PROCESSORBacking Storage Main Memory
Output Devices
Input Devices
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 human-readable form.
Backing Storage
Is a means of storing large amounts of data
• Keyboard
• Graphics Tablet
• Touch Sensitive Screen
• Mouse
• Trackpad
• Joystick
• Scanner
• Microphone
• Digital Camera
• Digital Video Camera
• Webcam
• Sound Card
• Specialised Input Device for disabled users and virtual reality
• Input devices for Multimedia
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.
Analogue to Digital
conversion
Digital SoundSound is analogue
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.
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.
Sound cards convert analogue signals into digital signals so the computer can understand them.
Plug the microphone into the sound card
socket.
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
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