IT Fundamentals
Chapter: 03
Organization of Computer System
“Input Unit”
Organization of Computer System

The internal structure of the computer system
differs from one system model to another
system model

The basic Organization remains the same for
all computers
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Inside computer
Floppy
CD
3
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Basic Organization of Computer System
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Units or parts of Computer System

Input Unit
 Processing Unit
 Output Unit
 Storage Unit
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Components of Computer System
Input
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Process
Output
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1.
Input Unit

Input is the process of entering and translating
data into machine readable form so that it can
be processed by a computer in order to
produce the output
 The data entered into the computer known as
input
 Input device is a device through which data
are entered and transformed into machine
readable form
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Types of Input Device
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Keyboard
Mouse
Trackball
Joystick
Touch Screen
Track Point
Touch Pad
Light Pen
Scanner
BCR
VRD
MVS
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Keyboard:
 The
keyboard is an essential input device
 It has typewriter like key with some
additional keys
 There are different types of keyboard used
with the computer system have a certain
number of features in common:





Standard typewriter keys.
Function Keys.
Special Purpose Keys.
Cursor movement Keys.
Numeric Keys.
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Typical keyboard
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Mouse:
 Mouse
is a hand held input device
connected to the computer by a small cable

Doug Engelbart developed the mouse for
the first time in 1960s
 The
mouse which has a ball on its
underside is rolled on a flat surface
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
The rolling movement corresponding to the
movement of the cursor on the screen
 Processing various keyboard keys can also move
the cursor
 We can communicate to the computer by
pressing a button on top of the mouse
 The mouse has three buttons but the left most is
commonly used
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Track Ball

A variation on the mouse is the trackball
 The trackball is like an upside-down mouse
 It has a ball on the top and you can roll the
ball directly with your hand
 The popularity of the trackball raised with the
advent of the laptop computers
 Trackballs are often built-in on portable
computers, but they can also be used as
separate input devices
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Joystick

A joystick is an input device that enables you
to move cursor/Control from one point to
another on the display screen
 A joystick uses a lever to control the position
of the cursor
 It performs the same function as arrow keys
in the keyboard, but it is fat and gives you
eight-direction movement as compared to four
 It is mostly used in video games.
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Touch Screen

The touch screen registers input when a finger
or other object comes in contact with the
screen

Touch screen have long been used in military
applications

Today because they have been less
expensive, touch screens are found in many
applications
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Track Point

The mouse is not practical for people using a
portable computer in a small space
 Some notebook computers provide a mouse
substitute called a trackpoint
 A button that protrudes from the middle of the
keyboard
 With a track point you imitate mouse
movements by pushing the button from side to
side
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Touch Pad

Many laptop computers use a touchpad in
front of the keyboard

You move your finger on the pad to move the
cursor on the screen

When you want to click, you can tap the pad
or use the buttons in front of the pad, which
work like mouse buttons
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Light Pen

The light pen looks like an ordinary pen, but its
tip is light sensitive detector
 The light pen uses a light-sensitive
photoelectric cell to signal screen positions to
the computer
 Light pens are frequently used by graphic
designers and drafting engineers.
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Scanner

scanner works very much like a
photocopier, but a scanner digitizes the
information into a computer, not onto the
other piece of paper

In a process called imaging, a scanner
converts a drawing, a picture, on any
document into computer recognizable form
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
Scanners take an electronic picture of the printed
page, break each image into thousands of light
and dark dots that can be stored in the computer

Then software in the computer tells it how to
interpret the dot patterns
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

Scanners consist of two components

First a data capturing subsystem light-up the document
so the image can be recorded

Then an image-processing subsystem uses
sophisticated software to convert the optical images
into digital form and store the date in a file
Scanners come in both handheld and desktop
models
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BCR (Bar Coded Reader)

Data coded in the form of light and dark lines
or bars are known as bar codes

Bar codes are used particularly by the retail
trade for labeling goods

BCR is a device used for reading bar coded
data
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Coded Bar
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BCR
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BCR
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VRD (Voice Recognition Device)
 Voice
Recognition has been possible for
over 20 years
 Voice recognition is one of the newest,
most complex input techniques used to
interact with the computer
 It requires a microphone and special voice
recognition software.
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
These devices can take place of keyboards for
text entry
 In addition some operating systems enable users
to give vocal commands (Voice Recognition
System)
 This device is used by the people whose jobs do
not allow them to keep their hands free and by
handicapped people who are not able to use
traditional input devices.
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VRD
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VRD
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Machine Vision System
 Computers
need cameras for their eyesight
 A camera digitizes the images of the entire
object then stores the images into
computer, database
 When a new image is seen the system
compares the digitized images with its
database
 The computer identifies the image by
matching the structure.
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
End Of Chapter-03
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