B.ped

UNIT-2 SYLLABUS
• Input concepts
• Input devices viz. keyboard, mouse, joystick, track ball, touch
screen, light pen, MICR, OMR, OBR, OCR, voice input, smart
cards, bar code readers, digitizer, scanner etc.
• Graphic display devices; DVST
• Graphical input devices; three dimensional input devices
• Voice output systems
• Hard copy devices viz. printer
• Types of printers
• Features of printer; plotter, types of plotters, features of
plotters;
• Soft copy devices viz. VDU and its types
• Types of cards (brief) viz. CGA, MGA/MDA, EGA, VGA,
SVGA, etc
1VIVEK SINHA (HOD CSE)11/16/17

• Storage devices viz. fixed disk or hard disk, floppy diskette,
• Data retrieval and characteristics
• Optical technology; CD – ROM, CD – ROM operation, CD –
ROM standards, origins of CD – ROM
• Hard disk drive
• Floppy disk drive
• CD drive
• DVD drive
• Tape drive
• Zip drive
• Jaz drive
• Pen drive

What Is Input?
What is input?
• Data
– Unprocessed
facts, figures,
and symbols
• Instructions
– Programs
– Commands
– User responses
DATA
Bradley Kinkade 42 hours $12.50 per hour
hard disk
COMMANDS
print the timecard
PROGRAMS
timecard
USER RESPONSES
Yes, the timecard entries are correct
No, the timecard entries are not correct
INSTRUCTIONSp. 5.3 Fig. 5-2
Next

What are Input Devices?
What is an input device?
• Any hardware component used to enter data,
programs, commands, and user responses into a
computer
scanners and
reading
devices
voice input
keyboard
pointing
device
video input
digital
camera4VIVEK SINHA (HOD CSE)11/16/17

Input Devices
•These are those devices, which facilitate a user to
give input. Information is entered in to a computer
through input devices.
•An input device converts input information in to
suitable binary format, which can be accepted by the
computer system.
•The computer system has to process details of each
command, therefore the command will have to be
converted in to machine readable format and this
work can be done through input unit.

Therain
in
Spain
Input Devices
• Devices used to enter data such as text, images, sound
or instructions into the computer
– Keyboard
– Mouse/pointing device
– Scanner
– Microphone
– Digital camera
ABCD

What’s available for input…
• touch - fingers
• sound - voice, other sounds
• Gaze.
• brainwaves…

and output…
• textual information
• visual images - photos, diagrams, icons
• moving images
• sounds - music, voice.

What do we need to input?
• Pointing
• Depressing/releasing a switch - clicking
• Dragging
• Text input
• (Can we reduce this range to "Point and click?"
Or simply a click or on-off switch?)

Inputting SoundInputting Sound
Microphones used for:
– Speech recognition
– Video-conferencing
– Webinars
– Internet phone calls
– Podcasts
Microsoft Office Speech Recognition
Tool

What do we need to input?
• Pointing
• Depressing/releasing a switch - clicking
• Dragging
• Text input
• (Can we reduce this range to "Point and click?"
Or simply a click or on-off switch?)

Other Input Devices
• Scanners
– Text
– Images
• Web Cam
– Live video
• EPOS Digital Pen
• Digital cameras
– Images
– Video
Handheld scanner
Digital camera
Camcorder
Flatbed scanner
EPOS Digital PenWeb Cam

The current norm for desktop
systems
Input via
keyboard
and mouse
Output via
text,
pictures,
movement
, sound

Keyboard
• Keyboard is one of the most widely used peripheral devices.
• Data is entered in to the computer system through keyboard.
• Keyboards are designed for the input of text and characters
and also to control the operation of a computer.
Most of the keyboard have a common number of features like:
• Standard type writer keys
• Function keys
• Special purpose keys
• Cursor Movement Keys
• Numeric keys 14VIVEK SINHA (HOD CSE)11/16/17

Enhanced Keyboard
• Standard alpha-numeric keys
• Specialty keys
Numeric
keypad
Function keys
Multimedia Internet
Arrow keysWindows keys
Toggle and
other keys

Keyboard
• Most keyboards have between 80 and 110
keys, including:
– Typing keys
– A numeric keypad
– Function keys
– Control keys

• The typing keys include the letters of the
alphabet, generally laid out in the same
pattern used for typewriters. According to
legend, this layout, known as QWERTY
for its first six letters.

• a set of 17 keys, arranged in the same
configuration found on adding machines
and calculators, was added to the
keyboard.

• Four arrow keys arranged in an inverted T
formation between the typing keys and
numeric keypad move the cursor on the
screen in small increments.

Other common control keys include:
–Home
–End
–Insert
–Delete
–Page Up
–Page Down
–Control (Ctrl)
–Alternate (Alt)
–Escape (Esc)

• It has its own processor and circuitry that carries
information to and from that processor.
• In all keyboards each circuit is broken at a point
below each key. When you press a key, it
presses a switch, completing the circuit and
allowing a tiny amount of current to flow through.

The Keyboard
What are alternative forms for commands?
• Many programs allow you to use button,
menu, or function key to obtain same result
p. 5.4 Fig. 5-4
Next

Specialty Keyboards
• Laptops
• PDAs
• Wireless
• Ergonomic
Laptop
Ergonomic
PDA

Use the keyboard correctly!

Ergonomic keyboard design

Ergonomic keyboards

Chord keyboards

Indirect Pointing Devices
• Need more cognitive processing than direct methods,
but can be more efficient
• mouse
• tracker ball
• trackpoint
• touchpad…

• A chip inside the computer receives the
signal bits and decodes them into the
appropriate keypress. The computer
then decides what to do on the basis of
the key pressed. Eg: Either display a
character on the screen, or perform
some action.

Mouse
• Mouse is a device which is used to move the cursor on
the screen and to select options.
• When the mouse is moved on the surface the cursor is
also moved in the same direction on the monitor.
• By moving the mouse the user can point to menu on
the screen i..e. Mouse is also known as pointing device.
• Pressing the button of a mouse is known as clicking.
Technicians often describe mouse speed in DPI(dots
per inch).
• One DPI is intended to be the number of pixels the
mouse cursor will move when the mouse is moved one
inch.

Click to view Web Link
then click Mouse
Mouse
What is a mouse?
• Pointing device that
fits under palm of
hand
• Controls movement
of pointer, also
called mouse
pointer, on screen
• Pointer on screen
takes several
shapesClick to
view video
p. 5.7
Next
I-beam block arrow pointing hand
mouse

• Rubber or metal
ball is on its
underside
• Movement of
mouse translates
into signals
computer
understands
Mouse
How does a mechanical mouse work?
mouse padmouse pad
ballball
wheel
button
wheel
button
mouse
buttons
mouse
buttons
p. 5.7 Fig. 5-9
Next

Mouse
How does an optical mouse work?
• Senses light to
detect mouse’s
movement
• More precise than
mechanical
mouse
• Connect using a
cable or wireless
back
button
back
button
wheel
button
wheel
button
forward
button
forward
button
optical
sensor
optical
sensor
p. 5.7 Fig. 5-10
Next

Other Pointing Devices
What are common mouse operations?
p. 5.8 Fig. 5-11
Next
• Point
• Click
• Right-click
• Double-click
• Drag
• Right-drag
• Rotate wheel
• Press wheel

What is a trackball?
• Stationary
pointing
device with a
ball on its top
• To move
pointer, rotate
ball with
thumb,
fingers, or
palm of hand
trackball
Click to view
Web Link then click
Trackballs
p. 5.10 Fig. 5-13
Next

What is a touchpad?
 Small, flat,
rectangular
pointing
device
sensitive to
pressure and
motion
touchpad

What is a pointing stick?
• Pointing
device
shaped like
pencil
eraser
positioned
between
keys on
keyboard
pointing stick
Click to
view
Web Link
then click
Pointing Sticks
p. 5.11 Fig. 5-15
Next

Mice
• Types of mice:
– Standard
– Optical
– Trackball
Standard
Wireless
Optical
Trackball

Indirect pointing devices - mouse
• Mouse
• Invented by Doug
Englebart, Xerox
PARC, in 1966
• "Mouse arm" -
wireless mice - for
home entertainment,
lectures, etc

Indirect
pointing
devices - other
• Trackerball, trackpad,
trackpoint
• Less space on desktop
• Good in moving
environments, e.g. car, train

Indirect pointing devices - other
• Footmouse
• Equivalent to
conventional
mouse.

Light pen
• A light pen is a device which is sensitive to
variations in patterns on a surface. Light pens act
like a miniature scanner and can read text as they
are dragged across the printed page.
This can be transferred directly to the current
open document.

Graphics Tablet
• A Graphics tablet consists of a flat surface
upon which the user may "draw" an image
using an attached stylus, a pen-like drawing
apparatus.

Light Pen
• A light pen is a pointing device. It is an input device in the
form of a light-sensitive wand used in conjunction with the
computer's CRT monitor.
• It allows the user to select a displayed menu option on the
CRT.
• A light pen can work with any CRT-based monitor, but not
with LCD screens, projectors or other display devices.
• It is capable of sensing a position on the screen when its tip
touches it ,its photocell sensing element detects the light
coming on the screen and sends the corresponding signal to
the processor.
• Screen pixels are constantly being refreshed. When the user
presses the button, the pen senses light, and the pixel being
illuminated at that instant identifies the screen location.
• The user brings the pen to the desired point on screen and
presses the pen button to make contact. 45VIVEK SINHA (HOD CSE)11/16/17

What is a stylus?
 Looks like a
ballpoint pen, but
uses pressure to
write text and draw
lines
 Used with graphics
tablets and
handheld
computers
stylus or pen
then click Stylus
p. 5.13 Fig. 5-19
Next

What is an electronic signature?
• Pen and
graphics tablet
used with special
software for
handwriting
recognition
• Legal as ink
signature
• Also called
e-signature
Click to view Web
Link
then click E-
signatures
p. 5.13 Fig. 5-20
Next

What is handwriting recognition software?
• Translates handwritten letters
and symbols into characters
that the computer can
understand
p. 5.14 Fig. 5-21
Next

 Press light
pen against
screen
surface and
then press
button on
pen
What is a light pen?
• Handheld input device that contains light source or
can detect light
p. 5.12 Fig. 5-17
Next
light pen

Joystick
• A joystick is also a pointing device.
• It is used to move cursor on the CRT screen.
• A joystick is a stick that has spherical ball at it’s
upper as well as its lower end.
• The lower spherical ball moves in a socket.
• The electronic circuitry inside the joystick
detects and measures the displacement from its
central position, the information is sent to the
processor.

What are a joystick and a wheel?
• Joystick is vertical lever
mounted on a base
• Wheel is steering-wheel
type input device
• Pedal simulates car
brakes and accelerator
joystick
pedal
wheel
p. 5.11 Fig. 5-16
Next

Indirect pointing devices - other
• Joystick
• Some with force
feedback for fun
experience

Joystick
• The basic idea of a joystick is to translate
the movement of a plastic stick into
electronic information a computer can
process.

Touch Screens
• It is a type of display screen in which one can
use finger to point the command displayed on
the screen. In this user touches the icon that
represent their choices and the computer display
information about their choices.
Pointing devices - direct

Touch Screen
• There are three basic systems that are used
to recognize a person's touch:
– Resistive
– Capacitive
– Surface acoustic wave

Resistive
The resistive system consists of a conductive and a
resistive metallic layer. These two layers are held
apart by spacers, and a scratch-resistant layer is
placed on top of the whole setup. An electrical
current runs through the two layers while the monitor
is operational. When a user touches the screen, the
two layers make contact in that exact spot. The
change in the electrical field is noted and the
coordinates of the point of contact are calculated by
the computer.

Capacitive
A layer that stores electrical charge is placed
on the glass panel of the monitor. When a user
touches the monitor with his or her finger,
some of the charge is transferred to the user, so
the charge on the capacitive layer decreases.
This decrease is measured in circuits located
at each corner of the monitor.

Surface Acoustic Wave
On the monitor of a surface acoustic wave system,
two transducers (one receiving and one sending) are
placed along the x and y axes of the monitor's glass
plate. Also placed on the glass are reflectors -- they
reflect an electrical signal sent from one transducer to
the other. The receiving transducer is able to tell if
the wave has been disturbed by a touch event at any
instant, and can locate it accordingly.

There are some types of touch
screen technology:
• A resistive touch screen panel is coated with a thin
metallic electrically conductive and resistive layer
that causes a change in the electrical current
which is registered as a touch event and sent to the
controller for processing.
• Surface wave technology uses ultrasonic waves
that pass over the touch screen panel. When the
panel is touched, a portion of the wave is
absorbed. This change in the ultrasonic waves
registers the position of the touch event and sends
this information to the controller for processing. 59VIVEK SINHA (HOD CSE)11/16/17

Touch screens
Often used for applications with occasional
use, for example
• Bank ATMs Information etc.
• No extra hardware - used for input and for
output
• Can be precise to 1 pixel
• Good for menu choice - not so good for other
functions

Touch screens
• BUT
• Tiring if at wrong angle (needs to be 30-45% from
horizontal)
• Get greasy, jammy
• Finger can obscure screen
• Alternative - use stylus to touch screen, or lightpen

Input Devices (continued)
• Scanning devices
• Optical data readers
Special scanner
OMR – standardized tests
OCR – convert handwritten to typed doc into
digital data
• Magnetic stripe card
– Swipe card
• Point-of-sale (POS) devices 62VIVEK SINHA (HOD CSE)11/16/17

VIVEK SINHA (HOD
CSE)
63
Input Devices (continued)
• Automated teller machine (ATM) devices
• Pen input devices
• Touch-sensitive screens
• Bar-code scanners
11/16/17

Scanner
• Scanner is that kind of input device which are capable of
entering the information directly in to the computer
system. A scanner is a device that analyzes an image such
as a photograph, printed text, or handwriting and
converts it to a digital image.
• Scanners typically read red-green-blue color (RGB) data
from the array. This data is then processed with some
proprietary algorithm to correct for different exposure
conditions and sent to the computer. The other qualifying
parameter for a scanner is its resolution, measured in
pixels per inch (ppi). The third important parameter for a
scanner is its density range. A high density range means
that the scanner is able to reproduce shadow details and
brightness details in one scan.

Scanner
• Scanner works on the basis of light source. In this light
source emit the light to the object. Some amount of light is
absorbed by the object, wherease some amount of light is
reflected by it to the sensor. The work of the sensor is to
convert that amount of light into the digital data and that
digital data is transmitted to the computer.
Types Of Scanner
• Drum scanners
• Flatbed scanner
• Handheld scanners

Scanners
object
Light source
Sensor

Scanners and Reading Devices
What is a scanner?
• Device that captures data directly from source
document
– Source document is original form of data
Click to
view animation
p. 5.24
Next
OCR
flatbed
scanner
67
VIVEK SINHA (HOD CSE)
11/16/17

Step 1
Step 2
Step 1
Step 2
Step 3
Step 1
Step 2
Step 3
Step 4
Step 1
Step 2
Step 3
Step 4
Step 5
How does a flatbed scanner work?
2: Bright light scans
document
3: Image reflected
into mirrors
4: Light converted to
analog electrical and
then to digital signal
5: Digital information
sent to computer
6: Print or save
document
Step 6
1: Place document
face down
Step 1
p. 5.25 Fig. 5-33
Next

What are various types of scanners?
then click Scanners Drum
Pen or
handheld
Sheet-fed
Flatbed
p. 5.26 Fig. 5-34
Next

What is image processing?
• Capturing, storing, analyzing, displaying, printing,
and manipulating images
• Converting paper documents
into electronic form
• Also called imaging
p. 5.26
Next

What is an optical reader?
• Device that uses light source to read characters,
marks, and codes and then converts them into
digital data
Optical
character
recognition
(OCR)
Optical
mark
recognition
(OMR)
Bar
code
scannerp. 5.27
Next

Parts Of Scanner
• Charge-coupled device (CCD) array
• Mirrors
• Scan head
• Glass plate
• Lamp
• Lens
• Cover
• Filters
• Stepper motor
• Stabilizer bar
• Belt
• Power supply
• Interface ports
• Control circuitry

Working
• The core component of the scanner is the CCD
array.
• CCD is the most common technology for image
capture in scanners.
• CCD is a collection of tiny light-sensitive diodes,
which convert photons (light) into electrons
(electrical charge). These diodes are called
photosites.
• Each photosite is sensitive to light -- the brighter
the light that hits a single photosite, the greater the
electrical charge that will accumulate at that site. 73VIVEK SINHA (HOD CSE)11/16/17

Light source, lens
and diode array
Document
being
scanned
Converts
diode signals
to numbers
To computer

Drum Scanner

Types Of Scanner
• Drum scanners: Drum scanners capture image
information with photomultiplier tubes (PMT). It is of
medium size. In this drum roles over the image for
scanning. The scanner drum, which rotates at high speed
while it passes in front of the precision optics that deliver
image information to the PMTs.
• Flatbed scanner: A flatbed scanner is usually composed of
a glass pane, under which there is a bright light which is
often of cold cathode fluorescent which illuminates the
pane.
• Hand scanner: Hand scanners are manual devices which
are dragged across the surface of the image to be scanned.
They typically have a "start" button which is held by the
user for the duration of the scan, some switches to set the
optical resolution, and a roller which generates a clock
pulse for synchronization with the computer.

SOURCE DATA ENTRY
Optical Readers
 a device that uses a light source
to read characters, marks and
codes  converts them into
digital data.
Optical Mark Recognition
(OMR)
read hand-drawn marks
such as small circles or
rectangle
e.g. for MCQ exam
Optical Character Recognition
(OCR)
Read typewritten, computer-
printed or hand-printed
characters from ordinary
documents  digital code

MICR
• Magnetic Ink Character Recognition, or MICR, is a
special kind of character recognition technology that
was adopted mainly by the banking industry to
facilitate the processing of cheques.
• A special ink called magnetic ink is used to write the
character of the cheques and deposit forms which
are to be processed by an MICR.
• The magnetic ink is magnetized during the input
process.
• The MICR reads these pattern and compared with
the special pattern stored in the memory 79VIVEK SINHA (HOD CSE)11/16/17

The MICR reading machine recognizes only a
particular type of characters, printed in the
standard font set for them by the American
Banking Association. MICR is used extensively in
the banking sector because magnetic-ink
characters are difficult to forge, and are
therefore ideal for marking and identifying
cheques.

• Magnetic ink character recognition
(MICR) devices
A system for reading banking data quickly
Use special ink readable by people and
computers
e.g. bank check
VIVEK SINHA (HOD
CSE)
8111/16/17

MICR Readers
Convert MICR characters  a form the
computer can process
MICR device - reads text printed with
magnetized ink.
Used by the banking industry - cheque
processing
VIVEK SINHA (HOD CSE) 8211/16/17

What is a magnetic ink character
recognition reader (MICR)?
• Can read text printed with magnetized ink
• Banking industry almost exclusively uses
MICR for check processing
check
number
bank
number
check
amount
account
number

Document Readers
• MICR- Generates the magnetic fields for
reading the chars. written by special ink.

OCR
• It is an abbreviated form of Optical Character
Reader. It detects the alphanumeric character
printed on paper.
• It works on the basis of light scanning techniques
in which each character is illuminated by the light
source and the reflected images of the character is
received by the photocells which provides binary
data corresponding to the lighted and dark areas.
• OCR is quite costly because the memory
requirement is very high.

What is an OCR font?
• OCR font, such as OCR-A, used with OCR
devices
• OCR device determines characters’ shapes
by detecting patterns of light and dark
• OCR software converts shapes into
characters the computer can understand

What is a turnaround document?
• You return it
to company
that sent it
Next
numbers are
read by OCR
device when
document is
returned

OCR
• The OCR software then converts the image
of the text into an actual text file by
recognizing each character.
• Convert the bitmap images of chars. To
equivalent ASCII code, by this it takes less
space in memory.

Optical Input Devices –
Image Scanners and OCR
• Image scanners digitize printed images for
storage and manipulation in a computer.
• A scanner shines light onto the image and
interprets the reflection.
• Optical character recognition (OCR)
software translates scanned text into
editable electronic documents.

OCR
• The basic principle of a scanner is to analyze an
image and process it in some way.
• Image and text capture (optical character
recognition or OCR) allow you to save
information to a file on your computer.
• You can then alter or enhance the image, print it
out

Bar Code Reader
• Bar code is a machine readable numerical code,
printed as a set of varying width vertical bars.
• A barcode reader is a computer peripheral for
reading barcodes printed on various surfaces.
• As you know bar codes are present on most of the
grocery item, it consist of a number of thick lines
with a varying distance between them.
• A barcode reader scans the bar code, and converts
it into a number that the computer can then
process and display on the screen.
• Bar code reader, generally consists of a light
source, a lens and a photo conductor translating
optical impulses into electrical ones. Therefore, it
read such bars and convert them in to electrical
pulses which is processed by the computer. 91VIVEK SINHA (HOD CSE)11/16/17

Bar code Reader
The reader uses a laser beam that is sensitive to the
different reflections from the lines and the spaces.

What is a bar code scanner?
• Uses laser beams to read
bar codes
bar code
scanners 93VIVEK SINHA (HOD CSE)11/16/17

What is a bar code?
• Identification code that consists of a set of
vertical lines and spaces of different widths
• Universal Product Code (UPC)
Number system
character identifies
type of product
Number system
character identifies
type of product
Manufacturer
identification number
(Kellogg’s, in this case)
Manufacturer
identification number
(Kellogg’s, in this case)
Check character verifies
accuracy of scanned
UPC symbol
Check character verifies
accuracy of scanned
UPC symbol
Item number (10 oz. box
of Froot Loops
Item number (10 oz. box
of Froot Loops

Optical Input Devices - Bar Code Readers
• Bar code readers can read bar codes
patterns of printed bars.
• The reader emits light, which reflects off
the bar code and into a detector in the
reader. The detector translates the code
into numbers.
• Flatbed bar code readers are commonly
found in supermarkets. Courier services
often use handheld readers.

Bar code readers
commonly track
sales in retail
stores 96VIVEK SINHA (HOD CSE)11/16/17

OMR
The infra-red light is not reflected when it
scans over a mark and the position of the
mark is passed back to the computer. 97VIVEK SINHA (HOD CSE)11/16/17

OMR (Optical Mark Reader)
• Special marks such as square or bubble are
prepared on examination answer sheets.
• The user fill in these squares or bubbles with soft
pencil or ink to indicate there choices. These
squares are detected by an OMR and the
corresponding signals are sent to the processor.
• If a mark is present, it reduces the amount of
reflected light . If a mark is not present the
amount of light reflected is reduced.

What is optical mark recognition (OMR)?
• Reads hand-
drawn pencil
marks, such
as small
circles or
rectangles

Optical Mark Recognition
An optical mark reader shines a light beam
onto the input document and is able to
detect the marks because less light is
reflected back from them than from the
paler, unmarked paper.
VIVEK SINHA (HOD CSE)11/16/17 100

Smart Card Reader
• Smart cards stores data in the magnetic stripes which is present
at the back side of the card.
• These data cannot be read visually, and therefore, to read this
data, special card reader machine is required, which can decode
data present on these magnetic stripes.
• The smart card can hold many information and it is impossible
to duplicate it because data is stored in magnetic strips.
• There is a , Contact Smart Cards which has a small gold chip
about ½ inch in diameter on the front. When inserted into a
reader, the chip makes contact with electrical connectors that
can read information from the chip and write information back.
The cards do not contain any batteries, energy is supplied by the
card reader. Contact smart card readers are used as a
communications medium between the smart card and a host,
e.g. a computer.

Smart Cards

Magnetic Strips
Magnetic strips are built into many plastic cards, the most
common example being credit cards.
The strip can contain up to 60 characters (numbers or digits) of
information which is stored magnetically. Usually the information is put
onto the strip when the card is made and is never changed. Magnetic strip
codes can also sometimes be found at the back of railway tickets, e.g., the
Metro Rail tickets in Delhi and Kolkata.

SOURCE DATA ENTRY
Magnetic Stripe Card Readers
 Reads the magnetic stripe on the back of credit cards,
bank cards and other similar cards.
 Contains information - your name, account number,
card’s expiration date, country code, etc.

Digitizer
• Digitization, is the process of turning
an analog signal into a digital
representation of that signal. An
example of digitizer is Graphic Tablet

Graphics Tablet
• A Graphics tablet consists of a flat surface
upon which the user may "draw" an image
using an attached stylus, a pen-like drawing
apparatus.

Digital Camera
• The resolution of a digital camera is determined
by the camera sensor which is usually a Charged
Coupled Device or CCD chip that turns light into
digital information, replacing the job of film in
traditional photography.
• Each pixel can store one digital value, which can
then be recalled and put with other pixel values to
generate a digital photograph.
• Common formats for digital camera images are
the Joint Photography Experts Group standard
(JPEG).

Audio-Visual (Multimedia) Input Devices –
Video Input
• PC video cameras digitize full-motion
images.
• Digital cameras capture still images.
• These cameras break images into pixels and
store data about each pixel.
• Video images may be compressed to use less
memory and storage space.

SOURCE DATA ENTRY
Digital Camera
 allows users to take pictures and
store the photographed imaged
digitally
 Transfer the image by downloading
or using storage media

SOURCE DATA ENTRY
Video Input
 the process of
capturing full-
motion images and
storing them on a
computer’s storage
medium
Video
conferencing
Web CamsPC video
camera

Voice Input System
• In voice input system the speech is
converted into electrical signals, by making
use of microphone.
• The signal are sent to the processor for
processing.
• The signal pattern is compared with the
pattern already stored in memory.
• A word is recognized only when a choice
match is found, and then the computer
gives the corresponding output.

SOURCE DATA ENTRY
Voice Input
 the process of entering input by speaking
 Voice or speech recognition  converts a person's speech
into digital code
comparing the electrical patterns produced by the
speaker's voice with a set of prerecorded patterns
stored in the computer
Audio Input
 the process of entering any sound (speech, music and
sound effects) into the computer.
0
1
Digital voiceWave form
voice
113
11/16/17

SOURCE DATA ENTRY
Biometrics
 the technology of authentication a person’s identity
by verifying a personal characteristic
Biometric device
translates a personal characteristic (the input) into a digital
code that is compared with a digital code stored in the
computer.

Examples of biometric technology
 Voice verification system compares live
speech with stored voice pattern
 Signature verification system recognizes
shape of signature
 Iris recognition system reads patterns in
blood vessels in back of eye
 Fingerprint scanner captures curves and
indentations of fingerprint
 Hand geometry system measures shape
and size of person’s hand
SOURCE DATA ENTRY

Output Devices
• Enable us to see or hear the processed information
• Send processed data out of the computer
– Monitors
– Printers
– Speakers
• Output devices make:
– Soft copies (video, sounds, control signals)
– Hard copies (print)
Monitor
Speaker
Printer

Output Devices
The output devices receive information from the
computer and provide them to user in a readable
format. The computer sends information to the
output devices in binary coded forms. Then, output
devices convert them in to a form, which can be used
by user. Some output devices are
•Printer
•Monitor
•Plotter
•Speaker

OUTPUT
 data that has been processed into useful form 
Information
4 categories of output

• Text
• Graphics
• Audio
• Video
Examples of text based output are
 memos
 letters
 announcements
 reports
 e-mail messages
Examples of graphics :-
 logos
 chart
 drawing
 clip art
 photographs
Example of audio :-
 audio clips
 live broadcasts of interview
 listen to music while working
with computer
 chat using microphone
OUTPUT
Categories of output
11/16/17 119VIVEK SINHA (HOD CSE)

Examples of graphics :-
 logos
 chart
 drawing
 clip art
 photographs
Example of audio :-
 audio clips
 live broadcasts of interview
 listen to music while
working with computer
 chat using microphone
Examples of text based output are
 memos
 letters
 announcements
 reports
 e-mail messages

OUTPUT
Any hardware component that conveys
information to one or more users.
printer speakerDisplay device
Output Devices

OUTPUT
Two kinds of output
Hardcopy
printed output
Softcopy
data that are kept in
any storage media

VDU can be categorized into
• CRT Display
• Non CRT Display

Non CRT Display
• LCD
• LED

VDU
• A computer display is a device that can display signals
generated by a computer as images on a screen.
Quality factors used in monitor are:
• Pixels: It is the smallest unit of monitor which is displayed
without disturbing the other point .While designing the
pixels, some distance between the pixels must be there in
the horizontal as well as in vertical direction also.
• Aspect Ratio: It is the ratio of the pixels in the horizontal
as well as in vertical direction also.
• Resolution: Number of pixels in a per unit area.
• Refreshing Rate: The rate by which the pixels glow again
Refreshing Rate = 1/Refreshing Time

COMPUTER DISPLAY
TECHNOLOGY
Quality of a CRT Monitor
 Resolution
the number of pixels (horizontal by vertical)
E.g. 640x480, 800x600, 1024x768
800 horizontal pixels
600 vertical
pixels
T otal of
480,000 pixels
on screen 126VIVEK SINHA (HOD CSE)11/16/17

Refresh Rate
measured in Hertz (Hz)
represents the number of frames displayed on
the screen per second
Used to control flicker
COMPUTER DISPLAY
TECHNOLOGY
Example :
If your CRT monitor has a refresh rate of 72 Hz, then it
cycles through all the pixels from top to bottom 72 times
per second.

CRT Display Devices

Examples of Computer Graphics
Devices
CRT, EGA/CGA/VGA/SVGA monitors,
plotters, data matrix, laser printers, flat
panel devices, video digitizers, scanners,
LCD panels. The most commonly used
display device is the
CRT monitor

COMPUTER DISPLAY
TECHNOLOGY
Cathode Ray Tube (CRT)
 a large, sealed glass tube
and the front of the tube is
the screen.
 Coated with thousands of
tiny phosphor dots.
Phosphors are chemicals
 emit light when
excited by a stream of
electron.
 Each dot consists of three
blobs of colored phosphor:
one red, one green, one blue
 a single pixel.
R G
B
Pixel

Types of CRT display devices
• DVST (Direct View Storage Tube)
• Calligraphic or Random scan display
system
• Refresh and raster scan display system

DVST – Direct View Storage Tube
• Storage Tube – It is a CRT with a long
persistence phosphor
• Provides flicker – free display
• No refreshing necessary

• A slow moving electron beam draws a line
on the screen
• Screen has a storage mesh in which the
phosphor is embedded
• Image is stored as a distribution of charges
on the inside surface of the screen
• Limited interactive support
DVST – Direct View Storage Tube
(contd.)

DVST (Direct View Storage
Tube)
Display
processor
CRT
keyboard
vertical and
horizontal cursor
thumbwheels
interface to host computer
(display commands) (interaction data)

Cathod Ray Tube
CRT stands for the cathode ray tube. To see
an image on the screen we have to glow that
part. Energy of the photon(electron) goes to
the fluorescent material, it produces the
light and a point is introduced on the
monitor.CRT makes use of the directing
devices to give direction to the
photon(electron) otherwise, it will goes
towards the center. Some amount of
magnetic field is applied to run photons in
correct directions. Magnetic field is nothing
but electrical signals.VIVEK SINHA (HOD CSE)
13511/16/17

Operation of an electron gun with an
accelerating anode

Electrostatic deflection of the electron beam in a CRT

Cathod Ray Tube
In the above figure, there is a photon(electron)
gun which is used to produce photons(electron)
but the speed of the generated photon is very slow,
therefore to increase its speed, there is an
accelerator. It will give velocity to the photon
(electron). Before shifting the photons(electron) to
different directions we have to coincident all the
photons at a point and this point is known as
coincidentor. Two horizontal and vertical
deflection plates are used to give direction to the
photon in the upward and the downward
direction. For color monitor, 3 electron gun is
used. VIVEK SINHA (HOD CSE) 13811/16/17

Cathod Ray Tube

COMPUTER DISPLAY
TECHNOLOGY
 Dot pitch
Physical distance between adjacent phosphor dots of the
same color.
The centre-to-centre distance between two nearest
phosphors dots of the same color
The smaller – the finer and better

COMPUTER DISPLAY
TECHNOLOGY
 Disadvantages
 generates more heat
 uses more power
 Advantages
 Less expensive
 produce a small amount
of electromagnetic
radiation (EMR)

COMPUTER DISPLAY
TECHNOLOGY
Flat-panel Display
- Lightweight display device  shallow depth &
flat screen
- Used by
- LCD Monitors and screen
- Plasma monitor

LCD Monitors and Screen
• Used liquid crystal display
• Images  sharp and flicker-free
• Contain fluorescent tubes that emit light wave to the liquid
crystal cells
COMPUTER DISPLAY
TECHNOLOGY

reflective
layer
horizontal
polarizer
horizontal
grid wires
liquid-
crystal
layer
vertical
grid wires
vertical
polarizer
viewing
direction
LCD ( Liquid Crystal Display )
Basics

Color TFT (Thin Film
Transistor) LCD
Color ?
Liquid Crystal
TFT (Thin Film Transistor)
 using a transistor at each grid point
 causing the crystals to change their state quickly
 controlling the degree to which the state has been changed
 holding the state until it changes
TFT
Color Filter

Advantages of LCDs
• Flat
• Lightweight
• Low power consumption

• Produce color using :
– Passive-matrix display
• Uses fewer transistors, requires less power, less expensive
• Best to view when working directly in front of it.
– Active-matrix display (TFT-Thin Film Transistor)
• Uses separate transistor
• Organic LED (OLED)  produce brighter, easy-to-read
display, less expensive, require less power
OLED Screen
COMPUTER DISPLAY
TECHNOLOGY

COMPUTER DISPLAY
TECHNOLOGY
LCD quality depends on
Resolution
the number of pixels (horizontal by vertical)
Response time
The time it takes to turn a pixel on and off (ms) 
change a pixel's color or brightness
Brightness
The amount of light emitted from the display
Measured in nits (unit visible light intensity equal to one
candela per square meter)
Dot pitch
The distance between the centers of two adjacent pixels
Contrast ratio
Difference in light intensity (brightest white and darkest
black)
The higher contrast the better

COMPUTER DISPLAY
TECHNOLOGY
Plasma Monitor
• Uses gas plasma technology – a layer of
gas between two gas plates
• When voltage is applied  gas releases
UV light causes the pixels to glow and
form images
• Advantages:
– Offers larger screen sizes
– high-quality display
• Disadvantages:
– Expensive 152VIVEK SINHA (HOD CSE)11/16/17

COMPUTER DISPLAY
TECHNOLOGY

Standard Graphic Add-on-Boards
Resolution
(by pixels)
CGA (Color Graphic Adapter) 640 x 200
EGA (Enhanced Graphic Adapter) 640 x 350
VGA (Video Graphic Array) 640 x 480
SVGA (Super Video Graphic Array) 1024 x 768
Displays – cont.
Input and Output Devices – cont.

PRINTER
• It is a device that produces a hard copy which is
permanent human-readable text of documents
stored in electronic form, usually on physical print
media such as paper or transparencies.
• The data received by a printer may be:
a string of characters
a bitmapped image

PRINTERS
Devices that produces text and graphic on a
physical medium  hardcopy/printout
• Two orientations: portrait and landscape
• Printer resolution is measured by number of
dots per inch (dpi).
• Higher the resolution, the higher the image
quality

300 dpi 1,200 dpi600 dpi
PRINTERS

PRINTERS QUALITY
1. Near Typeset quality
2. Letter quality
3. Near letter quality print
4. Standard quality print
5. Draft quality print

Categorized based on whether there is
mechanical contact between printer head and
paper
1. Impact
• These are those type of printers which have direct
mechanical contact between the head of the printer and
paper.
• Form character/graphics by striking a mechanism against an
inked ribbon  leaving an image on paper physically
2. Non-impact
• These are those type of printers where there is no direct
mechanical contact between the head of the printer and
paper.
• Place image on a page without touching the page physically
PRINTERS
159
11/16/17

PRINTERS
• Impact
Impact printers can generally categorized into
following types depending on the way they print
a character : -
• Solid font
• Dot Matrix
– Serial or character printer s
» Dot Matrix Printer
» Daisy Wheel Printer
– Line Printers

PRINTERS
• Non-Impact
The most commonly used categories of non -
impact printers are : -
• Thermal
• Ink jet
• Laser
• Electrographic
• Electrostatic

PRINTERS
• Impact
Dot Matrix Printer
• Produced images when
tiny wire pins strike an
inked ribbon.
• Widely used for business
• Useful for low quality
carbon copy printing
• Advantages:
– Handle continuous-
form paper
– cheap and fast
DOT MATRIX PRINTER

Dot Matrix Printer
• Use a matrix of small pins to create precise dots.
• In this character is printed by printing the selected no of
dots from a matrix of dot. The formation of a character
has been shown 5 dot rows and 7 dot columns. This pattern
is called 5×7 dot matrix. In this character is printed by
printing the selected no of dots from a matrix of dot. The
formation of a character has been shown 5 dot rows and 7
dot columns. This pattern is called 5×7 dot matrix.
• Such printers would have either 9 or 24 pins on the print
head. Print head is that part of the printer that creates the
printed image.

daisy
wheels
Daisywheel Printer
Molded metal characters like those in a
typewriter are mounted on extensions
attached to a rotating wheel and are printed
onto the paper by means of a hammer and
print ribbon.
This results in a great deal of movement
and noise during the printing of
documents, so printing is slow
(less than 90cps).
The standard of print is similar to that
produced by an electric typewriter. As
the characters on the wheel are fixed, the
size and font can only be changed by
using a different wheel. However, this is
very rarely done.
Daisy-wheel printers cannot print
graphics, and in general they are noisy
and slow, printing from 10 to about 75
characters per second

PRINTERS
– Line Printer
• Print an entire line
at a time
• Speed – measured
by number of lines
per minute

Line Printers
These are the printers which print total line
at a time. These printer use special
mechanisms to print one line at a time.
They are faster and can print about 1000-
5000 lines per minute.

Special Features:
Features Dot matrix
printer
Daisy wheel
printer
Line
printer
Speed 30 – 550 cps about 75 cps 3,000 lines per
minute
Sound Most
noisiest
noisy noisy
Printer
quality
letter-quality
type
cannot print
graphics
cannot print
graphics
Printing
method
needle Daisy wheels Hammer and
print ribbon

Disadvantages and Advantages
Type of
printer
Dot matrix
printer
Daisy wheel
printer
Line printer
Disadvantage It is the most
noisiest and slow.
The printing
quality is very
poor.
It is a great deal
of movement
and noisy, so
printing is slow.
It cannot print
graphics, the
print quality is
low, and they are
very noisy .
Advantage It is cheap to run
and relatively
fast.
It is cheap. It has a high-
speed.

PRINTERS
• Nonimpact
 Ink-jet Printer
• Spray tiny drop of liquid
ink onto paper using
multiple jet nozzles
• Can print – black/ white
and several different
colors
• Resolution – measured
by dpi (dots per inch)
• Dot – a drop of ink
(the higher dpi, the
smaller drops of
ink)
• Speed - measured by
ppm (pages per minute)

PRINTERS
Laser Printer
• Used a laser beam and powdered
ink (toner) to transfer images
onto paper
• Prints text and graphics in very
high-quality resolution

Laser printer
• Laser printer are page printer. They make use of laser
beam to produce an image of the page containing text
/graphics on a photo sensitive drum.
• A laser printer uses a rotating disc to reflect laser beam
onto a photosensitive drum, where the image of the page is
converted in to an electrostatic charge.

PRINTERS
 Thermal Printer
• Generates images by
pushing electrically
heated pins against
heat-sensitive paper
• Print quality – low
(tends to fade)
 Photo Printer
• Produces photo-
lab quality
pictures
• Use ink-jet
technology

 Mobile Printer
• Small lightweight,
battery-powered printer
• allows mobile user to
print from notebook
computer, Tablet
PC, or PDA while
traveling.
PRINTERS

Compare with non-impact
printer and impact printer
•quality of type: The output produced by printers is said
to be either letter quality (as good as a typewriter), near
letter quality, or draft quality. Only daisy-wheel, ink-jet,
and laser printers produce letter-quality type. Some dot-
matrix printers claim letter-quality print, but if you look
closely, you can see the difference.
•speed: Measured in characters per second (cps) or pages
per minute (ppm), the speed of printers varies widely.
Daisy-wheel printers tend to be the slowest, printing about
30 cps. Line printers are fastest (up to 3,000 lines per
minute). Dot-matrix printers can print up to 500 cps, and
laser printers range from about 4 to 20 text pages per
minute.

•impact or non-impact: Impact printers include all printers
that work by striking an ink ribbon. Daisy-wheel, dot-matrix,
and line printers are impact printers. Non-impact printers
include laser printers and ink-jet printers. The important
difference between impact and non-impact printers is that
impact printers are much noisier.
•graphics: Some printers (daisy-wheel and line printers) can
print only text. Other printers can print both text and graphics.
•fonts : Some printers, notably dot-matrix printers, are limited
to one or a few fonts. In contrast, laser and ink-jet printers are
capable of printing an almost unlimited variety of fonts. Daisy-
wheel printers can also print different fonts, but you need to
change the daisy wheel, making it difficult to mix fonts in the
same document.
Compare with non-impact printer and
impact printer (contd…)

A plotter is an output device that is used to create
high quality graphics, visuals, charts, graphs,
tables or diagrams.
Plotters use ink pens or jets of ink to draw
graphics or drawings. Pen plotters may be
designed to hold one or several different
colored pens. Drawings can be prepared on
paper or polyester film. Plotters are slow
devices, but the graphics produced by
plotters are uniform and of very good
quality.
PLOTTER

Plotter
• Large printers
specialized to produce
high-quality graphics
• Large-format printer
creates photo-realistic
quality
color prints
• Print signs, posters and
other professional
quality displays 177VIVEK SINHA (HOD CSE)
PLOTTER
11/16/17

Plotters are of the following four types:
1. Drum plotters
2. Micrographic plotters
3. Flatbed plotters
4. Inkjet plotters
PLOTTER

Drum Plotters
A drum plotter contains a long cylinder and a pen
carriage. The output paper is placed over the drum.
The drum rotates under the control of plotting
instructions sent by the computer either in the
clockwise or in the anti-clockwise direction. The pen is
mounted horizontally on the carriage. It moves
horizontally along with the carriage left to right, or
right to left, on the paper to produce drawings. The
drum and the pen both function under a computer’s
control.

Micrographic Plotters
A micrographic plotter does not use a
drum. The paper, or any other medium, is
held on both sides at the edges by pinch
wheels which help move the paper back
and forth.

Flatbed Plotters
A flatbed plotter a pen plotter consists of a
stationary horizontal flat surface on which paper or
any other medium is fixed. The pen or pens are
mounted on a carriage which can move along the
horizontal and vertical axis. The size of the plot is
limited only by the size of the plotter’s bed.

The inkjet plotter uses jets of ink in place of
ink pens. The paper is placed on a drum and
inkjets with different colored inks are
mounted on a carriage. These are capable of
producing multicolored, large drawings.
Inkjet Plotters

Choosing a Printer
• Speed:
– Pages per minute (ppm)
– Inkjets print 6-12 ppm
– Lasers print 20-30 ppm
• Resolution:
– Image clarity
– Dots per inch (dpi)
– 300 dpi for general
printing
– 1200 dpi for printing
photos
• Color output:
– Quality of color images
– Inkjets use 4 or 6 color
cartridges
– Lasers use separate
color toner cartridges
• Memory:
– Inkjets need 4-8 MB
– Lasers need 16 MB
• Cost:
– Inkjets are inexpensive
– Lasers are more
expensive 183VIVEK SINHA (HOD CSE)11/16/17

What is storage?
Saving the data or output so
that it can be used again later

What are storage devices ?
Hard Drive
Floppy Disk Drive
Zip Drive
CD / DVD
Drive
Jazz
Drive
Tape
Drive
Micro Drive

Two Types of Storage
• Secondary storage
long-term storage
• Primary storage or memory
temporary storage

• It is needed because
– Main memory stores data temporarily
– Main memory space is limited
Secondary Storage
 Benefits of secondary storage
 Space
 Reliability
 Convenience
 Economic

Secondary Storage Devices
• Secondary memory is also known as auxiliary
memory.
• The magnetic memory is used as secondary
memory.
Some important features of secondary storage
devices are:
• Permanent
• Voluminous Storage:
• Cheaper
• Computing Capability
• Portable

VIVEK SINHA (HOD
CSE)
189
Cost v.s. Speed
11/16/17

VIVEK SINHA (HOD
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190
Direct Access Devices vs. Sequential Access
Analogy:
• Record/CD vs. Cassette Tape
11/16/17

VIVEK SINHA (HOD
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191
Sequential Access Devices
Sequential Access = In order to access specific information, the
device must sequentially pass through all preceding information
• 9 Track Tape (Reel to Reel)
• Cartridge Tapes
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VIVEK SINHA (HOD
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Reel to Reel Tape (9 Track
Tape)
11/16/17

VIVEK SINHA (HOD
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Using a Cartridge Tape Drive
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Storing Data on Tape
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VIVEK SINHA (HOD
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Recording information
• Bits are recorded as positive and negative polarity on
magnetic tape (“magnetic media”)
Advantages
• inexpensive
• durable
• portable
Disadvantages
• slow access rate
Primary Use
Backing up “on-line” information
Storing Data on Tape
11/16/17

VIVEK SINHA (HOD
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Direct Access Devices
Direct Access = The specific information is accessed directly
Examples
• floppy disk drives
• hard disk drives
• cartridge disk drives
• CD ROM and DVD drives
11/16/17

Magnetic disk
• It is just like a gramaphone record.
• It is usually made up of plastic like material called mylar
which is coated with ferromagnetic material.
• The magnetic are classified into
Drive with Fixed Head
Drives with moving Head.

Floppy Disk
• It is small, flexible, faster and cheap alternative to
store data by using magnetic tape.
• It is made up of a very thin plastic plate coated with
magnetic material like iron-oxide.
• In floppy disk, data is recorded in the form of minute
invisible magnetic spot.
• Disk capacity depends on recording density.
Recording density means the no of bits written per
inch.
• The floppy disk has to be divided in to tracks and
sectors.

Secondary Storage Device
Floppy Disk (FDD)

VIVEK SINHA (HOD
CSE)
200
Floppy Disks
Floppy Disk = iron oxide coating on a portable mylar plastic disk
Becoming obsolete
Old 5 1/4 inch diskettes (FYI)
• double density = 360K capacity
• high density = 1.2 MB capacity
11/16/17

VIVEK SINHA (HOD
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Newer 3 1/2 inch diskettes
• double density = 720K capacity
• high density = 1.4 MB capacity
(Right drive for the right densities)
Advantages of 3 1/2 inch
• size, capacity, speed, durability
Notch with slide = write protection
• closed = Read/Write
• open = Read Only
Floppy Disks
11/16/17

VIVEK SINHA (HOD
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• Bits are recorded as positive and
negative polarity on magnetic tape
(“magnetic media”)
Recording information
11/16/17

VIVEK SINHA (HOD
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203
• temperature
• magnets
• touch, smoke, dirt
• folding, bending, pressure
Magnetic Media is sensitive
to:
11/16/17

Some of the floppy disk that are
commonly used:
• 3.5 inches floppy disk
• 5.25 inches floppy disk

3.5 inch floppy disk
1.Write-protect tab
2. Hub
3. Shutter
4. Plastic housing
5. Paper ring
6. Magnetic disk
7. Disk sector

VIVEK SINHA (HOD CSE) 3-206
Input Devices
• Magnetic Technology
– Two parts to most of the magnetic forms of
information storage:
• The medium that stores the magnetic information.
– Example: Floppy disk. Tiny spots on the disk are
magnetized to represent 0s and 1s.
• The device that can “read” that information from
the medium.
– The drive spins the disk.
– It has a magnetic sensing arm that moves over the disk.
– Performs nondestructive reading.
11/16/17

207
Floppy Disks
A floppy disk is a portable, inexpensive storage medium that
consists of a thin, circular, flexible plastic disk with a
magnetic coating enclosed in a square-shaped plastic shell.
11/16/17 VIVEK SINHA (HOD CSE)

208
Structure Of Floppy Disks
• Initially Floppy disks were 8-inches wide, they then
shrank to 5.25 inches, and today the most widely
used folly disks are 3.5 inches wide and can typically
store 1.44 megabytes of data.
• A folly disk is a magnetic disk, which means that it
used magnetic patterns to store data.
• Data in floppy disks can be read from and written to.
• Formatting is the process of preparing a disk for
reading and writing.
• A track is a narrow recording band that forms a full
circle on the surface of the disk.

209
• The disk’s storage locations are divided into pie-
shaped sections called sectors.
• A sectors is capable of holding 512 bytes of data.
• A typical floppy stores data on both sides and has 80
tracks on each side with 18 sectors per track.

Hard Disk
• A hard disk drive is also known as hard disk, hard
drive, or the now-near-obsolete terms fixed disk,
fixed drive, fixed disk drive, hard file.
• It is a non-volatile, digitally encoded data storage
device that stores data on the magnetic surfaces of
hard disk platters.
• It contain more than one disk or platters that is
packed together.

VIVEK SINHA (HOD
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Hard Disk Drives
Hard Disk = Iron oxide coating on one or
more rigid aluminum disks called
platters
11/16/17

VIVEK SINHA (HOD
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Common Sizes
Older Disks
• 5 MB, 10 MB, 20 MB,
etc.
Newer Disks
• 50 GB and more!
• Smaller, cheaper and
faster!
Advantages of Hard
Hard Disk Drives
11/16/17

VIVEK SINHA (HOD
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How data is stored on disks
Hotel analogy
• What is in charge of storing information
on the hard disk drive (and other storage
devices)?
• The operating system software!
11/16/17

Hard Disk
•
surface 0
surface 1
surface 2
surface 3
surface 4
surface 5
cylinder k
spindle
platter 0
platter 1
platter 2

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track = a series of concentric rings on the
disk
• A track is divided into several sectors
(track) sector =a section of a track which
stores a predetermined number of bytes
(bits)
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Several sectors are combined to create clusters or blocks
cluster (Windows and Macs) or block (UNIX) = The number of
sectors which is allocated on the disk each time a file needs
space on the disk.
Windows 95 (later versions) and Windows 98 using FAT32
• 1 cluster = 8 sectors (4K bytes)
• Recognizes disk drives up to 2 terabytes (2 trillion bytes)
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FAT (File Allocation Table) and Directory = A file, a table, which is
found on one of the first sectors of every diskette and hard disk drive
(created when the disk is formatted), and contains information
regarding every file stored on that disk including the file name, the
date and time that file was created or modified, the size of the file, and
which sectors are allocated for that file.
Example
Creating a new file
and saving an
existing file to disk
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Fragmentation and
Defragmenting
11/16/17

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How data is physically stored
on the disk
Read/Write Heads = Part of disk drive
which skims the disk (ten millionths of
an inch) in order to retrieve or store
information.
Disk Crash or Head Crash = When the
R/W head touches the disk.
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Formatting a disk
Q: Why do we format a disk and
what actually does it?
A: We format a disk so it can be
used by the operating system
software. The operating system
software does the formatting of
the disk.
Q: How does the operating system
do it?
A: There is a operating system
software file (program) which
does the formatting. (CPU/RAM)
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What does formatting a disk do?
1. Erases all of the information on the disk
2. Prepares disk to be used by the
operating system software.
• divides tracks into sectors
• determines cluster size
• creates a file allocation table (FAT) or
similar table on other operating systems
3. Optional: Copies operating system files
to this disk in order to make this a “boot
Formatting a disk
11/16/17

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How Data is Removed from Floppy disks and Hard disks
Who's in charge of deleting files?
Deleting a file:
Unerasing a file
11/16/17

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Recovering Data
• Norton Utilities™
– Optimizes and
defragments files for
faster hard drive
performance.
– Detects and fixes
many Windows®
and disk problems
automatically.
– Can monitor your PC
continuously to spot
problems before11/16/17

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Optical Disks - CD ROMs
Recording bits of data
• Data is permanently recorded by a laser
beam on a disk
• WORM = Write Once Read Many
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Pit = On
No Pit (Land) = Off
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Advantages of CD ROM over magnetic
disks
• capacity and durability
Disadvantage
• WORM
Read Only Drives and Read/Write CD
ROM Drives
11/16/17

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What are CD ROMs good
for?
• graphics, videos,
games, software,
(backups)
Speed of CD ROM Drives
• 4x, 6x, 8x, 10x, etc.
• larger the number,
faster the transfer
speed from the CD
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http://www.computerhope.com/help/cdrom.htm
• OTHER CD TECHNOLOGIES
• CD-R - (CD Recordable) Drive which you are able to write to once.
Once the drive is written to it cannot be erased.
CD-RW - (CD ReWritable) drive which is a popular alternative to the
CD-R drive. CD-RW has the capability of being written to at least
one thousand times. The drawback with CD-RW diskettes is with the
lower reflectivity of the disc itself can limit the readability. Many CD-
ROM and CD-R drives may have a difficult time reading these disks.
DVD - (Digital Versatile Disc) New standard released in 1995 which
originally was called Digital Video Disc was later changed to Digital
Versatile Disc. DVD offers an initial storage capacity of 4.7GB (of
digital information on a single-sided, single-layer disc the same
diameter and thickness of a current CD-ROM.
DVD-RAM - ReWritable drive type that uses a phase-change
technology like the CD-RW drives. However , DVD-RAM discs
cannot be read by standard DVD-ROM drives because of the
differences in both reflectivity of the medium and the data format.
11/16/17

Input Devices
• Optical
– Uses lasers to “read” the binary information
from the medium, usually a disc.
• Millions of tiny holes are “burned” into the surface
of the disc.
• The holes are interpreted as 1s. The absence of
holes are interpreted as 0s.
11/16/17

Output Devices
• Optical Disks: CD-ROM and DVD
– CD-ROM (Compact Disk - Read Only
Memory)
• By its definition, CD-ROM is Read Only.
• Special CD drives “burn” information into blank
CDs.
– Burn: A laser is used to “burn” craters into the surface to
represent a binary 1.
– Two main types of CDs:
» CD-R (Compact Disk - Recordable)
» CD-WR (Compact Disk - ReWritable)
• It takes longer to write to a CD-R than a hard drive.11/16/17

CD drive
• CD-ROM (Compact Disc Read-Only Memory) is a
compact disc that contains data accessible by a computer.
• While the compact disc format was originally designed for
music storage and playback, the format was later adapted to
hold any form of binary data.
• CD-ROMs are popularly used to distribute computer
software, including games and multimedia applications,
though any data can be stored (up to the capacity limit of a
disc).
• Some CDs hold both computer data and audio with the
latter capable of being played on a CD player, whilst data
(such as software or digital video) is only usable on a
computer. These are called Enhanced CDs.
• CD-ROM discs are identical in appearance to audio CDs,
and data is stored and retrieved in a very similar manner
(only differing from audio CDs in the standards used to
store the data).

CD drive
• Discs are made from a 1.2 mm thick disc of polycarbonate
plastic, with a thin layer of aluminium to make a reflective
surface.
• The most common size of CD-ROM disc is 120 mm in
diameter, though the smaller Mini CD standard with an
80 mm diameter, as well as numerous non-standard sizes
and shapes (e.g. business card-sized media) are also
available.
• Data is stored on the disc as a series of microscopic
indentations ("pits", with the gaps between them referred to
as "lands").

• A laser is shone onto the reflective surface of the disc
to read the pattern of pits and lands.
• Because the depth of the pits is approximately one-
quarter to one-sixth of the wavelength of the laser
light used to read the disc, the reflected beam's phase
is shifted in relation to the incoming beam, causing
destructive interference and reducing the reflected
beam's intensity.
• This pattern of changing intensity of the reflected
beam is converted into binary data.

CD drive
Standards
• There are several formats used for data stored on compact
discs, known collectively as the Rainbow Books.
• These include the original Red Book standards for CD
audio, White Book and Yellow Book CD-ROM. ISO 9660
defines the standard file system of a CD-ROM, although it
is due to be replaced by ISO 13490.
• UDF format is used on user-writable CD-R and CD-RW
discs that are intended to be extended or overwritten.
• The bootable CD specification, to make a CD emulate a
hard disk or floppy, is called El Torito.

DVD
• It is an optical disc storage media format that can be used
for data storage, including movies with high video and
sound quality.
• DVDs resemble compact discs as their physical dimensions
are the same (120 mm (4.72 inches) or occasionally 80 mm
(3.15 inches) in diameter) but they are encoded in a
different format and at a much higher density.
• It is able to hold about 15 times more information and
transfer it to the computer about 20 times faster from CD-
ROM.DVD comes in some format:

Output Devices
• DVD (Digital Versatile Disk)
– Allows up to 17 gigabytes of storage (from 4.7
GB to 17 GB).
– Compatible with older CD-ROM technology.
– The four versions of the DVD:
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• Over 2 hours of high-quality digital video (over 8 on a double-sided, dual-
layer disc).
• Support for widescreen movies and standard or widescreen TVs (4:3 and
16:9 aspect ratios).
• Up to 8 tracks of digital audio (for multiple languages), each with up to 8
channels.
• Up to 32 subtitle/karaoke tracks.
• Multilingual identifying text for title name, album name, song name, actors,
etc.
• Automatic "seamless" branching of video (for multiple story lines or ratings
on one disc).
• Up to 9 camera angles (different viewpoints can be selected during
playback).
• Menus and simple interactive features (for games, quizzes, etc.).
• "Instant" rewind and fast forward, including search to title, chapter, track,
and timecode.
• Durability (no wear from playing, only from physical damage).
• Not susceptible to magnetic fields. Resistant to heat.
• Compact size (easy to handle and store, players can be portable).
What are the features of DVD-
Video?
11/16/17

• DVD-Video : DVD-Video discs require a DVD-drive
and an MPEG-2 decoder e.g. a DVD-player, or a DVD
computer drive with a software DVD player. It is mostly
used for entertainment like seeing movies etc. The
specifications for video files on a DVD can be any of the
following:
• Up to 9.8 Mbit/s (9800 kbit/s) MPEG-2 video
• Up to 1.856 Mbit/s (1856 kbit/s) MPEG-1 video
• DVD-ROM: The abbreviation stands for DVD-Read
only memory format. It is mostly used in computer to
store data. Through this we are able to play games as
well as able to see certain movies.
• DVD-R: It is a recordable DVD. The user can write data
once and abe to read the da the data as many times as
desired.

Moving Information
Within the Computer
• How do binary numerals move into, out of,
and within the computer?
– Information is moved about in bytes, or
multiple bytes called words.
• Words are the fundamental units of information.
• The number of bits per word may vary per
computer.
• A word length for most large IBM computers is 32
bits:
11/16/17

Moving Information
Within the Computer
• Bits that compose a word
are passed in parallel from
place to place.
– Ribbon cables:
• Consist of several
wires, molded
together.
• One wire for each bit
of the word or byte.
• Additional wires
coordinate the activity
of moving
information.
• Each wire sends
information in the
form of a voltage
11/16/17

Moving Information
Within the Computer
• Example of sending
the word WOW over
the ribbon cable
– Voltage
pulses
correspondi
ng to the
ASCII
codes
would pass
through the
cable.
11/16/17

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Disk Cartridges
Disk Cartridges = portable disks which
store almost as much information and is
almost as fast as a hard disk drive
Uses
• same as floppy or tape
Examples:
Iomega Zip Drive = 100 MB
Iomega Jaz Drive = 1 GB
11/16/17

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Flash Drives
• Capacity
– 64 MB
– 128 MB
– 256 MB
– 512 MB
– 1 GB
– And more
• $35 to $175
11/16/17

Packaging the Computer
• The many physical forms of the
general purpose computer:
– All follow general
organization:
• Primary memory
• Input units
• Output units
• Central Processing
Unit
– Grouped according
to speed, cost, size,
Super Computers
Mainframe Computers
Minicomputers
Microcomputer
Palmtop Computer
Calculator
Fast Expensive Complex Large
Slow Cheap Simple Small
11/16/17

Software Tools for Maintaining
Your Computer Hardware
• Utility Programs exist that can help diagnose and solve computer
hardware problems.
– Four major problem areas where utility
programs are helpful:
• Finding and fixing problems.
– Testing Input/Output peripherals.
– Testing RAM, motherboard, video cards.
– Recovering deleted files or fixing damaged disks.
• Improving computer performance.
– De-fragmenting a disk (Packs all files closer together).
• Preventative maintenance.
• Troubleshooting.
– Locates incompatible programs.11/16/17

Graphical Display Devices
• CRT
Graphical Input Devices
Keyboard
Mouse
Joystick
Trackball
Digitizer

Three Dimensional Input Devices
• Accoustic devices: It consist of accoustic
tablet. To measure the styulus position in
3 dimension.we can use 3 microphones
aligned with the axes.
• The perpendicular distances of the stylus
from these microphones can be
determined from 3 arrival times and from
these 3 distances the stylus coordinate
can be computed.

• Mechanical Devices: Three dimensional
coordinate input can also be achieved with
the aid of mechanical linkage of various
kinds.
• The simplest of these uses wires
strectching from spring loaded reels
mounted at fixed position.

Video Cards
• CGA
• MGA
• EGA
• VGA
• SVGA

Key Monitor Features
• Screens are grids made up of millions of
pixels.
• LCDs: Liquid Crystal Display
• Used for notebook computers, PDAs, cellular
phones, and personal computers
• Resolution
Increasing resolution allows more
to be displayed
• Size:
17, 19, 21, 30 inch 250VIVEK SINHA (HOD CSE)11/16/17

Dot-matrix
Printers
Inkjet
Multifunction
Laser
Plotter
Thermal printer
• Impact printers
– Dot-matrix
• Nonimpact printers
– Inkjet
– Laser
• Multifunction
• Specialty printers
– Plotters
– Thermal printers Multi copy formsinvoices

Choosing a Printer
• Speed:
– Pages per minute (ppm)
– Inkjets print 6-12 ppm
– Lasers print 20-30 ppm
• Resolution:
– Image clarity
– Dots per inch (dpi)
– 300 dpi for general
printing
– 1200 dpi for printing
photos
• Color output:
– Quality of color images
– Inkjets use 4 or 6 color
cartridges
– Lasers use separate
color toner cartridges
• Memory:
– Inkjets need 4-8 MB
– Lasers need 16 MB
• Cost:
– Inkjets are inexpensive
– Lasers are more
expensive 252VIVEK SINHA (HOD CSE)11/16/17

AUDIO OUTPUT
• Component of a computer – produces music, speech and
other sound
 Speaker
 Headphones
 Earphones

Outputting Sound
• Speakers and headphones
• Inexpensive speakers
• Sophisticated sound system
– Surround sound
– Subwoofer

Speaker
• Speaker is one of the output devices which is mainly used for
entertainment, video conferencing etc.Computer speakers, or
multimedia speakers, are external speakers and are usually
equipped with a male-end stereo jack plug.
• The sound capability of the computer system does not work
unless and unti there is a sound card. Speaker recieves the data
from the sound card in the form of electric signal and then
convert it in to the sound format.

Audio-Visual (Multimedia) Input
Devices
• Microphones and Speech Recognition
Software
• Video Input
• Digital Cameras

Audio-Visual (Multimedia) Input Devices -
Microphones and Speech Recognition
• Microphones can accept auditory input. A
microphone requires a sound card in the PC.
• A sound card can digitize analog sound signals, and
convert digital sound signals to analog form.
• With speech recognition software, you can use your
microphone to dictate text, navigate programs, and
choose commands.

Digital Audio Output
[electrical signals]
(ex. 11100011) to
computer
Analog Sound Signals
Analog Signals are Digitized

Audio-Visual (Multimedia) Input Devices –
Video Input
• PC video cameras digitize full-motion images.
• Digital cameras capture still images.
• These cameras break images into pixels and store
data about each pixel.
• Video images may be compressed to use less memory
and storage space.

The Front Panel
• Power control
• Drive bays
• Memory card reader
• Productivity ports

The Back
• Ports for peripheral
devices
• Types of ports:
– Serial
– Parallel
– VGA
– USB
– Connectivity
DVI
Speaker
M
icrophone
PS/2,
M
ouse
K
eyboard
Serial
VG
A
Netw
or
k
FireW
ire
Parallel
U
SBS-Video

Types of Ports
• Universal Serial Bus
(USB)
– Transfer speed up to 480
Mbps
– hot swapping
• FireWire
– Transfer rate of 400 Mbps
USB Port USB Connector
FireWire Port FireWire Connector

Types of Ports
• Ethernet
– Fast Ethernet: Transfer rate
of 1Gbps
– Connects computers to
networks
Ethernet jackEthernet Port

Types of Ports
• Parallel
– Transfers eight bits of data
simultaneously (printer)
– Max speed: 12 Mbps
• Serial port (legacy)
– Transfers data one bit at a
time
– Max speed: 56Kbps

Types of Ports
• Bluetooth
– Transfer rate of 1 Mbps to 3 Mbps
– Radio waves send data over short distances
• HDMI
– HDMI connects digital audio/video sources
• set-top boxes
• Blu-ray Disc players
• PCs
• video game consoles
• AV receivers to compatible digital audio devices
• video monitors
• digital televisions (DTV).

Adding Ports
• Expansion cards:
– New port standards
• Expansion hubs:
– Enable several devices to
be connected to a port

Inside the System Unit
• Essential electronic components used to
process data
• Types of components:
– Power supply
– Motherboard
– CPU
– Hard disk drive
– Memory (RAM/ROM)
– Expansion cards

The Motherboard
Click on the motherboard components for
details
Click on expansion cards last

Memory Module
• Random access memory (RAM)
• Primary storage
• Stores instructions and data
• Temporary (volatile) storage
• Operates in nanoseconds

Central Processing Unit (CPU)
• Referred to as the “brains” of the computer
• Controls all functions of the computer
• Processes all commands and instructions
• Can perform billions of tasks per second

Expansion Slots & Expansion
Cards
• Expansion Slots provide connections for expansion cards
• Expansion Cards
– augment the computer’s basic functions
– provide connections for peripheral devices
– Common types: Sound, Video, and Network (NIC)

Bits and Bytes: The Language of Computers
• Bit
– Binary digit
– 0 or 1
• Byte
– Eight bits
– Represent letters, numbers, and special
characters
OFF
0
ON
1
Microchip
Switch
10 0 001 1
= 4
0 0 0 0 01 1
= A
0
0

How Much is a Byte?
NAME SYMBOL NUMBER OF BYTES RELATIVE SIZE
Byte B 1 byte Can hold one character of data.
Kilobyte KB 1,024 bytes Can hold 1,024 characters or about half of a
typewritten page double-spaced.
Megabyte MB 1,048,576 bytes A floppy disk holds approximately 1.4 MB of data,
or approximately 768 pages of typed text.
Gigabyte GB 1,073,741,824 bytes Approximately 786,432 pages of text. Since 500
sheets of paper is approximately 2 inches, this
represents a stack of paper 262 feet high.
Terabyte TB 1,099,511,627,776 bytes This represents a stack of typewritten pages almost
51 miles high.
Petabyte PB 1,125,899,906,842,624
bytes
The stack of pages is now 52,000 miles high, or
about one-fourth the distance from the Earth to the
moon.

Storage Devices
• Enable us to store data or information to
be accessed again
Hard Disk Drive CD / DVD Drive
Floppy Disk Drive
Flash Drive

Hard Disk Drive
• Stores data and program instructions
• Permanent (nonvolatile) storage
• Storage capacities up to 750 GB – 1.5 TB
• Transfers data in milliseconds
Solid State Hard Disk Drive 278VIVEK SINHA (HOD CSE)11/16/17

CDs and DVDs
• Optical media: Store data as tiny pits
burned into a disk by a laser
 CD or DVD Readers or Writers
• Disk Types
– CD-ROM, DVD-ROM –read only
– CD-R, DVD-R—write only once
– CD-RW, DVD-RW—write multiple times
• Blu-ray disk (BD) —HD

Storage Media Capabilities

Flash Drives/Flash Memory
• Flash drives (jump drives)
– Newer storage alternative
– Plug into USB ports
• Flash memory cards
– Slide into slots in the system

What To Buy
• Intel® Core™2 Duo Processor
• 2 GHz CPU speed
• 2 GB RAM (needed for Vista)
• Hard Drive minimum 300 GB
• Flat Panel Display 17”
• DVD R/RW (Also does CD’s)
• Video 256 MB, HDMI
• Keyboard
• Wireless or optical mouse
• Printer, ink jet

Setting it all up: Ergonomics
• Ergonomics refers to minimizing injury or
discomfort while using the computer
• Steps to follow:
– Position monitor correctly
– Use adjustable chair
– Assume proper position while typing
– Take breaks
– Ensure adequate lighting

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