Efficiency, system performance and user convenience
Classes of operating systems
Batch processing system,
Multi programming systems
Time sharing systems
Real time operating systems
Operation of an O.S
Structure of an operating system,
Operating systems with monolithic structure
Layered design of an operating system
Virtual machine operating systems
Kernel based operating systems
The purpose of developing a Mobile-Based Attendance System is to computerized the tradition way of taking attendance. Another purpose for developing this software is to generate the report automatically at the end of the session or in the between of the session
This project is based on online Attendance System for the college and School Attendance managing purpose. And it is also a major project for cs b.tech final year.
Efficiency, system performance and user convenience
Classes of operating systems
Batch processing system,
Multi programming systems
Time sharing systems
Real time operating systems
Operation of an O.S
Structure of an operating system,
Operating systems with monolithic structure
Layered design of an operating system
Virtual machine operating systems
Kernel based operating systems
The purpose of developing a Mobile-Based Attendance System is to computerized the tradition way of taking attendance. Another purpose for developing this software is to generate the report automatically at the end of the session or in the between of the session
This project is based on online Attendance System for the college and School Attendance managing purpose. And it is also a major project for cs b.tech final year.
A presentation on different CPU scheduling algorithms such as SJF, RR and FIFO detailed explanation with advantages and disadvantages of each algorithm. This ppt also contains brief information about the multiprocessor scheduling and the performance evaluation of Scheduling algorithms.
In recent times, higher education institutions have been paying close attention to student opinions about the
experience of learning and teaching through internal surveys. The online feedback system is a web-based application
that provides students' feedback to college’s base online. This online system is a good place to find the kind of feedback
you need and it is efficient to get feedback analysis. Students provide feedback online through the use of a standard
designed form. In the proposed system, security is included, the result of which is visible only to accredited users. Online
feedback is an indispensable feature of evaluating effective and efficient teaching and learning methods. Report is made
in the proposed system for creating and the semantic web seeks to recreate the existing web concept that will enable us.
Advanced automation of web content, so that data can be distributed and processed by humans and software.
PowerPoint Presentation on Distributed Operating Systems,reasons for opting for distributed systems over centralized systems,types of Distributed Systems,Process Migration and its advantages.
INTRODUCTIONTO OPERATING SYSTEM
What is an Operating System?
Mainframe Systems
Desktop Systems
Multiprocessor Systems
Distributed Systems
Clustered System
Real -Time Systems
Handheld Systems
Computing Environments
A presentation on different CPU scheduling algorithms such as SJF, RR and FIFO detailed explanation with advantages and disadvantages of each algorithm. This ppt also contains brief information about the multiprocessor scheduling and the performance evaluation of Scheduling algorithms.
In recent times, higher education institutions have been paying close attention to student opinions about the
experience of learning and teaching through internal surveys. The online feedback system is a web-based application
that provides students' feedback to college’s base online. This online system is a good place to find the kind of feedback
you need and it is efficient to get feedback analysis. Students provide feedback online through the use of a standard
designed form. In the proposed system, security is included, the result of which is visible only to accredited users. Online
feedback is an indispensable feature of evaluating effective and efficient teaching and learning methods. Report is made
in the proposed system for creating and the semantic web seeks to recreate the existing web concept that will enable us.
Advanced automation of web content, so that data can be distributed and processed by humans and software.
PowerPoint Presentation on Distributed Operating Systems,reasons for opting for distributed systems over centralized systems,types of Distributed Systems,Process Migration and its advantages.
INTRODUCTIONTO OPERATING SYSTEM
What is an Operating System?
Mainframe Systems
Desktop Systems
Multiprocessor Systems
Distributed Systems
Clustered System
Real -Time Systems
Handheld Systems
Computing Environments
An operating system acts as an intermediary between the user of a computer and computer hardware. The purpose of an operating system is to provide an environment in which a user can execute programs in a convenient and efficient manner.
FellowBuddy.com is an innovative platform that brings students together to share notes, exam papers, study guides, project reports and presentation for upcoming exams.
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ER Publication,
IJETR, IJMCTR,
Journals,
International Journals,
High Impact Journals,
Monthly Journal,
Good quality Journals,
Research,
Research Papers,
Research Article,
Free Journals, Open access Journals,
erpublication.org,
Engineering Journal,
Science Journals,
Engineering Research Publication
Best International Journals, High Impact Journals,
International Journal of Engineering & Technical Research
ISSN : 2321-0869 (O) 2454-4698 (P)
www.erpublication.org
Operating Systems, Introduction of OS, Objectives of OS, Service provided by the OS, OS as resource manager, Evolution of OS, Simple batch systems, Multi programmed batch systems, Time sharing systems, Major achievements of OS, Process, memory management, information protection and security, scheduling and resource management, System structure of OS, developments leading to modern operating systems, microkernal architecture, multithreading, distributed OS, Symmetric multiprocessing, object oriented design
An Operating System or OS is the most important software and program that can run all types of Computer, Mobile phone, Hand Held Device, etc. It helps to connect and interface computer hardware to program and application software and other common essential services. The OS is initially loaded on at boot time. Like a host, the OS acts for running and handling of application programs and operation of the hardware on the machine. The working principle of OS is first to configure then check ability to perform and then allow the program to run. Its main purpose is to handle the activities based on computer hardware. The OS also provides management of input, output and storage devices. Mostly in a system, some different computer programs run at the same time and they need to access CPU, memory, and storage. In an operating system, the user can communicate with the Command Line Interface by typing some command, and the user receives the response back from the system. But Modern Time Operating system uses a graphical user interface or GUI for easy to use. Now user can communicate with a system using a mouse to click button, menus, and everything is displayed on the screen using Text, Graphics or image. It is like a bank manager-- it makes sure that the working of application software must not be interfered by any other activity. Sumanta Kabiraj | Anjli Gupta | Prof. Subhashis Kumar Chandra"Operating System a Case Study" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-2 | Issue-3 , April 2018, URL: http://www.ijtsrd.com/papers/ijtsrd10780.pdf http://www.ijtsrd.com/computer-science/operating-system/10780/operating-system-a-case-study/sumanta-kabiraj
Transducers and sensors
Sensors in robotics
Tactile sensors
Proximity and range sensors
Miscellaneous sensors and sensor based system
Use of sensors in Robotics
Methods of robot programming
Leadthrough programming methods
A robot program as a path in space
Motion interpolation
WAIT, SIGNAL and DELAY commands
Branching
File system and IOCS
Files and file organization
Fundamentals of file organizations
Directory structures
File protection
Interface between file system and IOCS
Allocation of disk space
Implementation of file access
Managing the memory hierarchy
Static and dynamic memory allocations
Memory allocation to a process
Reuse of memory
Contiguous and non contiguous memory allocation
Paging
Segmentation
Segmentation with paging
Definition
Embedded systems vs. General Computing Systems
Core of the Embedded System
Memory
Sensors and Actuators
Communication Interface
Embedded Firmware
Other System Components
PCB and Passive Components
Introduction
Types of end effectors
Mechanical gripper
Other types of grippers
Tools as end effectors
The Robot/End effectors interface
Considerations in gripper selection and design
Fundamentals of Robotics and Machine Vision Systemanand hd
Automation and Robotics
Robotics in science Fiction
A brief history of robotics
Robot Anatomy & Work volume
Robot drive systems
Control systems and Dynamic performance
Precision of movement
End effectors
Robotic sensors,
Robot programming and work cell control
Robot applications
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
NO1 Uk best vashikaran specialist in delhi vashikaran baba near me online vas...Amil Baba Dawood bangali
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Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Immunizing Image Classifiers Against Localized Adversary Attacksgerogepatton
This paper addresses the vulnerability of deep learning models, particularly convolutional neural networks
(CNN)s, to adversarial attacks and presents a proactive training technique designed to counter them. We
introduce a novel volumization algorithm, which transforms 2D images into 3D volumetric representations.
When combined with 3D convolution and deep curriculum learning optimization (CLO), itsignificantly improves
the immunity of models against localized universal attacks by up to 40%. We evaluate our proposed approach
using contemporary CNN architectures and the modified Canadian Institute for Advanced Research (CIFAR-10
and CIFAR-100) and ImageNet Large Scale Visual Recognition Challenge (ILSVRC12) datasets, showcasing
accuracy improvements over previous techniques. The results indicate that the combination of the volumetric
input and curriculum learning holds significant promise for mitigating adversarial attacks without necessitating
adversary training.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
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Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Technical Specifications
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
Key Features
Indigenized remote control interface card suitable for MAFI system CCR equipment. Compatible for IDM8000 CCR. Backplane mounted serial and TCP/Ethernet communication module for CCR remote access. IDM 8000 CCR remote control on serial and TCP protocol.
• Remote control: Parallel or serial interface
• Compatible with MAFI CCR system
• Copatiable with IDM8000 CCR
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
Application
• Remote control: Parallel or serial interface.
• Compatible with MAFI CCR system.
• Compatible with IDM8000 CCR.
• Compatible with Backplane mount serial communication.
• Compatible with commercial and Defence aviation CCR system.
• Remote control system for accessing CCR and allied system over serial or TCP.
• Indigenized local Support/presence in India.
• Easy in configuration using DIP switches.
Pile Foundation by Venkatesh Taduvai (Sub Geotechnical Engineering II)-conver...
OS introduction
1. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56
OPERATING SYSTEM
Mr. Anand H. D.
1
Operating System: Introduction
Department of Electronics & Communication Engineering
Dr. Ambedkar Institute of Technology
Bengaluru-56
2. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 2
Operating System: Introduction
Goals of an Operating System : Efficient Use User Convenience Noninterference
Operation of an Operating System: Program management Resource management Security and protection
Topics to be covered:
Goals of an Operating System
Operation of an Operating System
https://youtu.be/pTdSs8kQqSA
3. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 3
Operating System: Introduction
Goals of an Operating System : User Convenience Noninterference
Operation of an Operating System: Program management Resource management Security and protection
Goals of Operating System:
Efficient Use
The fundamental goals of an operating system are:
• Efficient use
• User convenience
• Noninterference
The goals of efficient use and user convenience sometimes conflict.
For example, emphasis on quick service would lead to inefficient use of resources,
the designer has to make a trade-off to obtain the combination of efficient use and user
convenience that best suits the environment-effective utilization of the computer system.
Interference with a user’s activities:-
Operating Systems:
illegal use or modification of a user’s programs or data,
denial of resources and services to a user.
: Ensure efficient use of a computer’s resources.
: Provide convenient methods of using a computer system.
: Prevent interference in the activities of its users.
fast service required by command and control applications,
make efficient use of computer resources to provide low-cost
computing
provide different combinations of the two extremes
4. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 4
Operating System: Introduction
Goals of an Operating System : User Convenience Noninterference
Operation of an Operating System: Program management Resource management Security and protection
Goals of Operating System:
Efficient Use
An operating system must ensure efficient use of the fundamental computer system
resources of memory, CPU, and I/O devices such as disks and printers.
Poor efficiency can result if a program does not use a resource allocated to it, e.g., if
memory or I/O devices allocated to a program remain idle - leads to snowballing effect
In addition, the OS itself consumes some CPU and memory resources during its own
operation, and this consumption of resources constitutes an overhead that also reduces the
resources available to user programs.
Efficient use of resources can be obtained by monitoring use of resources and performing
corrective actions when necessary. However, monitoring use of resources increases the
overhead, which lowers efficiency of use.
In practice, operating systems that emphasize efficient use limit their overhead by either
restricting their focus to efficiency of a few important resources, like the CPU and the
memory, or by not monitoring the use of resources at all, and instead handling user
programs and resources in a manner that guarantees high efficiency
5. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 5
Operating System: Introduction
Goals of an Operating System : Noninterference
Operation of an Operating System: Program management Resource management Security and protection
Goals of Operating System:
Efficient Use User Convenience
User convenience has many facets, as shown in following Table:
Fulfillment of necessity
Good Service
User friendly interfaces
New programming model
Web-oriented features
Evolution
Ability to execute programs, use the file system
Speedy response to computational requests
Easy-to-use commands, graphical user interface (GUI)
Concurrent programming
Means to set up Web-enabled servers
Add new features, use new computer technologies
Facet Examples
Table: Facets of User Convenience
6. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 6
Operating System: Introduction
Goals of an Operating System : Noninterference
Operation of an Operating System: Program management Resource management Security and protection
Goals of Operating System:
Efficient Use User Convenience
In the early days of computing, user convenience was synonymous with bare necessity
Other facets of user convenience evolved with the use of computers in new fields. Early
operating systems had command-line interfaces, which required a user to type in a
command and specify values of its parameters- scientists or computer professionals
Simpler interfaces were needed to facilitate use of computers by new classes of users. Hence
graphical user interfaces (GUIs) were evolved. These interfaces used icons on
a screen to represent programs and files and interpreted mouse clicks on the icons and
associated menus as commands concerning them.
New models were proposed for developing cost-effective solutions to new classes of
problems. Some of these models could be supported by the compiler technology and required
little support from the OS; modular and object-oriented program design are two such models.
Other models like the concurrent programming model required specific support features in
the OS.
Advent of the Internet motivated setting up of Web-enabled servers, which required
networking support and an ability to scale up or scale down the performance of a server in
response to the amount of load directed at it.
Users and their organizations invest considerable time and effort in setting up their
applications through an operating system. This investment must be protected when new
application areas and new computer technologies develop,
7. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 7
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Program management Resource management Security and protection
Goals of Operating System:
Efficient Use User Convenience Noninterference
A computer user can face different kinds of interference in his computational activities.
Execution of his program can be disrupted by actions of other persons, or the OS services.
The OS prevents such interference by allocating resources for exclusive use of
programs and OS services, and preventing illegal accesses to resources.
Another form of interference is when a computer user may collaborate with some other users
in the development or use of a computer application, so he may wish to share some of his files
with them.
Attempts by any other person to access his files are illegal and constitute interference.
To prevent this form of interference, an OS has to know which files of a user can
be accessed by which persons. It is achieved through the act of authorization,
whereby a user specifies which collaborators can access what files. The OS uses this
information to prevent illegal accesses to files.
8. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 8
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Resource management Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management
The primary concerns of an OS during its operation are execution of programs,
use of resources, and prevention of interference with programs and resources.
Accordingly, its three principal functions are:
• Program management: The OS initiates programs, arranges their execution on the CPU,
and terminates them when they complete their execution.
Since many programs exist in the system at any time, the OS performs a function called
scheduling to select a program for execution
• Resource management: The OS allocates resources like memory and I/O devices when a
program needs them.
When the program terminates, it de-allocates these resources and allocates them to other
programs that need them.
• Security and protection: The OS implements noninterference in users’ activities through
joint actions of the security and protection functions.
As an example, consider how the OS prevents illegal accesses to a file.
The security function prevents nonusers from utilizing the services and resources in the
computer system, hence none of them can access the file.
The protection function prevents users other than the file owner or users authorized by
him, from accessing the file.
9. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 9
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Resource management Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management
Table describes the tasks commonly performed by an operating system.
Construct a list of resource
Maintain information for security
Verify identity of a user
Initiate execution of programs
Maintain authorization information
Perform resource allocation
During booting
While registering new users
At user commands
When a user specifies which collaborators can access what
programs or data
When requested by users or programs
Task When performed
Table: Common Tasks Performed by Operating Systems
At login time
Maintain current status of resources
Maintain current status of programs
and perform scheduling
During resource allocation/de-allocation
Continually during OS operation
10. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 10
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Resource management Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management
When a computer system is switched on, it automatically loads a program stored on a
reserved part of an I/O device, typically a disk, and starts executing the program. This
program follows a software technique known as bootstrapping to load the software called
the boot procedure in memory
The boot procedure makes a list of all hardware resources in the system, and hands over
control of the computer system to the OS.
A system administrator specifies which persons are registered as users of the system. The
OS permits only these persons to log in to use its resources and services.
A user authorizes his collaborators to access some programs and data. The OS notes this
information and uses it to implement protection.
The OS also performs a set of functions to implement its notion of effective utilization.
These functions include scheduling of programs and keeping track of resource status
and resource usage information.
11. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 11
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Resource management Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management
Modern CPUs have the capability to execute program instructions at a very high rate, so it is
possible for an OS to interleave execution of several programs on a CPU and yet provide good
user service.
The key function in achieving interleaved execution of programs is scheduling, which decides
which program should be given the CPU at any time.
Figure shows an abstract view of scheduling.
Figure: A schematic of scheduling.
Scheduler CPU
Completed
Program
New
Program
…..
Programs in ready Queue
waiting for CPU
Scheduled
Program
P1P2Pn
Preempted Program
12. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 12
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Resource management Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management
The scheduler, which is an OS routine that performs scheduling, maintains a list of programs waiting
to execute on the CPU, and selects one program for execution.
In operating systems that provide fair service to all programs, the scheduler also specifies how long
the program can be allowed to use the CPU.
The OS takes away the CPU from a program after it has executed for the specified period of time, and
gives it to another program. This action is called preemption. A program that loses the CPU because of
preemption is put back into the list of programs waiting to execute on the CPU.
The scheduling policy employed by an OS can influence both efficient use of the CPU and user service.
If a program is preempted after it has executed for only a short period of time, the overhead of
scheduling actions would be high because of frequent preemption. However, each program would
suffer only a short delay before it gets an opportunity to use the CPU, which would result in good user
service.
If preemption is performed after a program has executed for a longer period of time, scheduling
overhead would be lesser but programs would suffer longer delays, so user service would be poorer
13. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 13
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management
Resource allocations and de-allocations can be performed by using a resource table. Each entry in the table
contains the name and address of a resource unit and its present status, indicating whether it is free or allocated
to some program.
Table below is one such table for management of I/O devices. It is constructed by the boot procedure by sensing
the presence of I/O devices in the system, and updated by the operating system to reflect the allocations and
deallocations made by it.
printer1
printer2
printer3
disk1
disk2
cdw1
Resource
Name
AddressClass Allocation
status
Printer
Printer
Printer
Disk
Disk
CD writer
101
102
103
201
202
301
Allocated to P1
Free
Free
Allocated to P1
Allocated to P2
Free
Resource Table for I/O Devices
14. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 14
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management
Two resource allocation strategies are popular.
In the resource partitioning approach, the OS decides a priori what resources should be allocated to
each user program,
for example, it may decide that a program should be allocated 1 MB of memory, 1000 disk
blocks, and a monitor. It divides the resources in the system into many resource partitions, or
simply partitions; each partition includes 1 MB of memory, 1000 disk blocks, and a monitor.
It allocates one resource partition to each user program when its execution is to be initiated. To
facilitate resource allocation, the resource table contains entries for resource partitions rather than
for individual resources as in Table shown.
Resource partitioning is simple to implement, hence it incurs less overhead; however, it lacks
flexibility. Resources are wasted if a resource partition contains more resources than what a
program needs.
Also, the OS cannot execute a program if its requirements exceed the resources available in a
resource partition. This is true even if free resources exist in another partition.
15. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 15
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management
In the pool-based approach to resource management, the OS allocates resources from a common pool of
resources. It consults the resource table when a program makes a request for a resource, and allocates the
resource if it is free. It incurs the overhead of allocating and de-allocating resources when requested.
However, it avoids both problems faced by the resource partitioning approach— an allocated resource is not
wasted, and a resource requirement can be met if a free resource exists.
A virtual resource is a fictitious resource—it is an illusion supported by an OS through use of a real resource.
An OS may use the same real resource to support several virtual resources. This way, it can give the impression
of having a larger number of resources than it actually does.
Each use of a virtual resource results in the use of an appropriate real resource. In that sense, a virtual resource
is an abstract view of a resource taken by a program. Use of virtual resources started with the use of virtual
devices.
To prevent mutual interference between programs, it was a good idea to allocate a device exclusively for use
by one program. However, a computer system did not possess many real devices, so virtual devices were used.
An OS would create a virtual device when a user needed an I/O device;
16. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 16
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Security and protection
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management
In Table it could be two virtual disks based on the real disk, which are allocated to programs P1
and P2, respectively.
Virtual devices are used in contemporary operating systems as well. A print server is a common
example of a virtual device.
When a program wishes to print a file, the print server simply copies the file into the print queue.
The program requesting the print goes on with its operation as if the printing had been performed.
The print server continuously examines the print queue and prints the files it finds in the queue.
Most operating systems provide a virtual resource called virtual memory, which is an illusion of a
memory that is larger in size than the real memory of a computer. Its use enables a programmer to
execute a program whose size may exceed the size of real memory.
Some operating systems create virtual machines (VMs) so that each machine can be allocated
to a user. The advantage of this approach is twofold.
Allocation of a virtual machine to each user eliminates mutual interference between users. It
also allows each user to select an OS of his choice to operate his virtual machine. In effect, this
arrangement permits users to use different operating systems on the same computer system
simultaneously
17. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 17
Operating System: Introduction
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management Security and protection
An OS must ensure that no person can illegally use programs and resources in the system, or interfere with
them in any manner.
The security function counters threats of illegal use or interference that are posed by persons or programs
outside the control of an operating system, whereas the protection function counters similar threats posed by its
users.
Figure illustrates how security and protection threats arise in an OS.
Overview of security and
protection threats.
18. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 18
Operating System: Introduction
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management Security and protection
In a classical stand-alone environment, a computer system functions in complete isolation. In such
a system, the security and protection issues can be handled easily..
The identity of a person wishing to use a computer system is verified through a password when
the person logs in. This action, which is called authentication, ensures that no person other than a
registered user can use a computer system. Consequently, security threats do not arise in the
system if the authentication procedure is foolproof.
The OS prevents disruption of program executions and OS services with the help of hardware
features such as memory protection.
It overcomes interference with files by allowing a user to access a file only if he owns it or has
been authorized by the file’s owner to access it
When a computer system is connected to the Internet, and a user downloads a program from
the Internet, there is a danger that the downloaded program may interfere with other programs
or resources in the system.
This is a security threat because the interference is caused by some person outside the system,
called an intruder, who either wrote the downloaded program, or modified it, so that it would
interfere with other programs.
19. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 19
Operating System: Introduction
Goals of Operating System:
operations of Operating System:
Efficient Use User Convenience Noninterference
Program management Resource management Security and protection
Another class of security threats is posed by programs called worms, which replicate by
themselves through holes in security setups of operating systems. Worms can replicate at
unimaginably high rates and cause widespread havoc. The Code Red worm of 2001 spread to a
quarter of a million computer systems in 9 hours.
Such security threats are posed either through a Trojan horse, which is a program that has a
known legitimate function and a well-disguised malicious function, or a virus, which is a piece of
code with a malicious function that attaches itself to other programs in the system and spreads to
other systems when such programs are copied.
Operating systems address security threats through a variety of means—
Users are expected to contribute to security by using passwords that are impossible to guess
and by exercising caution while downloading programs from the Internet
by using Internet firewalls to filter out unwanted Internet traffic through a computer system.
by using sophisticated authentication techniques,
by plugging security holes when they are discovered,
by ensuring that programs cannot be modified while they are copied over the Internet,
20. Prepared by Prof. Anand H. D., Dept. of ECE, Dr. AIT, Bengaluru-56 20
Operating System: Introduction
Goals of an Operating System :
Operation of an Operating System: Program management Resource management Security and protection
Goals of Operating System:
operations of Operating System:
Reference
1. D.M.Dhamdhare, “Operating Systems”,
Second Edition, TMH, 2008
NoninterferenceEfficient Use User Convenience
21. 21
Prof. Anand H. D.
M. Tech. (PhD.)
Assistant Professor,
Department of Electronics & Communication Engineering
Dr. Ambedkar Institute of Technology, Bengaluru-56
Email: anandhdece@dr-ait.org
Phone: 9844518832