Revision:The 'Inputs' of Systems

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The ins and outs of a video library

When designing any information system, you need first to consider what information you what to get out of the system. The output depends on the type of job (application).

Input devices

Input devices are used to get data into a system. The ideal input device would be able to get data into a system as accurately as possible, in the least amount of time and preferably without human intervention. The device would also be relatively cheap.

Unfortunately, no perfect input device is available and the choice of is always a compromise. The fastest input devices are suitable only for narrow range of applications. Here are some of the main input devices in use today.

Keyboard

The keyboard is the oldest and most familiar of all the input devices. Keyboards are intelligent devices and contain their own chips. Basically each key acts as a switch which closes when the key is pressed. The microprocessor scans the keyboard hundreds of times.

Concept Keyboards

The arrangement of keys on a traditional computer keyboard is very similar to that on a typewriter keyboard. On a typewriter this arrangement was chosen for its slowness. New keyboards, called concept keyboard, have been developed which makes use of the latest research into ergonomics. Concept the keyboards are less tiring to use and higher typing speeds can be achieved.

Mouse

A mouse is an input device that translates its movement on the desktop into digital information; this is fed to the computer which in turn causes the cursor to move on the screen. Underneath the mouse is a ball which rotates as the mouse id moved on the desktop.

Touch Sensitive Pad

Touch sensitive pads or track pads are commonly found on notebook computers. You move your finger across the pad and this moves the cursor on the screen.

Light Pen

A screen cursor can be moved by touching the screen with a light pen. Light pens are mainly used for design work and need special software to make them work.

Touch Screen

A touch screen is a special kind of screen which is sensitive to touch. A selection is made from a menu on the screen by touching part of it. These screens are ideal for use in banks and building societies, where customers who are not used to keyboards can obtain information about the services offered. You can also see touch screens in restaurants and bars.

Magnetic Stripe Reader

You can see magnetic stripe readers at the side of computerised tills.

Barcode Readers

If you think that barcodes are used only in supermarkets, your wrong. barcodes are used in library systems, luggage handling systems at airports and for use at warehouse control. Barcode systems are now at an advanced stage and readers can record barcodes at five meters or more. This has increased the number of applications.

In America, researchers have painstakingly glued barcodes to the backs of some bees. These barcodes are scanned every time the bee enters or leaves its hive thus providing valuable information about pollination. imagine the problem if a swam of bees went into a supermarket.

Magnetic Ink Character Reader and Optical Character Recognition (MICR)

Magnetic ink characters are the rather strange looking numbers that you see at the bottom of cheques. The characters are printed using an ink which contains iron and may be magnetised.

Optical Mark Readers and Optical Mark Recognition (OMR)

Optical Mark readers are able to sense marks made on a special form in a certain places. People who have never completed optical mark reading sheets can have problems filling them in.

Kimball Tag

Kimball tags are the small cards with holes punched in them that you see attached to clothing in certain shops. When you buy the goods, one of the tags is removed and sent for processing to a computer centre.

Microphone

A Microphone is an input device which is voice activated. Once sound waves are sent through the microphone, it will transform these sound waves into data in which the computer can process.

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