The Purpose & Functionality of Operating Systems (OCR GCSE Computer Science): Revision Notes

The Purpose & Functionality of Operating Systems

An Operating System (OS) is a type of systems software that manages hardware, provides a user interface, and enables communication between software and hardware. It performs many essential tasks to ensure the smooth operation of a computer system.

User Interface

• The user interface (UI) allows users to interact with the computer hardware.
• Types of user interfaces include:
  • Graphical User Interface (GUI): Uses visual elements like Windows, Icons, Menus, and Pointers (WIMP).
  • Command Line Interface (CLI): Text-based interaction where users type commands.
  • Menu-driven and Voice-Controlled interfaces also exist.
• The UI makes the system user-friendly and accessible, allowing users to easily perform tasks.

Memory Management and Multitasking

• The OS manages memory allocation for running programmes and frees up memory when no longer needed.
• It facilitates multitasking, allowing several applications to run simultaneously by efficiently sharing the CPU's processing time between tasks.
• Virtual memory is used when the system runs out of RAM; the OS moves data between RAM and a portion of the hard drive.
• The OS ensures that active applications get the processor time needed to execute their instructions.

Peripheral Management and Drivers

• Peripheral devices (e.g., printers, keyboards, monitors) need device drivers to communicate with the OS.
• A device driver is software that allows the OS to manage the input and output from these external devices.
• The OS handles the connection and communication with peripherals, ensuring data is passed between the devices and the CPU correctly.

User Management

• The OS provides user accounts and manages access rights for security.
• Users are given specific levels of access to files and resources, ensuring only authorised users can access sensitive data.
• Single-user and multi-user systems exist, where multi-user operating systems allow multiple users to interact with the system simultaneously (e.g., on mainframes or servers).

File Management

• The OS organises data in a hierarchical structure (folders and files) for easy storage and retrieval.
• It manages the creation, naming, saving, moving, and deleting of files.
• Users can store and access data without needing to understand the technical details of where and how the data is stored on the hardware.