heena presentation

8/10/2019 Heena Presentation

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Operating System

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Submitted by:-

Heena Ahuja

M.Tech CSE-A


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Overview of Operating System

A program that controls the execution of application programs

An interface between users and hardware - an environment"architecture

Allows efficient usage; parallel activity, avoids wasted cycles Provides information protection

Gives each user a slice of the resources

Acts as a control program.

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Features of Operating System

Process management

I/O management

Main Memory management

File & Storage Management

Protection

Networking

Command Interpreter

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1. Process Management

Process (or job): A program or a fraction of a program that isloaded in main memory.

Motivation:

1.We do not need a whole program code at once.

2.To process an instruction, CPU fetches and executes oneinstruction of a process after another in main memory.

Tasks of Process Management of an OS:1.Create, load, execute, suspend, resume, and terminate processes

2.Switch system among multiple processes in main memory.

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2. I/O Management

Tasks of I/O Management of OS

1.Hide the details of H/W devices

2.Maintain and provide device driver interfaces.

Motivations:

1. Provide an abstract level of H/W devices and keep the details fromapplications to ensure proper use of devices.

3. Main Memory management

Motivations:

1. Increase system performance by increasing hit ratio.2. Maximize memory utilization

Tasks of Main Memory Management of OS

1.Allocate/de-allocated memory as need

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4. File & Storage Management

Tasks of File Management1.Create, manipulate, delete files and directories

Tasks of Storage Management

1.Allocate, de-allocate, and defrag blocks

2.Bad block marking

3.Scheduling for multiple I/O

5. Networking

Block is the unit of data transfer of the storage device. If theblock size is 1Kbyte, each access to the device will read or write1Kbyte. Thus, for example, to read a whole file, whose size is1024Kbyte, we should access the hard drive 1024 times.

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6. Protection

Protect hardware resources, Kernel code, processes, files, anddata from erroneous programs and malicious programs.

7. Command Interpreter

Motivation:

1.Allow human users to interact with OS

2. Provide convenient programming environment to users.

Tasks:

1. Execute a user command by calling one or more number ofunderlying system programs or system calls

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Components of Operating System

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 systemresources are used to solve the computing problems of the

users Word processors, compilers, web browsers, database systems, video

games

Users People, machines, other computers

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Components & Layers of Operating System

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Needs of Advanced OS

Multitasking

Flexible

Less power consumption.

easy to use

user friendly

intermediate between all hardware and software ofthe system

no need to know any technical languages Its the platform of all programs

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Types of OS

1. Batch operating system

The users of batch operating system do not interact with the

computer directly. Each user prepares his job on an off-line device like punch cards

and submits it to the computer operator.

To speed up processing, jobs with similar needs are batchedtogether and run as a group.

Difficult to provide the desired priority

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2.Time-sharing operating systems

Time sharing is a technique which enables many people, locatedat various terminals, to use a particular computer system at thesame time.

Time-sharing or multitasking is a logical extension ofmultiprogramming.

The objective is to minimize response time.

Advantages of Timesharing operating systems are following

Provide advantage of quick response.

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3.Distributed operating System

It use multiple central processors to serve multiple real timeapplication and multiple users.

The processors communicate with one another through various

communication lines. Speedup the exchange of data with one another via electronic

mail.

Better service to the customers.

Reduction of delays in data processing.

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4. Network operating System

It can runs on a server and provides server the capability tomanage data, users, security, applications, and other networkingfunctions.

Security is server managed.

Upgrades to new technologies.

High cost of buying and running a server.

Dependency on a central location for most operations.

Regular maintenance and updates are required.

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5.Real Time operating System

Real time system is defines as a data processing system inwhich the time interval required to process and respond toinputs is so small.

It is always on line whereas on line system need not be real

time.

The time taken by the system to respond to an input anddisplay of required updated information is termed as responsetime.

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