II Colossi were built (The Mk I was converted to a Mk II making ten machines in total). Colossus Level I contained 1500 thermionic valves (tubes), but Level II with 2400 valves, was both 5 times faster and much better to operate than Mark 1, greatly speeding the decoding process.

This US-built ENIAC [36] (Electronic Numerical Integrator and Computer) was the first electronic programmable computer built the united states. Although the ENIAC was similar to the Colossus it was much quicker and more flexible. It was unambiguously a Turing-complete device and may even compute any problem that would fit into its memory. Such as Colossus, a "program" on the ENIAC was defined by this states of its patch cables and switches, a far cry on the stored program electronic machines that came later. Once a software program was written, it had to be mechanically set into the appliance with manual resetting of plugs and switches.
It combined the high speed of electronics web site be programmed for many complex problems. It could add or subtract 5000 times a 2nd, a thousand times faster than any other machine. It likewise had modules to multiply, divide, and square root. High speed memory was on a 20 words (about 80 bytes). Built under this direction of John Mauchly and J. Presper Eckert for the University of Pennsylvania, ENIAC's development and construction lasted from 1943 to full operation right at the end of 1945. The machine was huge, weighing 30 tons, using 200 kilowatts of energy and contained over 18, 000 vacuum tubes, 1, 500 relays, and tons of resistors, capacitors, and inductors.

Stored programs

A a part of the Manchester Small-Scale Experimental Machine , the first stored-program computer system.
Early computing machines had fixed programs. Changing its function required the re-wiring and re-structuring on the machine. [31] With the proposal of the stored-program computer system this changed. A stored-program computer includes by design an instruction set and can store in memory a few instructions (a program ) that details the calculation . The theoretical basis for the stored-program computer was lay by Alan Turing in his 1936 paper. In 1945 Turing joined the National Physical Laboratory and began work towards developing an electronic stored-program digital computer. His 1945 report ‘Proposed Electronic Calculator’ was the primary specification for such a device. John von Neumann for the University of Pennsylvania , also circulated his First Draft of any Report on the EDVAC in 1945. [19]

Ferranti Mark1.

This Manchester Small-Scale Experimental Machine, nicknamed Baby, was the world's first stored-program computer . It was built for the Victoria University of Manchester by Frederic C. Williams , Tom Kilburn and Geoff Tootill , in addition to ran its first program on 21 June 1948. [38] It was designed as a testbed for the Williams tube the primary random-access digital storage device. [39] Although the computer was considered "small and primitive" because of the standards of its time, it was the first working machine to contain all of the elements essential to a modern electronic computer. [40] As soon as the SSEM had confirmed the feasibility of its design, a project was initiated at the university to develop it in a more usable computer, the Manchester Mark 1 .
The Mark 1 in turn quickly became the prototype with the Ferranti Mark 1 , the world's first commercially available general-purpose computer. [41] Built by Ferranti , ıt had been delivered to the University of Manchester in February 1951. At least seven of most of these later machines were delivered between 1953 and 1957, one of them to Shell labs with Amsterdam . [42] In October 1947, the directors of British catering company J. Lyons & Company thought i would take an active role in promoting the commercial development of computers. The LEO I computer system became operational in April 1951 [43] and ran the world's first regular routine company computer job .

Transistors

This bipolar transistor was invented in 1947. From 1955 onwards transistors replaced vacuum tubes with computer designs, giving rise to the "second generation" of computers. Compared to vacuum tubes, transistors have several positive aspects: they are smaller, and require less power than vacuum tubes, so give off less warm. Silicon junction transistors were much more reliable than vacuum tubes and had longer, indefinite, services life. Transistorized computers could contain tens of thousands of binary logic circuits in a somewhat compact space.
At the University of Manchester , a team under the leadership of Tom Kilburn designed and built a machine when using the newly developedtransistors instead of valves. [44] Their first transistorised computer and the first on this planet, was operational by 1953 , and a second version was completed there in April 1955. Even so, the machine did make use of valves to generate its 125 kHz clock waveforms and from the circuitry to read and write on its magnetic drum memory , so it was not the primary completely transistorized computer. That distinction goes to the Harwell CADET of 1955, [45] built because of the electronics division of the Atomic Energy Research Establishment at Harwell .

Integrated circuits

Your next great advance in computing power came with the advent of the integrated circuit . The idea of the integrated circuit was initially conceived by a radar scientist working for the Royal Radar Establishment of the Ministry of Defence , Geoffrey N. A. Dummer . Dummer presented the first public description of an integrated circuit at the Symposium on Progress in Excellent Electronic Components in Washington, D. C. on 7 May 1952. [48] 

The first practical ICs were invented by means of Jack Kilby at Texas Instruments and Robert Noyce at Fairchild Semiconductor . [49] Kilby recorded his initial ideas about the integrated circuit in July 1958, successfully demonstrating the first working integrated example on 12 September 1958. [50] In his or her patent application of 6 February 1959, Kilby described his new device as "a body of semiconductor material... wherein all the different parts of the electronic circuit are completely integrated". [51] [52] Noyce also came up with his own idea of an integrated circuit half 1 year later than Kilby. [53] His chip solved many practical problems that Kilby's had not. Produced at Fairchild Semiconductor, ıt had been made of silicon , whereas Kilby's chip was made of germanium .
This new development heralded an explosion in the commercial and personal by using computers and led to the invention of the microprocessor . While the subject of exactly which device was the primary microprocessor is contentious, partly due to lack of agreement on the exact definition of the term "microprocessor", it is largely undisputed which the first single-chip microprocessor was the Intel 4004, [54] designed and realized by Ted Hoff , Federico Faggin , in addition to 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. [56] 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 range of operating systems and have become the dominant computing device on the market, with manufacturers reporting having shipped an estimated 237 million devices in 

Programs

The defining feature of modern computers which distinguishes them from all other machines is that they may be programmed . That is to say that some type of instructions (theprogram ) can be given to the computer, and it will process them. Modern computers based on the von Neumann architecture often have machine code in the form of animperative programming language .
With 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 an error in judgment 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

Replica in the Small-Scale Experimental Machine (SSEM), the world's first stored-program computer , at the 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 an alternative, send a message to some external device, etc. These instructions are read from the computer's memory and are generally carried out (executed ) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other put in place the program and to carry on executing from there. These are called "jump" instructions (or branches ). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external celebration. Many computers directly support subroutines 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 range 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 satisfied. 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 engages. 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 recommendations. The following example is written in the MIPS assembly language :
begin:
addi $8, $0, 0 # initialize sum to 0
addi $9, $0, 1 # set first number to add = 1
loop:
slti $10, $9, 1000 # check if the number is less than 1000
beq $10, $0, finish # if odd number is in excess of n then exit
add $8, $8, $9 # update sum
addi $9, $9, 1 # get next number
j loop # repeat the summing process
finish:
add $2, $8, $0 # put sum in output register
Once told to run this program, the computer will perform the repetitive addition activity 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

Practically 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 such as 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[citation needed ], architecture. In some cases, a computer might store some or all of its program in memory that is kept separate on 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 ) buying enough this technique was used with many early computers, [58] 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 like 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.