Operating systems (OS) are vital software that manage hardware and software resources, facilitating user interaction with computing devices like Windows and Linux. Key functions include process management, memory management, file system management, device management, user interface, and security. Understanding these functions is foundational for advanced fields such as systems programming and cybersecurity.

1. HOW OPERATING
SYSTEMS WORK
A Comprehensive Guide for Computer
Science Undergraduate Students

2. Introduction
 Operating systems (OS) are essential software
powering every modern computing device.
 Understanding operating systems provides
foundational knowledge for managing
resources, process control, memory
management, file systems, and security.

3. What is an Operating System?
 An OS is system software that manages
hardware and software resources, providing
services for applications.
 Acts as an intermediary between users and
hardware, facilitating seamless interaction.
 Examples: Windows, macOS, Linux, Android.

4. Core Functions of an Operating
System
 1. Process Management
 2. Memory Management
 3. File System Management
 4. Device Management
 5. User Interface
 6. Security and Protection

5. Process Management
 Involves creating, scheduling, and terminating
processes.
 Key Concepts:
 - Scheduling: Decides order of process execution.
 - Multitasking: Allows concurrent process
execution.
 - Context Switching: Enables efficient process
transitions.
 - Process States: Ready, running, or waiting states.

6. Memory Management
 Controls and coordinates the computer’s RAM.
 Key Concepts:
 - Virtual Memory: Expands usable memory via
disk swapping.
 - Paging and Segmentation: Organize memory
allocation.
 - Memory Protection: Ensures stability across
processes.

7. File System Management
 Enables data storage and retrieval in a
structured format.
 Key Concepts:
 - File Types and Access Methods.
 - Permissions: Control data accessibility.
 - Directory Structure: Organizes files
efficiently.

8. Device Management
 Handles communication between hardware
devices and the OS.
 Key Concepts:
 - Device Drivers: Facilitate hardware-software
communication.
 - I/O Scheduling and Interrupts: Manage and
optimize device usage.

9. User Interface
 The interface allows users to interact with the
OS.
 Two main types:
 - GUI: Graphical interface with icons and
menus.
 - CLI: Command-line interface for textual
commands.

10. Security and Protection
 Protects resources and data from unauthorized
access.
 Key Concepts:
 - Authentication and Authorization: Verifies
user identity.
 - Encryption and Firewalls: Secure data
transmission.

11. Types of Operating Systems
 1. Batch OS
 2. Time-Sharing OS
 3. Distributed OS
 4. Real-Time OS (RTOS)
 5. Embedded OS
 Each type is designed for specific operational
requirements.

12. How an Operating System Works in
Practice
 1. Booting: Loading OS into memory and
initializing hardware.
 2. User Login: Grants access to resources.
 3. Running Applications: Allocates resources to
programs.
 4. File Management: Organizes data storage.
 5. System Shutdown: Releases resources
gracefully.

13. Conclusion
 Operating systems are crucial for efficient
hardware and software management.
 Understanding OS functions is foundational
for advanced topics like systems programming
and cybersecurity.

14. Compiled by:
 Engr. Asim Aziz
 Lecturer SST/ CS
 UMT, Lahore