user kerneal thimgs ppt full format.pptx

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1. Operationg System MUQADDAS ANSAR

2. Kernel and user mode: The mode where the operating system has full control over the hardware. All instructions are allowed, and the OS can access all resources . Purpose: Ensures system stability and security. Kernel mode The mode where applications run with limited privileges. Most instructions are restricted, and direct hardware access is prohibited . Purpose : Protects system processes from user processes. User mode

3. Key Topics: OS Protection OS Services User OS interfaces

4. OS Protection: Purpose of Memory Protection : Prevents unauthorized access to memory regions. Ensures system stability and security by isolating processes. Key Mechanisms: Segmentation: Divides memory into segments, each with a specific purpose (code, data, stack ). Each segment has its own base and limit, defining its starting point and size .

5. Paging : Divides memory into fixed-size pages, typically 4KB each . Pages are mapped to frames in physical memory through page tables . Example Windows OS : Uses paging extensively to manage virtual memory.

6. OS Services: Process Management : Creation, scheduling, and termination of processes. Handles process synchronization and communication. Memory Management : Allocation and deallocation of memory spaces. Manages swapping between main memory and disk storage. File System Management: Organizes and manages file storage. Provides file operations like creation, deletion, read, write, and access control. Device Management: Monitors and controls hardware devices. Provides drivers and interfaces for device interaction. Security Management: Protects system resources and data. Implements authentication, authorization, and auditing mechanisms.

7. User OS Interfaces Command-Line Interface (CLI ): Text-based interface where users type commands to perform tasks. Examples: Bash (Linux), Command Prompt (Windows). Graphical User Interface (GUI ): Visual-based interface with windows, icons, and menus. Examples: Windows Desktop, macOS , GNOME (Linux). Application Programming Interface (API): Set of functions and protocols for building software. Examples: WinAPI (Windows), POSIX (Unix/Linux), Cocoa ( macOS ). Touch and Gesture Interfaces: Modern interfaces for touch-enabled devices. Examples: iOS , Android, Windows Touch.

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