Input Devices

Backing Storage

PROCESSOR
Output Devices

Main Memory
Peripherals
Peripherals are devices that can be attached to a
computer system to do specialised jobs.
Peripherals can be input, output, or backing storage
devices which can be connected to the central
processing unit.
Input Device
Can accept data, presented in the appropriate
machine-readable form, decodes it and transmit it as
electrical pulses to the CPU.
Output Device
Translates signals from the computer into a humanreadable form.
Backing Storage
Is a means of storing large amounts of data
• Keyboard
• Webcam
• Graphics Tablet
• Sound Card
• Touch Sensitive Screen • Specialised Input Device
for
disabled
users
and
• Mouse
virtual reality
• Trackpad
• Input devices for
• Joystick
Multimedia
• Scanner
• Microphone
• Digital Camera
• Digital Video Camera
Keyboard
The keyboard enables you to enter data into a computer.
Often referred to as QWETY keyboards.
Each character has a unique code, which is passed to
the operating system. The operating system translates
the code into ASCII.
Function Keys
Some computers can program function keys
Numeric Keypad
Can speed up your work if you are entering a lot of
number.
Concept Keyboard (Credit)
The Concept Keyboard is a particularly useful input
device. It allows the user to select the keyboard layout
best suited to the required application.
It has a touch-sensitive surface overlaid by a rectangular
sheet of paper. This "overlay" may be designed to meet
the requirements of each individual program.
Graphics Tablet
Flat pressure sensitive board with a pen or a pointer
connected to it.
Allows free drawing using the hand held pointer on a
board.
A graphics tablet is often used for computer aided design
(CAD) applications.
Two types of screens:
Cathode Ray Tube (CRT)
Liquid Crystal Display/thin film transistor (LCD/TFT)
Touch Sensitive Screen
A screen with sensitive areas on it. The user presses
particular areas to input into the computer such as a
palmtop.
Handwriting Recognition
User writes in his/her handwriting and the computers
reads the shapes of the writing and decides it into text.
Mouse
A device that controls the movement of the cursor or
pointer on a display screen.
The movement of the ball are detected by a sensor and
sent via the interface to the OS.
• Optical Mouse has a light underneath instead of a ball.
Any movement is detected by a sensor which picks up
the reflected light from the surface.
Trackball
Works the same as a mouse, except the ball is on the top.
The advantage of trackballs over mice is that the trackball
is stationary so it does not require much space to use it.
Popular on laptops because they're compact.
Trackpad
A touchpad is an input device commonly used in laptop
computers. They are used to move the cursor, using
motions of the user's finger. They substitute for a
computer mouse.
Joystick
Connect to computers to plat computer games. Able to
move in eight directions.
Scanner
Computer hardware designed to scan documents and
graphics into computers and to read barcodes from
materials or patron cards into an automation system.
You can use a scanner with optical character recognition
(OCR) software to input text into a word processing
document.
Microphone
Allow sound to be inputted into the computer.
Sound is analogue
Analogue to
Digital
conversion
Digital Sound
Computers only understand digital signals so the sound
must be converted from analogue to digital.
Voice Recognition
The technology by which sounds, words or phrases
spoken by humans are converted into electrical signals,
and these signals are transformed into coding patterns
that can be identified by a computer.
Based on this identification, the computer usually takes
some action.
To use voice recognition the computer must have voice
recognition software.
Digital Camera
A camera equipped with an electronic photosensitive
sensor. The digital pictures are stored directly in the
camera's memory and can be used immediately on a
computer.
Resolution
Resolution refers to the size of the digital image the
camera produces, and is usually expressed in terms of
"megapixels" or how many million pixels it can record in a
single image.
The number of pixels a camera captures is called the
camera's resolution.
Memory Cards
Most digital camera come with a removable memory card.
Digital Video Camera
Used for taking movies. Works on the same principle as a
digital camera.
Webcam
A small digital camera, which is normally positioned one
or beside a computer monitor in order to capture images
which can be transmitted across a network.
Used for video conferencing.
Sound card
Improve the quality of sound output from the games and
multimedia applications.
Additional bundled of software allows uses to compose, edit
and print music, record and edit digital audio, and play audio
and multimedia CD’s.
Plug the
microphone into
the sound card
socket.
Sound cards convert analogue signals into digital signals so the
computer can understand them.
Specialised Input Devices
Touch Talker
Input device used to communicate with other people.
Works by touching pictures on the touch talker which
contain a speech synthesiser.
Magic Wand
It is designed to be used
with little or no arm
movement and is the only
computer keyboard, and
mouse, that requires no
strength.
Virtual Reality
Is a method of reproducing the outside world digitally
within a computer system.
To take part in virtual reality the user wears a headset and
gloves.
Input Devices for Multimedia
Multimedia is the presentation of information by a
computer system using graphics, animation, sound and
text.
To view multimedia:
• Computer System
• Interactive whiteboard
• Multimedia Projector