In this section, we will look at how computers work and also at some different pieces of COMPUTER HARDWARE and find out more about what they are used for.
This section will be concerned with:
INPUT - getting data INTO the computer;
PROCESS - doing calculations, searching in order to find something and sorting things in order;
OUTPUT - getting information OUT of the computer;
BACKING STORAGE - is storing data and information for later use.
Here are the FOUR STAGES OF COMPUTING which show how computers work.
The following pieces of computer hardware are used as input devices:-
| Keyboard |  |
Used to type IN numbers, letters and words and can also be used to give instructions to the computer. |
| Mouse |  |
Also used for input - very good for drawing shapes and painting on the computer. Can be used to point to and select objects on the screen, as well as for loading and quitting from computer programs. |
| Concept Keyboard |
Large touch sensitive keyboard with pictures - good for very young children. |
|
| Video Digitiser | A video digitiser is used to transfer a TV picture or a picture from video cassette to the computer system. This can then be stored, changed and used in documents. |
The device that does the calculations and the searching and sorting is the processor (or microprocessor).
A processor is a special type of microchip.
The following pieces of computer hardware are used as output devices:-
| Monitor or VDU |  |
When you type numbers, letters and words, they are displayed on the VDU or MONITOR. Results of calculations are also output to this device. |
| Printer |  |
Used to get a copy of our work on paper. |
| Mobile robot or vehicle |  |
Computers can also control mobile robots and vehicles like Trekkers, and turtles. The instructions that the computer gives are output to the mobile vehicles to control their movements. |
There are different types of printers:-
This works by the print head having a block (or matrix) of pins which form themselves into the shape of each letter to be printed. The letter shape then strikes an inked ribbon which then hits the paper to produce the letter.
Dot-Matrix Printers can work in draft quality to produce a rough copy at high speed. This is useful for checking your work before printing a final copy.
They can also work in Near Letter Quality (or NLQ for short) to produce a high quality print out. It is slower to print things out in NLQ because the printer operates more slowly.
Dot-Matrix Printers can print text and graphics. You get black and white and also colour dot-matrix printers.
This works by having little cartridges filled with different colours of ink - normally black, cyan (blue), magenta (red) and yellow.
The Inkjet printer works by the print head having a row of nozzles with a heating element near the nozzle. When ink is heated up near the nozzle, a bubble forms and gets transferred onto the paper. Different combinations of the four colours are used to produce other colours.
As with dot-matrix printers, you can have low or high quality print outs.
Inkjet printers can print both text and graphics.
The image of what has to be printed is put on a drum. Toner (very fine black ink particles) is then transferred from a cartridge to the drum and then on to paper. It does not rub off because it is heat sealed.
These produce very high quality printouts combining text and graphics.
We have already seen that the following devices can be used for storing computerised information:-
Here is another backing storage device:-
The hard disk comes built in to computer systems and is part of the main system unit. Hard disks have a very large amount of space for storage, more than floppy disks and more then CD ROMs, which means that much more can be kept on them. It is usually much faster to load programs from the hard disk than it is to load them from floppy disk or CD ROM.
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