Topic: Operating Systems

A. Learning Objectives

By the end of this topic, the learner should be able to:

1. Define an Operating System (OS) and explain its purpose in a computer system.

2. Describe the main functions of an OS, including process management, memory management, file management, and device management.

3. Differentiate between types of operating systems, such as batch, multiprogramming, multitasking, real-time, distributed, and network OS.

4. Explain the concept of process, threads, and CPU scheduling and their importance in system performance.

5. Describe different memory management techniques like paging, segmentation, and virtual memory.

6. Explain file systems and directory structures used by operating systems.

7. Identify common operating system security features and threats.

8. Perform basic OS operations and commands (e.g., Windows, Linux).

9. Analyze performance issues related to operating systems and suggest solutions.

B. Summary of Key Concepts in Operating Systems

1. Definition of Operating System

An Operating System is system software that acts as an intermediary between the user and the computer hardware. It manages hardware resources and provides services for computer programs.

2. Functions of an Operating System

• Process Management
  Manages processes, CPU scheduling, creation/termination of processes, and multitasking.

• Memory Management
  Allocates and tracks memory usage, implements techniques like paging and virtual memory.

• File Management
  Organizes, stores, retrieves, and protects data on storage devices.

• Device/IO Management
  Controls communication between hardware devices and applications.

• Security and Protection
  Ensures authorized access, protects data, and prevents system misuse.

• User Interface
  Provides CLI (Command Line Interface) or GUI (Graphical User Interface).

3. Types of Operating Systems

• Batch OS – executes jobs without user interaction.

• Time-sharing / Multitasking OS – supports multiple users by quickly switching between tasks.

• Multiprogramming OS – runs multiple programs in memory simultaneously.

• Real-Time OS (RTOS) – processes tasks within strict time constraints (e.g., medical systems).

• Distributed OS – manages a group of networked computers as one system.

• Network OS – provides network services to connected computers.

4. Processes and Threads

• Process: An executing program.

• Thread: The smallest unit of CPU execution within a process.

• CPU Scheduling: Deciding which process runs next (e.g., FCFS, Round Robin, Priority).

5. Memory Management Concepts

• Logical vs. Physical Memory

• Paging & Segmentation

• Virtual Memory (using secondary storage as extension of RAM)

• Memory Allocation Algorithms

6. File System Concepts

• File organization methods

• Directory structures (single level, two-level, hierarchical)

• File attributes and permissions

• File access methods (sequential, direct)

7. Input/Output System

• Device drivers

• Interrupts

• Buffers and spooling

8. Operating System Security

• Authentication (passwords, biometrics)

• Authorization and permissions

• Malware protection

• Encryption

• System auditing

9. Examples of Operating Systems

• Windows OS

• Linux/Unix systems

• macOS

• Android & iOS

• Real-time OS (VxWorks, FreeRTOS)