IB Computer Science Topic A1.3.2: Functions of an Operating System Notes

Functions of an Operating System

As discussed in the previous chapter, an operating system (OS) is the backbone of any computing device, acting as an intermediary between hardware and software.

It manages resources, ensures system stability, and provides a user-friendly interface. Let's explore the core functions of an operating system in detail.

Maintaining System Integrity

1. System integrity refers to the ability of a computer system to perform its intended functions correctly and reliably, without unauthorized or unintended alterations.
2. The OS ensures this through several mechanisms:
   1. Process Isolation: Each process operates in its own virtual memory space, preventing interference with other processes or the OS itself.
   2. Memory Protection: The OS enforces boundaries between processes, ensuring that one process cannot access the memory of another.
   3. User Mode and Kernel Mode: These modes separate operations that require direct hardware access (kernel mode) from those that do not (user mode).

Memory Management

Memory management is a critical function of the OS, ensuring efficient use of both physical and virtual memory.

1. Allocation and Deallocation: The OS assigns memory to processes as needed and reclaims it when no longer in use.
2. Virtual Memory: This allows processes to use more memory than physically available by swapping data between RAM and disk storage.
3. Paging and Segmentation: These techniques divide memory into manageable units, enabling efficient allocation and protection.

File System Management

The OS manages data storage through file systems, which organize and control access to files and directories.

1. File Creation and Deletion: The OS handles the creation, modification, and deletion of files.
2. Permissions and Security: It enforces access controls to ensure only authorized users can read, write, or execute files.
3. Disk Space Allocation: The OS optimizes the use of storage space and maintains file system integrity.
4. Abstraction: The OS provides an interface of directories, sub-directories and files for the user to access rather than the user having to memorize exact addresses of files and applications.