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Ex 1.1.4 - Input, Output Devices |
| KNOWLEDGE |
| INPUT DEVICES |
| Input devices are pieces of
hardware that send electronic instructions to the computer
(keyboard,
mouse) or pieces of hardware that send information
to the computer (floppy
disc, CD drive). The information that is sent could be a word processed
document or a file of some kind. Input devices of a computer include: |
 The keyboard The main function of a keyboard is to type words and enter numbers. As such keyboards are electronic input devices containing alphanumeric characters (A to Z and 0 to 9) as well as a number of special keys. As a key is pressed an electronic signal is sent to the computer which processes that signal. If you are working in a word processor and press the A key a  signal will be sent to the computer which will in
turn send a signal to the screen to display the character A.
However if you were to hold down the key labelled Ctrl and then
press the key A a different signal will be sent to the computer.
If you are using Microsoft Word or Microsoft Excel pressing Ctrl A
(this means hold down the Ctrl key and press the A key)
will highlight all the information on the current screen - Ctrl A
means hold down the Ctrl key and press the A key. |
|
A mouse A mouse commonly comes with a desk top computer and is used to point at and select options on the screen. These include selecting commands from  menus or clicking on buttons to perform some
operation such as saving or printing your work. Laptop or portable
computer don't always come with a mouse but instead have a built in
"tracker ball" which performs the same function. |
| Light pen Light pens are similar to the mouse and are used to point at and select options on the screen. The shape of a light pen is different from a mouse and is basically like an ordinary pen but with a cable attached to the computer. The advantage of the light pen comes where you are working with drawing packages and you are producing sketches. Light pens are not normally supplied with a computer but are an additional device bought by the specialist user. |
| Floppy disc drive The floppy disc drive is normally found in the main box which contains the CPU and other electronic circuit boards. The disc drive is a self contained unit which rotates the floppy disc whilst reading information from it. Floppy discs have for a number of years now been a standard size. Physically they are 3.5" wide and as such you will see them referred to as 3 1/2" Floppy Discs. They also able to save 1.44MB of information which means that typically 30 or 40 files can be saved on one disc. It is also possible to attach an external floppy disc drive to a machine, such as a laptop or portable computer. |
|
CD drive The CD drive is also normally found in the main box. The CD drive is a self contained unit  which, like the floppy drive, rotates the CD whilst
reading information from it. More accurately the CR drive should be
referred to as a CD-ROM drive where the
ROM
(read only memory) means that the drive is capable of
"reading" data only. It is also possible to attach an
external CD drive to a machine, such as a laptop or portable computer. |
| DVD drive The DVD (digital versatile disc) drive is also normally found in the main box and can in fact be the same unit as the CD drive. The DVD drive is a self contained unit which, like the floppy drive, rotates the DVD whilst reading information from it. It is also possible to attach an external DVD drive to a machine, such as a laptop or portable computer. |
|
Product demonstrations/Scanners Scanner Scanners are like photocopiers and can be used to copy images, and also text, from paper documents and save them digitally. Graphics can be saved in different file formats (*.bmp, *.gif, *.jpeg) for usage in 
different packages. The quality of the image obtained depends on the
resolution (600dpi, 1200dpi or even 2400dpi) of the particular scanner.
The better the resolution the greater the cost of the scanner. Text documents can be saved as images (i.e. a
picture of the page) or they can be converted to text or Word documents
thus enabling the user to edit the text later. Scanners can also be
used to copy, fax or e-mail information. |
| Joystick Joysticks are used when playing computer games. They consist of a vertically mounted stick  on a support with an activation button to "fire"
at targets. The motion of the stick controls the movement of the
"character" on the screen. |
| Digital Camera Digital cameras containing memory cards started replacing traditional film cameras in the  early 2000's. Digital cameras can be connected to all
PC's via USB ports and a single cable. Images stored on a digital
camera can be downloaded to graphics software on any PC. Images can
then be printed and/or digitally altered. |
| OUTPUT DEVICES |
| Output devices are pieces of
hardware that the computer sends electronic instructions to (monitor,
printer) or pieces of hardware that the computer sends
information to
(floppy disc, CD-RW drive). The information that is sent could be a word
processed document or a file of some kind. Output devices of a computer include: |
| The monitor The monitor can also be referred to as the Screen or Visual Display Unit (VDU). Monitors are normally colour these days and come in different 
sizes ranging from 14" to 21" with the most common sizes being 15" and
17". Information is processed by the computer and sent to the
screen resulting in the image that you see. Like a TV screen the
image on your computer monitor is made up of a series of dots. |
|
Product demonstrations/Dot Matrix-Inkjet-Lasers Printer Printers are required to produce "hard copies" of documents that are created. The computer sends information to the printer in a format that  the printer understands and the printer generates a series of dots on
the paper which make up the words, the numbers, and the images that are on
the screen. The types of printer available include Laser printers,
Inkjet printers and dot-matrix printers. |
| Plotter Plotters are similar to printers in that they are used to create hard copy. Plotters use felt tip type pens to draw the output on paper. Plotters are typically used for engineering or architectural drawings. Different coloured pens can be used by the plotter to create coloured drawings. One major advantage with plotters is that their construction allows drawings to be made on very large sheets of paper. |
| Floppy disc drive The floppy disc drive is normally found in the main box which contains the CPU and other electronic circuit boards. The disc drive is a self contained unit which rotates the floppy disc whilst information is saved to it. It should be noted that a floppy disc drive is both an input and output device. |
|
CD-RW drive A CD drive that is capable of having information saved to it is normally referred to as a CD-RW drive. As well as information being
read from the CD it can also be "written" (W).
A typical CD is capable of storing 650MB of information compared to a
floppy disc where only 1.44MB can be saved. It should be
noted that a CD-RW drive is both an input and output device. |
| Recordable DVD drive A recordable DVD drive is one that allows you to save information on a DVD disc. A typical DVD is capable of storing 8.5GB (i.e. 8,500MB) of information compared to a CD where only 700MB can be saved. It should be noted that a recordable DVD drive is both an input and output device. |
| Speakers Most modern computers come with speakers which allow the user to play multimedia CD's  (with text, graphics, sound and video) or to listen to the
radio over the
Internet. |
| INPUT/OUTPUT DEVICES | ||
| There are some devices which are both input
and output devices at the same time. Hard discs, floppy discs and
re-writable CD's are all data storage media which can both receive data
from and supply data to the computer's memory. Hence, the devices
these media are placed in can all be considered to be both input and
output devices. Some specialist forms of monitor known as
touchscreen monitors (because you can touch them with your finger to
activate some change) are also input/output devices. Hence a list of devices that are both input and output devices includes:
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| FURTHER INFORMATION | ||
| To read further information about the topic(s) discussed in this exercise try visiting the following web site(s): www.pcworld.co.uk - IT Supplier |
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