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Operating System Concepts: An Introduction to OS Components, Functions, and Management, Study notes of Computer Science

An excerpt from the 8th edition of 'operating system concepts' by silberschatz, galvin, and gagne. It introduces the concept of operating systems, their components, functions, and management. Topics include computer system structure, operating system definition, computer startup, interrupt handling, i/o structure, process management, memory management, and storage management.

Typology: Study notes

2009/2010

Uploaded on 12/09/2010

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Silberschatz, Galvin and Gagne ©2009
Operating System Concepts – 8th Edition
Chapter 1: Introduction
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Operating System Concepts – 8th^ Edition Silberschatz, Galvin and Gagne ©

Chapter 1: Introduction

Chapter 1: Introduction

 (^) What Operating Systems Do  (^) Computer-System Organization  (^) Computer-System Architecture  (^) Operating-System Structure  (^) Operating-System Operations  (^) Process Management  (^) Memory Management  (^) Storage Management  (^) Protection and Security  (^) Distributed Systems  (^) Special-Purpose Systems  (^) Computing Environments  (^) Open-Source Operating Systems

What is an Operating System?

 (^) A program that acts as an intermediary between a user of a computer and the computer hardware.  (^) Operating system goals:  (^) Execute user programs and make solving user problems easier  (^) Make the computer system convenient to use  (^) Use the computer hardware in an efficient manner

Computer System Structure

 (^) Computer system can be divided into four components:  (^) Hardware – provides basic computing resources  (^) CPU, memory, I/O devices  (^) Operating system  (^) Controls and coordinates use of hardware among various applications and users  (^) Application programs – define the ways in which the system resources are used to solve the computing problems of the users  (^) Word processors, compilers, web browsers, database systems, video games  (^) Users  (^) People, machines, other computers

Operating System Definition

 (^) OS is a resource allocator  (^) Manages all resources  (^) Decides between conflicting requests for efficient and fair resource use  (^) OS is a control program  (^) Controls execution of programs to prevent errors and improper use of the computer

Operating System Definition (Cont.)

 (^) No universally accepted definition  (^) “Everything a vendor ships when you order an operating system” is good approximation  (^) But varies wildly  (^) “The one program running at all times on the computer” is the kernel. Everything else is either a system program (ships with the operating system) or an application program.

Computer System Organization

 (^) Computer-system operation  (^) One or more CPUs, device controllers connect through common bus providing access to shared memory  (^) Concurrent execution of CPUs and devices competing for memory cycles

Computer-System Operation

 (^) I/O devices and the CPU can execute concurrently  (^) Each device controller is in charge of a particular device type  (^) Each device controller has a local buffer  (^) CPU moves data from/to main memory to/from local buffers  (^) I/O is from the device to local buffer of controller  (^) Device controller informs CPU that it has finished its operation by causing an interrupt

Interrupt Handling

 (^) The operating system preserves the state of the CPU by storing registers and the program counter  (^) Determines which type of interrupt has occurred:  (^) polling  (^) vectored interrupt system  (^) Separate segments of code determine what action should be taken for each type of interrupt

Interrupt Timeline

Direct Memory Access Structure

 (^) Used for high-speed I/O devices able to transmit information at close to memory speeds  (^) Device controller transfers blocks of data from buffer storage directly to main memory without CPU intervention  (^) Only one interrupt is generated per block, rather than the one interrupt per byte

Storage Structure

 (^) Main memory – only large storage media that the CPU can access directly  (^) Secondary storage – extension of main memory that provides large nonvolatile storage capacity  (^) Magnetic disks – rigid metal or glass platters covered with magnetic recording material  (^) Disk surface is logically divided into tracks , which are subdivided into sectors  (^) The disk controller determines the logical interaction between the device and the computer

Storage-Device Hierarchy

Caching

 (^) Important principle, performed at many levels in a computer (in hardware, operating system, software).  (^) Information in use copied from slower to faster storage temporarily  (^) Faster storage (cache) checked first to determine if information is there.  (^) If it is, information used directly from the cache (fast)  (^) If not, data copied to cache and used there  (^) Cache smaller than storage being cached  (^) Cache management important design problem  (^) Cache size and replacement policy