Operating Systems Overview and Goals

Operating System Overview

• An operating system (OS) serves as an intermediary between users and computer hardware.
• OS functions include managing hardware resources, executing user programs, and controlling system operations.
• The kernel is the core component of an OS, always running and interfacing with hardware.

Goals of an Operating System

• Facilitate execution of user programs and enhance problem-solving efficiency.
• Provide convenience for computer system users.
• Optimize resource usage to avoid wastage.

Computer System Components

• Hardware: Comprises CPU, memory, and I/O devices creating the foundational computing resources.
• Operating System: Coordinates resource usage among applications and users.
• System/Application Programs: Software that utilizes system resources to solve specific user challenges (e.g., word processors, web browsers).
• Users: Include individuals and other systems interacting with the computing environment.

Types of Operating Systems

• Batch Systems: Users submit jobs offline for processing without direct interaction. Jobs are clustered by type to optimize processing.
• Multiprogrammed OS: Multiple processes in memory simultaneously to maximize CPU usage; organizes job scheduling for active execution without idleness.
• Timesharing/Multitasking OS: Similar to multiprogramming, but involves quick context switching between processes for simultaneous execution.
• Multiprocessing OS: Utilizes multiple processors for enhanced computing power, sharing resources, and operating under a unified OS.
• Distributed Systems: Interconnected systems maintaining copies of data for reliability; includes client-server and peer-to-peer architectures.
• Real-Time Systems: Time-sensitive systems categorized as soft (allowing delays) or hard (strict time enforcement required).

Operating System Perspectives

• User View: OS aims to maximize user productivity and minimize effort, simulating a dedicated processing environment.
• System View: OS serves as a resource allocator, managing resource allocation, access control, and execution monitoring to prevent conflicts and errors.

Operating System Operations

• Operate on an interrupt-driven basis, waiting for events (like I/O requests) to process.
• Dual-mode operation distinguishes between user mode and kernel mode using a mode bit for security and system integrity.

Operating System Structures

• Simple Structure (MS-DOS): Minimal modularity, prioritizes functionality and efficiency over clear abstraction layers.
• Non-Simple Structure (UNIX): Consists of system programs and a kernel with well-defined functions including CPU scheduling and memory management.
• Layered Approach: Organizes the OS into layers, each depending only on lower levels for functionality, allowing for modular design.

Operating System Services

• Provides an environment for program execution, supporting various functionalities like user interfaces (CLI, GUI), program management, and I/O operations.
• Types of System Calls: Include process control (create, terminate), file management (create, open, read), device management (request, release), communication (send, receive), and information maintenance (get/set attributes).

Summary of OS System Calls

• Process Control: End, create, execute processes; manage attributes and memory allocation.
• File Management: Operations related to file creation, deletion, and reading/writing.
• Device Management: Manage devices in terms of allocation and status.
• Communications: Establish connections and send/receive messages.
• Information Maintenance: Handle system time and data attributes for processes, files, and devices.

Explore the vital role of operating systems as intermediaries between users and hardware. This quiz delves into OS functions, components, and their optimization goals, enhancing your understanding of computer systems.