Purpose of Operating System

Monil Adhikari

Agenda• Introduction• Responsibilities of Operating System• User Interfaces• Command Line Interface• Graphical User Interface

• Exercise

Introduction• Operating System (OS) - a set of programs that manage computer

hardware resources and provide common services for application software.• The operating system acts as an interface between the hardware and

the programs requesting I/O. It is the most fundamental of all system software programs.

Introduction

Responsibilities of OS• Hiding the complexities of hardware from the user.•Managing between the hardware's resources which

include the processors, memory, data storage and I/O devices.• Handling "interrupts" generated by the I/O controllers.• Sharing of I/O between many programs using the CPU.

User Interface• Command Line Interface (CLI)• Graphical User Interface (GUI)

The most well known Operating Systems include:• System Software - programs that manage the operation of a

computer.• Application Software - programs that help the user perform a

particular task.

Command Line Interface

Command Line Interface (Contd.)• The more primitive User Interface, the user would type in a line of

command or a single word followed by pressing the Return key. • The computer then willingly follows that exact command, informing

the user of its progress. For example, the user may want to type in the command to print a document. • The user will type the statement Print, then the name of the Printer

and finally the name of the file to be printed:

Pros and Cons• Pros• CLIs can run on simple hardware with limited resources.• Some commands may be simpler to perform in a CLI than in a GUI.

• Cons• Learning the commands may make it not suitable for a new user.• Some commands may be harder to perform in a CLI than in a GUI.

Graphical User Interface (GUI)

Graphical User Interface (GUI)• The GUI is made up of boxes or Windows which will display as an array of usually

colourful tiny blocks called Pixels, and a group of pixels is a called an image. • The maximum number of colours that can be used are called the Graphics. This

User interface will display a Main window (also known as the Desktop) which then can be accompanied by more windows. • GUI is the most common of the User interfaces, and the most user friendly,

made up of event driven software. • This type of UI is best for users lacking in computer coding skills, since GUI only

needs you to make use of the mouse's events. • There are still some people who prefer the use of a Command Line Interface to a

Graphical User Interface.

Pros and Cons• Pros• Simple and intuitive for new users.• Some commands may be simpler to perform in a GUI than in a CLI

• Cons• GUIs require system resources and more complex hardware than CLIs.• Some commands may be harder to perform in a GUI than in a CLI

Exercises1. Name the two types of Operating System Interfaces.2. Give two benefits and a draw back of using a CLI.3. Give two benefits and a draw back of using a GUI.4. Why do some system administrators prefer to use Telnet (a CLI) instead of a GUI to control remote computers?

Thank You