OPERATING SYSTEMS INTRODUCTION chapter 1.pptx

Operating Systems
Chapter One: Overview of Operating Systems
(OS)
 What is Operating System?

Introduction
 Os is the core component of computer systems.
Os is a program that designed to control the operation of a computer system.
 Os act as an interface between computer and the users/outside world.
 Os is the layer between users and computer /hard ware parts.
What is the job of OS?
 Os is used to manage devices
Os helps a user easily interact with computer systems
Os controls the allocation and use of a computer's hardware.
Os act as a communicator between the user, the computer’s system.
Os provides various services such as: resource allocation, scheduling, I/O control and
data/file management etc.

Functions of operating system
 What are the faction of OS?
OS perform a few basic tasks, such as:
Recognizing input from the keyboard,
Sending output to the display screen,
Keeping track of files and directories on the disk,
Controlling peripheral devices such as disk drives and printers, and
Os also responsible for security, i.e. ensuring that unauthorized users do not access the system.
In general basic functions of OS are:-
Process Management
Memory management
File Management
Device Management

Cont.….
 Process Management:
Is a process of assignment/allocation of processor to different
tasks/processes being performed by the computer system.
It allows two or more processes to be executed at a time, using
multitasking concept.
 Memory management
Allocating: Assign main memory and other storage areas to the system
programs as well as user programs.
Swapping: exchange the content of memory to the disk storage.
Paging: means the virtual address space is divided into units. It helps the
program data is loaded into pages of memory.

Cont..….
 Device Management (Input/output management)
A coordination and assignment of different input and output device to a given
process, while one or more programs are being executed.
 File Management
Create and maintain a file System, where users can create, delete and move files
from structured file system.
It allows all files to be easily changed and modified using text editors or any other
files manipulation.

Types of Operating Systems
 There are several types of operating systems. The most widely used
Windows: is the popular Microsoft brand preferred by most personal users.
Unix/Linux
 UNIX: It is well known for its stability and often used more as a server than a
workstation.
 Linux: was designed based on the UNIX system, with the source code being a part of
GNU open-source project.
Macintosh: Recent versions OS, including the Mac OS X, follow the secure
architecture of UNIX.
It is efficient and easy to use, but can only function on Apple branded hardware.

 Type of Os based on the:-
Number of users they can serve at one or different stations and
Number of programs the operating system handle/ support on a time,
Times required to response the given request/input.
Real-time operating system (RTOS):
This kind of Os is used when there are time requirement are very strict like missile
system, robots, scientific instruments and other industrial systems.
This Os very small response time. i.e. The time interval required to process and
response to input is very small.
Advantage
 Error free
 Effective results
Disadvantage
Limited tasks run at the same time
Complex algorithm for designer to write on.
RTOS has very little user-interface capability, and no end-user utilities.

Single-user, single task:
 This kind of OS allows only one user to access the system at a time. i.e. It runs only one
program at a time.
 Examples: MS-DOS (Micro Soft Disk Operating System) produced by Microsoft.
Advantage
Execution speed is good b/c only one process run a time.
Disadvantage
 A low degree of resource utilization b/c a number of resources are present in a computer
system and only one of these resources being utilized by the process
Cont….

 Single-user, multi-tasking:
In this operating system, all resources are dedicated to only one user. But the user can
use more than one program (resource).
It overcomes a single user-single tasking operating system limitation.
Single user have a permission to run multiple programs at the same time.
Example Microsoft's Windows (98, 2000, XP, Vista etc) and Apple's MacOS X.
Multi-user multi tasking:
It is mostly used on the networked environment.
 More than one user can utilized the resources available on the computer simultaneously
like hard wares and soft wares.
Example: Linux, UNIX, etc

When OS start its work?
OS start its work, when the computer is turned on, at that time the
Os will be loaded from the hard drive into the computer's memory.
The process of loading the operating system into memory is called
bootstrapping, or booting the system.

OPERATING SYSTEMS INTRODUCTION chapter 1.pptx

OPERATING SYSTEMS INTRODUCTION chapter 1.pptx

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OPERATING SYSTEMS INTRODUCTION chapter 1.pptx