"Computer technology" redirects here. For the company, see Computer Technology Limited. For other uses, see Computer (disambiguation).
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The Columbia Supercomputer, located at the NASA Ames Research Center.
An HP laptop computer.
A computer is a programmable machine that receives input, stores and manipulates data, and provides output in a useful format.
While a computer can, in theory, be made out of almost anything (see misconceptions section), and mechanical examples of computers have existed through much of recorded human history, the first electronic computers were developed in the mid-20th century (1940–1945). Originally, they were the size of a large room, consuming as much power as several hundred modern personal computers (PCs).[1] Modern computers based on integrated circuits are millions to billions of times more capable than the early machines, and occupy a fraction of the space.[2] Simple computers are small enough to fit into mobile devices, and can be powered by a small battery. Personal computers in their various forms are icons of the Information Age and are what most people think of as "computers". However, the embedded computers found in many devices from MP3 players to fighter aircraft and from toys to industrial robots are the most numerous.
History of computing
Main article: History of computing hardware
The first use of the word "computer" was recorded in 1613, referring to a person who carried out calculations, or computations, and the word continued to be used in that sense until the middle of the 20th century. From the end of the 19th century onwards though, the word began to take on its more familiar meaning, describing a machine that carries out computations.[3]
Limited-function ancient computers
The Jacquard loom, on display at the Museum of Science and Industry in Manchester, England, was one of the first programmable devices.
The history of the modern computer begins with two separate technologies—automated calculation and programmability—but no single device can be identified as the earliest computer, partly because of the inconsistent application of that term. Examples of early mechanical calculating devices include the abacus, the slide rule and arguably the astrolabe and the Antikythera mechanism, an ancient astronomical computer built by the Greeks around 80 BC.[4] The Greek mathematician Hero of Alexandria (c. 10–70 AD) built a mechanical theater which performed a play lasting 10 minutes and was operated by a complex system of ropes and drums that might be considered to be a means of deciding which parts of the mechanism performed which actions and when.[5] This is the essence of programmability.
The "castle clock", an astronomical clock invented by Al-Jazari in 1206, is considered to be the earliest programmable analog computer.[6][verification needed] It displayed the zodiac, the solar and lunar orbits, a crescent moon-shaped pointer travelling across a gateway causing automatic doors to open every hour,[7][8] and five robotic musicians who played music when struck by levers operated by a camshaft attached to a water wheel. The length of day and night could be re-programmed to compensate for the changing lengths of day and night throughout the year.[6]
The Renaissance saw a re-invigoration of European mathematics and engineering. Wilhelm Schickard's 1623 device was the first of a number of mechanical calculators constructed by European engineers, but none fit the modern definition of a computer, because they could not be programmed.
First general-purpose computers
In 1801, Joseph Marie Jacquard made an improvement to the textile loom by introducing a series of punched paper cards as a template which allowed his loom to weave intricate patterns automatically. The resulting Jacquard loom was an important step in the development of computers because the use of punched cards to define woven patterns can be viewed as an early, albeit limited, form of programmability.
It was the fusion of automatic calculation with programmability that produced the first recognizable computers. In 1837, Charles Babbage was the first to conceptualize and design a fully programmable mechanical computer, his analytical engine.[9] Limited finances and Babbage's inability to resist tinkering with the design meant that the device was never completed.
In the late 1880s, Herman Hollerith invented the recording of data on a machine readable medium. Prior uses of machine readable media, above, had been for control, not data. "After some initial trials with paper tape, he settled on punched cards ..."[10] To process these punched cards he invented the tabulator, and the keypunch machines. These three inventions were the foundation of the modern information processing industry. Large-scale automated data processing of punched cards was performed for the 1890 United States Census by Hollerith's company, which later became the core of IBM. By the end of the 19th century a number of technologies that would later prove useful in the realization of practical computers had begun to appear: the punched card, Boolean algebra, the vacuum tube (thermionic valve) and the teleprinter.
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.
Alan Turing is widely regarded to be the father of modern computer science. In 1936 Turing provided an influential formalisation of the concept of the algorithm and computation with the Turing machine, providing a blueprint for the electronic digital computer.[11] Of his role in the creation of the modern computer, Time magazine in naming Turing one of the 100 most influential people of the 20th century, states: "The fact remains that everyone who taps at a keyboard, opening a spreadsheet or a word-processing program, is working on an incarnation of a Turing machine".[11]
The Zuse Z3, 1941, considered the world's first working programmable, fully automatic computing machine.
The ENIAC, which became operational in 1946, is considered to be the first general-purpose electronic computer.
EDSAC was one of the first computers to implement the stored program (von Neumann) architecture.
Die of an Intel 80486DX2 microprocessor (actual size: 12×6.75 mm) in its packaging.
The Atanasoff–Berry Computer (ABC) was among the first fully electronic digital binary computing devices. Conceived in 1937 by Iowa State College physics professor John Atanasoff, and built with the assistance of graduate student Clifford Berry[12], the machine was not programmable in the modern sense, being designed only to solve systems of linear equations. The computer did employ parallel computation. A 1973 court ruling in a patent dispute found that the patent for the 1946 ENIAC computer derived from the Atanasoff–Berry Computer.
The inventor of the program-controlled computer was Konrad Zuse, who built the first working computer in 1941 and later in 1955 the first computer based on magnetic storage.[13]
George Stibitz is internationally recognized as a father of the modern digital computer. While working at Bell Labs in November 1937, Stibitz invented and built a relay-based calculator he dubbed the "Model K" (for "kitchen table", on which he had assembled it), which was the first to use binary circuits to perform an arithmetic operation. Later models added greater sophistication including complex arithmetic and programmability.[14]
A succession of steadily more powerful and flexible computing devices were constructed in the 1930s and 1940s, gradually adding the key features that are seen in modern computers. The use of digital electronics (largely invented by Claude Shannon in 1937) and more flexible programmability were vitally important steps, but defining one point along this road as "the first digital electronic computer" is difficult.Shannon 1940 Notable achievements include.
* Konrad Zuse's electromechanical "Z machines". The Z3 (1941) was the first working machine featuring binary arithmetic, including floating point arithmetic and a measure of programmability. In 1998 the Z3 was proved to be Turing complete, therefore being the world's first operational computer.[15]
* The non-programmable Atanasoff–Berry Computer (commenced in 1937, completed in 1941) which used vacuum tube based computation, binary numbers, and regenerative capacitor memory. The use of regenerative memory allowed it to be much more compact than its peers (being approximately the size of a large desk or workbench), since intermediate results could be stored and then fed back into the same set of computation elements.
* The secret British Colossus computers (1943),[16] which had limited programmability but demonstrated that a device using thousands of tubes could be reasonably reliable and electronically reprogrammable. It was used for breaking German wartime codes.
* The Harvard Mark I (1944), a large-scale electromechanical computer with limited programmability.[17]
* The U.S. Army's Ballistic Research Laboratory ENIAC (1946), which used decimal arithmetic and is sometimes called the first general purpose electronic computer (since Konrad Zuse's Z3 of 1941 used electromagnets instead of electronics). Initially, however, ENIAC had an inflexible architecture which essentially required rewiring to change its programming.
Stored-program architecture
Several developers of ENIAC, recognizing its flaws, came up with a far more flexible and elegant design, which came to be known as the "stored program architecture" or von Neumann architecture. This design was first formally described by John von Neumann in the paper First Draft of a Report on the EDVAC, distributed in 1945. A number of projects to develop computers based on the stored-program architecture commenced around this time, the first of these being completed in Great Britain. The first working prototype to be demonstrated was the Manchester Small-Scale Experimental Machine (SSEM or "Baby") in 1948. The Electronic Delay Storage Automatic Calculator (EDSAC), completed a year after the SSEM at Cambridge University, was the first practical, non-experimental implementation of the stored program design and was put to use immediately for research work at the university. Shortly thereafter, the machine originally described by von Neumann's paper—EDVAC—was completed but did not see full-time use for an additional two years.
Nearly all modern computers implement some form of the stored-program architecture, making it the single trait by which the word "computer" is now defined. While the technologies used in computers have changed dramatically since the first electronic, general-purpose computers of the 1940s, most still use the von Neumann architecture.
Beginning in the 1950s, Soviet scientists Sergei Sobolev and Nikolay Brusentsov conducted research on ternary computers, devices that operated on a base three numbering system of −1, 0, and 1 rather than the conventional binary numbering system upon which most computers are based. They designed the Setun, a functional ternary computer, at Moscow State University. The device was put into limited production in the Soviet Union, but supplanted by the more common binary architecture.
Semiconductors and microprocessors
Computers using vacuum tubes as their electronic elements were in use throughout the 1950s, but by the 1960s had been largely replaced by transistor-based machines, which were smaller, faster, cheaper to produce, required less power, and were more reliable. The first transistorised computer was demonstrated at the University of Manchester in 1953.[18] In the 1970s, integrated circuit technology and the subsequent creation of microprocessors, such as the Intel 4004, further decreased size and cost and further increased speed and reliability of computers. By the late 1970s, many products such as video recorders contained dedicated computers called microcontrollers, and they started to appear as a replacement to mechanical controls in domestic appliances such as washing machines. The 1980s witnessed home computers and the now ubiquitous personal computer. With the evolution of the Internet, personal computers are becoming as common as the television and the telephone in the household[citation needed].
Modern smartphones are fully programmable computers in their own right, and as of 2009 may well be the most common form of such computers in existence[citation needed].
Programs
The defining feature of modern computers which distinguishes them from all other machines is that they can be programmed. That is to say that some type of instructions (the program) can be given to the computer, and it will carry process them. While some computers may have strange concepts "instructions" and "output" (see quantum computing), modern computers based on the von Neumann architecture are often have machine code in the form of an 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
Main articles: Computer program and Computer programming
A 1970s punched card containing one line from a FORTRAN program. The card reads: "Z(1) = Y + W(1)" and is labelled "PROJ039" for identification purposes.
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 memory and are generally carried out (executed) in the order they were given. However, there are usually specialized instructions to tell the computer to jump ahead or backwards to some other place in the program and to carry on executing from there. These are called "jump" instructions (or branches). Furthermore, jump instructions may be made to happen conditionally so that different sequences of instructions may be used depending on the result of some previous calculation or some external event. Many computers directly support subroutines by providing a type of jump that "remembers" the location it jumped from and another instruction to return to 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. For example:
mov #0, sum ; set sum to 0
mov #1, num ; set num to 1
loop: add num, sum ; add num to sum
add #1, num ; add 1 to num
cmp num, #1000 ; compare num to 1000
ble loop ; if num <= 1000, go back to 'loop'
halt ; end of program. stop running
Once told to run this program, the computer will perform the repetitive addition task without further human intervention. It will almost never make a mistake and a modern PC can complete the task in about a millionth of a second.[19]
Bugs
Errors in computer programs are called "bugs". Bugs may be benign and not affect the usefulness of the program, or have only subtle effects. But in some cases they may cause the program to "hang"—become unresponsive to input such as mouse clicks or keystrokes, or to completely fail or "crash". Otherwise benign bugs may sometimes may 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.[20]
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. 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,[21] 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. Machine languages and the assembly languages that represent them (collectively termed low-level programming languages) tend to be unique to a particular type of computer. For instance, an ARM architecture computer (such as may be found in a PDA or a hand-held videogame) cannot understand the machine language of an Intel Pentium or the AMD Athlon 64 computer that might be in a PC.[22]
Higher-level languages and program design
Though 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.[23] 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.
The task of developing large software systems presents a significant intellectual challenge. Producing software with an acceptably high reliability within a predictable schedule and budget has historically been difficult; the academic and professional discipline of software engineering concentrates specifically on this challenge.
Function
Main articles: Central processing unit and Microprocessor
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 busses, 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.
The control unit, ALU, registers, and basic I/O (and often other hardware closely linked with these) are collectively known as a central processing unit (CPU). Early CPUs were composed of many separate components but since the mid-1970s CPUs have typically been constructed on a single integrated circuit called a microprocessor.
Control unit
Main articles: CPU design and 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 a series of control signals which activate other parts of the computer.[24] Control systems in advanced computers may change the order of some instructions so as 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.[25]
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:
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).
It is noticeable that the sequence of operations that the control unit goes through to process an instruction is in itself like a short computer program—and indeed, in some more complex CPU designs, there is another yet smaller computer called a microsequencer that runs a microcode program that causes all of these events to happen.
Arithmetic/logic unit (ALU)
Main article: Arithmetic logic unit
The ALU is capable of performing two classes of operations: arithmetic and logic.[26]
The set of arithmetic operations that a particular ALU supports may be limited to adding and subtracting or might include multiplying or dividing, trigonometry functions (sine, cosine, etc.) and square roots. Some can only operate on whole numbers (integers) whilst others use floating point to represent real numbers—albeit with limited precision. However, any computer that is capable of performing just the simplest operations can be programmed to break down the more complex operations into simple steps that it can perform. Therefore, any computer can be programmed to perform any arithmetic operation—although it will take more time to do so if its ALU does not directly support the operation. An ALU may also compare numbers and return boolean truth values (true or false) depending on whether one is equal to, greater than or less than the other ("is 64 greater than 65?").
Logic operations involve Boolean logic: AND, OR, XOR and NOT. These can be useful both for creating complicated conditional statements and processing boolean logic.
Superscalar computers may contain multiple ALUs so that they can process several instructions at the same time.[27] Graphics processors and computers with SIMD and MIMD features often provide ALUs that can perform arithmetic on vectors and matrices.
Memory
Main article: Computer data storage
Magnetic core memory was the computer memory of choice throughout the 1960s, until it was replaced by semiconductor memory.
A computer's memory can be viewed as a list of cells into which numbers can be placed or read. Each cell has a numbered "address" and can store a single number. The computer can be instructed to "put the number 123 into the cell numbered 1357" or to "add the number that is in cell 1357 to the number that is in cell 2468 and put the answer into cell 1595". The information stored in memory may represent practically anything. Letters, numbers, even computer instructions can be placed into memory with equal ease. Since the CPU does not differentiate between different types of information, it is 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 (2^8 = 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: random-access memory or RAM and read-only memory or ROM. RAM can be read and written to anytime the CPU commands it, but ROM is pre-loaded with data and software that never changes, so the CPU can only read from it. ROM is typically used to store the computer's initial start-up instructions. In general, the contents of RAM 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.[28]
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)
Main article: Input/output
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.[29] Devices that provide input or output to the computer are called peripherals.[30] 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.
Often, I/O devices are complex computers in their own right with their own CPU and memory. A graphics processing unit might contain fifty or more tiny computers that perform the calculations necessary to display 3D graphics[citation needed]. Modern desktop computers contain many smaller computers that assist the main CPU in performing I/O.
Multitasking
Main article: Computer multitasking
While a computer may be viewed as running one gigantic program stored in its main memory, in some systems it is necessary to give the appearance of running several programs simultaneously. This is achieved by multitasking i.e. having the computer switch rapidly between running each program in turn.[31]
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.[32]
Before the era of cheap computers, the principle use for multitasking was to allow many people to share the same computer.
Seemingly, multitasking would cause a computer that is switching between several programs to run more slowly — in direct proportion to the number of programs it is running. However, most programs spend much of their time waiting for slow input/output devices to complete their tasks. If a program is waiting for the user to click on the mouse or press a key on the keyboard, then it will not take a "time slice" until the event it is waiting for has occurred. This frees up time for other programs to execute so that many programs may be run at the same time without unacceptable speed loss.
Multiprocessing
Main article: Multiprocessing
Cray designed many supercomputers that used multiprocessing heavily.
Some computers are designed to distribute their work across several CPUs in a multiprocessing configuration, a technique once employed only in large and powerful machines such as supercomputers, mainframe computers and servers. Multiprocessor and multi-core (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.[33] They often feature thousands of CPUs, customized high-speed interconnects, and specialized computing hardware. Such designs tend to be useful only for specialized tasks due to the large scale of program organization required to successfully utilize most of 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.
Networking and the Internet
Main articles: Computer networking and Internet
Visualization of a portion of the routes on the Internet.
Computers have been used to coordinate information between multiple locations since the 1950s. The U.S. military's SAGE system was the first large-scale example of such a system, which led to a number of special-purpose commercial systems like Sabre.[34]
In the 1970s, computer engineers at research institutions throughout the United States began to link their computers together using telecommunications technology. This effort was funded by ARPA (now DARPA), and the computer network that it produced was called the ARPANET.[35] The technologies that made the Arpanet possible spread and evolved.
In time, the network spread beyond academic and military institutions and became known as the Internet. The emergence of networking involved a redefinition of the nature and boundaries of the computer. Computer operating systems and applications were modified to include the ability to define and access the resources of other computers on the network, such as peripheral devices, stored information, and the like, as extensions of the resources of an individual computer. Initially these facilities were available primarily to people working in high-tech environments, but in the 1990s the spread of applications like e-mail and the World Wide Web, combined with the development of cheap, fast networking technologies like Ethernet and ADSL saw computer networking become almost ubiquitous. In fact, the number of computers that are networked is growing phenomenally. A very large proportion of personal computers regularly connect to the Internet to communicate and receive information. "Wireless" networking, often utilizing mobile phone networks, has meant networking is becoming increasingly ubiquitous even in mobile computing environments.
Misconceptions
A computer does not need to be electric, nor even have a processor, nor RAM, nor even hard disk. The minimal definition of a computer is anything that transforms information in a purposeful way.
Required technology
Main article: Unconventional computing
Computational systems as flexible as a personal computer can be built out of almost anything. For example, a computer can be made out of billiard balls (billiard ball computer); this is an unintuitive and pedagogical example that a computer can be made out of almost anything. More realistically, modern computers are made out of transistors made of photolithographed semiconductors.
Historically, computers evolved from mechanical computers and eventually from vacuum tubes to transistors.
There is active research to make computers out of many promising new types of technology, such as optical computing, DNA computers, neural computers, and quantum computers. Some of these can easily tackle problems that modern computers cannot (such as how quantum computers can break some modern encryption algorithms by quantum factoring).
Computer architecture paradigms
Some different paradigms of how to build a computer from the ground-up:
RAM machines
These are the types of computers with a CPU, computer memory, etc., which understand basic instructions in a machine language. The concept evolved from the Turing machine.
Brains
Brains are massively parallel processors made of neurons, wired in intricate patterns, that communicate via electricity and neurotransmitter chemicals.
Programming languages
Such as the lambda calculus, or modern programming languages, are virtual computers built on top of other computers.
Cellular automata
For example, the game of Life can create "gliders" and "loops" and other constructs that transmit information; this paradigm can be applied to DNA computing, chemical computing, etc.
Groups and committees
The linking of multiple computers (brains) is itself a computer
Logic gates are a common abstraction which can apply to most of the above digital or analog paradigms.
The ability to store and execute lists of instructions called programs makes computers extremely versatile, distinguishing them from calculators. The Church–Turing thesis is a mathematical statement of this versatility: any computer with a certain 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.
Limited-function computers
Conversely, a computer which is limited in function (one that is not "Turing-complete") cannot simulate arbitrary things. For example, simple four-function calculators cannot simulate a real computer without human intervention. As a more complicated example, without the ability to program a gaming console, it can never accomplish what a programmable calculator from the 1990s could (given enough time); the system as a whole is not Turing-complete, even though it contains a Turing-complete component (the microprocessor). Living organisms (the body, not the brain) are also limited-function computers designed to make copies of themselves; they cannot be reprogrammed without genetic engineering.
Virtual computers
A "computer" is commonly considered to be a physical device. However, one can create a computer program which describes how to run a different computer, i.e. "simulating a computer in a computer". Not only is this a constructive proof of the Church-Turing thesis, but is also extremely common in all modern computers. For example, some programming languages use something called an interpreter, which is a simulated computer built on top of the basic computer; this allows programmers to write code (computer input) in a different language than the one understood by the base computer (the alternative is to use a compiler). Additionally, virtual machines are simulated computers which virtually replicate a physical computer in software, and are very commonly used by IT. Virtual machines are also a common technique used to create emulators, such game console emulators.
Further topics
* Glossary of computers
Artificial intelligence
A computers will solve problems in exactly the way they are programmed to, without regard to efficiency nor alternative solutions nor possible shortcuts nor possible errors in the code. Computer programs which learn and adapt are part of the emerging field of artificial intelligence and machine learning.
Hardware
The term hardware covers all of those parts of a computer that are tangible objects. Circuits, displays, power supplies, cables, keyboards, printers and mice are all hardware.
Source: http://en.wikipedia.org/wiki/Computer
Jumat, 26 November 2010
"Fifth Generation" redirects here. For other uses, see Fifth Generation (disambiguation).
The Fifth Generation Computer Systems project (FGCS) was an initiative by Japan's Ministry of International Trade and Industry, begun in 1982, to create a "fifth generation computer" (see history of computing hardware) which was supposed to perform much calculation using massive parallel processing. It was to be the end result of a massive government/industry research project in Japan during the 1980s. It aimed to create an "epoch-making computer" with supercomputer-like performance and to provide a platform for future developments in artificial intelligence[1].
The term fifth generation was intended to convey the system as being a leap beyond existing machines. Computers using vacuum tubes were called the first generation; transistors and diodes, the second; integrated circuits, the third; and those using microprocessors, the fourth. Whereas previous computer generations had focused on increasing the number of logic elements in a single CPU, the fifth generation, it was widely believed at the time, would instead turn to massive numbers of CPUs for added performance[2].
The project was to create the computer over a ten year period, after which it was considered ended and investment in a new, Sixth Generation project, began. Opinions about its outcome are divided: Either it was a failure, or it was ahead of its time.
History
In the late 1960s and early '70s, there was much talk about "generations" of computer hardware — usually "three generations".
1. First generation: Vacuum tubes. Mid-1940s. IBM pioneered the arrangement of vacuum tubes in pluggable modules. The IBM 650 was a first-generation computer.
2. Second generation: Transistors. 1956. The era of miniaturization begins. Transistors are much smaller than vacuum tubes, draw less power, and generate less heat. Discrete transistors are soldered to circuit boards, with interconnections accomplished by stencil-screened conductive patterns on the reverse side. The IBM 7090 was a second-generation computer.
3. Third generation: Integrated circuits (silicon chips containing multiple transistors). 1964. A pioneering example is the ACPX module used in the IBM 360/91, which, by stacking layers of silicon over a ceramic substrate, accommodated over 20 transistors per chip; the chips could be packed together onto a circuit board to achieve unheard-of logic densities. The IBM 360/91 was a hybrid second- and third-generation computer.
Omitted from this taxonomy is the "zeroth-generation" computer based on metal gears (such as the IBM 4077) or mechanical relays (such as the Mark I), and the post-third-generation computers based on Very Large Scale Integrated (VLSI) circuits.
There was also a parallel set of generations for software:
1. First generation: Machine language.
2. Second generation: Assembly language.
3. Third generation: Structured programming languages such as C, COBOL and FORTRAN.
4. Fourth generation: Domain-specific languages such as SQL (for database access) and TeX (for text formatting)
Background and design philosophy
Throughout these multiple generations up to the 1990s, Japan had largely been a follower in the computing arena, building computers following U.S. and British leads. The Ministry of International Trade and Industry (MITI) decided to attempt to break out of this follow-the-leader pattern, and in the mid-1970s started looking, on a small scale, into the future of computing. They asked the Japan Information Processing Development Center (JIPDEC) to indicate a number of future directions, and in 1979 offered a three-year contract to carry out more in-depth studies along with industry and academia. It was during this period that the term "fifth-generation computer" started to be used.
Prior to the 1970s, MITI guidance had successes such as an improved steel industry, the creation of the oil supertanker, the automotive industry, consumer electronics, and computer memory. MITI decided that the future was going to be information technology. However, the Japanese language, in both written and spoken form, presented and still presents major obstacles for computers. These hurdles could not be taken lightly. So MITI held a conference and invited people around the world to help them.
The primary fields for investigation from this initial project were:
* Inference computer technologies for knowledge processing
* Computer technologies to process large-scale data bases and knowledge bases
* High performance workstations
* Distributed functional computer technologies
* Super-computers for scientific calculation
The project imagined a parallel processing computer running on top of massive databases (as opposed to a traditional filesystem) using a logic programming language to define and access the data. They envisioned building a prototype machine with performance between 100M and 1G LIPS, where a LIPS is a Logical Inference Per Second. At the time typical workstation machines were capable of about 100k LIPS. They proposed to build this machine over a ten year period, 3 years for initial R&D, 4 years for building various subsystems, and a final 3 years to complete a working prototype system. In 1982 the government decided to go ahead with the project, and established the Institute for New Generation Computer Technology (ICOT) through joint investment with various Japanese computer companies.
Implementation
So ingrained was the belief that parallel computing was the future of all performance gains that the Fifth-Generation project generated a great deal of apprehension in the computer field. After having seen the Japanese take over the consumer electronics field during the 1970s and apparently doing the same in the automotive world during the 1980s, the Japanese in the 1980s had a reputation for invincibility. Soon parallel projects were set up in the US as the Strategic Computing Initiative and the Microelectronics and Computer Technology Corporation (MCC), in the UK as Alvey, and in Europe as the European Strategic Program of Research in Information Technology (ESPRIT), as well as ECRC (European Computer Research Centre) in Munich, a collaboration between ICL in Britain, Bull in France, and Siemens in Germany.
Five running Parallel Inference Machines (PIM) were eventually produced: PIM/m, PIM/p, PIM/i, PIM/k, PIM/c. The project also produced applications to run on these systems, such as the parallel database management system Kappa, the legal reasoning system HELIC-II, and the automated theorem prover MGTP, as well as applications to bioinformatics.
[edit] Failure
The FGCS Project did not meet with commercial success for reasons similar to the Lisp machine companies and Thinking Machines. The highly parallel computer architecture was eventually surpassed in speed by less specialized hardware (for example, Sun workstations and Intel x86 machines). The project did produce a new generation of promising Japanese researchers. But after the FGCS Project, MITI stopped funding large-scale computer research projects, and the research momentum developed by the FGCS Project dissipated. However MITI/ICOT embarked on a Sixth Generation Project in the 1990s.
A primary problem was the choice of concurrent logic programming as the bridge between the parallel computer architecture and the use of logic as a knowledge representation and problem solving language for AI applications. This never happened cleanly; a number of languages were developed, all with their own limitations. In particular, the committed choice feature of concurrent constraint logic programming interfered with the logical semantics of the languages.[3]
Another problem was that existing CPU performance quickly pushed through the "obvious" barriers that experts perceived in the 1980s, and the value of parallel computing quickly dropped to the point where it was for some time used only in niche situations. Although a number of workstations of increasing capacity were designed and built over the project's lifespan, they generally found themselves soon outperformed by "off the shelf" units available commercially.
The project also suffered from being on the wrong side of the technology curve. During its lifespan, GUIs became mainstream in computers; the internet enabled locally stored databases to become distributed; and even simple research projects provided better real-world results in data mining.[citation needed] Moreover the project found that the promises of logic programming were largely negated by the use of committed choice.
At the end of the ten year period the project had spent over 50 billion yen (about US $400 million at 1992 exchange rates) and was terminated without having met its goals. The workstations had no appeal in a market where general purpose systems could now take over their job and even outrun them. This is parallel to the Lisp machine market, where rule-based systems such as CLIPS could run on general-purpose computers, making expensive Lisp machines unnecessary.[4]
In spite of the possibility of considering the project a failure, many of the approaches envisioned in the Fifth-Generation project, such as logic programming distributed over massive knowledge-bases, are now being re-interpreted in current technologies. The Web Ontology Language (OWL) employs several layers of logic-based knowledge representation systems, while many flavors of parallel computing proliferate, including multi-core architectures at the low-end and massively parallel processing at the high end.
Timeline
* 1982: the FGCS project begins and receives $450,000,000 worth of industry funding and an equal amount of government funding.
* 1985: the first FGCS hardware known as the Personal Sequential Inference Machine (PSI) and the first version of the Sequential Inference Machine Programming Operating System (SIMPOS) operating system is released. SIMPOS is programmed in Kernel Language 0 (KL0), a concurrent Prolog-variant with object oriented extensions.
* 1987: a prototype of a truly parallel hardware called the Parallel Inference Machine (PIM) is built using several PSI:s connected in a network. The project receives funding for 5 more years. A new version of the kernel language Kernel Language 1 (KL1) which looks very similar to "Flat GDC" (Flat Guarded Definite Clauses) is created, influenced by developments in Prolog. The operating system written in KL1 is renamed Parallel Inference Machine Operating System, or PIMOS.
Source: http://en.wikipedia.org/wiki/Fifth_generation_computer
The Fifth Generation Computer Systems project (FGCS) was an initiative by Japan's Ministry of International Trade and Industry, begun in 1982, to create a "fifth generation computer" (see history of computing hardware) which was supposed to perform much calculation using massive parallel processing. It was to be the end result of a massive government/industry research project in Japan during the 1980s. It aimed to create an "epoch-making computer" with supercomputer-like performance and to provide a platform for future developments in artificial intelligence[1].
The term fifth generation was intended to convey the system as being a leap beyond existing machines. Computers using vacuum tubes were called the first generation; transistors and diodes, the second; integrated circuits, the third; and those using microprocessors, the fourth. Whereas previous computer generations had focused on increasing the number of logic elements in a single CPU, the fifth generation, it was widely believed at the time, would instead turn to massive numbers of CPUs for added performance[2].
The project was to create the computer over a ten year period, after which it was considered ended and investment in a new, Sixth Generation project, began. Opinions about its outcome are divided: Either it was a failure, or it was ahead of its time.
History
In the late 1960s and early '70s, there was much talk about "generations" of computer hardware — usually "three generations".
1. First generation: Vacuum tubes. Mid-1940s. IBM pioneered the arrangement of vacuum tubes in pluggable modules. The IBM 650 was a first-generation computer.
2. Second generation: Transistors. 1956. The era of miniaturization begins. Transistors are much smaller than vacuum tubes, draw less power, and generate less heat. Discrete transistors are soldered to circuit boards, with interconnections accomplished by stencil-screened conductive patterns on the reverse side. The IBM 7090 was a second-generation computer.
3. Third generation: Integrated circuits (silicon chips containing multiple transistors). 1964. A pioneering example is the ACPX module used in the IBM 360/91, which, by stacking layers of silicon over a ceramic substrate, accommodated over 20 transistors per chip; the chips could be packed together onto a circuit board to achieve unheard-of logic densities. The IBM 360/91 was a hybrid second- and third-generation computer.
Omitted from this taxonomy is the "zeroth-generation" computer based on metal gears (such as the IBM 4077) or mechanical relays (such as the Mark I), and the post-third-generation computers based on Very Large Scale Integrated (VLSI) circuits.
There was also a parallel set of generations for software:
1. First generation: Machine language.
2. Second generation: Assembly language.
3. Third generation: Structured programming languages such as C, COBOL and FORTRAN.
4. Fourth generation: Domain-specific languages such as SQL (for database access) and TeX (for text formatting)
Background and design philosophy
Throughout these multiple generations up to the 1990s, Japan had largely been a follower in the computing arena, building computers following U.S. and British leads. The Ministry of International Trade and Industry (MITI) decided to attempt to break out of this follow-the-leader pattern, and in the mid-1970s started looking, on a small scale, into the future of computing. They asked the Japan Information Processing Development Center (JIPDEC) to indicate a number of future directions, and in 1979 offered a three-year contract to carry out more in-depth studies along with industry and academia. It was during this period that the term "fifth-generation computer" started to be used.
Prior to the 1970s, MITI guidance had successes such as an improved steel industry, the creation of the oil supertanker, the automotive industry, consumer electronics, and computer memory. MITI decided that the future was going to be information technology. However, the Japanese language, in both written and spoken form, presented and still presents major obstacles for computers. These hurdles could not be taken lightly. So MITI held a conference and invited people around the world to help them.
The primary fields for investigation from this initial project were:
* Inference computer technologies for knowledge processing
* Computer technologies to process large-scale data bases and knowledge bases
* High performance workstations
* Distributed functional computer technologies
* Super-computers for scientific calculation
The project imagined a parallel processing computer running on top of massive databases (as opposed to a traditional filesystem) using a logic programming language to define and access the data. They envisioned building a prototype machine with performance between 100M and 1G LIPS, where a LIPS is a Logical Inference Per Second. At the time typical workstation machines were capable of about 100k LIPS. They proposed to build this machine over a ten year period, 3 years for initial R&D, 4 years for building various subsystems, and a final 3 years to complete a working prototype system. In 1982 the government decided to go ahead with the project, and established the Institute for New Generation Computer Technology (ICOT) through joint investment with various Japanese computer companies.
Implementation
So ingrained was the belief that parallel computing was the future of all performance gains that the Fifth-Generation project generated a great deal of apprehension in the computer field. After having seen the Japanese take over the consumer electronics field during the 1970s and apparently doing the same in the automotive world during the 1980s, the Japanese in the 1980s had a reputation for invincibility. Soon parallel projects were set up in the US as the Strategic Computing Initiative and the Microelectronics and Computer Technology Corporation (MCC), in the UK as Alvey, and in Europe as the European Strategic Program of Research in Information Technology (ESPRIT), as well as ECRC (European Computer Research Centre) in Munich, a collaboration between ICL in Britain, Bull in France, and Siemens in Germany.
Five running Parallel Inference Machines (PIM) were eventually produced: PIM/m, PIM/p, PIM/i, PIM/k, PIM/c. The project also produced applications to run on these systems, such as the parallel database management system Kappa, the legal reasoning system HELIC-II, and the automated theorem prover MGTP, as well as applications to bioinformatics.
[edit] Failure
The FGCS Project did not meet with commercial success for reasons similar to the Lisp machine companies and Thinking Machines. The highly parallel computer architecture was eventually surpassed in speed by less specialized hardware (for example, Sun workstations and Intel x86 machines). The project did produce a new generation of promising Japanese researchers. But after the FGCS Project, MITI stopped funding large-scale computer research projects, and the research momentum developed by the FGCS Project dissipated. However MITI/ICOT embarked on a Sixth Generation Project in the 1990s.
A primary problem was the choice of concurrent logic programming as the bridge between the parallel computer architecture and the use of logic as a knowledge representation and problem solving language for AI applications. This never happened cleanly; a number of languages were developed, all with their own limitations. In particular, the committed choice feature of concurrent constraint logic programming interfered with the logical semantics of the languages.[3]
Another problem was that existing CPU performance quickly pushed through the "obvious" barriers that experts perceived in the 1980s, and the value of parallel computing quickly dropped to the point where it was for some time used only in niche situations. Although a number of workstations of increasing capacity were designed and built over the project's lifespan, they generally found themselves soon outperformed by "off the shelf" units available commercially.
The project also suffered from being on the wrong side of the technology curve. During its lifespan, GUIs became mainstream in computers; the internet enabled locally stored databases to become distributed; and even simple research projects provided better real-world results in data mining.[citation needed] Moreover the project found that the promises of logic programming were largely negated by the use of committed choice.
At the end of the ten year period the project had spent over 50 billion yen (about US $400 million at 1992 exchange rates) and was terminated without having met its goals. The workstations had no appeal in a market where general purpose systems could now take over their job and even outrun them. This is parallel to the Lisp machine market, where rule-based systems such as CLIPS could run on general-purpose computers, making expensive Lisp machines unnecessary.[4]
In spite of the possibility of considering the project a failure, many of the approaches envisioned in the Fifth-Generation project, such as logic programming distributed over massive knowledge-bases, are now being re-interpreted in current technologies. The Web Ontology Language (OWL) employs several layers of logic-based knowledge representation systems, while many flavors of parallel computing proliferate, including multi-core architectures at the low-end and massively parallel processing at the high end.
Timeline
* 1982: the FGCS project begins and receives $450,000,000 worth of industry funding and an equal amount of government funding.
* 1985: the first FGCS hardware known as the Personal Sequential Inference Machine (PSI) and the first version of the Sequential Inference Machine Programming Operating System (SIMPOS) operating system is released. SIMPOS is programmed in Kernel Language 0 (KL0), a concurrent Prolog-variant with object oriented extensions.
* 1987: a prototype of a truly parallel hardware called the Parallel Inference Machine (PIM) is built using several PSI:s connected in a network. The project receives funding for 5 more years. A new version of the kernel language Kernel Language 1 (KL1) which looks very similar to "Flat GDC" (Flat Guarded Definite Clauses) is created, influenced by developments in Prolog. The operating system written in KL1 is renamed Parallel Inference Machine Operating System, or PIMOS.
Source: http://en.wikipedia.org/wiki/Fifth_generation_computer
Fifth Generation (Present and Beyond)
Fifth Generation (Present and Beyond)
Fifth generations computers are only in the minds of advance research scientiets and being tested out in the laboratories. These computers will be under Artifical Intelligence(AI), They will be able to take commands in a audio visual way and carry out instructions. Many of the operations which requires low human intelligence will be perfomed by these computers.
Parallel Processing is coming and showing the possibiliy that the power of many CPU's can be used side by side, and computers will be more powerful than thoes under central processing. Advances in Super Conductor technology will greatly improve the speed of information traffic. Future looks bright for the computers.
Source: http://library.thinkquest.org/C0125787/fourthgen.htm
Fifth generations computers are only in the minds of advance research scientiets and being tested out in the laboratories. These computers will be under Artifical Intelligence(AI), They will be able to take commands in a audio visual way and carry out instructions. Many of the operations which requires low human intelligence will be perfomed by these computers.
Parallel Processing is coming and showing the possibiliy that the power of many CPU's can be used side by side, and computers will be more powerful than thoes under central processing. Advances in Super Conductor technology will greatly improve the speed of information traffic. Future looks bright for the computers.
Source: http://library.thinkquest.org/C0125787/fourthgen.htm
Fourth Generation
Fourth Generation (1971-Present)
Fourth Generation computers are the modern day computers. The Size started to go down with the improvement in the integerated circuits. Very Large Scale(VLSI) and Ultra Large scale(ULSI) ensured that millions of components could be fit into a small chip. It reduced the size and price of the computers at the same time increasing power, efficiency and reliability. "The Intel 4004 chip, developed in 1971, took the integrated circuit one step further by locating all the components of a computer (central processing unit, memory, and input and output controls) on a minuscule chip."
Due to the reduction of cost and the availability of the computers power at a small place allowed everyday user to benefit. First came the minicomputers, which offered users different applications, most famous of these the word processors and spreadsheets, which could be used by non-technical users. Video game systems like Atari 2600 generated the interest of general populace in the computers.
In 1981, IBM introduced personal computers for home and office use. "The number of personal computers in use more than doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being used." Computer size kept getting reduced during the years. It went down from Desktop to laptops to Palmtops. Machintosh introduecd Graphic User Interface in which the users didnt' have to type instructions but could use Mouse for the purpose.
The continued improvement allowed the networking of computers for the sharing of data. Local Area Networks(LAN) and Wide Area Network(WAN), were potential benefits, in that they could be implemented in corporations and everybody could share data over it. Soon the internet aand World Wide Web appeared on the computer scene and formented the Hi-Tech revolution of 90's.
Source : http://library.thinkquest.org/C0125787/fourthgen.htm
Fourth Generation computers are the modern day computers. The Size started to go down with the improvement in the integerated circuits. Very Large Scale(VLSI) and Ultra Large scale(ULSI) ensured that millions of components could be fit into a small chip. It reduced the size and price of the computers at the same time increasing power, efficiency and reliability. "The Intel 4004 chip, developed in 1971, took the integrated circuit one step further by locating all the components of a computer (central processing unit, memory, and input and output controls) on a minuscule chip."
Due to the reduction of cost and the availability of the computers power at a small place allowed everyday user to benefit. First came the minicomputers, which offered users different applications, most famous of these the word processors and spreadsheets, which could be used by non-technical users. Video game systems like Atari 2600 generated the interest of general populace in the computers.
In 1981, IBM introduced personal computers for home and office use. "The number of personal computers in use more than doubled from 2 million in 1981 to 5.5 million in 1982. Ten years later, 65 million PCs were being used." Computer size kept getting reduced during the years. It went down from Desktop to laptops to Palmtops. Machintosh introduecd Graphic User Interface in which the users didnt' have to type instructions but could use Mouse for the purpose.
The continued improvement allowed the networking of computers for the sharing of data. Local Area Networks(LAN) and Wide Area Network(WAN), were potential benefits, in that they could be implemented in corporations and everybody could share data over it. Soon the internet aand World Wide Web appeared on the computer scene and formented the Hi-Tech revolution of 90's.
Source : http://library.thinkquest.org/C0125787/fourthgen.htm
History of Computer
Instituto Rosedal Lomas
History of Computer
Computing
1st Secondary
"Who invented the computer?" is not a question with a simple answer. The real answer is that many inventors contributed to the history of computers and that a computer is a complex piece of machinery made up of many parts, each of which can be considered a separate invention.
First Generation - 1940-1956: Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.
'History of computer'
Second Generation - 1956-1963: Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.
'History of computer'
Third Generation - 1964-1971: Integrated Circuits.
The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
'History of computer'
Fourth Generation - 1971-Present: Microprocessors.
The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer - from the central processing unit and memory to input/output controls - on a single chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.
'History of computer'
'History of computer'
Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.
Source: http://html.rincondelvago.com/history-of-computer.html
History of Computer
Computing
1st Secondary
"Who invented the computer?" is not a question with a simple answer. The real answer is that many inventors contributed to the history of computers and that a computer is a complex piece of machinery made up of many parts, each of which can be considered a separate invention.
First Generation - 1940-1956: Vacuum Tubes
The first computers used vacuum tubes for circuitry and magnetic drums for memory, and were often enormous, taking up entire rooms. They were very expensive to operate and in addition to using a great deal of electricity, generated a lot of heat, which was often the cause of malfunctions. First generation computers relied on machine language to perform operations, and they could only solve one problem at a time. Input was based on punched cards and paper tape, and output was displayed on printouts.
The UNIVAC and ENIAC computers are examples of first-generation computing devices. The UNIVAC was the first commercial computer delivered to a business client, the U.S. Census Bureau in 1951.
'History of computer'
Second Generation - 1956-1963: Transistors
Transistors replaced vacuum tubes and ushered in the second generation of computers. The transistor was invented in 1947 but did not see widespread use in computers until the late 50s. The transistor was far superior to the vacuum tube, allowing computers to become smaller, faster, cheaper, more energy-efficient and more reliable than their first-generation predecessors. Though the transistor still generated a great deal of heat that subjected the computer to damage, it was a vast improvement over the vacuum tube. Second-generation computers still relied on punched cards for input and printouts for output.
Second-generation computers moved from cryptic binary machine language to symbolic, or assembly, languages, which allowed programmers to specify instructions in words. High-level programming languages were also being developed at this time, such as early versions of COBOL and FORTRAN. These were also the first computers that stored their instructions in their memory, which moved from a magnetic drum to magnetic core technology.
The first computers of this generation were developed for the atomic energy industry.
'History of computer'
Third Generation - 1964-1971: Integrated Circuits.
The development of the integrated circuit was the hallmark of the third generation of computers. Transistors were miniaturized and placed on silicon chips, called semiconductors, which drastically increased the speed and efficiency of computers.
Instead of punched cards and printouts, users interacted with third generation computers through keyboards and monitors and interfaced with an operating system, which allowed the device to run many different applications at one time with a central program that monitored the memory. Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their predecessors.
'History of computer'
Fourth Generation - 1971-Present: Microprocessors.
The microprocessor brought the fourth generation of computers, as thousands of integrated circuits were built onto a single silicon chip. What in the first generation filled an entire room could now fit in the palm of the hand. The Intel 4004 chip, developed in 1971, located all the components of the computer - from the central processing unit and memory to input/output controls - on a single chip.
In 1981 IBM introduced its first computer for the home user, and in 1984 Apple introduced the Macintosh. Microprocessors also moved out of the realm of desktop computers and into many areas of life as more and more everyday products began to use microprocessors.
As these small computers became more powerful, they could be linked together to form networks, which eventually led to the development of the Internet. Fourth generation computers also saw the development of GUIs, the mouse and handheld devices.
'History of computer'
'History of computer'
Fifth Generation - Present and Beyond: Artificial Intelligence
Fifth generation computing devices, based on artificial intelligence, are still in development, though there are some applications, such as voice recognition, that are being used today. The use of parallel processing and superconductors is helping to make artificial intelligence a reality. Quantum computation and molecular and nanotechnology will radically change the face of computers in years to come. The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self-organization.
Source: http://html.rincondelvago.com/history-of-computer.html
Third Generation Computers
Third Generation Computers (1964-1971)
Although transistors were great deal of improvement over the vacuum tubes, they generated heat and damaged the sensitive areas of the computer. The Intergreated Circuit(IC) was invented in 1958 by Jack Kilby. It combined electronic components onto a small silicon disc, made from quartz. More advancement made possible the fitings of even more components on a small chip or a semi conductor. Also in third generation computers, the operating systems allowed the machines to run many different applications. These applications were monitored and coordinated by the computer's memory.
Source: http://library.thinkquest.org/C0125787/thigen.htm
Although transistors were great deal of improvement over the vacuum tubes, they generated heat and damaged the sensitive areas of the computer. The Intergreated Circuit(IC) was invented in 1958 by Jack Kilby. It combined electronic components onto a small silicon disc, made from quartz. More advancement made possible the fitings of even more components on a small chip or a semi conductor. Also in third generation computers, the operating systems allowed the machines to run many different applications. These applications were monitored and coordinated by the computer's memory.
Source: http://library.thinkquest.org/C0125787/thigen.htm
Second Generation Computers
Second Generation Computers (1956-1963)
The invention of Transistors marked the start of the second generation. These transistors took place of the vacuum tubes used in the first generation computers. First large scale machines were made using these technologies to meet the requirements of atomic energy laboratories. One of the other benefits to the programming group was that the second generation replaced Machine language with the assembly language. Even though complex in itself Assemly language was much easier than the binary code.
Second generation computers also started showing the characteristics of modern day computers with utilities such as printers, disk storage and operating systems. Many financial information was processed using these computers.
In Second Generation computers, the instructions(program) could be stored inside the computer's memory. High-level languages such as COBOL (Common Business-Oriented Language) and FORTRAN (Formula Translator) were used, and they are still used for some applications nowdays.
Source: http://library.thinkquest.org/C0125787/secgen.htm
The invention of Transistors marked the start of the second generation. These transistors took place of the vacuum tubes used in the first generation computers. First large scale machines were made using these technologies to meet the requirements of atomic energy laboratories. One of the other benefits to the programming group was that the second generation replaced Machine language with the assembly language. Even though complex in itself Assemly language was much easier than the binary code.
Second generation computers also started showing the characteristics of modern day computers with utilities such as printers, disk storage and operating systems. Many financial information was processed using these computers.
In Second Generation computers, the instructions(program) could be stored inside the computer's memory. High-level languages such as COBOL (Common Business-Oriented Language) and FORTRAN (Formula Translator) were used, and they are still used for some applications nowdays.
Source: http://library.thinkquest.org/C0125787/secgen.htm
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