Operating System About the Tutorial An operating system (OS) is a collection of software that manages computer hardware resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system. This tutorial will take you through step-by-step approach while learning Operating System concepts. Audience This tutorial has been prepared for the computer science graduates to help them understand the basic to advanced concepts related to Operating System. Prerequisites Before you start proceeding with this tutorial, we are making an assumption that you are already aware of basic computer concepts like what is keyboard, mouse, monitor, input, output, primary memory and secondary memory etc. If you are not well aware of these concepts, then we will suggest to go through our short tutorial on Computer Fundamentals. Copyright & Disclaimer © Copyright 2016 by Tutorials Point (I) Pvt. Ltd. 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If you discover any errors on our website or in this tutorial, please notify us at [email protected] 1 Operating System Table of Contents About the Tutorial ................................................................................................................................... 1 Audience ................................................................................................................................................. 1 Prerequisites ........................................................................................................................................... 1 Copyright & Disclaimer ............................................................................................................................ 1 Table of Contents .................................................................................................................................... 2 1. OPERATING SYSTEM – OVERVIEW ....................................................................................... 1 Definition ................................................................................................................................................ 1 Memory Management ............................................................................................................................ 2 Processor Management .......................................................................................................................... 2 Device Management ............................................................................................................................... 2 File Management .................................................................................................................................... 2 Other Important Activities ...................................................................................................................... 3 2. OPERATING SYSTEM ─ TYPES ............................................................................................... 4 Batch Operating System .......................................................................................................................... 4 Time-sharing Operating Systems ............................................................................................................. 4 Distributed Operating System ................................................................................................................. 5 Network Operating System ..................................................................................................................... 5 Real-Time Operating System ................................................................................................................... 6 3. OPERATING SYSTEM ─ SERVICES ......................................................................................... 7 Program Execution .................................................................................................................................. 7 I/O Operation .......................................................................................................................................... 7 File System Manipulation ........................................................................................................................ 8 Communication ....................................................................................................................................... 8 Error Handling ......................................................................................................................................... 8 Resource Management ........................................................................................................................... 9 2 Operating System Protection ............................................................................................................................................... 9 4. OPERATING SYSTEM ─ PROPERTIES ................................................................................... 10 Batch Processing ................................................................................................................................... 10 Multitasking .......................................................................................................................................... 11 Multiprogramming ................................................................................................................................ 12 Interactivity ........................................................................................................................................... 13 Real-Time Systems ................................................................................................................................ 13 Distributed Environment ....................................................................................................................... 13 Spooling ................................................................................................................................................ 13 5. OPERATING SYSTEM ─ PROCESSES .................................................................................... 15 Process .................................................................................................................................................. 15 Program ................................................................................................................................................ 16 Process Life Cycle .................................................................................................................................. 16 Process Control Block (PCB)................................................................................................................... 17 6. OPERATING SYSTEM ─ PROCESS SCHEDULING .................................................................. 19 Definition .............................................................................................................................................. 19 Process Scheduling Queues ................................................................................................................... 19 Two-State Process Model ...................................................................................................................... 20 Schedulers ............................................................................................................................................. 20 Long-Term Scheduler ............................................................................................................................ 20 Short-Term Scheduler ........................................................................................................................... 20 Medium-Term Scheduler ....................................................................................................................... 21 Comparison among Schedulers ............................................................................................................. 21 Context Switch ...................................................................................................................................... 21 7. OPERATING SYSTEM ─ SCHEDULING ALGORITHMS ........................................................... 23 First Come, First Served (FCFS) .............................................................................................................. 23 3 Operating System Shortest Job Next (SJN) ......................................................................................................................... 24 Priority Based Scheduling ...................................................................................................................... 25 Shortest Remaining Time .....................................................................................................................