What is a Computer?A computer is a programmable The two principal characteristics of a computer are: it responds to a specific set of instructions in a well-defined manner and it can execute a prerecorded list of instructions (a program)Modern Computers DefinedModern computers are electronic and The actual machinery -- wires， transistors， and circuits -- is called hardware; the instructions and data are called All general-purpose computers require the following hardware components:memory: enables a computer to store， at least temporarily， data and ass storage device: allows a computer to permanently retain large amounts of Common mass storage devices include disk drives and tape input device: usually a keyboard and mouse， the input device is the conduit through which data and instructions enter a utput device: a display screen， printer， or other device that lets you see what the computer has al processing unit (CPU): the heart of the computer， this is the component that actually executes In addition to these components， many others make it possible for the basic components to work together For example， every computer requires a bus that transmits data from one part of the computer to Computer Classification， By Size and PowerComputers can be generally classified by size and power as follows， though there is considerable overlap:personal computer: a small， single-user computer based on a In addition to the microprocessor， a personal computer has a keyboard for entering data， a monitor for displaying information， and a storage device for saving workstation: a powerful， single-user A workstation is like a personal computer， but it has a more powerful microprocessor and a higher-quality inicomputer: a multi-user computer capable of supporting from 10 to hundreds of users ainframe: a powerful multi-user computer capable of supporting many hundreds or thousands of users supercomputer: an extremely fast computer that can perform hundreds of millions of instructions per Computer Related Q What is computer history? What is computer hardware? What is computer software? What is computer science? What is computer interface? What is computer history?The history of computer development is often referred to in reference to the different generations of computing Each of the five generations of computers is characterized by a major technological development that fundamentally changed the way computers The history of computer development is often referred to in reference to the different generations of computing Each of the five generations of computers is characterized by a major technological development that fundamentally changed the way computers operate， resulting in increasingly smaller， cheaper， more powerful and more efficient and reliable computing In this Webopedia reference article you'll learn about each of the five generations of computers and the technology developments that have led to the current devices that we use Our journey starts in 1940 with vacuum tube circuitry and goes to the present day -- and beyond -- with artificial Related Webopedia Definitions: computer， magnetic drums， binary， integrated circuit， semiconductor， nanotechnologyFirst Generation (1940-1956) Vacuum TubesThe first computers used vacuum tubes for circuitry and magnetic drums for memory， and were often enormous， taking up entire 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 First generation computers relied on machine language， the lowest-level programming language understood by computers， to perform operations， and they could only solve one problem at a Input was based on punched cards and paper tape， and output was displayed on The UNIVAC and ENIAC computers are examples of first-generation computing The UNIVAC was the first commercial computer delivered to a business client， the US Census Bureau in A UNIVAC computer at the Census BureauA UNIVAC computer at the Census BImage Source: United States Census BureauSecond Generation (1956-1963) TransistorsTransistors replaced vacuum tubes and ushered in the second generation of The transistor was invented in 1947 but did not see widespread use in computers until the late 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 Though the transistor still generated a great deal of heat that subjected the computer to damage， it was a vast improvement over the vacuum Second-generation computers still relied on punched cards for input and printouts for Second-generation computers moved from cryptic binary machine language to symbolic， or assembly， languages， which allowed programmers to specify instructions in 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 The first computers of this generation were developed for the atomic energy Third Generation (1964-1971) Integrated CircuitsThe development of the integrated circuit was the hallmark of the third generation of Transistors were miniaturized and placed on silicon chips， called semiconductors， which drastically increased the speed and efficiency of 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 Computers for the first time became accessible to a mass audience because they were smaller and cheaper than their Fourth Generation (1971-Present) MicroprocessorsThe microprocessor brought the fourth generation of computers， as thousands of integrated circuits were built onto a single silicon What in the first generation filled an entire room could now fit in the palm of the 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 In 1981 IBM introduced its first computer for the home user， and in 1984 Apple introduced the M 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 As these small computers became more powerful， they could be linked together to form networks， which eventually led to the development of the I Fourth generation computers also saw the development of GUIs， the mouse and handheld Fifth Generation (Present and Beyond) Artificial IntelligenceFifth generation computing devices， based on artificial intelligence， are still in development， though there are some applications， such as voice recognition， that are being used The use of parallel processing and superconductors is helping to make artificial intelligence a Quantum computation and molecular and nanotechnology will radically change the face of computers in years to The goal of fifth-generation computing is to develop devices that respond to natural language input and are capable of learning and self- What is computer hardware?Hardware refers to objects that you can actually touch， like disks， disk drives， display screens， keyboards， printers， boards， and In contrast， software is Software exists as ideas， concepts， and symbols， but it has no Books provide a useful The pages and the ink are the hardware， while the words， sentences， paragraphs， and the overall meaning are the A computer without software is like a book full of blank pages -- you need software to make the computer useful just as you need words to make a book What is computer software?Software means computer instructions or Anything that can be stored electronically is software， in contrast to storage devices and display devices which are called The terms software and hardware are used as both nouns and For example， you can say: "The problem lies in the software，" meaning that there is a problem with the program or data， not with the computer You can also say: "It's a software "The distinction between software and hardware is sometimes confusing because they are so integrally Clearly， when you purchase a program， you are buying But to buy the software， you need to buy the disk (hardware) on which the software is Categories of SoftwareSoftware is often divided into two Systems software includes the operating system and all the utilities that enable the computer to Applications software includes programs that do real work for For example， word processors， spreadsheets， and database management systems fall under the category of applications What is computer science?Computer science is the study of computers， including both hardware and software Computer science is composed of many broad disciplines， including artificial intelligence and software Most universities now offer bachelor， master， and doctorate degrees in computer What is computer interface?Interface is a boundary across which two independent systems meet and act on or communicate with each In computer technology， there are several types of user interface - the keyboard， mouse， menus of a computer The user interface allows the user to communicate with the operating Also see GUIsoftware interface - the languages and codes that the applications use to communicate with each other and with the hardware interface - the wires， plugs and sockets that hardware devices use to communicate with each
We build computer to solve Early computer solved mathematical and engineering problems，and later computers emphasized information processing for business T- oday，computers also control machines as diverse as automobile engines，robots，and microwave A computer system solves a problem from any of these domains by accepting input，processing it，and producing F 1-1 illustrates the function of a computer Computer systems consist of hardware and Hardware is the physical part of the Once designed，hardware is difficult and expensive to Software is the set of programs that instruct the hardware and is easier to modify than Computers are valuable because they are general-purpose machines that can solve many different kinds of problems，as opposed to special-purpose machines that can each solve only one kind of Different problems can be solved with the same hardware by supplying the system with a different set of hat is，with different undefined
