Basic Concepts of Computer System Operations

Jul 22, 2024

Operating System: Basic Concepts of Computer System Operations

Introduction

  • Review of the last lecture: Introduction to Operating Systems
  • Today's focus: Basic concepts needed to understand Operating Systems, specifically the structure of the computer system
  • Importance of understanding computer system structure for grasping how operating systems work

Modern General Purpose Computer System

  • Consists of one or more CPUs (central processing units)
  • CPUs: The brain of the computer; responsible for all computations and processing
  • Common misconceptions about CPU: It's not the entire box, but a small chip on the motherboard
  • Device controllers connected via a common bus to shared memory

Components and Their Connections

  • CPU: Central processing unit
  • Device Controllers: Control specific types of devices (e.g., disk controller, USB controller, video adapter)
  • Common Bus: Connects the CPU and device controllers
  • Shared Memory: Accessed by the CPU and device controllers for executing tasks

Key Points

  • Device controllers handle the functioning of specific hardware devices
  • CPU and device controllers can execute tasks concurrently (simultaneously)
  • Importance of memory controllers to ensure orderly, synchronized access to shared memory

Terms and Concepts

Bootstrap Program

  • The initial program run when a computer is powered up or rebooted
  • Stored in ROM (Read Only Memory)
  • Responsible for loading the OS and starting execution
  • Loads the OS kernel into the main memory

Interrupt

  • Triggered by hardware or software, signals the CPU to stop its current task and execute a different task
  • Interrupts can be hardware-initiated or software-initiated (system call/monitor call for software)
  • CPU stops current work, executes the interrupt service routine, and then resumes its previous task

System Call (Monitor Call)

  • A type of interrupt triggered by software
  • Executed via a special operation called a system call

Response to Interrupts

  • Step 1: CPU is interrupted and stops its current task
  • Step 2: Transfers execution to the starting address of the interrupt service routine (ISR)
  • Step 3: ISR executes
  • Step 4: CPU resumes the interrupted task upon completion of the ISR

Summary

  • Basic introduction to computer system operations
  • Explanation of the structure and functioning of the computer system components
  • Discussion on Bootstrap programs, interrupts, and system calls
  • Next lecture: Storage structures and memory