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Lecture No. 01

Dated: 14-03-2025

Organization of a Computer System

The major high-level components of a computer system are

Hardware

Manages basic computing resources such as CPU, memory and I/O devices etc.

Operating System

Provides user an easy to use access to the machine.

Application Programs

Defines the ways to solve computational problems for the user.

Users

Includes peoples, programs or machines.

Purpose of a Computer, Setting the Stage for Os Concepts and Principles

Computer systems are combination of software and hardware to provide solutions to computational problems.
The layout seems as follows:
Memory units (such as RAM, ROM, Storage) are connected to CPU (with its own internal units) through memory bus.
The CPU is also connected to other peripherals through system bus.

Problems while Executing Programs

  • Storing on storage devices.
  • Loading into main memory.
  • Setting up the CPU state for usage of this program.
  • Creating multiple cooperating processes which talk with each other.

Requirements from the Operating System

  • Manage secondary storage
    • Allocate appropriate amount of disk space when files are created
    • Deallocate space when files are removing
    • Insure that a new file does not overwrite an existing file
    • Schedule disk requests
  • Manage primary storage
    • Allocate appropriate amount of memory space when programs are to be loaded into the memory for executing
    • Deallocate space when processes terminate
    • Insure that a new process is not loaded on top of an existing process
    • Insure that a process does not access memory space that does not belong to it
    • Minimize the amount of unused memory space
    • Allow execution of programs larger in size than the available main memory
  • Manage processes
    • Allow simultaneous execution of processes by scheduling the CPU(s)
    • Prevent deadlocks between processes
    • Insure integrity of shared data
    • Synchronize executions of cooperating processes
  • Allow a user to manage his files and directories properly
    • User view of directory structure
    • Provide a mechanism that allows users to protect their files and directories

What is an Operating System

An operating system is a resource manager which bridges the gap between software and hardware. It abstracts away the details from user to make his work easier.