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Unit-6 Operating System.

Introduction

The operating system is the master control program that manages the resources of the computer system and its overall operations. It has instructions that coordinate the activities of the hardware devices. An operating system is the first program loaded into the computer’s memory after the computer is switched on. Without it, the system cannot function. The most popular operating system used on personal computers is Ms-Dos, Microsoft Windows, Mac OS and Linux.

Some of the important function is listed below:

  • Provides the instruction to display on-screen elements with which you interact. Collectively, these elements are known as the user interface.
  • Loads programs (such as word processing and spreadsheet programs) into the computer’s memory so that you can use them.
  • Control the flow of data into and out of the computer, as well as to and from peripheral devices.
  • Manages the data stored on the secondary storages.
  • Provides security by preventing unauthorized access to the computer’s resources.

Types of operating system

There are different types of operating system available, which require different types of hardware to run upon. All operating system can be based on the types of computer they control and the sort of applications they support. The different types of operating system are as follows:

Real- Time Operating System

Real- time operating system is a computer operating system designed to handle events as they occur. Real time operating system are commonly found and used in robotics , cameras, complex multimedia animation system, communication and has various military and government uses. Almost any general purpose operating system such as Microsoft’s windows 2000 or IBM’s OS/390 can be evaluated for its real-time operating system qualities.

Single-User, Single Tasking Operating System

Single-user, single tasking is a type of operating system that allows only one user to run one program at a time. The computer devotes all its hardware resources and CPU time to time each program, as it executes. MS-DOS and PC-DOS.

Single- User, Multi- Tasking Operating System

Single- user, multi-tasking is the types of operating system which most people use on the desktop and laptop computers today. It is capable of running multiple programs at the same time on a single computer. Microsoft’s Windows and Apple’s Mac OS platforms are the examples of single-user, multi-tasking operating system.

Multi-User operating system

Multi-user operating system is a computer operating system (OS) that allows multiple users on different computers or terminals to access a single system with one operating system on it. Microsoft Windows NT, UNIX and LINUX are the most popular examples of multi-user operating system.

Distributed Operating System

Distributed operating system is a model where distributed applications are running on multiple computers linked by communications. A distributed operating system is an extension of the network operating system that supports higher levels of communication and integration of the machines on the network. This system looks to its users like an ordinary centralized operating system but runs on multiple, independent central processing units (CPUs).

PC Operating Systems

A personal computer is a general purpose computer based on a single tiny silicon chip called a microprocessor that contains all the essential elements of computers. There are different types of operating system available, which require different types of hardware to run upon. All operating system can be based on the types of computers they control and the sort of applications they support. The different types of OS are as follows:

Microsoft Disk Operating System

Microsoft Disk Operating System (MS-DOS) is a single-user, Single tasking operating system. It was developed for the IBM range of computer at the Microsoft Inc, USA, in 1981. It provides system function like disk input ND output, monitor support, keyboard control, and internal function related to program execution and file maintenance.

The main features of MS-DOS are listed below:

  • It is a simple operating system that is text-oriented system that is a text-oriented and command-based.
  • It is a machine independent (supports various computer languages).
  • It supports pipes and input/output redirection.
  • It supports both hard disk and floppy disk drives.
  • It supports flexible file allocation.

Booting the Computer

Booting is the process of starting or resetting the computer. When the computer is first turned on, the computer executes the software that loads and starts the computer’s more complicated operating system and prepares it for us. Thus, the computer can be said to pull itself up by its own bootstraps.

The main files necessary to start up a computer are: IO.SYS, MSDOS.SYS and “system”, which protect the files from being seen and inadvertently deleted or changed by users. COMMAND.COM is the command processor that sends the system prompt to the monitor and interpretes the character typed at the keyboard.

The computer can be booted in one of the two ways:

Cold Booting

Cold booting is the start-up of a computer from a powered-down, or off, state. typically, a cold boot involves some basic hardware checking by the system, after which the operating system is loaded form the disk into the main memory of the computer. It is also called hard boot.

Warm Booting

Warm booting refers to restarting a computer that is already turned on via the operating system. Restarting it returns the computer that is already turned on via the operating system. Restarting it returns the computer to its initial state. A warm boot is sometimes necessary when a program encounters and error from which it cannot recover. On PC,s you can perform a warm boot by pressing the Control, Alt and Delete keys simultaneously. On Macs, you can perform a warm boot by pressing the Restart button. It is also called a soft boot.

Directory

Directory is a table of contents the names of files, their sizes and the dates they were last modified. It lets the user arrange the files in convenient categories.  These directories, in turn, may contain other directories (referred to as subdirectories) this type of arrangement is known as a multilevel or hierarchical directory system. The hierarchical structure of directories and files are developed just like a tree. The first level in a multilevel directory is the root directory, which is created automatically when you format a disk. Root directory is the parent of all directories is called subdirectories. The directory the user is in, at any point of time, is called the working directory.

 Files

File is a collection of related information stored in the computer. It is the basic unit of storage that enables a computer to distinguish one set of information from another. It is the “glue” that binds a conglomeration of instruction, numbers, words, or images into a coherent unit that a user can retrieve, change, delete, save or send to output devices

Each file must have its own, unique filename. Each file is made up of two parts: filename and extension. Here’s an examples of a filename with an extension:

                               COMMAND.COM

   FILENAME                                                          EXTENSION

Each file on a disk has a name. This name has two parts: a filename and an extension.

  • Filename is the identifier of files on a disk.
  • Extension is a set of characters added to a filename that serves to extend or clarify its meaning or to identify a file as a member of a category.

The rules that govern filenames in DOS are listed below:

  • Filenames can have a maximum of eight characters from A to Z or 1-9 or special characters such as $ & # @! % ‘ () – {} _~.
  • Filenames should not contain any blank character (space) and any of the following characters: ? /| [] : | <> =.
  • Each extension can contain a maximum of three characters.
  • Files with Extensions. Exe, .COM and .BAT are called executable files and should be used only for a very specific purpose.

Wildcard Characters

Wild characters are those special characters which are used for substituting one character or a set of characters. They are useful in MS-DOS command lines because they give you flexibility when you are specifying path and files. The most commonly used wildcard characters are asterisk (*) and question mark (?).

Asterisk (*) is used to substitute a set of character. The examples given below list all the filenames having an execution as COM.

C:\>DIR*.COM

Question (?) mark is used to substitute a single character at a particular position. The examples given below lists all the files having six characters long with the first character as P and the extension is COM.

C:\DIR P?????.COM

DOS COMMANDS

Command is an instruction to a computer program that, when issued by the user, causes an action to be carried out. Commands come in different forms. They can be keywords, Function keys, choices in a menu or buttons or other graphical objects on your screen. MS-DOS command can have up to three parts- a command name, parameter and switch. MS-DOS command uses the following syntax:

Command [option]

Command Types

The entire set of commands available in DOS can be divided into two types. These are:

Internal Resident commands

Internal commands are the simplest, most commonly used commands. These are in-built commands of MS-DOS i.e. these are stored in the command interpreter file (command.com). These commands do not require any special files for being executed. They reside in the memory of your PC automatically along with DOS at the time of booting. It is also called resident command. Some of the internal commands contained within the command interpreter COMMAND.COM are listed below:

CHDIR (CD)              CLS                COPY            DATE            DEL

     DIR                MKDIR (MD)       PATH          PROMPT       REN

  RMDIR             TIME                    TYPE              VER             VOL

External commands

The commands that are stored on the system disk as program files are called external commands. They must be read from the disk before they are executed. External commands reside in COM, EXE or BAT files. Some of MS-DOS external commands are listed below:

ATTRIB                    BACKUP                 CHKDSK                 DISKCOMP

DISKCOPY               FORMAT                 LABEL                    MORE

SYS                           TREE                       XCOPY

Command                             Syntax/Purpose

DEL                                          DEL [drive:] [path] Filename [/p]

                                                                    Or

                                                  ERASE [drive:] [path] Filename [/p]

                                                   Del (Erase) allows deleting one or more  

                                                     unwanted files.

                                                      Examples:

                                                       C:\˃DEL *.EXE

                                                     Deletes a group of file ending with an

                                                      Extension EXE from Drive C:.

EDIT                                           EDIT [/b] [/h] [/r] [/s] [/˂nnn˃] [/?]

                                                   [File(s)] edit command starts the MS-DOS

                                                    Editor used to create and edit ASCII text

                                                     Files. Example: 

                                                     C:\˃Edit AUTOEXEC.BAT

                                                      Starts the MS-DOS editor and allows to

                                                      Edit text file named AUTOEXEC.BAT.

FORMAT                                      Format drive: [/v] [: label]] [/q] [/s] [/f:size]

                                                       Format command formats the disk in the

                                                        Specified drive to accept MS-DOS files.

                                                        Examples:

                                                        C:\˃FORMAT A:

                                                         Formats a disk in Drive A

                                                         C:\˃FORMAT A:/S

                                                         Formats a disk in drive A: and copies the system

                                                          Files onto it.

MD (MKDIR)                                  MD [drive:] path

                                                                        Or

                                                          MKDIR [drive:] path

                                                           MD (MKDIR) command allows creating new

                                                           Sub directories.

                                                           Example:    

                                                            C:\˃MD HELLO

                                                             Creates an new subdirectory called HELLO on

                                                             Drive C:

CD (CHDIR)                                         CHDIR [drive:] [ path ]

                                                                                Or

                                                                   CD [drive:] [path]

                                                                   CHIDR [..] or CD [..]

                                                                   CHDIR [\] or CD [\]

                                                                    CD (Chdir) command displays working                                         

                                                                    (Current) directory and / or changes to a              

                                                                    Different directory.

                                                                    Examples:

                                                                    C:\˃ CD HELLO

                                                                    Changes to a subdirectory called HELLO of

                                                                    Drive C:

RD (RMDIR)                                              RD   [drive:] path

                                                                                Or

                                                                    RMDIR [drive:] path

                                                                    RD (Rmdir) removes an existing subdirectory                                                                                                 

                                                                    From a disk. The directory to be removed must

                                                                    Be empty.

                                                                    Examples:

                                                                   C:\˃ RD HELLO                

                                                                   Removes a subdirectory called HELLO of

                                                                     Drive C:

DIR                                                            DIR [drive:] [path][filename][/p][/w][/a[[:]attributes]]          

                                                                   [/0[[:] sort order]][s][/b][/l]

                                                                  DIR command displays list of files and

                                                                  Subdirectories stored on the disk.

                                                                    Examples:

                                                                   C:\˃ DIR/P

                                                                   Displays all the files and directories in page     

                                                                   -wise of Drive C:.

 VOL                                                           VOL [drive:]

                                                                    Vol command displays the disk volume label

                                                                     And serial number, if they exist.

                                                                      Example:

                                                                      C:\˃VOL

                                                                      Displays the volume label and serial

                                                                      Number of drive C:.

Windows 7

     Windows 7 is an operating system that was produced by Microsoft for use on personal computers. It is a GUI- style operating system produced by US based Microsoft, the world’s largest software company. It is the operating system designed for businesses of all sizes and for advanced home computing. Windows 7 made its official debut to the public on October 22, 2009.

It provides the following advantages:

  • It is easier for a new user to learn and use the computer.
  • It has the ability to run more than one program at the same time on the same computer.
  • It manages computer’s memory and storage, enhancing their performance and extending their capabilities.
  • It enables to exchange information between different applications.                                           
  • Facts Corner

Windows 8 is a personal computer operating system developed by Microsoft as a part of Windows NT family of operating systems.

Windows Desktop

    The windows desktop is the opening screen for Windows and is the place where you begin your work using the computer. It is called the desktop because window uses your whole screen in a way that is similar to the way you use the top of the desk. The different components of Windows 7 are listed below:

  Components of the Desktop                                   Explanation

  Icons                                                                             Small pictures that represent commands and

                                                                                         Programs in Windows.

 Taskbar                                                                           The bar at the bottom of the windows screen

                                                                                          Where active applications appear along with

                                                                                           The system clock appears.

Start Button                                                                    The button at the left of the taskbar that allows

                                                                                           You to open or to use several other windows  

                                            programs.

                                              

Windows Explorer

   Windows explorer is an application program included with Windows 7. It allows you to efficiently manage files and folders present in the computers disk and view the contents of the computer. It is divided vertically into two sections. The left side displays the disk drives and folders in the form of a folder tree and the right side displays folders and files you have chosen from the left pane.

To view files using windows explorer, do the following:

  1. Click on the start button (or press CTRL+ESC) to see the start menu.
  2. Choose all programs І Accessories І Windows Explorer.Click the plus sign (+) next to the first folder that you want to investigate on the left side of the windows explorer window.
  3. Keep clicking the plus signs until you arrive at the folder you are looking for.
  4. Click the folders name or icon to see its folders and files on the right side of the window. When you have found the folder you want, click a folder or file on the right side of the window and delete or copy or rename it.

Creating a new folder

   You can create a new folder to organize the information stored on your computer. Creating a folder is like placing a new folder in a filing cabinet. We can create a folder on the desktop so as to have quick and easy access to it.

To create a new folder, do the following:

  1. Right-click and empty area of the desktop. A menu appears.
  2. Click on New.
  3. Click on folder on the submenu. Type a name for the new folder and then press Enter key.

Creating a file

  A file is a collection of related records of data. You can instantly create, name and store a new file in the location you want.

To create a file, do the following:

  1. Right-click an empty area on the desktop. A menu appears.
  2. Click on New.
  3. Click on the type of the file that you want to create. Type a name for the new file and then press Enter key.

Renaming a File or Folder

 Windows 7 allows you to give a file/folder a new name to better describe the contents of the file. Renaming a file/folder can make the file easier to find.

To rename files and folders, do the following:

  1. Right-click on the file/folder which you want to rename. A menu appears.
  2. Click rename on the shortcut menu.
  3. Type a new name for the file or folder.
  4. Press Enter key.

Moving or Copying Files or Folders

 Windows 7 offers different techniques for copying and moving files and folders stored on your computer to new locations. The most common techniques are menu command, and drag and drop.

To move or copy files and folders do the following:

  1. Right-click the file/folder which you want to move or copy.

Click cut on the shortcut menu to move the files or folders.

                                                            Or

Click Copy on the shortcut menu to copy the files or folders.

Display and double click the folder that is to receive the files or folders. Right-click and then select paste on the shortcut menu.

Deleting Files and Folders

   Windows 7 allows you to delete files or folders that you no longer need. There are many ways to delete files and folders from My Computer and Windows Explorer windows, as well as from the Windows 7 desktop.

    To delete files or folder, do the following:

  1. Select the file or folder that you want to delete.
  2. Press the Delete Key. The confirm File Delete dialog box appears.
  3. Click yes to delete the file. The file now disappears.

Windows places the file in the Recycle Bin in case you later want to restore the file.

Restoring or Emptying a Deleted Files and Folders

    The Recycle Bin Stores all the files you have deleted. Except from files deleted from removable disks, such as floppy disks, Windows stores items you delete in the Recycle Bin, where they can be restored to their original locations, if needed.

       To restore files or folder, do the following:

  1. Double-click the Recycle Bin on the desktop. The recycle Bin opens.
  2. Examine the files and folders that you want to restore.
  3. Select the files and folders you want to restore.
  4. Right-click an item you’ve selected and choose Restore from the shortcut menu. The items you restore will be placed in the same old folders.

To empty the Recycle Bin, do the following:

  1. Right-click the Recycle Bin icon on the desktop.
  2. Choose Empty Recycle Bin from the shortcut menu.

Brainstorming Task

  Complete each statement in the spaces provided.

  1. The operating system is the master control program that manages the resources of the computer system and its overall operations.
  2. Single user, single tasking is a type of operating system that allows only one user to run one program at a time.
  3. Booting is the process of starting or resetting a computer.

Tricky Terms

  1. Operating system    : The master control program that manages the resources of the

                                       computer system and its overall operations.

  • GUI                             : A computer program that enables a person to communicate with a

                                      computer through the use of symbols, visual metaphors, and pointing                

                                      devices.

  • Booting                       : The process of starting or resetting a computer.
  • Directory                    : A table of contents for a disk.
  • File                               : A collection of related information stored in the computer.
  • Wildcard characters : The special characters which are used for substituting one character

                                        or a set of characters.

Let Us Revise

  • The operating system is the master control program that manages the resources of the computer system and its overall functions.
  • Real-time operating system is a computer operating system designed to handle events as they occur.
  • The user interface is the way a person interacts with a computer or electronic device.
  • Graphical user interface (GUI) is a computer program that enables a person to communicate with a computer through the use of symbols, visual metaphors, and pointing devices.
  • Microsoft Disk Operating System (MS DOS) is single-user, single tasking operating system.
  • Booting is the process of starting or resetting a computer.
  • File is the collection of related information stored in the computer.
  • Wildcard characters are those special characters which are used for substituting one character or a set of characters.
  • Command is an instruction to a computer that, when issued by the user, causes an action to be carried out.
  • Windows 7 is an operating system that was produced by Microsoft for use on PCs.
  • The windows desktop is the opening screen for Windows and is the place where you begin your work using the computer.

Solved Exercises

  1. What is an operating system? What purpose does the operating serve to the computer and the user?

Ans An operating system is software that controls the operation of a computer, directs the input and output of data, keeps track of files and controls the processing of computer programs. The operating system narrows the gap between the user and the computer by receiving and interpreting users request and then getting the required work done through hardware.

  • What is user interface? What are two common types of user interface?

Ans User interface is a program that controls the display for the user and allows the user to interact with the system. Two common types of user interface are Character User Interface (CUI) and Graphical User Interface (GUI).

  • What is booting a computer? What are two common types of booting a computer?

Ans Booting is the process of starting or restarting a computer.  Its two types are Cold booting and Warm booting.

  • What is a file? What is it made up of?

Ans File is group of related information stored in computer also a basic unit of storage that enables a computer to distinguish one set of information from another. Each file is made up of two parts: filename and extension.

  • Write effects of following MS-DOS commands:
  • C:\˃COPY REPORT.TXT B:

Ans Copies the REPORT.TXT from drive C: to drive B:

  • C:\˃FORMAT A:/S

Ans Formats a disk in drive A: and copies the system files onto it.

  • C:\˃DIR*.COM

Ans Displays all the files having COM as an extension.

  • What is the difference between copying and moving files and folders?

Ans When the file or folder is copied, and then it is duplicated at the target location. That is, the file or folder remains at the original location as well as it is copied at the target location. When a file or folder is moved, then it is removed from the original location and placed at the target location.

  • What is the significance of Recycle Bin?

Ans Recycle bin is the place that holds the deleted files temporarily. Windows stores deleted items in the Recycle Bin. The files can be restored to their original locations, if needed.

Chapter Review 

1. State whether the following statements are true or false.

  1. The operating system is the master control program that manages the resources of the computer system and its overall operations. (True)
  2. Distributed operating system is a type operating system that allows only one user to run one program at a time. (False)
  3. The main files necessary to start a computer are: IO.SYS, MSDOS.SYS and COMMAND.COM. (True)
  4. Directory is a collection of related information stored in the computer. (False)
  5. The Windows Desktop is the opening screen for Windows and is the place where you begin your work using the computer. (True)

2. Match the following:

Group A                                                 Group B

  1. Operating System                          The master control program that manages

                                                           the resources of the computer system and

                                                           its overall operations.

  • GUI                                                     A computer program that enables a

                                                           person to communicate with computer

                                                            through use of symbols, visual metaphors

                                                            and pointing device.

  • Booting                                              The process of starting or resetting

                                                            a computer.

  • Directory                                            A table of contents for a disk.
  • File                                                      A collection of related information stored

                                                             in computer.

  • Wildcard Characters                         The special characters which are used for

                                                              substituting one or set of characters.

3. Select the best answer from the given options.

  • The operating system is capable of handling more than one processor to execute instructions.
  • i. Multiprocessing       ii. Multi-user      iii. Single-user, multi-tasking
  • A single- tasking, single-user operating system with a command-line interface developed by Microsoft.
  • Windows XP                ii. MS-DOS          iii. Windows 8
  • The command that displays the contents of a text file on the screen.
  • Type command           ii. Copy command      iii. Edit command
  • A place that stores documents, graphics, video, sound clips and other files.
  • My computer        ii. My Network Places         iii. My Documents
  • A group of related information stored in the computer.
  • File                          ii. Wildcard                             iii. Folder

4. Answer the following questions.

  1. What are the basic functions of an operating system?

Ans The basic functions of an operating system are:

  1. It provides the instructions to display the on-screen elements with which you interact. Collectively, these elements are known as the user interface.
  2. It loads programs (such as word processing and spread sheet programs)
  3. Into the computer’s memory so that you can use them.
  4. It controls the flow of data into and out of the computer, as well as to and from peripheral devices.
  5. It manages the data stored on the secondary storage.
  6. It provides security by preventing unauthorized access to the computer’s resources. 

2. What is the difference between multi-user operating system and multiprocessing operating system?

Ans The difference between multi-user operating system and multiprocessing operating system are:

Multi-user operating systemMultiprocessing operating system
a. It is a computer operating system that allows multiple users on different computers or terminals to access a single system with one operating system on it. a. It is the operating system that is capable of handling more than one processor to execute instructions.
b.   A multiuser operating system enables two or more users to run programs simultaneously.b. A multiprocessing operatingsystem supports two or more processors running programs at the same time also known as Multitasking.
  1. What do you mean by graphical user interface?

 Ans Graphical User Interface also known as (GUI) is a computer program that enables a person to communicate with a computer through the use of symbols, visual metaphors, and pointing devices.

  1. What do you mean by booting? Name the essential files required to boot a computer?

Ans Booting is the process of starting or restarting a computer. It is also known as loading a computer system. The main files necessary to start up a computer are: IO.SYS, MSDOS.SYS and COMMAND.COM.

  • What are the root directory and subdirectory?

Ans The first level in a multilevel directory that is created automatically when we format a disk and is indicated by backslash (\) also the parent of all directories is known as Root Directory. The directories within a directory are Subdirectories.

  • What is the difference between internal and external commands?

Ans Difference between internal and external command are:

Internal Command   External Command
a. It isthe simplest and most commonly used commands which are in built command of MS-DOS that do not require any special files for being executed.a. Those commands that are stored on the system disk as program files are called External Commands.
b. It is also called resident command. For e.g. CLS, DATE, etc.b. For e.g.SYS, MORE,XCOPY,TREE. These commands reside in COM, EXE or BAT files.
  • What are wildcard characters? Write the use of ‘?’ and ‘*’ wildcard characters.

Ans Wildcard characters are those special characters which are used for substituting one character or a set of characters. Asterisk (*) is used to substitute a set of characters and Question mark (?) is used to substitute a single character at a particular position.

  • Define command. What are the advantages of Windows XP operating system?

Ans Command is an instruction to a computer that, when issued by the user, causes an action to be carried out. Advantages of Windows XP operating system are: 

a. Microsoft Windows XP has a high stability of the system

   b. Applications that run on the Windows XP system can be run by a computer stable internet.

 c. There is no problem or conflict between the software and hardware

     d. Installing the software is easy compared to installation on other operating System.  

  • What is a desktop? List the main elements of Windows Desktop?

Ans The opening screen for the windows where we begin our work is desktop.

        Its main elements are:

a. Icons        b. Taskbar   c. Start Button 

5. Write down the appropriate DOS commands to perform the following tasks.

           a. Sets the system time to 9:00 A.M.

           b. Renames the file WORK.TXT, which is stored on the B: drive in the

PROJECT directory.

           c. Copies all the files of A: having EXE as an extension of the subdirectory project to B:

                drive staying in C: drive.

            d. Deletes all the files whose filename is 6 characters wide starting with a letter E

                 having HLP as an extension.

             e. Creates a directory called WORK on drive C:.

              f. Displays all the files having 3 characters long with the first character as T and the

                  extension is COM.

              g. Displays all the files having COM as an extension.

              h. Displays all the files and directories in a wide list format.

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