Basics of Computer

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					                             COMPUTER, AN INTRODUCTION

        Computer is an electronic machine, which processes large volume of data
and give us desirable results.
        It can be defined as an electronic device that receives, stores and processes data
according to the given set of instructions.
        It differs from calculator because It can do very complex mathematical and logical
calculations, and also can store huge data for future use. It differs from the typewriter because of
its numerous options for editing and presentation of data. It beats human beings because of its
speed, accuracy, memory and diligence.
        Whole functioning of computer includes getting information or input working or
processing on it and giving results or output. On this basis, broadly computer can be divided
into three units i.e.

(1) Input Unit
(2) Central Processing Unit (CPU)
(3) Output Unit.

          It consists of those devices which help us to give instructions, feed data or any sort of
input to the CPU. Following are the main Input devices:-
(a) Keyboard: It consists of alphabet, numeric, symbol, function and many more keys
arranged on a board. Keyboard is mainly used to give numeric and alphabetic instructions to the
(b) Mouse: Mouse is small hand held input device that rolls on the small flat surface called
Mouse Pad. It is used for designing and to give instructions in window .
(c) Trackball: It is an input device similar to the mouse, but in trackball, the ball or roller is fit
on the top position which is spinned with fingers by the user.
(d) Light Pen: It is used to draw graphics or drawings directly on the screen.
(e) Digitizer: The digitizer consists of a flat surface called tablet and a pen-like device
called stylus. The stylus is used to input drawings into the computer.
(f) Touch Screen: Some monitors have touch sensitive screens. The user can enter data into
the computer by touching the screen by a finger or a pointer.
(g) Scanner: Scanner is a device that can transfer an images of photographs or written
     information to the computer. It acts like photocopy machine which copy images in the
(h) Camera: Different types of cameras can be attached to the computer for photographic input.
(i) Mic: Mic is used to record audio information in computer.

         Output unit include those devices which give us output after being processed in the
CPU. Following are the important output devices:-
(a) Monitor/VDU (Video Display Unit): The output of the computer is displayed on the device
called monitor. The format of the monitor screen is generally 23 to 24 lines with up to 80
characters per line. The display that appears on the monitor is made up of a collection of dots of
light called Pixels that are arranged in rows and columns on the screen.Clarity of the display
called resolution depends on the number of rows and columns of the pixels on the screen.
(2) Printers: Printer is an another important output device which give us printed output on

      the paper called Hardcopy. Widely used printers are of following type:-
(a) Dot Matrix Printers: Dot Matrix Printers are so called because the characters printed are
made up of dots.The print-head of a dot matrix printer has a series of pins( usually 9, 24.) It
print by activating by those pins which form the shape of the character to be printed.
(c) Inkjet Printers: Inkjet printers print on the paper directly spraying ink on the paper through
(d) Laser Printers: They use laser to form image on the page.
        Beside these, there are other output devices like Plotter, used for high quality
multicolored drawings such as charts, maps and architectural designs. COM (Computer Output
Microfilm), is used to reduce the computer output photographically on the microfilm.
(3) Speakers: speakers give us all kinds of audio output.

         CPU is most important part of the whole system. Following are the main components
of CPU:-
 CABINET:- It is outer body of the CPU in which all the components are fixed. Two types of
caninets are available in the market i.e. AT & ATX. These two models again comes in two
shapes one is Desk Top Model another is Tower Model. Each cabinet also have a SMPS fixed
On its back. SMPS is Switch Mode Power Supply used to convert the high voltage current to
a low voltage.It give an output for various components like motherboard, HDD, FDD etc. of
DRIVES: Drives are data storage devices, following are the common derives:-
Hard Disk:- It is used to store data and to load and run the programmes on computer.
Various programmes we run on computer are stored on the harddisk drive(i.e. C:)
CD Drive :- It is used to run the collection of software,and audio-video programmes
Floppy Drives & Floppies:- Two types of floppy drives i.e. 1.44mb & 1.2mb are used to store
data . These drives represent A: & B: on screen.
Zip Drive:- It is used to keep backup of important data .
MOTHERBOARD: Motherboard, also called PCB (Printed Circuit Board) is the main
board inside the CPU on which all the important components are fixed, and are linked by thin
interconnecting copper strips printed on its surface. Following are the components attached on
the motherboard:-
Cards: Each motherboard has number of expansion slots fixed on one side of the board which
are used for further expansion. We can plug FAX, LAN, Multimedia, TV tuner, TV output and
many other high graphic cards according to the need.
RAM (Random Access Memory): RAM is the temporary memory of the computer in which
software files get loaded when we operate it. Whatever work we do on computer it remain in
the RAM until we quit it. A CPU can have RAM from 32MB to 256MB or above.
Microprocessor (CPU): It is most important component of the CPU which do all sort of logical
functions and run the programmes.


SPEED: Computers work very fast.Its speed is measured in million- millionth of a second.
Latest PC`s can do processing upto 800 Mhrtz.
MEMORY: Computers have large memory. Simple PC`s can store data up to 30 GB. (around
200 Lakh pages)
ACCURACY: Computer work is always error free.
DILIGENCE: Computers can work continuously without getting tired or bored.
AUTOMATION: Computers carry on its work step by step automatically.

LOGIC: Computers can do all logical functions. Logic is a way of approaching problems step by
NETWORKING: Through computers we can share information with other computers.

        Presently computers are being used in all walks of life. IN SCIENCE new theories are
developed with the assistance of computers. They help engineers to solve complex design
problems. IN FACTORIES Computer Aided manufacturing help to increase the efficiency and
quality of manufacturing operations. They are used to design, test and control the big
electromechanical devices like spacecraft, missiles, aircraft etc.
        Computers are also used for weather forecasting, air traffic control, airlines, railway seat
reservations etc. In the areas of education and entertainment computers are being acquiring
knowledge and playing games. Similarly in banks, shops or factories, offices, this machine is
used to maintain accounts, to keep records, to make salary or pay bills etc.
        In short we can say computers are being used almost in every field now, and every day
new areas of activities are being discovered.

     Broadly computers can be categorised under following categories:-

(i) Micro Computers: These computers are small enough to fit on the desktop, and can be
operated by single person. Home computers, laptops and palmtop come under this category.
Laptops and palmtop are portable computers, which can easily be carried while travelling.
(ii) Mini Computers: It refers to those computers having more speed and memory size, used in
large organisations and are operated by several persons.
(iii) Super or Mainframe Computers: These computers are very large in size , installed in
several cabinets and are managed by many operators.

       Computer Hardware refer to all those components or parts of the computer which we can
touch and see. Under it we can include all those parts which have some physical structure. All
the input-output devices and CPU are computer hardware.
       Computer Software refer to set of programs used to run the computers. What ever we
operate on the computer is software. Broadly software can be put under two categories:

(i) System Operating Software: These software help us to run, control, manage and
coordinate the entire working of computer system. Every computer has one or another
operating system. DOS Window and UNIX are the popular operating systems.
(ii) Application Software: All software used for specific purpose or application like accounting,
designing, word processing or data management etc., are application software. Standard
application software Wordstar, Write, Aldus PageMaker, Win Word, MS Word etc. are the
word processing software; Dbase, Foxpro etc. are database software; Lotus 1-2-3, Excel etc.
are related to spreadsheet; Coreldraw, paintbrush, MS Paint, Power Point, Autocad, 3Dstudio
etc. are the popular graphic software.

       Computer languages are used for programming purpose. Languages are learnt by those
who are interested in software development. Following are the main languages:
(i) FORTRAN: Formula Translation is mainly used for scientific and engineering purpose. (ii)
COBOL: Common Business Oriented Language is used for development of software for

business application. (iii) BASIC: Beginner`s All Purpose Instruction Code is used in the field
of education to teach computer programming to the beginners. (iv) PASCAL: It is used in
structured programming. (v) LOGO: It is used in schools to teach mathematics and
programming. (vi) `C': & C++ languages are used for software development.

         History of the computer goes back to many centuries ago when first time man used a
tool called ABACUS for calculating. After this many mechanical tools and machines were
being developed in the different phases of history. Development of computer can be understood
from the point of view of technology used in different generations. On this basis we can
categorize as follow:-
The first generation computers used valves, an electronic component, as their main
technology which was better to the mechanical calculating devices.
The second generation computers used transistor as their basic technology which were
compact and better to the first generation computers.
The third generation computers used integrated circuits (IC), which were still more faster and
compact to the second generation computers.
The forth generation computers made use of large scale integrated circuits which work very
fast to the previous generation.

         At present PC is the most popular machine used in various institutions and business
organizations for education, accountancy, designing, data management, programming,word
processing and many more purposes. It was IBM company of United States who introduced
the first PC on 12th.Aug.,1981. The word PC which stands for Personal Computer was firstly
used by the IBM company to name their product. It is named so because it was designed for
personal use of an individual or small organizations.IBM PC was the first computer of the
Series. After the gap of two years in 1983 IBM PC XT ( personal computer with extended
technology) came in the market with a bit improved technology. In 1984 IBM PC AT (i.e.
personal computer with advance technology) came in the market. The popular computers of this
series were 80-286,386 486 and 586(Pentium). At present Pentium-III and P-IV are hot selling
products in the market. Each successive model has fast speed and more memory to the
previous one.

        Networking refers to an interconnection of more than one computer and peripheral
devices. It enables an individual computer user to take an advantages of the entire systems
through sharing the information, data and other peripherals. Networking is of various kinds:
LAN (LOCAL AREA NETWORKING): When personal computers are connected to the main
server within building or a group of buildings i.e. within 1km. of radius, for sharing of
resources, such a networking is known as LAN.
WAN (WIDE AREA NETWORKING): When PC`s on network are connected to the different
cities or even countries through telephone lines or satellite for sharing resources, such a
networking is known as WAN.
INTERNET: Internet is a network of networks. The internet has no central authority.
Networks on the internet simply agree to cooperate with each other. Individual computers on
these networks can share files and transmit information because all the various interconnected
networks format massage on the internet with IP (Internet Protocol).


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