Application Software and Operating Systems (AQA GCSE Computer Science): Revision Notes
Application software and operating systems
What is application software?
Application software refers to the programmes that you actually use to get things done on your computer. These are the end-user programmes designed for specific tasks that make your computer useful for everyday activities.
Think of application software as the tools that help you complete particular jobs. For example, when you want to write an essay, you might use Microsoft Word. When you want to edit photos, you could use Photoshop. When you want to have fun, you might play games or watch videos.
The key difference between application software and other types of software is that application software is designed specifically for end users to accomplish their daily tasks and goals.
Application software can be grouped into different categories:
- Productivity software: Word processors, spreadsheets, presentation software
- Creative software: Photo editors, video editors, music production tools
- Entertainment software: Games, media players, streaming applications
- Specialized software: Business systems like payroll software, pupil management systems, or air traffic control programmes
The key thing to remember is that application software is what makes your computer actually useful for the tasks you want to do.
Understanding operating systems
An operating system (OS) is like the manager of your computer - it controls everything that happens and provides a way for you and your programmes to interact with the hardware.
Where you'll find operating systems
Operating systems are found in almost every computing device you can think of:
- Desktop and laptop computers: Windows, macOS, Linux
- Mobile devices: Android, iOS
- Gaming consoles: Xbox OS, PlayStation OS
- Servers and supercomputers: Various versions of Linux, Windows Server
- Tablets: iOS, Android, Windows
What operating systems actually do
The operating system manages the hardware in your computer and creates an environment where applications can run. It's absolutely essential - without an operating system, your computer would just be an expensive collection of parts that can't do anything useful.
The OS acts as a bridge between you (and your applications) and the computer's hardware, handling all the complex technical stuff so you don't have to worry about it.
The five key functions of operating systems
1. Processor management
Modern operating systems are brilliant at making it seem like your computer can do many things at once. This ability is called multitasking - when a computer appears to perform multiple tasks simultaneously.
How Multitasking Actually Works
The operating system rapidly switches between different programmes, giving each one a tiny slice of processor time. It happens so quickly (thousands of times per second) that it appears as though everything is running at the same time.
When you're listening to music while writing a document and browsing the web, the processor is actually switching between these tasks incredibly fast. The OS decides which programme gets processor time and for how long.
If your computer has a multi-core processor (which most modern computers do), the operating system can allocate different tasks to different cores, making multitasking even more efficient.
2. Memory management
Memory management is like being a librarian who has to organise books (programmes) on shelves (RAM) efficiently.
The memory manager controls how RAM is used by dividing it into fixed-size blocks called pages. When you start a programme, the OS:
- Figures out how much memory the programme will need
- Allocates enough pages to hold the programme and its files
- Keeps track of where everything is stored
- Frees up the memory when you close the programme so other programmes can use it
The memory management system maintains a record of where each programme's data is stored, so it can quickly find and access the information when needed. This is crucial for keeping your computer running smoothly without programmes interfering with each other.
3. Input/output device management
Your computer needs to communicate with lots of different devices - keyboards, mice, printers, cameras, monitors, and more. These external devices are called peripherals.
The operating system controls these peripherals using special small programmes called device drivers. Think of device drivers as translators that help your computer and peripherals understand each other.
How Device Drivers Work
- Each peripheral has its own device driver
- The device driver enables the peripheral to communicate properly with the computer
- Drivers can usually be downloaded automatically from the internet
- Each driver can be updated independently when needed
The device manager (part of the OS) controls how data flows between the computer and all these connected devices, making sure everything works together smoothly.
4. Application management
Applications can't run by themselves - they need the operating system to provide support and resources. The OS manages applications through something called an Application Programme Interface (API).
The API is like a set of rules that allows programmes to communicate with the operating system. When an application needs something (like memory space or processor time), it makes requests through the API.
The operating system:
- Helps install new applications
- Provides the environment applications need to run
- Allocates memory space for applications
- Manages the queue of jobs that need processor time
- Handles communication between applications and hardware
5. Security management
The operating system has several important jobs when it comes to keeping your computer and data safe:
User account control: The OS manages user accounts, allowing administrators to create or delete accounts as needed. This ensures only authorised people can access the computer.
Password protection: Users must enter passwords to access the software and files on the computer, providing a first line of defence against unauthorised access.
Access Rights and Privileges
Different users can have different levels of access:
- Standard users might only be able to run programmes and save files
- Administrator users can install new software and change system settings
- This prevents users from accidentally (or deliberately) damaging the system
Automatic updates: The OS can download and install patches automatically. Patches are updates that fix security problems and other issues, helping to close any security loopholes.
Data encryption: Information stored on secondary storage (like hard drives) can be encrypted by the OS to keep it secure, even if someone gains physical access to the storage device.
Key Points to Remember:
- Application software are the programmes you use to complete specific tasks - like word processing, gaming, or photo editing
- Operating systems manage computer hardware and provide the environment for applications to run
- Multitasking allows computers to appear to run multiple programmes simultaneously by rapidly switching between tasks
- The OS has five main functions: processor management, memory management, input/output device management, application management, and security management
- Device drivers are special programmes that allow peripherals to communicate with the computer through the operating system