Types of Software and Interrupts

2026 Syllabus Objectives

By the end of these notes, you should be able to:

  1. Describe the difference between system software and application software and provide examples of each
  2. Describe the role and basic functions of an operating system, including: managing files, handling interrupts, providing an interface, managing peripherals and drivers, managing memory, managing multitasking, providing a platform for running applications, providing system security, and managing user accounts
  3. Understand how hardware, firmware and an operating system are required to run applications software
  4. Describe the role and operation of interrupts, including: how an interrupt is generated, how it is handled using an interrupt service routine, and what happens as a result of the interrupts

1. System Software and Application Software

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Software can be divided into two main categories: system software and application software.

What is System Software?

System software is essential software that makes the computer system work. Without system software, the computer would not be able to operate at all.

System software:

  • Provides the services that the computer needs to function
  • Gives users a platform to run other programs and carry out tasks
  • Works in the background to keep the computer running smoothly

Examples of system software:

  • Operating system (e.g. Windows, macOS, Linux, Android) - the most important system software
  • Utility software - programs that help maintain and look after the computer

What is Utility Software?

Utility software is designed to help maintain, enhance (improve), and troubleshoot (fix problems with) a computer system.

Characteristics of utility software:

  • Designed to perform a limited number of specific tasks
  • Interacts directly with the computer's hardware (like hard drives)
  • Some utility software comes pre-installed with the operating system

Examples of utility software and their purposes:

Utility SoftwarePurposeCategory
DefragmentationReorganizes scattered files on a hard drive to make it work fasterMaintain
CompressionReduces file sizes to save storage spaceEnhance
EncryptionScrambles data to keep it secure from unauthorized accessEnhance
Task managerShows what programs are running and lets you close programs that aren't respondingTroubleshoot/Repair

What is Application Software?

Application software (often called "apps") is software chosen by a user to help them carry out specific tasks they want to do.

Application software:

  • Provides the services that the user needs or wants
  • Is installed on top of system software
  • Is chosen by individual users to suit their own needs

Common categories of application software:

  1. Productivity software - helps you get things done efficiently

    • Word processors (for writing documents)
    • Spreadsheets (for working with numbers and data)
    • Presentation software (for creating slideshows)

  2. Communication software - helps you stay connected with others

    • Email clients (for sending and receiving emails)
    • Browsers (for accessing websites)
    • Messaging apps (for chatting with others)

  3. Entertainment software - for leisure activities

    • Media players (for watching videos or listening to music)
    • Games
    • Streaming apps

Important exam tip: When giving examples, always use generic types like "word processor" or "browser" rather than brand names like "Microsoft Word" or "Google Chrome". Examiners award marks for the type of software, not specific product names.

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