OMCA103 Operating Systems Unit 1-12 SMU Sem-1
Unit 1 – Operating System – An Introduction
1. Introduction
Operating Systems (O.S): An essential software layer that manages hardware and software resources in computing devices. It serves as an interface between users and the computer hardware.
1.1 Objectives
Define and describe the functions of operating systems.
Explain the evolution of operating systems.
Discuss operating system structures.
2. Definition and Functions of Operating System
Definition: An Operating System is system software that provides an environment to help users execute programs.
Functions:
Processor Management: Allocates processors to tasks to be performed.
Memory Management: Manages allocation of both main and secondary storage for system and user programs/data.
Input and Output Management: Coordinates and assigns tasks among input/output devices.
File System Management: Handles file creation, deletion, movement, and management.
Priority System: Establishes and enforces the order of job executions based on priorities.
3. Evolution of Operating Systems
Describes the evolution from primitive systems to complex ones. Categories include:
Simple Batch Operating Systems
Multi-programmed Batch Operating Systems
Time-sharing Operating Systems
Personal Computer Operating Systems
Multi-Processor Operating Systems
Distributed Systems
Real-time Systems
3.1 Simple Batch Operating Systems
Early systems with job control manual execution.
3.2 Multi-programmed Batched Operating Systems
Introduced to reduce CPU idle time by executing jobs from memory based on demand.
3.3 Time-sharing Operating Systems
Allows multiple users to interact with processes by quickly switching between them.
3.4 Personal Computer Operating Systems
Designed primarily for individual users, featuring single-task execution.
3.5 Multi-Processor Operating Systems
Resources shared among multiple processors to enhance performance and reliability.
3.6 Distributed Systems
Systems that function in a network where resources and processes are shared across multiple locations.
3.7 Real-time Systems
Designed to respond timely to inputs/events, critical in applications needing high responsiveness.
4. Operating System Structures
Layered Approach: Divides the OS into layers, each with specific functionality.
Kernel-based Approach: A nucleus that supports basic operations while the system expands outside that nucleus.
Virtual Machine Approach: Provides users with the illusion of an entire machine environment, independent from hardware limitations.
5. Summary
Summary of concepts learned including history, functions, and structures of operating systems.
6. Terminal Questions
Questions focusing on definitions, functionalities, and structures of operating systems.
7. Answers
Self-assessment answers covering definitions, operating system evolution, and specific functions.