Computer components

2. Computers are made of the following basic components:
1.Case with hardware inside:
1. Power Supply -The power supply comes with the case, but this
component is mentioned separately since there are various types of
power supplies.The one you should get depends on the
requirements of your system.This will be discussed in more detail
later
2. Motherboard -This is where the core components of your computer
reside which are listed below. Also the support cards for video,
sound, networking and more are mounted into this board.
1. Microprocessor -This is the brain of your computer. It performs
commands and instructions and controls the operation of the
computer.
2. Memory -The RAM in your system is mounted on the
motherboard.This is memory that must be powered on to retain
its contents.
3. Drive controllers -The drive controllers control the interface of
your system to your hard drives.The controllers let your hard
drives work by controlling their operation. On most systems,
they are included on the motherboard, however you may add
additional controllers for faster or other types of drives.

3. 4. Hard disk drive(s) -This is where your files are permanently stored
on your computer. Also, normally, your operating system is installed
here.
5.CD-ROM drive(s) -This is normally a read only drive where files are
permanently stored.There are now read/write CD-ROM drives that
use special software to allow users to read from and write to these
drives.
6.Floppy drive(s) - A floppy is a small disk storage device that today
typically has about 1.4 Megabytes of memory capacity.
Other possible file storage devices include DVD devices, Tape
backup devices, and some others.
3.Monitor -This device which operates like aTV set lets the user see how the
computer is responding to their commands.
4.Keyboard -This is where the user enters text commands into the
computer.
5.Mouse - A point and click interface for entering commands which works
well in graphical environments.

4. Sr.No. Operation Description
1 Take Input The process of entering data and
instructions into the computer system
2 Store Data Saving data and instructions so that they
are available for processing as and when
required.
3 Processing Data Performing arithmetic, and logical
operations on data in order to convert
them into useful information.
4 Output Information The process of producing useful
information or results for the user, such as
a printed report or visual display.
5 Control the workflow Directs the manner and sequence in which
all of the above operations are performed.
All types of computers follow a same basic logical structure and
perform the following five basic operations for converting raw input
data into information useful to their users.

6. Input Unit
This unit contains devices with the help of which we enter data into
computer.This unit makes link between user and computer.The input
devices translate the information into the form understandable by
computer.
CPU (Central Processing Unit)
CPU is considered as the brain of the computer. CPU performs all types of
data processing operations. It stores data, intermediate results and
instructions(program). It controls the operation of all parts of computer.
CPU itself has following three components
ALU(Arithmetic Logic Unit)
Memory Unit
Control Unit
Output Unit
Output unit consists of devices with the help of which we get the
information from computer.This unit is a link between computer and
users. Output devices translate the computer's output into the form
understandable by users.

7.  CPU consists of the following features:
 CPU is considered as the brain of the computer.
 CPU performs all types of data processing operations.
 It stores data, intermediate results and instructions(program).
 It controls the operation of all parts of computer.
 CPU itself has following three components.
 Memory or Storage Unit
 Control Unit
 ALU(Arithmetic Logic Unit)

8. Following are few of the important input devices
which are used in a computer:
 Keyboard
 Mouse
 Joy Stick
 Light pen
 Track Ball
 Scanner
 GraphicTablet
 Microphone
 Magnetic Ink Card Reader(MICR)
 Optical Character Reader(OCR)
 Bar Code Reader
 Optical Mark Reader(OMR)

9. Following are few of the important output
devices which are used in a computer.
 Monitors
 Graphic Plotter
 Printer

10.  Monitors, commonly called asVisual Display
Unit (VDU), are the main output device of a
computer. It forms images from tiny dots, called
pixels that are arranged in a rectangular form.
The sharpness of the image depends upon the
number of pixels.
 There are two kinds of viewing screen used for
monitors.
 Cathode-RayTube (CRT)
 Flat- Panel Display
Back

11.  The CRT display is made up of small picture elements
called pixels.The smaller the pixels, the better the image
clarity, or resolution. It takes more than one illuminated
pixel to form whole character, such as the letter ‘e’ in the
word help.
 A finite number of characters can be displayed on a screen
at once.The screen can be divided into a series of
character boxes - fixed location on the screen where a
standard character can be placed. Most screens are
capable of displaying 80 characters of data horizontally
and 25 lines vertically.There are some disadvantages of
CRT:
 Large in Size
 High power consumption Back

12.  The flat-panel display refers to a class of video devices
that have reduced volume, weight and power requirement
in comparison to the CRT.You can hang them on walls or
wear them on your wrists. Current uses of flat-panel
displays include calculators, video games, monitors,
laptop computer, graphics display.
 The flat-panel display is divided into two categories:
 Emissive Displays - The emissive displays are devices that
convert electrical energy into light. Example are plasma
panel and LED(Light-Emitting Diodes).
 Non-Emissive Displays - The Non-emissive displays use
optical effects to convert sunlight or light from some other
source into graphics patterns. Example is LCD(Liquid-
Crystal Device) Back

13.  A plotter is a computer hardware device much like a printer that is used
for printing vector graphics. Instead of toner, plotters use a pen, pencil,
marker, or another writing tool to draw multiple, continuous lines onto
paper rather than a series of dots like a traditional printer.Though once
widely used for computer-aided design, these devices have more or less
been phased out by wide-format printers. Plotters are used to produce
a hard copy of schematics and other similar applications.
 Advantages of plotters
 Plotters can work on very large sheets of paper while maintaining high
resolution.
 They can print on a wide variety of flat materials including plywood,
aluminium, sheet steel, cardboard, and plastic.
 Plotters allow the same pattern to be drawn thousands of times without
any image degradation.
 Disadvantages of plotters
 Plotters are quite large when compared to a traditional printer.
 Plotters are also much more expensive than a traditional printer. Back

14.  Printer is an output device, which is used to
print information on paper.
 There are two types of printers:
 Impact Printers
 Non-Impact Printers
Back

15.  The impact printers print the characters by striking
them on the ribbon which is then pressed on the
paper.
 Characteristics of Impact Printers are the following:
 Very low consumable costs
 Very noisy
 Useful for bulk printing due to low cost
 There is physical contact with the paper to produce an
image
 These printers are of two types
 Character printers
 Line printers Back

16.  Character printers are the printers which print
one character at a time.
 These are further divided into two types:
 Dot Matrix Printer(DMP)
 DaisyWheel
Back

17.  In the market one of the most popular printers is Dot
Matrix Printer.These printers are popular because of their
ease of printing and economical price. Each character
printed is in form of pattern of dots and head consists of a
Matrix of Pins of size (5*7, 7*9, 9*7 or 9*9) which come
out to form a character that is why it is called Dot Matrix
Printer.
 Advantages
 Inexpensive
 Widely Used
 Other language characters can be printed
 Disadvantages
 Slow Speed
 Poor Quality Back

18.  Head is lying on a wheel and pins corresponding to
characters are like petals of Daisy (flower name) that is
why it is called Daisy Wheel Printer.These printers are
generally used for word-processing in offices which
require a few letters to be sent here and there with very
nice quality.
 Advantages
 More reliable than DMP
 Better quality
 The fonts of character can be easily changed
 Disadvantages
 Slower than DMP
 Noisy
 More expensive than DMP Back

19.  Line printers are the printers which print one
line at a time.
 These are of further two types
 Drum Printer
 Chain Printer
Back

20.  This printer is like a drum in shape so it is called drum
printer.The surface of drum is divided into number of
tracks.Total tracks are equal to size of paper i.e. for a
paper width of 132 characters, drum will have 132 tracks. A
character set is embossed on track.The different
character sets available in the market are 48 character set,
64 and 96 characters set. One rotation of drum prints one
line. Drum printers are fast in speed and can print 300 to
2000 lines per minute.
 Advantages
 Very high speed
 Disadvantages
 Very expensive
 Characters fonts cannot be changed Back

21.  In this printer, chain of character sets are used
so it is calledChain Printer. A standard
character set may have 48, 64, or 96
characters.
 Advantages
 Character fonts can easily be changed.
 Different languages can be used with the
same printer.
 Disadvantages
 Noisy Back

22.  Non-impact printers print the characters without
using ribbon.These printers print a complete page at
a time so they are also called as Page Printers.
 These printers are of two types
 Laser Printers
 Inkjet Printers
 Characteristics of Non-impact Printers
 Faster than impact printers.
 They are not noisy.
 High quality.
 Support many fonts and different character size.
Back

23.  These are non-impact page printers.They use
laser lights to produce the dots needed to form
the characters to be printed on a page.
 ADVANTAGES
 Very high speed
 Very high quality output
 Give good graphics quality
 Support many fonts and different character size
 DISADVANTAGES
 Expensive.
 Cannot be used to produce multiple copies of a
document in a single printing. Back

24.  Inkjet printers are non-impact character printers based on
a relatively new technology.They print characters by
spraying small drops of ink onto paper. Inkjet printers
produce high quality output with presentable features.
 They make less noise because no hammering is done and
these have many styles of printing modes available.
Colour printing is also possible. Some models of Inkjet
printers can produce multiple copies of printing also.
 ADVANTAGES
 High quality printing
 More reliable
 DISADVANTAGES
 Expensive as cost per page is high
 Slow as compared to laser printer Back