Operating System: What It Does Than By What It Is

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OPERATING SYSTEM what it does than by what it is

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Assembler Text Editor ……….. Database System Operating System

Computer Hardware

Abstract View of the components of a computer system

Design & Implementation Overview Process Management Storage Management I/ O Systems Distributed Systems Protection & Security

Overview A modern computer system consists of one or more processors, some main memory, disks, printers, a keyboard, a display, network input/ output devices other interfaces and other.

INTRODUCTION A computer cannot perform any work without software. With its software a computer can store, process, and retrieve information, play music and videos; send e-mail, search the Internet. Computer Software can be divided in two kinds: System programs, which manage the operation of the computer itself, and application programs, which perform the actual work the user wants. Fundamental system program is the operating system, whose job is to control all the computer’s resources and provide upon which the application programs can be written.

Operating Systems can be viewed from two viewpoint: 1) Resource Manager 2) An Extended Machine

As Resource Manager the job of operating system is to efficiently manage the different parts of the system. The operating system is designed to maximize resource utilization. In the extended machine view the job of the system is to provide the users with a virtual machine which is more convenient to use than actual machine.

Performance is important to the users. We can view an operating system as a resource allocator. An operating system is a control program written in C language. A control program manages the execution of user programs to prevent errors and improper use of the computer.

The operating system resides in memory

The operating system could perform job scheduling.

Mainframe Systems : Used to tackle commercial & scientific application

Batch Systems: To speed up processing, operators batched together jobs with similar needs and ran them through the computer as a group.

Multiprogrammed Systems: Multiprogramming increases CPU utilisation by organising jobs so that the CPU always has one eecute. Operating system keeps several jobs in memory simultaneously in a queue. Operating system picks and begins to eeute one of the jobs in the memory.

Time-Sharing systems: Also known as multitasking CPU executes multiple jobs by switching from one job to another frequently and user can interact with each program while it is running. An interactive computer system provides direct communication between user and system.

A time shared operating system allows many users to share the computer simultaneously. As the system switches rapidly from one user to the next , each user is given the4 impression that the entire computer system is dedicated to her, though it is shared by many users.

Desktop Systems Multiprocessor Systems: Also known as parallel system or tightly coupled system.are growng in importance. Distributed Systems:

Client- Server Systems Computer –server systems File- server systems Peer-to-Peer Systems : Client

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Clustered Systems Real- Time Systems Handheld Systems