Operating System
OS Part-1
OS Part-2
- File Concepts and Access methods
- Free Space Management and Allocation methods
- Directory Systems and Protection
- File Organization, Sharing and Implementation issues
- Disk and Drum Scheduling
- I/O Devices Organisation & I/O Buffering
- I/O Hardware, Kernel I/O subsystem and Transforming I/O Requests to Hardware Operations
- Device Drivers and Path Management
- Device Driver Sub Modules and Procedure
- Device Scheduler and Handler
- Interrupt Service Routine (ISR)
- File System in Linux and Windows
OS Part-3
- Process and Process Control Block(PCB)
- Process Scheduling( Preemptive and Non Preemptive)
- Scheduling Algorithms
- Algorithm Evaluation
- Multiple Processor Scheduling
- Real Time Scheduling
- Operations on Processes
- Threads
- Inter-Process Communication
- Precedence Graphs
- Critical Section Problem
- Semaphores
- Classical Problems of Synchronization
- DeadLock
- Deadlock Prevention and Avoidance
- Deadlock Detection and Recovery
- Process Management in Linux
OS Part-4
- Memory Hierarchy in OS
- Concepts of Memory Management
- MFT and MVT
- Logical and Physical Address Space
- Swapping
- Contiguous and Non Contiguous Memory Allocation
- Paging
- Segmentation
- Paging Combined with Segmentation
- Structure and Implementation of Page Table
- Virtual Memory in OS
- Cache Memory Organization
- Demand Paging
- Page Replacement Algorithms
- Allocation of Frames and Thrashing
- Demand Segmentation
OS Part-5
- Distributed Operating System: Introduction and Types
- Distributed OS: Design Issues
- Distributed OS: File System
- Distributed OS: Remote File Access
- Remote Procedure Call(RPC)
- Remote Method Invocation(RMI)
- Distributed Shared Memory
- Parallel Processing and Concurrent Programming
- Security and Threats Protection in Distributed OS
- Security Design Principles and Authentication in Distributed OS
- Sensor Network and Parallel OS
1. Operating System Services
Operating System services ka kaam users aur programs ke liye hardware aur software manage karna hota hai.
OS ke Main Services:
1. Process Management
Kya karta hai?
Naye processes create, schedule aur terminate karta hai.
CPU time ko processes ke beech allocate karta hai.
Example:
Agar tum browser, music player, aur VS Code ek saath use kar rahe ho, toh OS multi-tasking handle karta hai.
Diagram:
[User ne program open kiya] → [OS ne process banaya] → [CPU process ko execute karega]
2. Memory Management
Kya karta hai?
Har program ko memory allocate aur free karta hai.
Jab RAM full hoti hai toh Virtual Memory ka use karta hai.
Example:
Agar tumne bohot saari Chrome tabs open kar li, toh OS memory efficiently assign karega.
Diagram:
[Process ne memory maangi] → [OS ne memory allocate ki] → [Process use karega]
3. File Management
Kya karta hai?
Files ko create, read, write aur delete karta hai.
File permissions control karta hai.
Example:
Agar tum MS Word me ek document save kar rahe ho, toh OS usko manage karega.
Diagram:
[User ne file save ki] → [OS ne file ko system me store kiya]
4. Device Management
Kya karta hai?
Input/output devices ko detect aur control karta hai.
Device drivers ka use karta hai taaki hardware properly work kare.
Example:
Agar tum USB pen drive connect karte ho, toh OS usko detect karega.
Diagram:
[USB plug-in] → [OS ne driver load kiya] → [Device ready to use]
5. Security & Protection
Kya karta hai?
Unauthorized access se data aur system ko protect karta hai.
Password protection, firewall, encryption provide karta hai.
Example:
Jab tum Windows ya mobile me password ya fingerprint lagate ho.
Diagram:
[User ne login kiya] → [OS ne verify kiya] → [Access allowed]
6. User Interface (UI) Services
Kya karta hai?
Users ko CLI (Command Line Interface) ya GUI (Graphical User Interface) provide karta hai.
Example:
Linux me Terminal (CLI) aur Windows me Explorer (GUI) hota hai.
7. I/O System Management
Kya karta hai?
Keyboard, mouse, printer jaise input/output devices manage karta hai.
Example:
Tumne MS Word se print command diya, toh OS print handle karega.
8. Networking Services
Kya karta hai?
Internet aur Wi-Fi, LAN, Bluetooth connections manage karta hai.
Example:
Agar tum files share kar rahe ho Wi-Fi se.
2. Operating System Structure
Operating Systems different structures me design hote hain taaki efficiency aur security badh sake.
OS ke Main Structures:
1. Monolithic Structure
Kya hota hai?
Saare OS services (Process, Memory, I/O, Files) ek hi kernel me combined hote hain.
Advantages:
Fast execution hota hai.
Disadvantages:
Modify karna mushkil hota hai.
Example OS:
MS-DOS, Purane UNIX versions
Diagram:
[Kernel (Single Unit)] → [File, Process, Memory, Device Management]
2. Layered Structure
Kya hota hai?
OS multiple layers me divide hota hai, har ek layer ka apna specific kaam hota hai.
Advantages:
Debugging aur updating easy hota hai.
Disadvantages:
Performance slow ho sakta hai kyunki har layer ek dusre se communicate karti hai.
Example OS:
Windows NT, THE OS
Diagram:
3. Microkernel Structure
Kya hota hai?
Sirf basic OS functions (CPU scheduling, memory management) kernel me hote hain, baaki sab user mode me execute hote hain.
Advantages:
Security aur stability zyada hoti hai.
Disadvantages:
Performance slow ho sakti hai context switching ki wajah se.
Example OS:
MacOS, QNX, MINIX
Diagram:
4. Modular Structure
Kya hota hai?
OS me modules load hote hain, jisme har service ek alag module hota hai.
Advantages:
Easily extendable (drivers bina reboot ke install ho sakte hain).
Disadvantages:
Agar ek module crash ho jaye toh system unstable ho sakta hai.
Example OS:
Modern Linux, Windows NT
Diagram:
[Kernel]→[Modules (File, Device, Network)]
5. Hybrid Structure (Mixed Structure: Monolithic + Microkernel)
Kya hota hai?
Monolithic aur Microkernel ka combination hota hai taaki speed aur security dono achi ho.
Advantages:
Fast, secure, aur modular design.
Disadvantages:
Development complex hota hai.
Example OS:
Windows 10, Linux, macOS
Diagram:
[ Hybrid Kernel ] → [ Mix of OS Services in Kernel & User Mode ]
Conclusion
OS Services user aur hardware ke beech bridge ka kaam karte hain.
OS Structure performance, security, aur modularity ko affect karta hai.
Modern OS (Windows, Linux, macOS) Hybrid ya Modular structure use karte hain.