MCA 1st Semester OPERATING SYSTEMS (OS) Paper Summary || PPU | Patna | MCA | Syllabus || Allrounder Sita Ram Sahu || Subscribe

Paper 3: OPERATING SYSTEMS from the MCA syllabus:

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Unit-I: Basics of Operating Systems

1. Definitions, Components, and Types:

   • Operating System (OS): A system software that manages hardware and software resources.
   • Components:
     • Kernel, Shell, File System, Device Drivers, Process Manager, Memory Manager.
   • Types:
     • Batch OS: Executes batches of jobs without user interaction.
     • Time-Sharing OS: Allows multiple users to interact with the system.
     • Distributed OS: Manages resources across multiple machines.
     • Real-Time OS: Provides immediate responses for critical systems.
     • Embedded OS: Designed for specific hardware.

2. Operating System Services:

   • User interface (CLI/GUI), file management, memory management, process management, I/O device management, and system security.

3. System Calls:

   • Interface for user programs to interact with the OS (e.g., open, close, read, write, fork).

4. Process Concepts:

   • A process is a running instance of a program.
   • States: New, Ready, Running, Waiting, Terminated.
   • Process Control Block (PCB): Stores process details like ID, state, program counter, registers, etc.

5. Process Scheduling:

   • CPU Scheduling: Allocates CPU to processes.
   • Algorithms:
     • FCFS (First-Come, First-Served).
     • SJF (Shortest Job First).
     • Round Robin (time-slice-based).
     • Priority Scheduling.
     • Multilevel Queue Scheduling.

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Unit-II: Process Synchronization and Deadlocks

1. Critical Section Problem:

   • Occurs when multiple processes access shared resources simultaneously.
   • Solution: Mutual exclusion, progress, bounded waiting.

2. Semaphores:

   • Synchronization tool to avoid race conditions.
   • Types: Binary Semaphore (0/1) and Counting Semaphore.

3. Classical Synchronization Problems:

   • Producer-Consumer Problem: Managing buffer space for producing and consuming items.
   • Readers-Writers Problem: Coordinating access to shared data for readers and writers.
   • Dining Philosophers Problem: Preventing deadlocks when philosophers share resources.

4. Deadlock:

   • Characterization: Mutual exclusion, hold and wait, no preemption, circular wait.
   • Handling:
     • Prevention: Avoids at least one of the four conditions.
     • Avoidance: Uses algorithms like Banker’s Algorithm.
     • Detection: Identifies deadlocks and resolves them (e.g., by terminating processes).
     • Recovery: Restores the system by rolling back processes.

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Unit-III: Memory Management

1. Logical vs Physical Address Space:

   • Logical Address: Generated by CPU.
   • Physical Address: Actual location in memory.

2. Swapping:

   • Moving processes in/out of memory for execution.

3. Memory Allocation:

   • Contiguous Allocation: Fixed-size memory blocks.
   • Paging: Divides memory into fixed-size pages.
   • Segmentation: Divides memory into variable-sized segments.

4. Virtual Memory:

   • Allows execution of processes larger than physical memory.
   • Implements demand paging.

5. Page Replacement Algorithms:

   • FIFO, LRU (Least Recently Used), Optimal Algorithm.

6. Thrashing:

   • Excessive swapping due to insufficient memory.

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Unit-IV: Storage and File Management

1. Disk Structure:

   • Logical blocks, tracks, sectors, and cylinders.

2. Disk Scheduling:

   • Algorithms to optimize access time:
     • FCFS (First-Come, First-Served).
     • SSTF (Shortest Seek Time First).
     • SCAN, C-SCAN (circular), LOOK, C-LOOK.

3. File System:

   • File Concepts: File types, attributes, access methods (sequential, direct).
   • Directory Structure: Single-level, two-level, tree-structured directories.
   • File Access Control: User permissions (read, write, execute).

4. I/O Management:

   • Handles input/output devices.
   • Includes spooling and buffering.

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Unit-V: Case Studies of Linux and Windows Systems

1. Linux System:

   • Components:
     • Kernel: Manages hardware resources.
     • Shell: User interface for command execution.
   • Process Management:
     • Scheduling, memory management, I/O management.
   • File System:
     • Uses ext4, ext3, and ext2 file systems.
   • Synchronization and Communication:
     • IPC (Inter-Process Communication) mechanisms like pipes, message queues, and shared memory.

2. Windows System:

   • Design Principles:
     • Modular design with layers.
     • Supports multitasking, multiprocessing, and multithreading.
   • Components:
     • Kernel, HAL (Hardware Abstraction Layer), Subsystems.
   • Memory Management:
     • Virtual memory with paging.
   • File System:
     • NTFS (New Technology File System).

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Key Features of the Subject

• Covers the theoretical foundations of operating systems.
• Explains process management, memory management, and file systems.
• Introduces practical algorithms for scheduling, synchronization, and deadlock prevention.
• Includes comparative studies of Linux and Windows operating systems.

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AllrounderSitaRamSahu

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