Operating System Exploration and Implementation

This repository serves as a comprehensive resource and codebase for exploring the fundamental principles, design patterns, and practical implementations of Operating Systems. It is structured to provide a system-level understanding of how software interacts with physical hardware.

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Operating System Architecture

The following diagram illustrates the high-level architecture of a typical operating system, separating the User Space from the Kernel Space and showing the interfaces to the physical hardware.

graph TD
    subgraph User Space
        App[Applications] --> Shell[Command Line / Shell]
        App --> Lib[System Libraries]
    end
    subgraph Kernel Space
        SysCall[System Call Interface] --> ProcMgmt[Process Management]
        SysCall --> MemMgmt[Memory Management]
        SysCall --> FileSys[File System Management]
        SysCall --> DeviceDrv[Device Drivers]
        
        ProcMgmt --> HardwareInterface[Hardware Interface]
        MemMgmt --> HardwareInterface
        FileSys --> HardwareInterface
        DeviceDrv --> HardwareInterface
    end
    subgraph Hardware Layer
        HardwareInterface --> CPU[CPU]
        HardwareInterface --> RAM[RAM]
        HardwareInterface --> Disk[Storage]
        HardwareInterface --> IO[I/O Devices]
    end
    
    Lib --> SysCall
    Shell --> SysCall

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Core Concepts and Learning Paths

The materials and implementations in this repository focus on key functional areas of operating systems:

Process and Thread Management

Understanding how the CPU is shared among multiple active programs.

• Process Lifecycle: Creation, scheduling, execution, and termination.
• CPU Scheduling: Algorithms such as First-Come-First-Serve, Shortest Job First, Priority Scheduling, and Round Robin.
• Concurrency Control: Semaphores, mutexes, locks, critical sections, and deadlock handling.

Process State Transitions

The lifecycle of a process as managed by the OS scheduler is outlined in the diagram below:

stateDiagram-v2
    [*] --> New : Created
    New --> Ready : Admitted to Queue
    Ready --> Running : Scheduler Dispatch
    Running --> Ready : Interrupt (Time Slice Out)
    Running --> Waiting : I/O or Event Blocked
    Waiting --> Ready : I/O or Event Completion
    Running --> Terminated : Execution Complete
    Terminated --> [*]

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Memory Management

How systems manage physical RAM and abstract it for executing programs.

• Memory Allocation: Contiguous allocation, fragmentation, paging, and segmentation.
• Virtual Memory: Demand paging, translation lookaside buffers (TLB), page faults, and page replacement policies (FIFO, LRU, Optimal).

File Systems and Storage

The organization of persistent storage and interfaces to input/output devices.

• Storage Architecture: Disk scheduling algorithms (SSTF, SCAN, LOOK).
• File Allocations: Contiguous, linked, and indexed allocations.
• Device Management: Buffering, caching, spooling, and device driver routing.

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Prerequisites

To effectively navigate and run code in this repository:

• Programming Language: Solid understanding of C or C++.
• Computer Organization: Basic knowledge of CPU registers, RAM, and hardware interrupts.
• Development Environment: POSIX-compliant environment (GNU/Linux, macOS, or WSL on Windows).

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Getting Started

To replicate the environment and explore the modules locally:

1. Clone the repository:

   git clone https://github.com/Anshitva7mishra/OperatingSystem.git

2. Navigate to the project root:

   cd OperatingSystem

3. Review the source code and instructions in the respective concept folders.

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Contributing

Contributions to documentation, optimizations, or additional implementations are welcome.

1. Fork the repository.
2. Create a feature branch.
3. Commit changes with clear, structured messages.
4. Push the branch and submit a pull request.