• Handles input and output
  • Selects and controls the operation of the hardware devices such as keyboards, mice, scanners, printers etc.
  • Recognises hardware device such as pen drive, camera etc. when they are attached to the computer and automatically loads the software (device driver) it needs to control the device.
  • Supervises the running of other programs
  • Provides a way for application programs like word processors, spreadsheets etc. to work with the hardware.
  • Handles the storage of data
  • Keeps track of all the files and folders on the disk.
  • Maximises the use of computer memory
  • Decides where in memory the program instructions are placed.
  • Ensures the parts of the program needed frequently are put in fastest part of the memory.
  • Handles interrupts and decides what action to take
  • Alerts the user when errors like printer cannot print because of paper jam or it has run out of paper.


Interface is used by the Operating System for interacting with the user.
Commonly used interfaces are:
Command Line Interface (CLI)
Graphical User Interface (GUI)



  • For an experienced user typing in commands using CLI is quicker than moving the mouse or clicking.
  • Uses less disk space than GUI when stored
  • Requires lesser memory (RAM) when being used.
  • Does not need powerful hardware like processor, graphics card to run a CLI.


  • User needs to remember commands and their syntax.
  • Commands must be issued in a specific order otherwise commands will be rejected.
  • Difficult to operate for a beginner.



  • User friendly - very easy to use for the novice user
  • Has features such as Windows, Icons, Menus and Pointers (WIMP)
  • No need to remember commands and its syntax.
  • Can be operated using point and click method. 



  • Takes more storage space on the disk.
  • Requires more memory (RAM) when being used.
  • Powerful hardware like processor, graphics card are needed to run latest version of a GUI.
  • Experienced user might find that typing in commands is quicker than moving the mouse or clicking.


Expected Questions:

Q: Graphical User Interfaces are very popular interfaces that are used with computers, mobile phones and other portable devices.

(a) Give three features of a graphical user interface [3]

Q: All computers need an Operating system.
(a) Explain what an operating system is. [2]
(b) List three functions of an operating system. [3]
Q: Name any one device other than computer and mobile that has GUI.
Q: List any two benefits of having this interface. [3]

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