Input devices

1. Input devices

2. 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).

3. Keyboard Advantages: • 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. 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.

4. Concept Keyboard • 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.

5. Concept Keyboard Advantages: • 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.

6. Numeric Keypad • Used 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. Advantages: • Faster than standard keyboard. • Some are small devices like mobile, so easy to carry. Disadvantages: • Difficult to use due to small keys. • Difficult to enter text. • Sometimes order of numbers on it is not intuitive.

7. Mouse Types: • Typical mouse with a ball underneath • Optical mouse • Cordless mouse Uses: • 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.

8. Mouse Advantages: • Fast to select an option rather than a keyboard. • Enable rapid navigation through applications and the internet. • Small so take little area. Disadvantages: • 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

9. Trackerball Advantages: • 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. Disadvantages: • Not supplied with computer as standard, so more expensive. • User may need training.

10. Joystick Uses: • Video/computer games. • Used in simulators e.g. flight simulator, to mimic actual controls. Advantages: • Easier to navigate round a screen using a joystick rather than a keyboard. • Control is in three dimensions. Disadvantages: • More difficult to control on-screen pointer with it than a mouse.

11. Touchpad Advantages: • 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. Disadvantages: • 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’.

12. Touch screen Uses: • 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.

13. Touch screen Advantages: • 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. Disadvantages: • Limited number of options available. • Can lead to health problems like RSI. • Screen can get very dirty with constant touching.

14. Graphics tablet • 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. Uses: • 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.

15. Graphics tablet Advantages: • Possible to modify drawings before they are input. • An accurate method of drawing, better than mouse or trackerball. Disadvantages: • More expensive than other pointing devices, such as mouse.

16. Light pen • 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. Uses: • For selecting objects on CRT screen. • For drawing on screen (e.g. with CAD packages).

17. Light pen Advantages: • More accurate than touch screen • Is small, so can be used where space is an issue. • Easy to use. Disadvantages: • At the moment, it works with only CRT monitors. • Not very accurate while drawing.

18. Scanner • 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.