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GROUP MEMBERSROHAN HALDANKAR (66)

MAYUR RAHATE (87)

SURAJ SHELAR (97)CHETAN TALAN (107)

KRUPA VAGAL (115)

MOMIN

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WHAT IS AN OPERATING SYSTEM?

y An interface between users and hardware - an environment "architecture

y Allows convenient usage; hides the tedious stuff

y Allows efficient usage; parallel activity, avoids wasted cycles

y Provides information protection

y Gives each user a slice of the resourcesy Acts as a control program.

1: Operating Systems Overview 3

OPERATING SYSTEM

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Computer SystemComponents1. Hardware provides basic computing resources (CPU,

memory, I/O devices).

2. Operating system controls and coordinates the use of thehardware among the various application programs for thevarious users.

3. Applications programs define the ways in which thesystem resources are used to solve the computing problemsof the users (compilers, database systems, video games,business programs).

4.Users (people, machines, other computers).

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Layers ofComputer System

5

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Historyy Back in the early 1950s there were very few

computers.

y Organizations that had computers soon started toemploy professional "computer operators".

y Changes made for more efficient programexecution

y Multiprogramming

y Virtual Memory

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EvolutionofOS

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Operating System Concepts

Process Concepty An operating system executes a variety ofprograms:y Batch system jobsy Time-shared systems user programs or tasks

y Textbook uses the terms job and process almostinterchangeably.y Process a program in execution; process

execution must progress in sequential fashion.y A process includes:

y

program countery stacky data section

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Operating System Concepts

Process State

y As a process executes, it changes statey new: The process is being created.y running: Instructions are being executed.

y waiting: The process is waiting for some event tooccur.

y ready: The process is waiting to be assigned to aprocess.

y terminated: The process has finished execution.

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Operating System Concepts

DiagramofProcess State

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View of System Components

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Description Windows 98 Windows XP Windows 7

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Howto Install Windows XP ?

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Video

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Features ofOperating Systemy Program execution system capability to load a program into memory and to

run it.

y I/O operations since user programs cannot execute I/O operations directly,the operating system must provide some means to perform I/O.

y File-system manipulation program capability to read, write, create, anddelete files.

y Communications exchange of information between processes executingeither on the same computer or on different systems tied together by anetwork. Implemented via shared memory or message passing.

y Error detection ensure correct computing by detecting errors in the CPU and

memory hardware, in I/O devices, or in user programs.

Contd..

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Additional functions exist not for helping the user, butrather for ensuring efficient system operations.

Resource allocation allocating resources to multipleusers or multiple jobs running at the same time. Accounting keep track of and record which users use

how much and what kinds of computer resources foraccount billing or for accumulating usage statistics.

Protection ensuring that all access to system resourcesis controlled.

Features ofOperating System