INPUT DEVICES

Keyboard Used to input data into application software. Used for typing in commands to the computer

(e.g. Ctrl + P for printing) The keys are arranged into sections:

•alphabet keys •Function or F keys (e.g. F1, F2, F3) •Numeric keys •Arrow keys •Command keys (e.g. insert, delete, home, end)

Commonly QWERTY layout, recently Ergonomic keyboards are developed to reduce health-related problems such as repetitive strain injury (RSI).

Keyboard

Enable fast entry of new text into a document. Well-tried technology and a well-known method of

entry. Easy to use for most of people. Easy to do verification checks as data entered

appears on the screen simultaneously.

Advantages:

Disadvantages: Some people find it difficult to use. It is slow when compared to direct data entry e.g.

OMR Needs a valuable desk space to keep.

A flat board that contains a grid of buttons.

Each button can be programmed to do whatever you want.

An overlay sheet with pictures or symbols is placed on grid so that user can tell what pressing on different areas will do.

These are used when fast input is needed and are ideally suited to selecting from a limited range of choices such as fast food restaurants, such as McDonalds.

Primary schools often use them with young children. The overlay image could be a picture of a farmyard. Pressing on an animal would cause the computer to make the right animal noise.

Concept Keyboard

Enable fast data entry. It is waterproof. It is tamper proof, and so are useful in certain applications

(e.g. at unmanned airport information kiosks), preventing people from keying in information which could result computer corruption.

Advantages:

Concept Keyboard

Numeric KeypadUsed in ATM to enter pin, amount etc. Also used in telephones.Electronic point of sale (EPOS) terminals have it to use in case

barcode reader fails to read.

Faster than standard keyboard.Some are small devices like

mobile, so easy to carry.

Difficult to use due to small keys.

Difficult to enter text.Sometimes order of numbers

on it is not intuitive.

Advantages:

Disadvantages:

Mouse

To open, close and minimise software.To group, move and delete files.Useful while editing images e.g. controlling

size and position of a drawing on a document.

Uses:

Typical mouse with a ball underneathOptical mouseCordless mouse

Types:

MouseAdvantages:

Disadvantages:

Fast to select an option rather than a keyboard.Enable rapid navigation through applications and the internet.Small so take little area.

People with restricted hand/wrist movement can find it hard to operate a mouse.

Can be easily damaged and older type quickly clogs up dirt.Difficult to use if there is no flat surface e.g. on aeroplane.Overuse can lead to RSI

TrackerballAdvantages:

Disadvantages:

It doesn’t need the same fine control as a mouse, so suitable for RSI disability.

People with limited hand/wrist movement find it easier to use than a mouse.

Pointer can be positioned more accurately on the screen than with a mouse.

Takes less desk space than mice since they are stationary.

Not supplied with computer as standard, so more expensive.User may need training.

JoystickUses:

Disadvantages:

Video/computer games.Used in simulators e.g. flight simulator, to

mimic actual controls.

More difficult to control on-screen pointer with it than a mouse.

Advantages:Easier to navigate round a screen using a

joystick rather than a keyboard.Control is in three dimensions.

TouchpadAdvantages:

Disadvantages:

Fast to select an option rather than a keyboard.Enable rapid navigation through applications

and the internet.Since it is integrated into laptop, so no need for

a separate mouse.Can be used even if no flat surface.

People with limited hand/wrist movement can find it hard to operate.

More difficult to control pointer as compared to mouse.Difficult to do certain operations like ‘drag and drop’.

Touch screenUses:

For self-service tills, e.g. petrol stations.For selecting options made on screen, e.g.

ATM, airport, railway station, tourist office.PDA, mobile phones and satellite navigation

systems.Interactive white boards used for education

are large touch screens.Used for computer based training (CBT)

where selections are made in answering on screen testing.

Touch screenAdvantages:

Disadvantages:

Faster and easy to use - intuitive, don't need much training.

No extra peripherals such as a mouse are needed.

Software can alter the screen while it is being used, making it more flexible than a concept keyboard which has a permanent overlay.

Tamper proof.

Limited number of options available.Can lead to health problems like RSI.Screen can get very dirty with constant touching.

A pointing device used by designers and artists to allow natural hand movements to be input to graphics applications.

A stylus is held like a pen and moved over the surface of the tablet. Data about the stylus movements are sent to the computer.

Graphics tablet

Used to create ‘hand-drawn’ sketches, drawings and computer graphics.

In countries where characters are complex (e.g. China, Japan), they are used as a form of input .

Used in Computer Aided Design (CAD) work.

Uses:

Graphics tablet

Advantages:

Disadvantages:

Possible to modify drawings before they are input.

An accurate method of drawing, better than mouse or trackerball.

More expensive than other pointing devices, such as mouse.

A light pen is a device used as a pointing device or to ‘write’ on the screen of a computer.

Contains sensors that send signals to computer whenever light changes are detected.

Only works with Cathode Ray Tube (CRT) monitors. With Thin film Transistor (TFT) monitors, at developmental stage.

Light pens are rarely used today since graphics tablets and high-quality touch screens provide similar functionality.

Light pen

For selecting objects on CRT screen.For drawing on screen (e.g. with CAD packages).

Uses:

Advantages:

Disadvantages:

More accurate than touch screenIs small, so can be used where

space is an issue.Easy to use.

At the moment, it works with only CRT monitors.

Not very accurate while drawing.

Light pen

A device that ‘scans’ images, book pages, etc.

The scanned image data is passed to the computer.

The most common type of scanner is the flat-bed scanner which has a glass plate on which the item to be scanned is placed. The item is illuminated and an image of it is captured by a moving scan ‘head’.

Scanned images can be further processed once inside the computer, e.g. OCR of printed text.

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