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 us e 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.
