Lect 01 Introduction

Operating System Concepts

In the Name of

Allah

WHO above ALL GIVE US THE ABILITY TO LEARN.

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Operating System Concepts

Chapter # 01

Operating System Concepts

Lesson Agenda

1. What is an Operating System?
2. Abstract View of Operating System
3. Abstract View of System Components
4. Operating System Environment
5. Functions of Operating System
6. Types of Operating System

Home TASK

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Operating System Concepts

Operating System

Operating system is a software.
Its is system software.
Its is the software who
manages and control the entire
computer system.

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Operating System Concepts

Operating System

The operating system is the most
important program that runs on a computer.
Operating systems perform basic tasks: Such
as

 Recognizing input from the input devices,
 Sending output to output devices,
 Keeping track of files and directories on the disk,
 Controlling peripheral devices such as disk
drives and printers.

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Operating System Concepts

Operating System

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Operating System Concepts User n

Abstract View of System
Components

User 1 User 2 User 3

...

compiler assembler Text editor Database system

System and Application Programs

Operating System

Computer
Hardware

7 Principles of Operating Systems - Lecture 1 7

Operating System Concepts

Operating System Environment

1) Hardware
 It provides basic computing resources (CPU, memory, I/O devices).
2) Operating system
 It controls and coordinates the use of the hardware among the

various application programs for the various users.
3) Applications programs
 It define the ways in which the system resources are used to
solve the computing problems of the users (compilers, database
systems, video games, business programs).
3) Users (people, machines, other computers).

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Operating System Concepts

Operating System Environment

 Kernel
 It is the one program(Core part of operating System) running at

all times on the computer System (all others being application
programs).
 click here

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Operating System Concepts

What OS DOES?

 Memory Management
 Processor Management
 Device Management
 File Management
 Security
 Control over system performance
 Job accounting
 Error detecting aids
 Coordination between other software and users

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Operating System Concepts

Types of Operating Systems

 Operating systems are there from the very first computer
generation.

 Operating systems keep evolving over the period of time.
 Following are few of the important types of operating system

which are most commonly used.
 Batch operating system
 Time-sharing operating systems
 Distributed operating System
 Network operating System
 Real Time operating System

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Operating System Concepts

Batch Operating System

 The users of batch operating system do not interact with the
computer directly.

 Each user prepares his job on an off-line device like punch cards
and submits it to the computer operator.

 To speed up processing , jobs with similar needs are batched
together and run as a group. Thus, the programmers left their
programs with the operator.

 The operator then sorts programs into batches with similar needs.

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Operating System Concepts

Batch Processing:

 Problems with Batch Processing:
 Lack of interaction between the user and job.
 CPU is often idle, because the speeds of the mechanical I/O

devices is slower than CPU.
 Difficult to provide the desired priority.

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Operating System Concepts

Batch Processing:

 Examples of Batch Processing:

 The extract, transform, load (ETL) step in populating data
warehouses is a batch process in most implementations.

 Batch processing may also be used for converting computer files
from one format to another.

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Operating System Concepts

Time Sharing Systems:

 Time sharing is a technique which enables many people, located
at various terminals, to use a particular computer system at the
same time.

 Time-sharing or multitasking is a logical extension of
multiprogramming.

 Processor's time is shared among multiple users simultaneously is
termed as time-sharing .

 Multiple jobs are executed by the CPU by switching between
them, but the switches occur very much quickly.

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Operating System Concepts

Time Sharing Systems:

 Thus, the user can receives an immediate response.
 For example, in a transaction processing , processor execute each

user program in a short burst or quantum of computation. That is
if n users are present, each user can get time quantum.
 Time slice or time quantum is defined by the OS, for sharing CPU
time between processes.
 Examples: Multics, Unix, etc.,

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Operating System Concepts

Time Sharing Systems:

 Advantages of Timesharing operating systems:
 Provide advantage of quick response.
 Avoids duplication of software.
 Reduces CPU idle time.

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Operating System Concepts

Mainframe Systems

 Mainframe computers also called "big iron" are powerful
computers used primarily by:

 Corporate and governmental organizations for critical
applications,

 Bulk data processing such as census,
 Industry and consumer statistics,
 Enterprise resource planning, and
 Transaction processing.

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Operating System Concepts

Mainframe Systems

 Super Reliable

 Mainframe operating systems are generally rock solid
because a lot of circuitry is designed to detect and correct
errors.

 Mainframes are incredibly reliable with mean time between
failure (MTBF) up to 20 years!

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Operating System Concepts

Mainframe Systems

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Operating System Concepts

Mainframe Systems

 Reduce setup time by batching similar jobs
 Automatic job sequencing:
 It also automatically transfers control from one job to another..
 Examples:

 z/OS, z/VM®, and Linux® z/VM, z/VSE™, Linux for System z®, and z/TPF.

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Operating System Concepts

Mainframe Systems

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Operating System Concepts

 Distributed systems use multiple central processors to serve multiple real time
application and multiple users.

 Data processing jobs are distributed among the processors.
 The processors communicate with one another through various communication

lines (such as high-speed buses or telephone lines).
 These are referred as loosely coupled systems or distributed systems.
 Processors in a distributed system may vary in size and function. These

processors are referred as sites, nodes, computers and so on.

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Operating System Concepts

 Requires networking infrastructure.
 Local area networks (LAN) or Wide area networks (WAN)
 May be either client-server or peer-to-peer systems.
 Examples:

 DYSEAC, Lincoln TX-2

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Operating System Concepts

 Resources Sharing
 Data Availability
 Computation speed up – load sharing
 Reliability
 Communications

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Operating System Concepts

 Network Operating System runs on a server and provides server the capability to
manage data, users, groups, security, applications, and other networking
functions.

 The primary purpose of the network operating system is to allow shared file and
printer access among multiple computers in a network, typically a local area
network (LAN), a private network or to other networks.

 Examples:

 Microsoft Windows Server 2003-2012, UNIX,
Linux, Mac OS X, Novell NetWare, and BSD.

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Operating System Concepts

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Operating System Concepts

 They are found every where from car engines and manufacturing robots to VCRs
and microwave ovens.

 Often used as a control device in a dedicated application such as controlling
scientific experiments, medical imaging systems, industrial control systems, and
some display systems.

 Well-defined fixed-time constraints.
 They have little or no interface, preferring to spend their time monitoring and

managing hardware devices, such as automobile engines and robotic arms.

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Operating System Concepts

 Personal Digital Assistants (PDAs)
 Cellular telephones
 Issues:
 Limited memory
 Slow processors
 Small display screens.

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