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hardware, and software resources, and provides services for computer | 3 programs. itacts as an intermediary between users andthe computer | ‘An Operating System (0S) is system software that manages computer i a hardware, ensuring effet and smoot peat, ly among pr 2. Memory Management Manages the allocation and deallocation of ‘memory for processes. Tracks which parts of memory are in use and by whom. 3. File System Management: Organizes and manages files and directories on storage devices. Provides methods for data storage, retrieval, and updating. Davee Management: Conte theinpuvouput ‘such as p ete. b function smoothly withthe CPU. clas inmracasProwes a user-friendly « -ine or graphical) for the system. Enables users to run programs and manage files. Real-life Example: A smartphone operating system, like Android or 10S, ‘manages apps, memory, sensors, and hardware resources such as the ‘camera and touch screen, providing a seamless experience to users while Interacting with their phones. J ‘aystem and application programe, with computer hardware 2 ‘Schematic Diagram of location of OS on a local system —> Goals of an OS: 1. Efficiency: Optimize resource use for fast, smooth 2. Resource Al : Fairly manage CPU, memory, and 1/0 ‘among processes. 3. Reliability: Minimize crashes, ensure system availability. 4. Security: Protect against threats, ensure data integrity. 5. Ease of Use: Provide a user-friendly interface. ‘em ‘Multiprogramming Batch OS: A Muliprogramming Batch Operating System is a ‘ype of operating system designed to manage and execute multiple jobs simultaneously by allowing them to reside in memory and share the CPU. ‘Key Features: 1. Concurrent Execution: Runs multiple jobs simultaneously for ‘efficient CPU use. 2. Job Scheduling: Priortzes and schedules jobs for optimal processing. 3. Memory Management: Allocates memory to active jobs while Preventing conflicts. 4. /O Management: Handles /0 operations, allowing the CPU to switch tasks during wait times. 5. Resource Sharing: Shares resources ‘among jobs for better system efficiency. How It Works: 1. Users submit jobs toa job pool. 2. The OS schedules jobs for hi execution using algorithms. 3. Memory is allocated for active jobs. 4. Jobs ai ‘execute concurrently, switching as needed. 5. CPU switches tasks during VO 3? ‘operations. 6. Completed jobs release resources for new tasks. ‘Advantages: 1. Maximized CPU utilization and reduced idle time. 2. Increased || throughput with more jobs processed. 3, Efficient resource usage Disadvantages: 1. system 2 resource, and bottlenecks. 3. Overhead from frequent context switching. f ‘Time:sharing OS (Multitasking 0S): 0S designed to enable muitiple users to ‘aocess and share system usly. They allow multiple torun switching between them, giving the illusion that al processes are executing atthe same time. ‘Key Features: 1. Multitasking: Runs multiple processes concurrently. 2. Interactive Computing: Provides real-time user interaction with instant feedback. 3. Resource Allocation: Efficiently manages CPU, memory, and I/O devices. 4. User Isolation: Maintains privacy and security among users. 5. Scheduling: Priortizes and allocates CPU time effectively. How It Works: 1. Users submit via interfaces. 2. The OS creates and cf with . 3. PU scheduling and context switching enable 19. 4, Memory and VO are manag = Fy ly by rapidly dynamically The operating system acts as a resource manager to ly and effectively ‘manage the systems resources. Here's how the OS manages different resources: The operating eystem acts as a resource manager by allocating and managing the systems resources efficiently. Here's a breakdown of its objectives and techniques for various resource management areas: 1, Processor Management: Optimizes CPU usage with ‘multitasking and scheduling algorithms like FCFS, SUN, Priority Scheduling, and Round Robi 2. Memory Management: Allocates memory using techniques like partitioning, paging, 2 ‘segmentation, and virtual memory. 3. Storage Management: Organizes data with filesystems (NTFS, FAT32, ext) and disk scheduling algorithms like FCFS and SSTF. 4,1/0 Device Management: Uses device drivers, buffering, and spooling for smooth hardware interaction. 5. Process Management: Handles process creation, termination, and communication through shared memory and message passing. 6, Security and Protection: Ensures safety with authentication, access control, and encryption, Z, Network Management: Manages secure ‘communication using protocols like TOP/IP and tools like firewalls and encryption. ‘SIMPLE BATCH OS: A simple batch operating system is designed to jobs in Without user. interaction during processing. A simple batch operating system processes jobs in batches without user interaction during execution. Key Features: 1. Job Sequencing: Organizes and prioritizes jobs for execution. 2. Job Scheduling: Optimizes the order of execution for efficient resource use. 3. No User interaction: Runs jobs continuously without input during cecution. 4. Resource Efficiency: Maximizes CPU and system resource utlization. if 5. Job Control Language (CL): Simplifies job submission and configuration. How It Works: 1. Users submitjobs to a queue using JCL. 2. The OS schedules andloads jobs| into memory. 8. Jobs are executed sequentially using available resources. 4. Completedjobs _* release resources, and outputs are generated. Adana. igh ficiency y rein CPU ie time. 2. Automated processing for winter operation Simply fo svalghforward teks. Dlsadantnts 1. Noineraclon ding exciton. 2, Rigi schedlng Aneutable or dame inefficiencies in ‘and Batch Ea ‘MULTIPROCESSOR/PARALLEL OS: A multiprocessor os is designed to manage and coordinate the resources and broceses of computer ester tht hes multe processor (CPUs). This ype of OS alas mull processors for active processes. Examples: UNIX, MULTICS, IBM TSO, DEC TOPS-10. ‘Advantages: 1. resource utilization. 2. i ‘and ‘user experience. 3. Supports multitasking, boosting productivity. 4. Cost-effective resource sharing. Disadvantages: 1. High system complexity. 2. Overhead from process | 1g . 3. ‘security risks. 4. ‘can affect pert [wetter |[rowerreme|| antivirus || SaRApe || cman | Operating system [Pu Multiprogramming Multitasking Uses a single CPU le exesutes suulliple prexgranns Allse:sten rolls tasks te the PU fer Only ines caantenl switching, Users bith exrntent sale hing and time sharing Seiiches ta anaiher jab when the eueent ane needs Switches tasks when Gine alice expen: on wher the 19 esis (4h, For VO}. uarenl lank new to wes Foeaes on masienizing CPU utilization by erganiing —Lilencls CPL ulilzation by improving responsive jobs threagh iran sharing. Uses jeb scheduling algorithms to run multisle programs s multaneousy Uses time snaring mecharisms to execute multiple tasks at che same time, Processes may sake more time to execute Processes execute tester due to time sharing, Real-Time Operating System (RTOS): A real-time operating system is designed to process data and respond to input within a specific time constraint, ensuring predictable response times. RTOS Is often used in embedded systems and work together to tasks, ing pert reliability, and capabilities. A multipr ‘multiple p (cous)t0 performance, ty, and ng capabilities by tasks across processors. i: Ove master processor handles Multiprocesso atric Multiprocessin taskalloaton while slave processors execute tase. Simple ut can lad obotenecks if the master processor overloaded, ions where timing is critical, such as in robotics, automotive systems, and industrial control. [RTOS vs. General-Purpose OS: - Response Time: RTOS ensures timely responses, while general-purpose OS may not ‘meet strict timing requirements. - Task Scheduling: RTOS uses deterministic scheduling; general-purpose OS uses priority-based or round-robin ng. - Resource | ¢ RTOS ‘on timing and pr Silty, while ‘general-purpose OS prioritizes throughput and resource utilization. - Applications: RTOS Is used in mission-critical 2. Symmetric Multiprocessing (SMP); All processors share memory and /0 , working i ‘communleating via shared memory. This model boosts performance, fault tolerance, and scalability. Benefits of SMP: - Improved performance with simultaneous task execution. - Scalability by adding processors without ile genera-pupate OS serves awier ange of tasks if Guarantees completion of critical tasks within strict deadlines. Missing a ‘deadline can cause failure, Examples: aviation, medical devices. 2, Soft Real-Time OS; Aims for deadline adherence but ‘major software changes. - Optimized resource utilization through load balancing. - Fault with pr task takeover. - Simplified programming via shared memory space. ] [ I I [memory Distributed Operating System (0S) A distributed operating system manages a group of Independent computers end mekes them appear ab sinle coherent system to user. resource: jon among wa [ reatctere | allowing p form oncifrent source sharing across multiple machines, eaing to beter tization, proved reliability and fault through | 3. ~ Scalability to handle loads by adding more machines. - Enhanced performance by distributing tasks across ‘multiple systems. Drawbacks: - Complexity in design and implementation. - Network dependency, which can lead to performance issues ifthe network is slow or unreliable. - ‘Security challenges due to multiple access points and potential vulnerabilities. ‘Network Operating System (NOS): A network operating system provides features for CPU, Memory. Disk CPU, Memory managing and puters to communi and share resources over @ local area network (LAN). It primarily focuses on enabling file sharing, printer computers within a Benefits: -C6r data management and sharing, - users via network protocols. - Simplified administration with tools for managing users and resources. - Compatibility with various network hardware. Drawbacks: - Limited to local networks, with less emphasis on ble to which can disrupt services. - Security risks due to centralized data storage and access. Pll Memory t 3 g z 5 Se ae Administrator |B nel 5 Agent & Agent allows misses without severe: 5. Examples: mul , gaming sy lel System Distributed System processor systems. load. aster lank execution. Slower las execation. Multiprocessor systems with shereci memory. Each processor hes its ovin memory. rightly coupled system, Loosely coup ed system, Shares memory, clock, and peripherals No shared memory or clack, Single master clock for aynchranication. Uses synelrenication slyerithins instiwe of a global ok Pr opm ve | Non-preemptive 1. Resources allocated to process for limited time. 2. Processes can be . Resources alotted till process is complete/switches to waiting, 2. Process cannot be interrupted, interrupted. 3. Low priority process may 3. Short timed process may slarve. starve. A, Has overheads. A. No overheads 5, Flexible. 5. Rigid. 6. Cost associated. 6. Not cost associative. 7. Waiting time, Response time ne, Response time is is less more. Program vs Process vs. Thread Ayes Seneca resources required by ar instence of an application. A thread isa schedulable entny that executes the code Ir includes: It contains: + Avirtusl address space + The conzents of CPU + Amapped executabic text} + Asecurity context : jacks (kernel & One or mare threads + Alist of handles user mace) Per-thread variables 
