20 March Introduction to Operating Systems

An Operating System? What is an Operating System? A program that acts as an interface between a user of a computer and the computer hardware. What is the purpose of an operating system? To provide an environment in which a user can execute programs. What are the goals of an Operating System? The primary goal of an Operating System is to make the computer system convenient to use. The secondary goal is to make the computer system efficient to use.

Computer System Components Hardware – provides basic computing resources (CPU, memory, I/O devices). Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. Applications programs – define the ways in which the system resources are used to solve the computing problems of the users. Users (people, machines, other computers).

Abstract View of System Components

Functions of Operating System Operating system performs the following functions: Booting: It is a process of starting computer. operating system starts the computer to work. it checks the computer and makes it ready to work. Memory Management: The memory cannot be managed without operating system. Different programs and data execute at one time. if there is no operating system,the programs may mix with each other. The system will not work properly.

Functions of Operating System Loading and Execution: A program is loaded in the memory before it can be executed. operating system provides the facility to load programs in memory easily and then execute it. Data Security: The operating system protects the data stored on the computer from illegal use, modification or deletion. Disk Management: It manages the disk space. It manages the stored files and folders in a proper way.

Functions of Operating System Process Management: CPU can perform one task at one time. if there are many tasks,operating system decides which task should get the CPU. Device Controlling: Operating system controls all devices attached to computer. the hardware devices are controlled with the help of small software called device driver. Printing Controlling: Operating system controls printing function. If a user issues two print commands at a time, it does not mix data of these files and print them separately.

20 March Function of Operating System Providing Interface: U ser interface is used to interact with the computer. Operating system provides two types of interface for the user: 1. Graphical User Interface 2. Command Line Interface

Types of Operating System 1. Stand-Alone Operating Systems 2. Network Operating System 3. Embedded Operating Systems

Stand-Alone Operating System An operating system that works on a desktop or notebook. operating system is called stand-alone operating system. Examples: 1. DOS 2. Mac OS 3. Windows

DOS Stands for Disk Operating System It was developed by Microsoft in early 1980s for personal computers It is single user operating system

20 March Mac OS It is product of Apple It was one of the first successful GUI. It was released with Macintosh computers in 1984 The latest version of this operating system is called Mac OS X

Windows Microsoft Windows is the most widely used operating system It uses Graphical User Interface The most commonly used versions of Windows are as follows: 1. Windows XP It is product of Microsoft corporation It was released in 2001 XP stands for Experience It provides quicker startup, better performance and new look

Windows 2. Windows Vista It was released in 2007 It provides new interface and enhanced features. It has an attractive design, easy to use search It is available in several editions of Home and Business categories.

Network Operating System An operating system that supports network is called network operating system It normally works on a server Examples 1. Windows NT Server 2. Windows 2000 Server 3. NetWare 4. UNIX 5. LINUX 6. Solaris

20 March Windows NT Server It is product of Microsoft It is designed for client/server network The server in the network uses Windows NT Server The client computers use Windows NT-workstation and stand-alone versions of Windows

UNIX UNIX is multitasking operating system It was developed in early 1970s Many versions of this operating system are available It uses command line interface It is mainly used in network environment

20 March Embedded Operating System That is used in most Handheld computers and small devices is called embedded operating system It resides on ROM chips Examples: 1. Windows CE 2. Windows Mobile Palm OS 4. Symbian OS 5. Embedded Linux

20 March LINUX It is free and multitasking operating system It was developed in 1991 It is an open-source operating system. It means that its code is available to the public Some versions of LINUX use command-line interface and others use GUI Most widely used version of LINUX is RedHat.

Introduction to LINUX

History In 1969, a team of developers in the Bell Labs laboratories started working on a solution for the software problem, to address these compatibility issues. They developed a new operating system, which was  Simple and elegant.  Written in the C programming language instead of in assembly code.  Able to recycle code. The Bell Labs developers named their project “UNIX.”

Linus and Linux Linus Torvalds, a young man studying computer science at the university of Helsinki thought it would be a good idea to have some sort of freely available academic version of UNIX, and promptly started to code. Linux is a full UNIX clone

Current application of Linux systems Today Linux has joined the desktop market. Linux developers concentrated on networking and services in the beginning. And then office applications have been introduced in Linux making it more famous in business group. On the server side, Linux is well-known as a stable and reliable O.S., providing database and trading services for companies like Amazon, the well-known online bookshop, US Post Office, the German army etc…..

Current application of Linux systems Linux machines connected through network connection are used in the creation of intense animation movies such as “Titanic” “SHREK” and many others.

Is Linux difficult? Linux is designed to be fast, responsive and flexible. There is excellent and free Internet support and documentation available The graphical user interface is similar in design to that on any other system and a very powerful command line alternative is also available. So Linux can get the things done you need doing. Linux is user friendly.

Linux for non-experienced users Nowadays you can log in graphically and start all required applications without even having to type a single character, while you still have the ability to access the core of the system if needed. Because of its structure, Linux allows a user to grow into the system: it equally fits new and experienced users. New users are not forced to do difficult things, while experienced users are not forced to work in the same way they did when they first started learning Linux.

Properties of Linux Linux is free: If you want to spend absolutely nothing, you don't even have to pay the price of a CD. Linux can be downloaded from the Internet completely for free. No registration fees, no costs per user, free updates, and freely available source code in case you want to change the behavior of your system. You don’t need to spend time and money to obtain licenses since Linux and much of its software are free. You can start to work immediately without worrying that your software may stop working anytime because the free trial version expires. Additionally, there are large repositories from which you can freely download high quality software for almost any task you can think of.

Properties of Linux Linux is portable to any hardware platform: A vendor who wants to sell a new type of computer and who doesn't know what kind of OS his new machine will run,can take a Linux kernel and make it work on his hardware, because documentation related to this activity is freely available.

Properties of Linux Linux is secure and versatile: The security model used in Linux is based on the UNIX idea of security, which is known to be robust and of proven quality. But Linux is not only fit for use as a fort against enemy attacks from the Internet: it will adapt equally to other situations, utilizing the same high standards for security.

Properties of Linux Linux is scalable: Add or remove the appropriate packages and Linux fits all. You don't need a supercomputer anymore, because you can use Linux to do big things using the building blocks provided with the system. If you want to do little things, such as making an operating system for an embedded processor, Linux will do that as well

Properties of Linux The Linux OS and quite some Linux applications have very short debug-times: Because Linux has been developed and tested by thousands of people, both errors and people to fix them are usually found rather quickly. It sometimes happens that there are only a couple of hours between discovery and fixing of a bug

Stability:  Linux doesn’t need to be rebooted periodically to maintain performance levels. It doesn’t freeze up or slow down over time due to memory leaks and such. Continuous up- times of hundreds of days (up to a year or more) are not uncommon.

Multitasking: Linux is designed to do many things at the same time; e.g., a large printing job in the background won’t slow down your other work. Security: Linux is one of the most secure operating systems. “Walls” and flexible file access permission systems prevent access by unwanted visitors or viruses. Linux users have to option to select and safely download software, free of charge, from online repositories containing thousands of high quality packages. No purchase transactions requiring credit card numbers or other sensitive personal information are necessary.

Open Source: If you develop software that requires knowledge or modification of the operating system code, Linux’s source code is at your fingertips. Most Linux applications are Open Source as well.

Compatibility: It runs all common Unix software packages and can process all common file formats. Fast and easy installation: Most Linux distributions come with user-friendly installation and setup programs. Popular Linux distributions come with tools that make installation of additional software very user friendly as well. Full use of hard disk: Linux continues work well even when the hard disk is almost full.

Network friendliness: Linux was developed by a group of programmers over the Internet and has therefore strong support for network functionality; client and server systems can be easily set up on any computer running Linux. It can perform tasks such as network backups faster and more reliably than alternative systems. Flexibility: Linux can be used for high performance server applications, desktop applications, and embedded systems. You can save disk space by only installing the components needed for a particular use. You can restrict the use of specific computers by installing for example only selected office applications instead of the whole suite.