S R Computer Institute

Introduction:

An operating system (OS) is an interface between hardware and user. It is responsible for the management and coordination of activities and the sharing of the resources of a computer.

Basics of Operating System:

An operating system plays an important role in the use of Computer. It prepares a bare machine for use by the user. In other words an operating system works as an interface between computer and user. The operating system enables the user to effectively use the system resources and access several other programs.

Windows operating system offers a new graphic based interface to the users and they can use mouse to perform a number of operations. It is also possible to work on multiple windows at a time. Other popular operating system are Linux, Solaris ,mac etc.

Functions of Operating System:

Today most operating systems perform the following important functions:

1. Processor management – Assignment of processor to different tasks being performed by the

computer system.

2. Memory management – Allocation of main memory and other storage areas to the system

programs as well as user programs and data.

3. Input/output management – Co-ordination and assignment of the different output and input

devices while one or more programs are being executed.

4. File management – Storage of files of various storage devices. It also allows all files to be easily

changed and modified through the use of text editors or some other files manipulation routines.

5. Prioritization – Establishment and enforcement of a priority system. That is, the OS determines

and maintains the schedule in which jobs are to be executed in the computer system.

6. Automatic transition from one job to another job as directed by special control statements.

7. Interpretation of commands and instructions.

8. Resource Allocation – Coordination and assignment of compilers, assemblers, utility programs, and other software to the various users of the computer system.

User Interface:

The Graphical User Interface has a visual environment using windows, buttons, and icons. As Microsoft Windows operating system is the most popular, we will discuss the different features of a

GUI based operating systems with the help of Windows operating system.

There are two types of operating systems:

1. Command Line Interface (CLI) – Here the user has to remember the commands that are to be given at the command prompt. Examples of such OS are DOS and UNIX.

2. Graphical User Interface (GUI) – GUI operating systems use icons and menus to carry out commands. Because of their ease of use, GUI Operating Systems have become the dominant operating system used by end-users today. Windows is the most popular GUI OS.

Types of Operating System:

1) Multi-user – A multi-user operating system allows for multiple users to use the same computer at the same time and different times. See the multi-user definition for a complete definition. Examples of operating systems that would fall into this category are:

Linux
Unix
Windows 2000

2)Multiprocessing – An operating system capable of supporting and utilizing more than one computer processor. Examples of operating systems that would fall into this category are:

Linux
Unix
Windows XP

3)Multitasking – An operating system that is capable of allowing multiple software processes to run at the same time. Examples of operating systems that would fall into this category are:

Linux
Unix
Windows 8

4) Multithreading – Operating systems that allow different parts of a software program to run concurrently. Examples of operating systems that would fall into this category are:

Linux
Unix
Windows XP

Linux:

Linux is one of popular version of UNIX operating System. It is open source as its source code is freely available. It is free to use. Linux was designed considering UNIX compatibility. Its functionality list is quite similar to that of UNIX.

Linux is an operating system or a kernel which germinated as an idea in the mind of young and bright Linus Torvalds when he was a computer science student. He used to work on the UNIX OS (proprietary software) and thought that it needed improvements.

Components of Linux System

Linux Operating System has primarily three components

• Kernel − Kernel is the core part of Linux. It is responsible for all major activities of this operating system. It consists of various modules and it interacts directly with the underlying hardware. Kernel provides the required abstraction to hide low level hardware details to system or application programs.
• System Library − System libraries are special functions or programs using which application programs or system utilities accesses Kernel’s features. These libraries implement most of the functionalities of the operating system and do not requires kernel module’s code access rights.
• System Utility − System Utility programs are responsible to do specialized, individual level tasks.

Basic Graphical Elements of GUI based Operating System

Task Bar:

Any work which has been started on computer is called as task . you can perform various tasks simultaneously. While one program is on and you want to start another program it is not necessary to close the first program. You can simply minimize the first program and work in other program.The icons of running programs are shown in the taskbar.

Taskbar is a bar displayed at the bottom of the GUI desktop. It is used to launch and monitor running

applications. The taskbar in Microsoft Windows may include the Start menu button, Quick Launch bar, taskbar buttons, and notification area.

Icons:

Icon is a graphic symbol that denotes a program or a command or a data file or a concept in a graphical user interface.

When you start(booting) the Computer. After completion of the booting process the first screen displayed is called as Desktop.

Various Items including Icons are present on this Desktop. With the help of these icons we can quickly access various programs, files and folders. Various shortcuts for programs, files, folders, disks etc are provided with the help of icons. Icons are special types of buttons which include image and label given to that button.

Tip: Users can quickly rename any highlighted Windows icon by pressing the F2 key on the keyboard, and then typing in a new name.

Types of icon:

1. System icon :Ex. My computer, Recycle bin, My network places.

2. Application icon: Tally, game, antivirus etc.

Start Menu:

Start menu or Start button provides list of commands to perform various jobs and applications. In various versions of Windows Start menu is displayed with the start label. In Windows Vista Start menu is displayed with the start button. In Start menu various programs installed on computer are shown using nested structure. With the help of link provided here you can quickly access desired program or perform any task. Thus you need not to remember the difficult commands and complicated file paths.

File:

Files are used for storing the data of the users for a long period of time. There are many files which have their own type and own names.
Each file has an extensions to indicate the format of files so operating systems know what to do with them.
extensions generally used on windows os:

• .docx for Ms-Word document(word processor) file
• .xlsx for Ms-Excel (spreadsheet) file
• .pptx for Ms-Powerpoint(presentation) file
• .mp3 for audio file
• .wmv for Windows Media Video

Folder:

A folder, also called a directory, is a special type of file on your computer’s file system which contains other files and folders. When you are browsing the files on your computer using a File Manager, such as Windows Explorer, the icon for a folder will typically look similar to the image at the right.

Common Utilities

Utility software is a kind of system software designed to help analyze, configure, optimize and maintain the computer. A single piece of utility software is usually called a utility or tool. Some of the utilities of OS are:

1. Disk defragmenters:

It can detect computer files whose contents are broken across several locations on the hard disk, and move the fragments to one location to increase efficiency.

2. Backup utilities:

It can make a copy of all information stored on a disk, and restore either the entire disk (e.g. in an event of disk failure) or selected files (e.g. in an event of accidental deletion).

3. Archive utilities:

output a stream or a single file when provided with a directory or a set of files. Archive utilities, unlike archive suites, usually do not include compression or encryption capabilities. Some archive utilities may even have a separate un-archive utility for the reverse operation.

4. Disk compression utilities

 It can transparently compress/ uncompressed the contents of a disk, increasing the capacity of the disk.