Chapter 9.pptx j3gevecegegerbrbrvnnnnnbbb

Chapter 9.pptx j3gevecegegerbrbrvnnnnnbbb

• 1.
  Chapter Nine Operating SystemConcepts and Other useful softwares.
• 2.
  What is OperatingSystem (OS)? • An OS is a software program that manages the hardware and software resources of a computer • OS is the system that run the computer at its basic level. • An OS is a program that acts as an interface between the user and the computer hardware and controls the execution of all kinds of programs. • OS are responsible for everything from starting up the computer when you push the "on" button to high level system security. • The type of operating system a computer has also determines what types of software can be run on it.
• 3.
  Cont. A Computer Systemconsists of the following components: • Computer Users are the users who use the overall computer system. • Application Software's are the software's which users use directly to perform different activities. These software's are simple and easy to use like Browsers, Word, Excel, different Editors, Games etc. These are usually written in high-level languages, such as Python, Java and C++. • System Software's are the software's which are more complex in nature and they are more near to computer hardware. These software are usually written in low-level languages like assembly language and includes Operating Systems (Microsoft Windows, macOS, and Linux), Compiler, and Assembler etc. • Computer Hardware includes Monitor, Keyboard, CPU, Disks, Memory, etc. Operating System - Examples • There are plenty of Operating Systems available in the market which include paid and unpaid (Open Source). Following are the examples of the few most popular Operating Systems: • Windows, Linux, MacOS, iOS, Android, etc…
• 4.
  History of OperatingSystem • Historically operating systems have been tightly related to the computer architecture • History of operating systems depends on the evolution architecture of the computers on which they run • OS have evolved through a number of distinct phases or generations The 1940's - First Generations • The earliest electronic digital computers had no operating systems • Machines of the time were so primitive that programs were often entered one bit at time on rows of mechanical switches (plug boards). • During this generation computers were generally used to solve simple math calculations, operating systems were not necessarily needed. • Programming languages were unknown (not even assembly languages)
• 5.
  The 1950's -Second Generation • The first operating system was introduced in the early 1950's, it was called General Motors OS. • The introduction of punch cards. • The General Motors Research Laboratories implemented the first operating systems in early 1950's for their IBM 701. • The system of the 50's generally ran one job at a time. • These were called single-stream batch processing systems because programs and data were submitted in groups or batches.
• 6.
  The 1960's -Third Generation • Also batch processing systems, but they were able to take better advantage of the computer's resources by running several jobs at once • So operating systems designers developed the concept of multiprogramming in which several jobs are in main memory at once; • A processor is switched from job as needed to keep several jobs
• 7.
  Fourth Generation • Thedevelopment of LSI (Large Scale Integration) circuits, chips • Microprocessor technology evolved to the point that it becomes possible to build desktop computers as powerful as the mainframes of the 1970s • Two operating systems have dominated the personal computer scene: • MS-DOS, written by Microsoft, Inc. for the IBM PC and other machines using the Intel 8088 CPU and its successors, and • UNIX, which is dominant on the large personal computers using the Motorola 6899 CPU family
• 8.
  Types of OperatingSystem 1. Batch Processing Operating System • Interaction between the user and processor is limited or • There is no interaction at all during the execution of work • Batch processing is execution of a series of programs on a computer without human interaction. • This OS does not directly interact with the computer. Instead, an operator takes up similar jobs and groups them together into a batch, and then these batches are executed one by one based on the first-come, first, serve principle. • Batch processing operating systems are ideal in situations where: • There are large amounts of data to be processed. • Similar data needs to be processed. • Similar processing is involved when executing the data. • Processing is all performed automatically without any user intervention.
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  Types of OperatingSystem 1. Batch Processing Operating System Advantages of Batch OS • Execution time taken for similar jobs is higher. • Multiple users can share batch systems. • Managing large works becomes easy in batch systems. • The idle time for a single batch is very less. Disadvantages of OS • It is hard to debug batch systems. • If a job fails, then the other jobs have to wait for an unknown time till the issue is resolved. • Batch systems are sometimes costly.
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  2. Real-time OperatingSystem: • A real-time system is a computer system where a timely response by the computer to external stimuli is vital • Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems • Real-Time systems may have either hard or soft real-time Hard real-time system: • The system has failed if a timing constraint, e.g. deadline, is not met. • All delays in the system must be bounded. • Many advanced features are absent. Soft real-time system: Missing a timing constraint is serious, but does not necessarily result in a failure unless it is excessive Example Multimedia Transmission and Reception Computer Games
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  Real-Time Systems Applications • Airtraffic control • Space shuttle • Navigation • Multimedia systems • Industrial control systems • Home appliance controller • Nuclear power plant • Games • User interface • Vision and speech recognition • PDA, telephone system
• 12.
  3. Single UserOperating System: • A single user OS as the name suggests is designed for one user to effectively use a computer at a time 4. Multi-Tasking Operating System • In this type of OS several applications maybe simultaneously loaded and used in the memory. • While the processor handles only one application at a particular time it is capable of switching between the applications effectively to apparently simultaneously execute each application. • This type of operating system is seen everywhere today and is the most common type of OS, the windows operating system would be an example.
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  • Single-user, singletask • This operating system is designed to manage the computer so that one user can effectively do one thing at a time. • The Palm OS for Palm handheld computers is a good example of a modern single-user, single-task operating system • Single-user, multi-tasking • This is the type of operating system most people use on their desktop and laptop computers today. • Microsoft's Windows and Apple's Mac OS platforms are both examples of OS that will let a single user have several programs in operation at the same time.
• 14.
  5. Multi-User OperatingSystem • This type of OS allows multiple users to simultaneously use the system, • While here as well, the processor splits its resources and handles one user at a time, the speed and efficiency at which it does this makes it apparent that users are simultaneously using the system • Some network systems utilize this kind of operating system • The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users
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  6. Distributed OperatingSystem • In a distributed system, software and data may be distributed around the system, programs and files maybe stored on different storage devices which are located in different geographical locations and maybe accessed from different computer terminals
• 16.
  The purpose ofan OS (Function) • The OS allows the computer programs to function correctly by allowing them to communicate with other programs and the computer • Memory Management • Processor Management • Device Management • File Management • Security • Control over system performance • Job accounting • Error detecting aids • Coordination between other software and users
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  Cont... • The operatingsystem must try to satisfy these requests in a multiuser, multi-process environment while managing. • Resource allocation • Error Detection • Protection
• 18.
  File systems • Ina computer, a file system is the way in which files are named and where they are placed logically for storage and retrieval • The DOS, Windows, OS/2, Macintosh, and UNIX-based operating systems all have file systems in which files are placed somewhere in a hierarchical (tree) structure. • A file is placed in a directory (folder in Windows) or subdirectory at the desired place in the tree structure • File systems specify conventions for naming files • These conventions include the maximum number of characters in a name, which characters can be used and, in some systems, how long the file name suffix can be. • A file system also includes a format for specifying the path to a file through the structure of directories.
• 19.
  FAT (File AllocationTable) • The FAT file system is simple yet robust. • It offers reasonable performance even in light- weight implementations and is therefore widely adopted and supported by virtually all existing operating systems for personal computers • FAT file systems are the default file system for removable media (with the exception of CDs and DVDs • While FAT12 is present on floppy disks, FAT16 and FAT32 are typically found on the larger media
• 20.
  Cont... • A FATfile system is composed of four different sections: 1. The Reserved sectors, located at the very beginning. • The first reserved sector (sector 0) is the Boot Sector. • It includes an area called the BIOS Parameter Block (with some basic file system information, in particular its type, and pointers to the location of the other sections) and usually contains the operating system's boot loader code. • For FAT32 file systems, the reserved sectors include a File System Information Sector at sector 1 and a Backup Boot Sector at sector 6. 2. The FAT Region. • This typically contains two copies (may vary) of the File Allocation Table for the sake of redundancy checking, although rarely used, even by disk repair utilities • These are maps of the Data Region, indicating which clusters are used by files and directories. In FAT12 and FAT16 they immediately follow the reserved sectors.
• 21.
  Cont... 3 The RootDirectory Region • This is a Directory Table that stores information about the files and directories located in the root directory • It is only used with FAT12 and FAT16 4. The Data Region: - • This is where the actual file and directory data is stored and takes up most of the partition
• 22.
  NTFS (New TechnologyFile System) • NTFS has features to improve reliability, such as transaction logs to help recover from disk failures • To control access to files, we can set permissions for directories and/or individual files. NTFS files are not accessible from other operating systems such as DOS. • For large applications, NTFS supports spanning volumes, which means files and directories can be spread out across several physical disks. • NTFS has several improvements over FAT and HPFS (High Performance File System), such as • improved support for metadata, and the • use of advanced data structures to improve performance, reliability, and • disk space utilization, plus additional extensions, such as security access control lists (ACL) and file system journaling.
• 23.
  HPFS (High PerformanceFile System) • HPFS or High Performance File System is a file system created specifically for the OS/2 operating system to improve upon the limitations of the FAT file system. • Among its improvements are: • Support for mixed case file names, in different code pages. • Support for long file names (255 characters as opposed to FAT's 8+3 characters) • More efficient use of disk space (files are not stored using multiple-sector clusters but on a per-sector basis). • An internal architecture that keeps related items close to each other on the disk volume. • Less fragmentation of data. • Extent-based space allocation.
• 24.
  Disk Sector • Incomputer disk storage, a sector is a subdivision of a track on a magnetic disk or optical disc. • Each sector stores a fixed amount of user data • Read more on disc sector…
• 25.
  Fragmentation • Fragmentation isa phenomenon in which storage space is used inefficiently, reducing storage capacity and in most cases reducing the performance. The term is also used to denote the wasted space itself. There are three different but related forms of fragmentation: • Internal fragmentation: Memory block assigned to process is bigger. Some portion of memory is left unused, as it cannot be used by another process. • External fragmentation: Total memory space is enough to satisfy a request or to reside a process in it, but it is not contiguous, so it cannot be used. • Data fragmentation. Data fragmentation occurs when a piece of data in memory is broken up into many pieces that are not close together