OPS-Reviewer-Module-1

Module 1: Introduction to Operating Systems

Objectives

• Define the operating system.

• Demonstrate the components of a computer system.

• Describe the services provided by the operating system.

• Explain the role and organization of the operating system in a computer system.

• Define interrupts, I/O structure, and storage structure.

• Discuss different computer architectures and systems.

Introduction to Operating Systems

• OS acts as an intermediary between users and hardware.

• Controls system resources, providing an environment for program execution.

Goals of Operating System

• Execute user programs to solve problems easily.

• Ensure convenience of use for the computer system.

• Use hardware efficiently.

Components of a Computer System

• Computer Hardware: CPU, memory, I/O devices.

• Application Programs: Include database systems, word processors, etc.

• Users: Various individuals/machines manipulating computer resources.

  • Users issue commands to application programs, which communicate requests to the OS.

OS Functions

1. Resource Allocator: Manages CPU time, memory, file storage, and I/O devices.

2. Control Program: Oversees execution of programs, preventing errors and managing I/O devices.

Services Provided by Operating Systems

1. Program Execution: Loads and runs user programs.

2. I/O Operations: Handles data reading/writing between I/O devices and memory.

3. File System Handling: Organizes files on disks, manages creation/deletion of files.

4. Error Detection: Identifies and responds to errors in the system.

Computer Startup

• Bootstrap Program: Loaded during power-up to initialize the system and load the OS kernel.

Computer System Organization

• Multiple CPUs with device controllers connect via a common bus to shared memory.

• I/O devices and CPUs execute concurrently; device controllers manage specific devices.

Interrupts and I/O Structure

• Interrupts: Transfer control to the interrupt service routine; preserve CPU state.

• **Types of Interrupts:

  • Polling: OS signals devices for requests.

  • Vectored: Device sends interrupt directly to OS.

Memory and Storage Management

• Main Memory: Central to CPU operations, stores data and instructions.

• Secondary Storage: Holds nonvolatile data with a significant capacity.

• Caching: Temporarily moves data to faster storage for improved access.

Process Management

• Process: A program in execution requiring CPU and memory resources.

• Activities: Creating, deleting and synchronizing processes; handling deadlocks.

Computing Environments

• Traditional Systems: Networked PCs and mainframes.

• Mobile Computing: Usage on smartphones and tablets.

• Distributed Systems: Networked systems providing shared resources.

• Client-Server: PCs acting as servers responding to client requests.

• P2P Systems: Nodes act as both clients and servers.

Cloud Computing

• Delivers computing and storage services over networks; includes public, private, and hybrid clouds.

• Provides SaaS, PaaS, and IaaS models.

Open-Source Operating Systems

• OS available in source-code format; examples include GNU/Linux and BSD UNIX.