Input Processing

Output

Secondary Storage

I/O Subsystem Diagram

Input DevicesInput devices are hardware components that enable

users to interact with a computer. Without input

devices, you would not be able to feed instructions to

a computer

KeyboardUsed to input data into the computer. Many desktop computer keyboards also have a numeric keypad located on the right side of the keyboard.

QWERTY - the name comes from the first six keys appearing on the top left letter row of the keyboard and read from left to right: Q-W-E-R-T-Y

Advantages:• faster than pointing devices• all computers are supplied with keyboards

Disadvantages:• takes a lot of time to practice in order to type quickly and accurately• using the keyboard can be very slow to control and move icons

Uses:• in Word Processing

Ergonomic/Natural Keyboard

A keyboard that lays out the keys in a more natural for your hands to help reduce strain on the hands. Ergonomic keyboards can make typing easier, faster and less awkward.

Advantages:• It reduces muscle strain • Typing can be much easier, faster and less awkwardDisadvantages:• more expensive than normal keyboards• takes up more space

Uses:• in Word Processing

Braille keyboard (Device for Special Needs)

Braille is a writing system for blind and visually impaired people. It is made up of raised dots that can be ‘read’ by touch

Advantages:• helps visually impaired persons to go about their daily lives.

Disadvantages:• Can be difficult to learn, not all people's finger tips are sensitive enough to use it

Uses:• in Word Processing

MouseA mouse is the most widely used pointing device on personal computers. Its position is shown by a marker on screen called cursor. A mechanical mouse has a rubber ball on its underside to detect movement while an optical mouse uses light. A cordless mouse transmits data using wireless technology such as radio waved or infrared.

Advantages:• Very easy to use

Disadvantages:• Requires a flat surface to operate.• Requires a good amount of desk space

Uses:• Selection

TrackballA trackball is a stationary pointing device with a ball mechanism on its top. To operate it the user rotates the ball which moves the pointer on screen. They are particularly easy to use for those with limited movement in their hands.

Advantages:• Good for limited desk space

Disadvantages:• Usually not as accurate as a mouse• Requires more frequent cleaning than a mouse

Uses:• Selection

TouchpadA small pressure and motion-sensitive area on a portable computer that you can use to move the cursor. To move the pointer, the user has to move his/her finger across the pad, the mouse pointer on the screen moves in the same directionAdvantages:

• Easy and fast one finger control• Ideal for portable devices

Disadvantages:• Expensive and only found in specific devices

Uses:• Selection

Joystick & Games Paddle

A joystick is a pointing device with a vertical lever mounted on a base. It usually includes buttons called triggers, which activate certain events when pressed. A Games Paddle may contain various buttons used to steer and utilize different optionsAdvantages:

• Fast interactions required in most games

Disadvantages:• Sometimes difficult to select objects accurately on the screenUses:

• Gaming and Simulations

Touchscreen (I/O)

A touch screen is an input/output touch sensitive display. The user provides instructions by using the touch feature of the screen, for which the result is displayed on the same screenAdvantages:

• No extra peripherals are needed except the monitor• Easy access to commands

Disadvantages:• Not suitable for inputting a large amount of data because they require a lot of arm movement• Only items already on screen can be selected

Uses:• Smart Phones, Tablets, PDA’s

ScannerA scanner can be used to digitize images. A flatbed scanner is similar to a photocopier but it makes a digital copy instead of a physical copy. A handheld scanner is passed over the image to be scanned. It is a hand-held device ideal for capturing small images, such as signatures and logos. A hand-held scanner is smaller, less expensive, and more portable than a flatbed scanner.

Advantages:• Scanned images can be edited• Very easy to obtain a soft copy

Disadvantages:• Difficult to scan 3-D• Scanned images take up a lot of storage spaceUses:

• to digitize hard copies

Light Pen

A pointing device that can detect the presence of light. It is connected to the computer by a wire.

Advantages:• Directed and precise• Convenient for applications with limited desktop space• Easy access to commands

Disadvantages:• Requires a specially designed monitor to work with• Can be tiring with large monitorsUses:• handheld or very small computers on which it is physically impossible to fit a keyboard

Bar-code Reader

Barcodes are represented by black vertical bars and are read by a barcode reader. Barcodes are printed on products which have unique codes. When the barcode is read, information stored in the shop’s database is recalled. This information would include prices and names.

Advantages:• Process of data entry is fast and accurate• No need to key in or write down the product’s nameDisadvantages:• may be misread if there is any dirt or marks on the code

Uses:• Point of sale

Graphics Tablet

A graphics tablet consists of a flat pad on which the user draws with a pen. As the user draws on the pad the image is created on the screen. Using a graphics tablet, a designer can produce very accurate on-screen drawings as if they were a drawing on a paper

Advantages:• A stylus can be pointed to different positions on the tablet quickly

Disadvantages:• A stylus and a graphics tablet normally have to work together, and cannot •Work separately

Uses:• Graphics Applications

Magnetic-Ink-Character-Reader (MICR)Magnetic ink characters appear at the bottom of cheques. Banks use MICR to read the numbers from bottom of cheques, to obtain data such as account numbers and bank sort codes. A particular font is used that makes it easy for the machine to distinguish between characters. The ink is magnetic, which makes it immune to dirty marks.

Advantages:• Difficult to forge•Documents can still be read when folded

Disadvantages:• MICR readers are very expensive• The system can only accept a limited character set

Uses:• Bank Applications

Optical Mark Recognition (OMR)

OMR readers can sense hand drawn marks such as small circles and rectangles made on pre-printed forms in certain places. The OMR reader first reads the answer key sheet to record the correct answers based on the patterns of light, and then reads the remaining documents and matches their patterns of light against the answer key sheet.

Advantages:• Cost of inputting data and chance of errors is reduced• Large volumes of data can be collected quickly and easily

Disadvantages:• Dirt may prevent the form to be read correctly• Needs to be re-programmed for each new document

Uses:• correction of multiple-choice examination questions

Audio Input & Speech Recognition

Through microphones the sound is digitized so that the computer can understand it. Microphones can be used as a communication device but also to control the computer such as opening windows. This is done by using voice recognition software.

Advantages:• Cheap to buy and easy to use

Disadvantages:• Difficult for the computer to understand the voice• Takes a lot of space from the memory

(Device for Special Needs)