Input computer hardware notes for UCEand UACE ICT

O level Computer Studies Topic Two: Computer Hardware
© Jinja College Computer Studies Department, 2011
840 COMPUTER STUDIES TOPIC 2:
COMPUTER HARDWARE
COMPUTER STUDIES DEPARTMENT
JINJA COLLEGE
04/21/13 1

TOPIC TWO:
Computer Hardware
Topic Summary
Unit One: Input Devices
Unit Two: Processing Devices
Unit Three: Storage Devices
Unit Four: Output Devices

3

TOPIC 2: COMPUTER HARDWARE
Unit One: Input Devices
COMPUTER STUDIES DEPARTMENT
JINJA COLLEGE
4

Unit Introduction
 Input devices are
used to enter data
or commands in a
form that the
computer can
use.
 They send the
data or
commands to the
processing unit.
 According to the type of data they
input, they can be grouped into the
following :
a) Text input devices
b)Pointing input Devices
c) Imaging input Devices
d)Gaming input Devices
e) Audio input Devices
f) Biometric input Devices and
g)Other Specialized input devices
5

a) Text input devices
 Text is a general word for
all characters such as
letters, numerical digits,
symbols and marks that
combine to form words,
sentences, paragraphs
and so on.
 There is a variety of
devices that help us to
input text into a computer.
Text input devices include:
1. The keyboard,
2. Voice Recognition
Equipment
3. OMR and Barcode readers
4. OCR and Optical readers
5. MICR readers
6. RFID readers
7. Magnetic Strip Card
Readers, etc.
04/21/13 6

1. The Keyboard
 Definition: A keyboard is an input
device, consisting of a set of keys
(buttons) used to operate a
computer. Each press of a key
corresponds to a single written
character of text, but to produce
some symbols, it requires
pressing and holding several
keys simultaneously.
 Usually a standard keyboard has
between 80 to 110 keys.
 A keyboard is the main and most
reliable computer input device
 The QWERTY is referred to as the
"Universal" keyboard.
 The name "QWERTY" comes from
the first six letters in the top
alphabet row (the one just below
the numbers).
 There are other setups also
available such as Dvorak, ABCDE,
GKOS, QWERTZ and AZERTY
 Keypads, Keyers and chorded
keyboards have fewer keys,
specially designed for devices
such a pocket sized computers.
04/21/13 7

The Keyboard (cont)
 Christopher Latham
Sholes was an
American newspaper
publisher
 In 1866, he invented
the first practical
typewriter and the
QWERTY keyboard
still in use today.
04/21/13 8
The
Sholes
typewrit
er.
(1866)

The Keyboard (cont)
Advantages of Keyboard
 Keyboards are very
common (commonly
supplied with computers)
 Entering data and
commands with keyboard
is faster as compared to
the mouse
 Keyboards are more
reliable
Demerits of Keyboard
 It takes a lot of time to
practice in order to type
quickly
 Keys can easily become
faulty due to dust.
 Some keyboards keys
are very hard to press,
causing fingers to hurt.
04/21/13 9

Equipment
 Voice Recognition
Equipment (a.k.a Speech
recognition ) converts
spoken words to text.
 Computers with Speech
recognition do not actually
understand speech, but
they are programmed to
recognize a vocabulary of
words, which can range
from two words to millions
of words.
 Advantages
 No typing of data is
necessary.
 Voice recognition can be
used by people whose
hands are disabled.
 Dictating text is faster than
typing.
 Voice Recognition systems
are also ideal for the blind .
04/21/13 10

04/21/13 11
HOW SPEECH RECOGNITION WORKS

Equipment (cont)
 Demerits of text input by speech Recognition
 Error rate is high, depending on user’s accent.
 Words with the same pronunciations (Homophones)
like see and sea can not be distinguished
 Speech Recognition does cant work in noisy
environment
 The Voice Recognition software must be trained to
recognize more words.
 It requires the user to speak in a writing style, i.e.
even pronouncing the marks such as comma.
04/21/13
12

3. Optical mark recognition
(OMR)
 Optical mark recognition (OMR) devices read hand-
drawn marks such as small circles or rectangles
 A person places these marks on a form, such as a
test, survey, or questionnaire answer sheet.
 The OMR device first reads a master document, such
as an answer key sheet for a test, to record correct
answers based on patterns of light;
 the remaining documents then are passed through
the OMR device and their patterns of light are
matched against the master document.
13

3. OMR and Barcode readers
14
OMR test form, with registration
marks and drop-out colors,
designed to be scanned by
dedicated OMR device

Barcode readers
 A bar code reader, is an optical reader that uses
laser beams to read bar codes that are printed
on items usually in super markets.
 A bar code is an identification code that
normally consists of a set of vertical lines and
spaces of different widths.
 The bar code represents some data that
identifies the item and the manufacturer.
15

Barcode readers
16

Optical character
recognition (OCR)
 Optical character recognition (OCR) is a
technology that involves reading typewritten,
computer-printed, or handwritten characters
from ordinary documents and translating the
images into a form that the computer can
understand.
 OCR devices include a small optical scanner for
reading characters and sophisticated software
(OCR software) for analyzing what is read.
17

Optical
character
recognition
(OCR)
18

5. MICR readers
 A magnetic-ink character recognition (MICR)
reader is used to read text printed with
magnetized ink.
 MICR readers are mainly used by the banking
industry for processing checks
 Each check is inserted into an MICR reader,
which sends the check information to a
computer for processing.
19

5. MICR readers
20

6. RFID readers
 Radio-frequency identification (RFID) is a
technology that uses radio waves to transfer
data from an electronic tag, attached to an
object, through a reader for the purpose of
identifying and tracking the object.
 RFID can work over a long distance.
 An RFID tag can be affixed to cars, computer
equipment, books, mobile phones, etc
21

Readers
 A magnetic stripe card reader reads the
magnetic stripe on the back of credit cards,
bank ATM cards, and other similar cards.
 Exposure to a magnet or magnetic field can
erase the information and contents of a card's
magnetic stripe.
22

Readers
23

b) Pointing Devices
 A pointing device is an input
device, which allows users to
move a pointer and make
selections on the computer
screen.
 A pointing device is any piece
of hardware that is used to
input spatial data into a
computer.
 There are many examples of
pointing devices such as:
1. Mouse
2. Stylus pen & digitizing
tablet
3. Cordless Mouse
4. Trackball
5. Touchpad
6. Light pen
7. Touch Screen
8. A Track Point
 Etc.
04/21/13
24

1. The Mouse
 Mouse - The mouse is a hand held device that
lets you point to and make selections of items
on your screen.
 In a PC mouse there are mostly 2-3 buttons.
 A ball under the mouse senses movement.
 An optical mouse uses a light-emitting diode
and photodiodes to detect movement relative to
the underlying surface.
04/21/13
25

2. Stylus pen & digitizing
tablet
 Stylus pen- The pen lets you draw on what is
called a digitizing tablet that mirrors the surface
area of the computer screen.
 The pen can be used as a standard mouse
(without wires connected to it) or also as a free
flowing drawing device.
 The pen is useful for drawing since drawing
graphics with a mouse tends to be somewhat
difficult.
26

Stylus pen & digitizing
tablet (illustration)
27

3. Cordless Mouse
 Cordless Mouse - The cordless mouse is a lot
better than a normal mouse. It reduces the
amount of work space needed to move the
mouse around.
 This mouse runs on a battery. When you move
the mouse it sends an infrared beam to a
sensor which interprets it causing the pointer
to move.
04/21/13
28

Cordless Mouse
04/21/13 29

4. Trackball
 Trackball - The trackball is an upside-down
mouse that remains stationary on your desk. It
is the same principle as the mouse except that
the rollers are reversed and the ball is on top.
This ball does not need as much attention as
the normal mouse because the only thing that
touches it is your hand as the normal mouse
touches a surface.
04/21/13
30

Trackball
04/21/13 31

5. Touchpad
 Touchpad - The touchpad has sensors that
sense your touch. When they sense your touch
they send a signal to the computer to move the
mouse pointer to that location on the screen.
Common on laptop computers
32

Touch Pad (Illustration)

7. Light pen
 Light pen- is a form of a light-sensitive wand
used in conjunction with a computer's CRT TV
set or monitor. It allows the user to point to
displayed objects, or draw on the screen, in a
similar way to a touch screen but with greater
positional accuracy. A light pen can work with
any CRT-based display, but not with LCD
screens, projectors and other display devices
04/21/13
34

Light pen
(Illustration)
35

8. Touch Screens
 A touch screen is a touch-sensitive input and display device.
Users can interact with these devices by touching areas of the
screen.
 You touch words, pictures, numbers, letter, pointers or special
locations identified on the screen.
 With some smart phones, portable media players, and other
personal mobile devices, you can touch the screen to perform
tasks such as dialing telephone numbers, entering text, and
making on-screen selections.
 Kiosks, which are freestanding computers, usually have touch
screens. Many ATMs also have touch screens.
04/21/13
36

Examples of touch Screens
37

9. Track Point
 A Track Point, also called a pointing stick, is a
cursor control device located in the middle of
the keyboard between the G, H, and B keys. The
control buttons are located in front of the
keyboard toward the user. The Track Point is
operated by pushing in the general direction
the user wants the cursor to move. Increasing
pressure causes faster movement.
38

9.Track Point
39

c) Imaging Devices
 Imaging input
Devices are devices
that input images
such as still
photos, motion
pictures, graphics,
video etc. into the
computer for
processing.
Common Imaging devices
include:
1.Image scanner
2.Digital Camera
3.Digital video (DV) camera
4.Camcorder
5.Web cam

1. Image scanner
 A scanner is a light-sensing input
device that converts hardcopy
documents, drawings, or pictures
to an electronic version (softcopy),
which can then be stored on a
disk.
 The electronic version of scanned
material is in the form of rows and
columns of dots called a bitmap
 Each dot on a bitmap consists of
one or more bits of data.
Common types of
scanners
include:
 Flatbed scanner
 Pen or handheld
scanner
 Sheet bed
scanner
 Drum scanner.
04/21/13 41

04/21/13 42
Image scanner ILLUSTRATIONS

Digital Camera
 A digital camera allows users to take pictures
and store the photographed images digitally
instead of storing on a traditional film.
 When you take pictures, the images are
electronically stored in the camera.
 Later, you transfer a copy of the stored pictures
to your computer or printer by connecting a
cable between the digital camera and your
computer.
04/21/13
43

44

Digital video (DV)
camera
 A digital video (DV) camera, by contrast records
video as digital signals instead of analog
signals.
 To transfer recorded images to the computer
hard disk, users connect DV cameras directly
to a port on the system unit.
 After saving the video on a storage medium,
you can play it or edit it and burn it to a DVD
using software programs on the computer.
45

Digital video (DV) camera
(Illustration)

Camcorder
 This is a light weight video camera that records
data in digital form onto a storage device such
as a videotape.
48OPEN CLOSED

Web cam
 A Web cam, also
called a PC video
camera, is a
 type of digital
video camera that
usually sits on top
of the monitor.
Some laptop
computers have
built-in Web cams.
Webcams enable users to:
 capture video and still images,
 send e-mail messages with
video attachments,
 add live images to instant
messages,
 broadcast live images over the
Internet,
 and make video telephone
calls
49

Illustration: Web cams
enable video conferencing
04/21/13 51

Gaming input Devices
 Gaming input
devices are
devices
specifically
designed to
be used for
playing
computer
games.
Examples Include:
1.Gaming keyboard
2.Gaming wheels
3.Joysticks
4.Game pad
5.Light guns
6.Dance pad
7.Motion sensing game
controllers
52

Gaming keyboard
 Gaming keyboards typically include
programmable keys so that gamers can
customize the keyboard to the game being
played.
 The keys on gaming keyboards light up so that
the keys are visible in all lighting conditions.
 Some have small displays that show important
game statistics, such as time to targets
remaining.
53

Gaming Keyboards
(Illustration)

Gaming wheels
 A gaming wheel is a steering wheel-type
input device. Users turn the wheel to
simulate driving a vehicle using programs
on a computer.
 Most gaming wheels also include foot
pedals for acceleration and braking
actions. Gaming wheels include buttons,
called triggers that you press to initiate
certain events.
55

6. Joystick
 Joystick- Consists of a stick that pivots on a
base and reports its angle or direction to the
device it is controlling. Joysticks are often used
to control video games, and usually have one
or more push-buttons whose state can also be
read by the computer.
57

Joystick
58

Gamepad
 A gamepad controls the movement and actions
of players or objects in video games or
computer games.
 On the gamepad, users press buttons with their
thumbs or move sticks in various directions to
trigger events.
 Gamepads communicate with a game console
or a personal computer via wired or wireless
technology.
60

Game pad
(Illustration)

Light guns
 A light gun is used to shoot targets and moving
objects after you pull the trigger on the weapon.
 Instead of emitting light, most light guns work
by detecting light. When the user pulls the
trigger, the screen uses one of several
techniques to send light, which is received by a
receptor in the barrel of the gun.
63

Light Guns
(Illustration)

Dance pad
 A dance pad is a flat electronic device divided
into panels that users press with their feet in
response to instructions from a music video
game.
 These games test the user’s ability to step on
the correct panel at the correct time, following a
pattern that is matching with the beat of a song.
65

Motion sensing game
controllers
 These are devices that allow the user to
guide onscreen elements by moving a
handheld input device in predetermined
directions through the air.
 Examples include the power glove, play
station move gadgets, among others.
67

Motion
Sensing
Game
Controllers

e) Audio input Devices
 Audio input is the process of
entering any sound into the
computer such as speech,
music, and sound effects.
 To enter sound into a computer,
it must have a sound card.
 Audio input devices are plugged
into a port on the sound card.
Examples of audio
input devices
include
 Microphones,
 Tape players,
 CD/DVD players,
 MIDI devices
 Dictaphone,E.t.c
69

Sound Card
 A device that can be slotted into a
computer to allow the use of audio
components for multimedia
applications.
Without a
sound card,
Audio input
and output
is not possible.

Microphones
 A microphone is an
instrument for converting
sound waves into electrical
energy variations, which may
then input into the computer
for processing, recording or
audio playback.
 Microphones are connected
to the sound card in the
system unit.
04/21/13 72

MIDI devices
 MIDI (musical instrument digital interface) is the
standard that defines how digital musical
devices represent sound electronically.
 MIDI devices such as electronic pianos allow
users to record and edit music
 For example, you can set the beat speed, and
add notes, to produce sound.
04/21/13
73

Dictaphone
 This the earliest device
most commonly used to
record speech for later
playback or to be typed
into print.
 It was established by
Alexander Graham Bell
in Washington, D.C. in
1881.
75

Biometric input Devices
 A biometric device
translates a
biological personal
characteristic into
a digital code that
is stored or
compared with a
digital code stored
in the computer.
Common biometric devices
include:
 Fingerprint scanner
 Face Recognition
systems
 Hand geometry systems
 Signature verification
systems
 Iris Recognition systems
77

Fingerprint scanner
 A fingerprint scanner captures curves
and indentations of a fingerprint.
 Some grocery and retail stores now
use fingerprint readers as a means of
payment, where the customer's
fingerprint is linked to a an account or
credit card.
04/21/13
78

Fingerprint scanner
79

Face Recognition systems
 A face recognition system captures a
live face image and compares it with a
stored image to determine if the
person is a legitimate user.
 Some buildings use face recognition
systems to secure access to rooms.
80

Hand geometry system
 Biometric devices measure the shape and
size of a person's hand using a hand
geometry system.
 Some large companies use this system as
time and attendance devices or as security
devices.
 Day-care centers use this system to verify
parents who pick up their children.
81

4. Signature verification
systems
 A signature verification system
recognizes the shape of your
handwritten signature, as well as
measures the pressure exerted and
the motion used to write the
signature.
 Signature verification system uses a
specialized pen and tablet.

Iris recognition system
 These are devices that use iris recognition
technology to read patterns in the iris of the
eye.
 These patterns are as unique as a fingerprint.
 Iris recognition systems are used by
government security organizations, the military,
and financial institutions that deal with highly
sensitive data.
84

85

g) Other Specialized input
devices
 There are many other special input
devices that are used for doing special
customized tasks. Some of them
include:
 Remote Control
 Sensors
 Etc.
86

Remote Control
 Remote control devices emit a beam of infrared
light, which carries data signals.
 Remote control is commonly used with TVs but
many laptop computers being produced come
with remotes and a form of input device, which
allow you to operate the laptop from a distance.
87

Remote Control

Sensors
 Chemical responses to the physical
environment or movement can be converted to
electrical signals by devices known as sensors,
which input them it to the computer for
processing.
 Various sensors can be used to measure heat,
light, pressure, acidity, oxygen concentration,
water flow, etc.
89

END OF UNIT
NEXT UNIT:
PROCESSING HARDWARE
04/21/13 90

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