heena presentation
TRANSCRIPT
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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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