Input and output devices
Input devices
As the name suggests, input devices are hardware devices that allow data to be input
into a computer. Many such devices exist, ranging from the more common ones,
such as the keyboard, through to the more specialist devices, such as barcode
readers. A number are described in this section.
Keyboards
These are the most common input devices and are used to input text, numbers and
instructions into the computer. Most use the QWERTY layout (this name comes
from the keys on the top row, which spell out ‘QWERTY’).
Ergonomic keyboards have also been developed recently. These are designed to
reduce health-related problems associated with the standard keyboard (e.g. carpal
tunnel syndrome or repetitive strain injury (RSI).
Uses
* Keyboards are used to input data into applications software (e.g. text into word
processors, numbers into spreadsheets, etc.).
* They are also used for typing in commands to the computer (e.g. Prnt Scrn,
Ctrl+P to print out, etc.)
Advantages
* Keyboards enable fast entry of new text into a document.
* They are a well-tried technology and a well-known method of entry.
* Most people find them easy to use.
* It is easy to do verification checks as data is entered, as it appears on the screen
simultaneously.
Disadvantages
* Users with limited arm/wrist use can find keyboards hard to use.
* Entering data using a keyboard is slow when compared to direct data entry
(e.g. optical mark recognition).
* Keyboards are fairly large devices that use up valuable desk space.
The concept keyboard uses icons or phrases instead of standard letters. These are
often used in, for example, fast food restaurants, offices and shops, where a single
key represents an item. For example, the symbol shown in the photo represents ‘add
tax’. The person using the keyboard only needs to touch this key to calculate the tax
on an invoice.
Advantages
* Concept keyboards enable fast data entry, as there is no need to type in whole
commands.
* They are waterproof, which is useful in a restaurant environment.
* These keyboards are tamper proof and so are useful in certain applications
(e.g. at unmanned airport information kiosks), preventing people from keying in
information which could potentially corrupt the computer system.
Numeric keypads
A numeric keypad is used to enter numbers only (although some have a function
key to allow input of alphabetic characters).
Uses
* Numeric keypads are used in automatic teller machines (ATMs), where
customers can key in their personal identification number (PIN), an amount of
money, etc.
* Telephones have numeric keypads to allow phone numbers, etc. to be keyed in.
* Electronic point of sale (EPOS) terminals have numeric keypads in case the
barcode reader fails to read the barcode and the number has to be keyed in
manually by the operator.
* Chip and PIN devices have numeric keypads for entry of PIN, amount of money, etc.
* They are used to enable fast entry of numeric data into a spreadsheet.
Advantages
* Numeric keypads are faster than standard keyboards for entry of numeric data.
* Since many are small devices (e.g. mobile phones), they are very easy to carry
around.
Disadvantages
* They can be difficult to use, due to very small keys.
* It is difficult to use them for entering text.
* Sometimes the order of the numbers on the keypad isn’t intuitive.
