Operating Systems Overview

Operating System Overview and Structure

• Operating systems act as intermediaries between users and computer hardware
• Operating systems are designed to execute user programs and address problems more efficiently
• They strive to make the computer system user-friendly and make efficient use of computer hardware
• An operating system's core function is resource management, which includes allocating resources among users or tasks and intervening in conflicting requests to ensure fair and efficient use
• Operating systems handle resource allocation efficiently by managing hardware, software, and data
• Operating systems control the execution of programs, preventing errors and ensuring proper use of the computer; these systems choose which requests to prioritize for execution
• The kernel is the principal program that continually runs on a computer
• OS main goals encompass convenience, efficiency, and the ability to adapt

Operating System Objectives and Functions

• Operating systems function as interfaces connecting users and computers
• They manage system resources, such as hardware, software, and data

Evolution of Operating Systems

• Early computing involved direct interaction of programmers with hardware through consoles
• This method was inefficient as time was wasted on setting up programs
• Batch systems grouped jobs together and submitted them to be processed sequentially by the monitor, a specialized piece of software
• Multiprogramming allowed multiple jobs to be present in the computer's memory simultaneously, leading to enhanced CPU utilization
• Time-sharing expanded on multiprogramming by enabling multiple users to simultaneously use the system, dividing the processor's time among their tasks

Uniprogramming

• In unprogrammed systems, the processor executes tasks sequentially, waiting for I/O instructions to complete before continuing execution

Multiprogramming (Multitasking)

• Multiprogramming allows multiple jobs to remain in memory concurrently, improving CPU utilization
• Jobs eligible to run are selected from a pool (job pool)
• Job prioritization is guided by the operating system

Time-Sharing Systems

• Time-sharing systems extend multiprogramming principles by interleaving the execution of multiple tasks, making the system highly responsive
• Interactive computing is the hallmark of time-sharing systems
• A short period (quantum) is allocated for each program's execution before switching to another program, enhancing responsiveness

Major Advances in Operating Systems

• Modern operating systems are notably complex
• Key improvements encompass:
  • Processes
  • Memory management
  • Information protection and security
  • Scheduling and resource management

Operating System Services

• Resource allocation is handled when numerous users or applications run simultaneously
• Protection and security ensure each user or process has control over its own information while preventing concurrent operations from impinging on each other
• The operating system provides a range of facilities for program development, including editors, debuggers, and compilers
• The steps to execute a program involve loading instructions and data, initializing I/O devices, and preparing other resources

User Interface

• Almost all operating systems feature a user interface for interaction
• CLI (command-line interface) allows direct command entry, fetch commands from users and execute them, utilizing built-in commands or program names
• GUI (graphical user interface) commonly use icons for representing files, programs, and actions: user actions over icons will trigger related actions
• Both CLI and GUI interfaces are prevalent in modern operating systems

System Calls

• System calls serve as interfaces between application programs and operating systems
• System calls translate high-level language requests into low-level instructions used by the hardware

System Programs

• System utilities facilitate program development and execution, handling tasks that are part of a user interface, such as file manipulation, program loading, and execution, and communications

This quiz covers the fundamental concepts of operating systems, including their structure, objectives, and core functions. It discusses how operating systems act as intermediaries between users and hardware, manage resources, and ensure efficient execution of programs. Test your understanding of these critical components of computer science.