PDF | It includes an introduction to Operating system (OS): Computer system structure and organization. Lecture Notes on Operating System. OVER VIEW OF OPERATING SYSTEM. What is an Operating System? A program that acts as an intermediary between a user of a computer and the computer. What is an Operating System? ▫ A basis for application programs. ▫ An intermediary between users and hardware. ▫ Amazing variety. ▫ Mainframe, personal.
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Lecture 1: Introduction to Operating Systems. • An operating system is a program that acts as an intermediary between a user of a computer and the computer. Operating Systems Lecture Notes. These lecture notes are drawn from material from a variety of sources. Lecture 01 -- Introduction ps pdf; Lecture 02 -- OS History ps pdf; Lecture 03 -- Computer System Structures ps pdf; Lecture Which OS takes better advantage of a given system capabilities? • Does the OS support all the devices I intend to connect to the computer? If not, what can I do?.
You just clipped your first slide! Search gets new emphasis and helps people find files on their PCs faster. When a page needs to be replaced page in the front of the queue is selected for removal. The size of a physical memory frame is equal to the size of a virtual memory frame. No notes for slide.
Drop-down menus, icons and dialog boxes made the programs easier to learn and use. Windows 2. With the improved speed, reliability and usability, computers now started becoming a part of daily life for some workers.
Desktop icons and use of keyboard shortcuts helped to speed up the work. Windows 3. This new Windows Operating System was quite handsomely popular because of its sensible performance, advanced graphics with 16 colors, and improved icons. The 3. In Windows 3. Program Manager, File Manager, Print Manager were some of the features that got place in this edition.
It was produced for servers and workstations. It introduced the concept of APIs Application Programming Interface , numerous network features, pre-emptive multitasking concept.
Windows 98 The major improvements that came up with this system are: This edition of Windows was rushed into the market on September It had features like Internet Explorer 5. On October 25, , Microsoft released Windows XP with a rejuvenated look and feel that focused on usability and a centered Help and support center. Awareness about the computer viruses and hackers increases, but due to online delivery of security updates, there was calmness to a certain extent.
In addition, Navigation simplicity of the Start menu, taskbar, and Control Panel are more intuitive in this edition of Windows. Windows Vista Windows Vista was released in This version was centered around security norms. User Account Control helps prevent potentially harmful software from making changes to your computer.
Many features like the taskbar, borders around Windows get a brand new look. Search gets new emphasis and helps people find files on their PCs faster. Windows 7 Released on 22 Oct , it had various features like increased performance, redesigned look and feel, touch and handwriting recognition, support for virtual hard disks, Direct Access, and kernel improvements.
Windows 8 Generation of Apps and Tiles 8. Microsoft came up with a totally new interface that smartly worked on both the touch and on mouse and keyboard. The start menu was revised in this edition with apps and tiles that connect to people, files and websites. Windows 10 The recent addition to the windows family is Windows It was introduced to the world on 29 July Microsoft Edge is the new Web browser of Windows 10 which is specially designed to be a lightweight web browser.
It was originally available in two versions that were essentially the same, but marketed under two different names. This is why so many DOS-related files such as. DLL, and. COM files are still used by Windows.
This made the operating system difficult for novices to use, which is why Microsoft later bundled the graphic-based Windows operating system with DOS. Operating System and loads it into memory RAM. This process is known Boot-strapping Booting. The OS once loaded takes control of the computer, handles user interaction and executes application programs.
To list all or specific files of any directory on a specified disk.
Fig 4. Fig 5. Change DOS current working directory to specified directory on specified disk or to check for the current directory on the specified or default drive. Removes a specified sub-directory only when it is empty. This command cannot remove root directory C: Displays all of the directory paths found on the specified drive.
Displays or sets a sequential search path for the executable files. Changes the name of a file Renaming. Sets or shows file attributes read, write, hidden, Archive. Provides a full screen editor to create or edit a text file. Sets or displays system date. To clear the screen. To check the version of Operating System installed. Figure 6. DOS emulator This means that original DOS programs including PC games are provided an environment in which they can run correctly, even though the modern computers have dropped support for that old environment.
An DOS operating system is called a "disk" operating system because it was stored on a floppy disk or hard drive, as opposed to either being embedded in a ROM chip like early versions of Mac OS were , or stored on a cartridge, cassette, tape reel, or some other storage medium. One of the first things you might want to do is to transfer your files and settings from your old computer to the brand new computer.
You can transfer almost everything from your old computer to the new one. This feature of Windows Operating System allows you to upgrade to any higher windows version available for your system, so you can take full advantage of enhanced digital entertainment and other features.
Windows anytime upgrade helps you compare features in each Windows edition and walks you through the upgrade process. Windows 8 being the latest Operating system currently available for all the user worldwide.
The upgrade will cost you as per the version being selected by you. If you are new to Windows or want to refresh your knowledge about areas such as security or working with digital pictures, this features will help you to get started. Here you can learn how to help keep your computer more secure, work with digital pictures, use the mouse and keyboard, work with files and programs, use email, connect to and explore the internet and many more. A solution for the critical section problem must satisfy the following three conditions: Mutual Exclusion — If a process Pi is executing in its critical section, then no other process is allowed to enter into the critical section.
Progress — If no process is executing in the critical section, then the decision of a process to enter a critical section cannot be made by any other process that is executing in its remainder section. The selection of the process cannot be postponed indefinitely. Bounded Waiting — There exists a bound on the number of times other processes can enter into the critical section after a process has made request to access the critical section and before the requested is granted.
Semaphores are of two types: Counting Semaphore — A counting semaphore is an integer variable whose value can range over an unrestricted domain. Mutex — Binary Semaphores are called Mutex.
These can have only two values, 0 or 1. The operations wait and signal operate on these in a similar fashion. Deadlock can arise if following four conditions hold simultaneously Necessary Conditions: Mutual Exclusion — One or more than one resource are non-sharable Only one process can use at a time.
Hold and Wait — A process is holding at least one resource and waiting for resources. No Preemption — A resource cannot be taken from a process unless the process releases the resource. Circular Wait — A set of processes are waiting for each other in circular form. Methods for handling deadlock: There are three ways to handle deadlock Deadlock prevention or avoidance: The idea is to not let the system into deadlock state.
Deadlock detection and recovery: Let deadlock occur, then do preemption to handle it once occurred. Ignore the problem all together —: If deadlock is very rare, then let it happen and reboot the system. Overlays — The memory should contain only those instructions and data that are required at a given time. Swapping — In multiprogramming, the instructions that have used the time slice are swapped out from the memory.
Variable Partition — The memory is divided into variable sized partitions. Variable partition allocation schemes: First Fit — The arriving process is allotted the first hole of memory in which it fits completely.
Best Fit — The arriving process is allotted the hole of memory in which it fits the best by leaving the minimum memory empty. Worst Fit — The arriving process is allotted the hole of memory in which it leaves the maximum gap. Best fit does not necessarily give the best results for memory allocation.
The cause of external fragmentation is the condition in Fixed partitioning and Variable partitioning saying that entire process should be allocated in a contiguous memory location.
Therefore Paging is used. Paging — The physical memory is divided into equal sized frames.
The main memory is divided into fixed size pages. The size of a physical memory frame is equal to the size of a virtual memory frame. Segmentation — Segmentation is implemented to give users view of memory. The logical address space is a collection of segments.
Segmentation can be implemented with or without the use of paging. In this algorithm, operating system keeps track of all pages in the memory in a queue, oldest page is in the front of the queue. When a page needs to be replaced page in the front of the queue is selected for removal. Optimal Page replacement — In this algorithm, pages are replaced which are not used for the longest duration of time in the future. Due to two levels there is a path name for every file to locate that file.
Directory is maintained in the form of a tree.
Searching is efficient and also there is grouping capability. File Allocation Methods: Continuous Allocation: A single continuous set of blocks is allocated to a file at the time of file creation. Linked Allocation Non-contiguous allocation: Allocation is on an individual block basis. Each block contains a pointer to the next block in the chain.
Indexed Allocation: It addresses many of the problems of contiguous and chained allocation. Seek Time: Seek time is the time taken to locate the disk arm to a specified track where the data is to be read or write.
Rotational Latency: Transfer Time: Introduction to Operating System Concept: Types of operating systems, operating systems concepts, operating systems services, Introduction to System call, System call types.
Memory Management: File system Interface- the concept of a file, Access Methods, Directory structure, File system mounting, file sharing, protection. File System implementation- File system structure, allocation methods, free-space management Mass-storage structure overview of Mass-storage structure, Disk scheduling, Device drivers,. Linux System: Android Software Platform: Share this article with your classmates and friends so that they can also follow Latest Study Materials and Notes on Engineering Subjects.
Delhi University B. Com 6th Semester Syllabus — B.