Computers, Data and Information

A computer is an information processing machine. Computers process data to produce information.

The sets of instructions that humans give computers are called programs or software.

Software that carries out a particular type of task for a user is often called applications software.

There are many reasons for using computers:

  • Computers can work much faster than humans;
  • Computers never get tired or need a rest;
  • Computers can do jobs that it would be dangerous for a human to do;
  • Computers can store large amounts of information in a very small space;
  • Computers can find information very quickly;
  • Computers never lose or misplace information.

The three stages of computing are input, processing and output.

A computer works through these stages by ‘running’ a program. A program is a set of step-by-step instructions which tells the computer exactly what to do with input in order to produce the required output.


  • This stage of computing is concerned with getting the data needed by the program into the computer.
  • Input devices are used to do this.
  • The most commonly used input devices are the mouse and the keyboard.


  • The instructions about what to do with the input are contained in a program.
  • During the processing stage the computer follows these instructions using the data which has just been input.
  • What the computer produces at the end of this stage is called output.


  • This stage of computing is concerned with producing the processed data as information in a form that is useful to the user.
  • Output devices are used to do this.
  • The most commonly used output devices are the screen, which is also called a monitor or visual display unit (VDU) and the printer.

Data & Information

  • Data is any collection of numbers, characters or other symbols that has been coded into a format that can be input into a computer and processed.
  • Data on its own has no meaning, or context.
  • It is only after processing by a computer that data takes on a context and becomes information.
  • There are many types of data
  • All data ends up being stored as a series of numbers inside the computer.
  • Data can be input to the computer by the user in many different ways.
  • The main types of data that can be input into a computer and processed are numeric, text, dates, graphics and sound.

Computer Systems

  • Hardware is the name that is given to any part of a computer that you can actually touch.
  • An individual piece of hardware is called a device.
  • The basic hardware of any computer consists of a central processing unit (CPU) along with input, output and backing storage devices.



The central processing unit (CPU)

  • This is the part of the computer where the searching and sorting of data, calculating and decision-making goes on.
  • The CPU contains the Main Memory, the Control Unit and the Arithmetic and Logic Unit (ALU).


An introduction to processors

This video provides an explanation of the parts within a processor and the functions of each part. The Central Processing Unit contains the Arithmetic Logic Unit, which carries out all arithmetic operations plus AND/OR functions, and the Control Unit, where decisions are made about collecting and sending data.


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