Types Of Software & Interrupts

Learn it by playing

Answer these questions to earn energy, then fish and explore. No account needed.

For teachers: ready-to-use lesson slides, revision notes, diagrams for Types Of Software & Interrupts (Computer Science, CIE) — use them in your lesson, or run the topic as a live class game.

Notes

System Software & Application Software

**System software** is essential for the computer to operate; it provides a platform to run applications.
Examples: **operating system** and **utility software**.
**Utility software** helps maintain, enhance, or troubleshoot a computer system (e.g., defragmentation, compression, encryption, task manager).
**Application software** is chosen by the user to perform specific tasks (e.g., word processor, browser, email client).
In exams, use generic software types, not brand names.

Purpose & Functions of an Operating System

An **operating system (OS)** manages hardware and provides a platform for running applications.
It acts as an interface between the user and hardware, hiding complexity.
Key functions: **file management**, **memory management**, **peripheral management**, **user interface**, **security**, **user management**, **handling interrupts**, and **providing a platform for applications**.
**File management**: creating, organising, naming, copying, moving, deleting files/folders; setting permissions; search facility.
**Memory management**: allocates RAM to programs, copies data from secondary to primary storage, enables multitasking.
**Peripheral management**: manages hardware devices; enables plug-and-play (PnP); uses **device drivers**.
**User interface**: CLI, GUI, menu, natural language (NLI) — each has advantages/disadvantages.
**Security**: password protection, firewall, virus scanning, file encryption.

Hardware, Firmware & the Operating System

Communication flow: **Application software → Operating System → Hardware**.
The OS acts as a bridge; never say software 'talks' directly to hardware without the OS.
**Firmware** is embedded in hardware (e.g., **BIOS** in ROM) and controls basic functions.
On startup, the **bootstrap loader** in ROM loads the OS into RAM.
Firmware translates between hardware and software; it is permanent, unlike device drivers.

Interrupts

An **interrupt** is a signal telling the CPU to pause its current task and handle a higher-priority event.
Interrupts can be **hardware** (e.g., mouse click, power button) or **software** (e.g., division by zero, program crash).
The CPU saves its current register values to a **stack** in RAM before handling the interrupt.
The **Interrupt Service Routine (ISR)** contains instructions to process the interrupt.
After the ISR completes, the CPU restores the saved state from the stack and resumes the original task.
Interrupts enable multitasking and ensure vital tasks are dealt with immediately.

Software categories: system software (OS, utilities) vs application software (user-chosen apps).

Eight key functions of an operating system.

Interrupt handling: CPU saves state, executes ISR, restores state, resumes.

Practice questions

Free preview — 8 of 40 questions. Sign up to see them all.

1.Which of the following is an example of system software?
Easy
- AOperating system
- BWord processor
- CWeb browser
- DSpreadsheet
2.What is the main purpose of utility software?
Easy
- ATo help maintain, enhance and troubleshoot/repair a computer system
- BTo provide a platform for running applications
- CTo allow users to create documents
- DTo manage user accounts
3.Which of the following is a function of an operating system?
Medium
- AFile management
- BWord processing
- CWeb browsing
- DSpreadsheet calculation
4.When an interrupt occurs, what does the CPU do with the contents of its registers?
Hard
- ACopies them to a stack in RAM
- BDeletes them permanently
- CStores them in the hard disk
- DIgnores them until the interrupt is serviced
5.Which of the following is an example of a software interrupt?
Medium
- ADivision by zero
- BMoving the mouse
- CPressing the power button
- DKeyboard press
6.What is the role of firmware in a computer system?
Easy
- ATo control basic hardware functions and translate between hardware and software
- BTo provide a graphical user interface
- CTo manage files and folders
- DTo run application software
7.Which of the following is a disadvantage of a Command Line Interface (CLI)?
Medium
- ARequires users to remember commands
- BUses more system resources
- CLess intuitive than a GUI
- DCan be frustrating when doing repetitive tasks
8.A user wants to ensure that files are stored in a more secure format. Which type of utility software should they use?
Hard
- AEncryption software
- BDefragmentation software
- CCompression software
- DTask manager

Slides

System Software vs Application Software

System software is essential for the computer to operate, e.g. OS and utility software.
Application software helps users perform specific tasks, e.g. word processors, browsers.
Utility software maintains/enhances/troubleshoots the system (e.g. defragmentation, compression).

Which of the following is an example of system software?

Word processor
Operating system
Web browser
Spreadsheet

Functions of an Operating System

File management: create, rename, move, delete files/folders.
Memory management: allocates RAM to programs, enables multitasking.
Peripheral management: controls devices via device drivers, supports plug-and-play.
User interface: provides CLI, GUI, menu, or natural language interaction.

The operating system manages ____ to allocate RAM between running programs.

Hardware, Firmware & the OS

Application software communicates with the OS, which interacts with hardware.
Firmware (e.g. BIOS) is embedded in ROM and controls basic hardware during startup.
The bootstrap loader in ROM starts the boot process.

What is the role of firmware in a computer system?

To manage files on the hard drive
To provide a user interface
To control basic hardware functions during startup
To run application software

What is an Interrupt?

An interrupt is a signal telling the CPU to pause its current task and handle a higher-priority event.
Interrupts can be generated by hardware (e.g. mouse click) or software (e.g. division by zero).
The CPU saves its current state to a stack, then runs the Interrupt Service Routine (ISR).
After the ISR, the CPU restores the saved state and resumes the original task.

Which of these are true about interrupts?

An interrupt causes the CPU to stop forever.
The CPU saves register values to a stack before handling an interrupt.
Interrupts can be generated by both hardware and software.
The interrupt service routine contains instructions to handle the interrupt.

Examples of Interrupts

Hardware interrupts: pressing the power button, moving the mouse, keyboard input.
Software interrupts: program not responding, division by zero, memory access conflict.

Which of the following is a software interrupt?

Pressing the power button
Moving the mouse
Division by zero
Keyboard press

Interrupt Handling Process

1. Interrupt signal sent to CPU.
2. CPU completes current instruction, then saves register contents to stack.
3. CPU loads the Interrupt Service Routine (ISR) address and executes it.
4. After ISR, CPU restores registers from stack and resumes original task.

Before handling an interrupt, the CPU copies register values to a reserved area in RAM called the ____.

Utility Software Examples

Defragmentation: reorganises files on disk to improve performance.
Compression: reduces file size to save space.
Encryption: secures data by converting it into a coded form.
Task manager: monitors and troubleshoots system performance.

Which utility software is used to reduce file size?

Defragmentation
Compression
Encryption
Task manager

User Interface Types

CLI: text-based commands, uses fewer resources, requires remembering commands.
GUI: visual (WIMP), intuitive, uses more resources.
Menu: successive menus, simple and efficient but limited flexibility.
Natural language: spoken input, accessible but not always reliable.

Which of these are advantages of a GUI?

Uses fewer system resources
Intuitive and user-friendly
Requires no previous knowledge to use
Commands are faster to type

Memory Management & Multitasking

The OS allocates RAM to programs based on priority and fairness.
Multitasking gives the illusion of running multiple programs simultaneously.
The CPU executes billions of instructions per second, switching rapidly between tasks.

What enables multitasking in a computer?

The CPU executing multiple instructions at once
Memory management by the OS
The use of multiple CPUs
Firmware handling all tasks

Unlock all 40 questions, slides & more

Create a free account to see every question, the slides, flashcards and revision notes for this topic.

Past papers

Past-paper practice for this topic is coming soon.

🗂️ Coming soon