Cambridge A-Level Computer Science 9618 – 5.1 Operating Systems
5.1 Operating Systems – Key Management Tasks
The operating system (OS) is the core software that manages computer resources and provides services to applications. Its primary management tasks can be grouped into five main categories:
1. Process Management
The OS is responsible for creating, scheduling, and terminating processes. It also handles process synchronization and communication.
Process Creation & Termination: The OS allocates resources, sets up the process control block (PCB), and cleans up after termination.
Scheduling: Determines the order in which processes access the CPU. Common algorithms include First‑Come First‑Serve (FCFS), Shortest Job Next (SJN), Round Robin (RR), and Priority Scheduling.
Context Switching: Saves the state of the currently running process and restores the state of the next process.
Deadlock Detection & Recovery: Detects circular wait conditions and takes corrective action.
Inter‑Process Communication (IPC): Provides mechanisms such as pipes, message queues, shared memory, and semaphores.
2. Memory Management
Memory management ensures that each process has enough memory and that the physical memory is used efficiently.
Allocation & Deallocation: The OS allocates memory blocks to processes and frees them upon termination.
Virtual Memory: Uses paging or segmentation to extend the apparent memory available to processes.
Swapping: Moves processes between main memory and secondary storage to free up RAM.
Protection: Prevents a process from accessing memory allocated to another process.
Fragmentation Management: Handles internal and external fragmentation through compaction or memory pooling.
3. File System Management
The OS manages data storage on secondary devices, providing a hierarchical structure for files and directories.
File Creation, Deletion, and Access: Controls permissions and ensures data integrity.
Directory Structure: Organises files in a tree or graph structure.
File Allocation: Uses allocation methods such as contiguous, linked, or indexed allocation.
Metadata Management: Stores file attributes like size, timestamps, and ownership.
Backup & Recovery: Provides mechanisms for data backup and restoration.
4. Device Management
The OS abstracts hardware devices and manages their operation.
Device Drivers: Software interfaces that allow the OS to communicate with hardware.
I/O Scheduling: Optimises the order of I/O requests to improve throughput.
Interrupt Handling: Responds to hardware interrupts and performs necessary actions.
Buffering & Caching: Improves I/O performance by temporarily storing data.
Device Allocation: Ensures that multiple processes can share devices safely.
5. Security and Protection
The OS enforces policies that protect system resources from unauthorized access.
Authentication: Verifies user identity before granting access.
Authorization: Determines what actions an authenticated user can perform.
Access Control Lists (ACLs): Specify permissions for files and devices.
Encryption: Protects data at rest and in transit.
Audit Trails: Records system events for security monitoring.
Summary Table of OS Management Tasks
Management Area
Key Functions
Process Management
Creation, scheduling, context switching, IPC, deadlock handling
Memory Management
Allocation, virtual memory, swapping, protection, fragmentation control
File System Management
File operations, directory structure, allocation, metadata, backup
Device Management
Drivers, I/O scheduling, interrupt handling, buffering, device allocation
Security & Protection
Authentication, authorization, ACLs, encryption, audit trails
Suggested diagram: OS architecture layers – User, Kernel, Device Drivers, File System, Memory Manager, Scheduler, Security Module.
Understanding these management tasks provides a foundation for analysing how operating systems enable efficient, secure, and reliable computing.