All computers follow the stages of Input-Process-Output-Storage.
            a.  The INPUT  stage involves putting information into the system.
            b.  The PROCESS stage involves doing something with the information.
            c.  The OUTPUT stage involves displaying results.
            d.  The STORAGE  stage keeping data when the computer is switched off.

Lots of other things follow the Input-Process-Output stages, like this:


For example, take a toaster.



For a washing machine you have :



A computer works in the same way :




The hardware devices are grouped by what they are used for in the system.

A computer system has four main components.


Input devices are used to put information in to the computer

The Processor is used to do all the work such as calculations, searches, comparisons

Output devices used to display the results

Storage devices used to keep information when the computer is switched off

Flow of Data

The arrows show how the data flows in the computer system.

Some devices are used for input, so information flows IN to the processor.

Some devices are used for output, so information flows OUT of the processor.

Some devices are used for backing storage.

Information flows OUT of the processor for saving and flows IN to the processor when loading.