Operating System
Definition
An Operating System (OS) is system software that acts as an interface between the user, application software, and the hardware. It manages the computer’s resources so that applications can run correctly.
Roles of the Operating System
User
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Application Software (word processors, browsers, games)
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Operating System ◄── You are here
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Hardware (CPU, RAM, storage, peripherals)
1. User Interface
- Provides a way for users to interact with the computer
- Can be a Graphical User Interface (GUI) (windows, icons, menus) or a Command Line Interface (CLI)
2. Memory Management
- Allocates RAM to programs when they are opened
- Tracks which memory regions are in use and which are free
- Handles Virtual Memory when RAM runs out
- Deals with memory fragmentation
3. Process Management
- Enables multitasking, running multiple programs “at once”
- Uses scheduling algorithms to share CPU time between processes
4. File Management
- Manages the file system on storage devices
- Handles reading, writing, creating and deleting files and directories
- Controls access permissions (who can read/write which files)
5. Hardware Communication
- Uses Device Drivers to translate OS commands into hardware-specific instructions
- Manages input/output for keyboards, mice, printers, screens, etc.
6. Security & User Accounts
- Manages user login, authentication and access levels
- Controls which users can access which files and features
Categories of System Software
| Type | Purpose | Examples |
|---|---|---|
| Operating System | Manages hardware, memory, files, processes | Windows, macOS, Linux, Android |
| Utility Software | Maintains and optimises the system | Antivirus, compression tools, defragmenter |
See Utility Software for the second category.
Exam Questions
Q: What is the primary role of an operating system?
To provide a platform for running application software, manage hardware resources (memory, files, peripherals) and provide a user interface.
Q: Why are device drivers necessary?
They translate the OS’s general instructions into the specific commands that a particular hardware device understands, allowing the OS and applications to use any hardware correctly.
Exam Tip
An OS is not application software (like a word processor). It is system software, it supports and manages the system so other software can run.