1.4.2 Input Devices

1.4.2 Input Devices
Input devices are hardware devices that allow data to be entered into a computer.
Input devices are part of the four main hardware components of a computer
system. The Image below shows where input devices fit into a computer system:
There are many different kinds of input devices. They are split into two categories
manual input devices and direct input devices.
Manual Input devices: Data is input into the computer by hand. Manual input
devices require humans to do most of the work needed to get data into the system.
(eg.) Keyboard, Mouse, Tracker ball, Joystick, graphics tablet, digital camera,
Webcam, microphone, touch screen, chip and pin.
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Direct Input devices (automatic input devices): Data is input into the computer
directly by a machine or device. Direct input devices do not require much human
interaction to get their data into a computer system. (eg.) Barcode scanner,
Magnetic stripe reader, OMR reader, OCR reader, biometric scanner, Sensor.
The following section will help summarize each of the input devices. For each one
you will see
Information about the device
Uses of the device
Advantages of the device
Disadvantages of the device
1. Keyboard:
The keyboard is the most common and widely used input device. It is made up of
buttons called 'keys'. The keys are arranged into sections:
Alphabet keys
Function or F keys (F1, F2, F3)
Numeric keys (one set above the alphabet keys and a numeric keypad on the
Arrow keys
Command keys (insert, delete, home, end, page up/down)
Keyboards are used to input Text, numbers and instructions into the computer.
Most keyboards use a QWERTY key layout. This name comes from the first six
letters on the top row of the alphabet keys.
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keyboards” have built-in-hand-rest which
prevents health issues such as RSI (Repetitive
Strain Injury).Ergonomic keyboards have
natural shape to reduce stress on wrist and
A concept keyboard is a specialized keyboard
with no pre-set keys. It relies on a touch
sensitive screen with the key or overlay
displayed on the screen. Each key can be
programmed with a wide range of different
functions. The overlay is often used as a quick
and easy way to input items with without
needing to type anything or use a mouse. If you
go to a fast food restaurant, the assistant will
normally be using a concept keyboard. Pictures
and icons can replace words and means that the assistant can quickly enter the
order without having to use a keyboard.
Numeric keypads are used for entering
numbers into a computer system. Some
numeric keypads allow you to enter simple text
and symbols. Numeric keypads are found in
ATM (Automatic Teller Machines), telephones
and chip and pin device. Electronic point of
sale (EPOS) terminals has numeric keypads in
case the barcode reader fails.
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Uses of keyboard:
• Keyboards are used to enter text, numbers and instructions into applications
like Word and Excel.
• Keyboards can also be used to enter commands(keyboard shortcuts) into the
Advantages of keyboards:
1. Enable fast entry of data.
2. Most computers come with a keyboard supplied
3. People need very little training to use keyboard.
Disadvantages of keyboards:
1. Keyboards are large and can take up a lot of desk space.
2. Keyboards are not suitable for creating diagrams.
3. Excessive use can lead to health problems such as repetitive strain injury
4. Entering data is slow compared to automatic methods. For example a
barcode scanner will input data into the computer almost instantly.
H.W: Function keys provide shortcuts to frequently used commands. Make a
list of function keys and their uses.
2. Mouse:
Mouse enables you to control what happens on
the screen by moving the mouse on your desk and
pointing, clicking and selecting items on the
screen. A mouse is also called a 'Pointing
device'. Pointing devices are used to control
curser and click icons and options on Graphical
User Interface (GUI) operating systems.
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Types of Mouse:
Ball mouse (Mechanical mouse) – uses a ball under the mouse to detect
Optical mouse –uses reflected light to detect movements
Wired and Wireless mice are available in the market.
Wireless mouse do not need a wire plugged into the computer, they are powered by
batteries instead of computers.
Uses of Mouse:
Opening, closing, Maximizing and Minimizing programs and files.
Moving, grouping and deleting files
Controlling a pointer on a screen to select icons or move around the page.
Editing images in terms of size and position on the screen.
Advantages of Mouse:
Ideal for use with desktop computers.
Works well in conjunction with a keyboard for data entry.
It is small in size and do not take up much space.
Faster to select icons and options when compared to a keyboard.
Disadvantages of Mouse:
1. Excessive use can lead to health problems such as repetitive strain injury
2. Older style mouse which has roller balls can become clogged with grease
and grime and lose their accuracy until cleaned.
3. Mouse needs a flat surface in order to work properly.
4. If the battery wears out in a wireless mouse, it cannot be used until it has
been replaced
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3. Tracker ball:
Tracker ball is similar to mouse but the ball is on top of
the device. Screen pointers are controlled by rotating the
large ball with your hand.
Uses of Tracker ball:
1. Tracker balls have the same functions as mouse.
2. They are much more comfortable to use than mouse. This means that people
with painful hand and wrist problems can use a tracker ball.
Advantages of Tracker ball
1. They are more comfortable than mouse because there is less wrist movement
required. They are more ergonomic.
2. More accurate than other pointing devices
3. Can be used even when there is no flat surface available.
Disadvantages of Tracker ball
1. More expensive than mouse.
2. More difficult to learn to use than a mouse.
4. Joystick:
Joysticks have similar functions to that of mouse
and tracker ball to control a pointer on a screen.
Joysticks are also popular devices for gaming.
Uses of Joystick:
1. To control characters or objects in video games.
2. To control industrial machinery such as cranes.
3. They are used in simulators.(eg.) Trainee pilots use joysticks to control the
simulate plane.
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To operate cranes
Flight simulators
Advantages of joystick:
1. They give a better gaming experience for racing or flying styles of computer
2. Easier to control an on screen cursor or move an in-game character.
Disadvantages of joysticks:
1. Difficult to input text with joystick than with keyboard.
2. Not as easy to control an on screen cursor when compared to using a mouse.
3. People with hand/wrist issues can find them painful to use.
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5.Graphics tablet:
Graphics tablet or Graphics pad is a flat
rectangular pad, which can be drawn on with a
special pen called stylus. Whatever is drawn on
to the tablet can be seen on a computer screen.
Anything drawn onto the tablet can be saved as
Uses of Graphics tablet:
A graphic tablet is used mainly for computer aided design and drawing (CAD).
This device allows designers to produce digital images much more accurately than
if they were using a mouse.
Graphics tablets are also often used by graphics designers, illustrators.
Advantages of graphics tablets
1. It is much more natural to draw diagrams with a pencil type implement (the
stylus) rather than with a mouse
2. A great level of accuracy can be achieved
Disadvantages of graphics tablets
1. Not really suitable for general selection work such as pointing and clicking
on menu items
2. Graphics tablets are much more expensive than a mouse
6. Scanners
Scanners can be used to convert images or text on paper into a digital format that
can be used by the computer.
There are three types of scanner:
Flatbed scanners
Handheld scanners
Sheet-fed scanner
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Flatbed scanner: The image is laid flat on the scanner’s surface
and is captured in a similar manner to that of a photocopier.
Hand-held scanner: It reads the image while being
dragged over it.
Sheet-fed scanner: It feeds the image in through rollers. The
scanner reads the image as the paper goes through. The image
must be printed on a flexible sheet of paper.
Uses of Scanner:
1. Used to convert printed images on paper to electronic form.
2. Old photos and important documents can be scanned into the computer. This
means you still have a copy if the original is damaged or lost.
Advantages of scanners
1. Flatbed scanners are very accurate and can produce reasonably high quality
2. Any image which is digitized by the scanner can then be included on
electronic documents.
3. Images once digitized can be enhanced with a graphics application.
Disadvantages of scanners
1. The accuracy of the data input is unlikely to be verified.
2. Images lose some quality in the scanning and digitizing process.
3. The quality of the final image is dependent on the quality of the original
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7. Digital Camera
Digital cameras store digital photographs on a
memory card and these images can easily be
transferred onto a computer for viewing or editing.
Most digital cameras have a built in screen to
allow for previewing the digital photograph. This
is useful so that the photographer can decide
which images to keep and which to delete.
The picture made by a digital camera is formed by a quantity of very small dots of
different colors called pixels or picture element. These are the number of dots that
make up the image. The digital camera image quality is measured in ‘Megapixels’.
The picture quality is related to the density of the dots making the picture, so the
higher the megapixels the higher the quality of the image.
Uses of Digital camera:
1. Used to capture digital images, which can be transferred to a computer for
2. By connecting directly to a photo printer, images can be printed straight
from the camera (no need to upload to a computer).
Advantages of digital camera:
1. Digital images can be improved and edited easily using editing software.
2. Digital images can be easily transferred through Bluetooth, Emails and
mobile phones.
3. Memory cards in digital cameras can store thousands of digital photographs.
Disadvantages of digital camera:
1. A corrupted memory card may result in lost photos.
2. The battery can run out meaning that you cannot take any more photographs
until it is recharged.
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8. Web Cameras (Webcam)
A web camera is an input device because it
captures a video image of the scene in front of it.
Webcams are similar to digital cameras in their
functions but they are directly connected to the
Webcams can capture both digital images and
videos. These images and videos are sent directly
to the computer where they can be stored and
Uses of Web cameras
1. Web cameras are used to hold video-conferencing meetings over the
2. Used to conduct face-to-face conversations and job interviews over the
3. Webcams are widely used in burglar alarm and other security equipment.
4. Sometimes used to allow drivers to view the traffic conditions on roads and
plan a different route if the traffic on a road is too congested.
Advantages of Web cameras:
1. Digital photos and video can be displayed on wide variety of devices, such as
smart phones and television screens. This allows access in a wide range of
locations and by several people at the same time.
2. Video conference business meetings and job interviews can be conducted very
cheaply over long distances.
3. Digital video can be broadcast over the Internet so that TV programs can be
available on demand.
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Disadvantages of Web cameras:
1. High quality photos and videos can be very large files. When these are sent
by email or broadcast over the Internet, this uses bandwidth and slows down
the network.
2. The image/video quality can be sometimes poor (low resolution).
3. They do not have their own storage and so must be permanently fixed to the
computing device.
9. Microphone
A microphone can be used to input sound. The
sound is detected by the microphone and an
electrical signal is transmitted to the computer.
Analogue-to-digital converter (ADC) is used to
convert this analogue data into digital data so it
can be stored and manipulated.
Computers have been programmed to do voice
recognition. Voice recognition software enables
the computer to know who is talking but not
what has been said. Voice Recognition can be
used like a fingerprint to identify a person.
Speech recognition is often used for voice command systems. For example to
control a computer, navigate telephone menus, etc. These require that the voice
first be recognized. A microphone is used to input the spoken words, which are
then analysed by the program. The sound is compared with other sounds stored in
the computer, to find the matching word; this match may be interpreted as a
command. This is an unreliable process because a user can make words sound
different at different times, and different users will say the same words differently.
As a result, the software may have to be trained to recognize a particular user.
Uses of Microphone
1. Used to input sounds/speech for use in a range of applications. For example
• Narration in presentations or in web sites
• Voice-over’s in movies
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• Speaking over the internet using VoIP(Voice over Internet
• Conducting video conferencing
2. Used in speech recognition software. For example
• Converting speech into text for use in Word processors (useful for
people who do not have use of their hands)
3. Hands-free mobile phones use a microphone to allow people to hold
conversations without using their hands (this makes driving much safer).
4. Used in gaming (along with headphones), so that gamers can talk to each
Advantages of Microphone:
1. Faster to read in text than to type it in using a keyboard.
2. Microphones are very cheap to buy.
3. Makes driving safer because people do not need to take their hands off the
steering wheel in order to use their mobile phone.
Disadvantages of Microphone:
1. Not accurate as using keyboard.
2. Microphone will only pick up sounds that are very close.
3. Fairly fragile.
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