Computer Basic

Disk Operating System (DOS)

Introduction

An operating system is a set of instructions, which control the whole system of a computer. An operating system act as an interpreter of between the computer and the user. It manages the resources of the computer and creates a well defined software environment for computer applications. An operating system is the first layer of the software on which the other application software lies. Some examples of Operating system are DOS, Windows, UNIX, LINUX, OS/2, Solaris etc. It is an operating system that controls the input and output system. It is system software. It is a single user, character user interface operating system. It is well known that without Operating system our computer is useless or without the operating hardware are no more accessible.

It acts as an interface between the user and the computer. Disk Operating System is the program that manages the disc operating and memory location. Managing the disc operation involves reading, writing, searching and sorting etc. the content present on the disc.

Evolution

The home computers were very successful in USA and this inspired IMB (International Business Machine) to introduce small computers (Personal Computers or PC's) in to the market. They also wanted an operating system for their Pac range. Mr. Bill gates of Microsoft Corporation purchased the copyright of the operating system called Q DOS (Quickly and Dirty Operating System), which was developed my Mr. Tim Peterson and used that as a basic for another operating system called MS–DOS (Microsoft Disc Operating System). There wan an understanding between Microsoft Corporation and IMB and copy of MS–DOS is sold with every IMB computers.

PC-DOS

PC–DOS and MS–DOS both of them represent the same Operating System. The only difference between them is, PC–DOS has been manufactured by IBM while MS–DOS has been manufactured by Microsoft Corporation.

What is an Operating System?

An Operating System is a set of programs that provides and interface the user and the machine.

Function of an Operating System

Whenever any program is executed or any job is to run, it has to be loaded on the memory first. But before your program is loaded on the memory the CS has to check any memory is free to give allocated to your job and after the execution of your program the allocated memory is freed so that is can be allocated job.

i.      CPU Management: The CPU does the actual processing of the job or programs. The CPU gets the job or program from the memory and processing. It after processing the job, the cup to the various jobs. This function is called Kip Scheduling.

ii.     Disc Management: Whenever the users need to retrieve any file from the disc, they need not to bother about how and where the files are stored. It is the job of operating system to keep a track of all the files addresses on the disc and retrieves them as and when required.

iii.   Input/Output Management:  The computer system is attached to too many peripherals and devices like keyboard, mouse etc. It is the Operating System that performs the task of co–ordination all the input and output devices.

iv.   User interface: The machine understands only the language 0 and 1 and the cannabis are as a user give to it are in English. There are user and the machine to translate the English like commands into machine language and vice–versa. It is the Operating system that acts as a bridge between the user and the machine.

Single user and the multi–user Operating System

A single user operating system is the operating system that supports only a single user at once. Whereas a multi–user operating system supports a number of users at a time. Examples of multi–user Operating System are UNIX, XENIX; the latest version of DOS is also multiuse while the early versions were single users. File security is required in the multi user operating system.

We can operate this software by giving command from the keyboard.

Booting: The process of loading the system files and COMMAND.COM files on the operating system from a disc to computer's memory (RAM) is called Booting. There are following two types of booting:

i.   Cold Booting: Booting the computer is in "OFF" stage by pressing "ON" switch so that power supply is provided is called Cold Booting.

ii.  Warm Booting The booting of the computer when it is at "ON" stage by pressing "RESET" button is called warm booting.

When the machine is switched on a number of steps are undertaken before system is ready but while booting, mainly three MS.DOS files are loaded on RAM.

i.   I.O.sys

ii.  MS. DOS.sys

iii. Command.com

Command: A command is a request or an order to the computer, which executes a series of sequential instructions and solves an assigned task such as clearing the screen, deleting the files, renaming the files etc. There are two types of DOS Commands:

i.   Internal Command

ii.  External Command

i.   Internal Command: Those commands that are built in to DOS and execute immediately are called internal commands. These commands cannot be listed on the screen because they are parts of a file COMMAND.COM that is located in the memory while booting, so they don't have to be loaded. Some internal commands are BREAK, CLS, CD, DEL, MD, COPY, COPY CON etc.

ii.  External Command: Those commands which are on the disc as program files are called external command. The helping files of these commands have to be loaded from disc before they're executed. These commands can be listed on the screen. Some external commands are FORMAT, CHKDSK, SYS, ATTRIB, LABEL etc.

Loading Process of DOS

The method of loading DOS in computer is as follows:

i.   First method

Ä Click of "Start Menu"

Ä Click on "Programs"

Ä Click on "MS DOS Prompt"

ii. Second method

Ä Click of "Start Menu"

Ä Click on "Shut Down"

Ä Choose "Restart in MS DOS Mode"

Ä Click "OK"

iii. Third method (Applicable on for Win'98 and win ME)

Ä Switch ON the computer

Ä Press "F8" of function key on keyboard as soon as possible

Ä Select "Command Prompt" moving UP and DOWN arrow keys on keyboard.

After loading DOS Prompt, we can get a blank black screen with following matters.

C:\WINDOWS\Desktop>         or,

C:\WINDOWS\>                    or,

C:\>

Getting out of DOS

We can quit DOS program by following steps:

We can type "EXIT" command in the present drive and press "Enter" key.

e.g.

C:\WINDOWS\Desktop>EXIT à        or,               (à means "Enter" key on keyboard)

C:\WINDOWS\> EXIT Ã

C:\> EXIT Ã

In this way we can return back to the Windows Program

Internal Commands

DOS program has following internal commands

CLS: To clear the screen.

Syn.: C:\>CLS Ã

DATE: To view Date and change the current date on your computer as per require.

Syn.: C:\>DATE Ã

TIME: To view Time and change the current date on your computer as per require.

Syn.: C:\>TIME Ã

COPY CON : To create file.

Syn.: C:\>COPY CON <filename and extension> Ã

(Now type the document and press "Ctrl + Z" or "F6" key to save the document.

e.g. C:\>COPY CON AASHIS.TXT Ã

My name is Aashis Kumar Sah. I'm from Siraha. I've been studying in Ambition Academy.

(Now press "Ctrl + Z" or "F6" key to save the document.)

                                1 file(s) copied    will display to prove your created document

TYPE: To view the print content of the document you have created.

Syn.: C:\>TYPE <filename and extension> Ã

e.g.   C:\>TYPE AASHIS.TXT Ã

RENAME:  To replace/change the name of old file with new name.

Syn.: C:\>REN <old filename> <new filename> Ã

e.g.   C:\>REN AASHIS.TXT ASHISIQ.TXT  Ã

DELETE:  To delete the file saved on the computer.

Syn.: C:\>DEL <filename> Ã

e.g.   C:\>DEL ASHISIQ.TXT  Ã

DELETE:  To copy the desired file from one location to another.

Syn.: C:\>COPY <filename> <location> Ã

e.g.   C:\>DEL ASHISIQ.TXT C:\WINDOWS  Ã

DIR:  To display the files and directory located on the current drive.

   a. Syn.: C:\>DIR Ã

             Volume in drive C is OS_98

                      Volume Serial Number is OD10-15F6

                      Directory of C:\

COMMAND        COM                       93,890    04-23-99    10:22P

COMMAND.COM

FRUNLOG          TXT                        1,010     08-11-04      2:45P FRUNLOG.TXT        

WINDOWS                  <DIR>                       08-11-04      2:37P WINDOWS

Index

i.        File Name: - The first column is filename. Maximum length of filename is eight characters.

ii.       Extension: - The second column is extension. It is just like a surname. By default, it is   optical and is not longer than three characters.

iii.      Size: - The third column shows the size of file on the disc. It is measures in bytes.

iv.      Date: - The fourth column shows the created date of the corresponding file.

v.       Time: - The fifth column shows the created time of the corresponding file.

   b. Syn.: C:\>DIR/P Ã

       (Pause the screen when the screen is full of names of files and directories, i.e. this       command helps to view the files and directories page wise.)

   c. Syn.: C:\>DIR/W à   

       (Displays five names per line. We can view only file name and extension, i.e. this       command helps to view the files and directories width wise.)

   d. Syn.: C:\>DIR *.EXE Ã

        (Search and displays only the files on disc having name length max'm 8 characters and extension EXE Executive file)

   e. Syn.: C:\>DIR P*.EXE Ã

        (Search and displays only the files on disc having name started with "P" and name length max 8 characters and having extension EXE Executive file)

     

   f. Syn.: C:\>DIR ???????.??? Ã

        (Search and displays only the files on disc having name length max of 7 characters and having extension length max of three characters)

      Wild Cards

Wildcards are the symbols used in DOS Program do view the unknown file name within the criteria of the wildcards used. The example of wild card are * ,  ?. They have the value of certain length of any characters.

* :– This symbol is used to view and filename having any the name length of 8 character   since the single * has the length value 8 characters.

? :- This symbol has the length value of 1 character per symbol.

Application : It is used to search the file of unknown name

 g. Syn.: C:\>DIR/O :- N/p Ã

        (Displays the files on disc in ascending order according to the name of file.)

 

   h. Syn.: C:\>DIR/O :- N/P Ã

        (Displays the files on disc in descending order according to the name of file.)

 

      O ==>Order

      N ==>File Name

      S ==>Extension

      D ==>File Created Date and Time

         ==>Describing Order

    i. Syn.: C:\>DIR/ah Ã

        (Displays the files on disc, which are hidden.)

 

    j. Syn.: C:\>DIR/ar Ã

        (Displays the files on disc, which are Read Only files.)

  

    k. Syn.: C:\>DIR/ad Ã

        (Displays only the list of directories.)

    l. Syn.: C:\>DIR/p Ã

        (Displays all the directories including system and hidden.)

  m. Syn.: C:\>DIR/L Ã

            (Uses the lowercase to display the list of files.)

VERSION:  To display the version/edition of the DOS currently being used.

Syn.: C:\>VER Ã

VOLUME: To display the volume label of the disc being currently used.

Syn.: C:\>VOL Ã

Directory/Folder Maintenance

The directory is folder displayed in the Windows file. It is just like a room where we store similar types of file.

To remember

i.      Any directory created in rood directory of any drive is "Directory or Folder"

ii.     Any directory created in the is called "Sub Directory or Sub Folder"

iii.    Thus Root directory, Directory and Sub Directory are related terms.

CREAT A NEW DIRECTORY

Syn.: C:\>MD <directory name> Ã OR, C:\>MKDir Ã

e.g.   C:\>MD CPN Ã

CHANGE THE DIRECTORY

Syn.: C:\>CD <directory name> Ã

e.g.   C:\>CD ASHIS Ã

It displays as

e.g.   C:\ASHIS>

REMOVING DIRECTORY

Syn.: C:\>RD <directory name> Ã

e.g.   C:\>RD ASHIS Ã

PROMPT : Change the appearance of MS DOS Prompt

e.g.

i.   C> Prompt $p$Gà                  [$p=Path (Drive and folder) and $G=Greater than sign]

ii.  C:\Prompt $g                [Display only the greater than sign]

iii. C:\Prompt $T                 [Display only the time]

iv. ---$P$G                        [Enter to default Position]

CHKDSK:  Helps to check the condition and status of the disc.

Syn.: C:\>CHKDSKÃ

SCANDISC:  Helps to scan or detect the disc.

Syn.: C:\>SCANDISCÃ

MORE:  Helps to the display the text document.

Syn.: C:\>MORE <filename>Ã

MEMORY:  Helps to check the memory of any disc.

Syn.: C:\>MEMÃ

ATTRIBUTES:  Display or Change the attributes of file.

R [Read Only File Attribute]

H [Hidden File Attribute]

S [System File Attribute]

+ [Set an attribute]

-  [Clear an attribute]

Syn.: C:\>ATTRIB +h <filename>à            [To hide the file]

Syn.: C:\>ATTRIB -h <filename>à             [To reappear the hidden file]

Syn.: C:\>ATTRIB +r <filename>à            [To make a file Read Only]

Syn.: C:\>ATTRIB -r <filename>à             [To make a file Read, Write]

EDIT:  It is a powerful MSDOS text editor, which allows us to create, edit, save, open, duplicate and print text files.

Syn.: C:\>EDIT <filename>à         

XCOPY:  Copies directories, subdirectories, and their files. The Xcopy command first loads the specified directories and files into RAM as much as it can hold after then, copies them from RAM to target drive and folder. So Xcopy command is faster than Copy command.

Syn.: C:\>XCOPY <Source with filename> <target>à               

Syn.: C:\>XCOPY/S <Source with filename> <target>à   [Copies all the files with                                                                                             Subdirectories]

Syn.: C:\>XCOPY/P <Source with filename> <target>à    [Copies files with permission]

Syn.: C:\>XCOPY/S/P <Source with filename> <target>à

Syn.: C:\>XCOPY/P/E <Source with filename> <target>à [Copies files with permission                                                                                       into an empty directory]

[Note: Under xcopy command all types of file features like Read-Only, Hidden system can be copied.]

LABEL:  Create, change or delete the volume label of the disc. User can give a name to the disc, which can be stored internally.

Syn.: C:\>LABEL <name>à  

MOVE: To move the files or directories that you have specified. It also renames files and directories. To move one or more file(s).

Syn.: C:\>MOVE <source> <target>à       

COMPUTER VIRUS

          Computer viruses are the program designed that can replicate and spread. They some times come to action with the indication of their presence. Computer viruses can produce an number of symptoms on your computer. Some viruses multiply without causing oblivious changes. More malicious strains can issue random messages and sounds. Viruses can corrupt the files and memory of your hard disc. Computer viruses can be classified on the basis of their infections on system.

Types                               Characteristics

Boot sector Virus                Boot sector is the portion of the hard disc that controls how your operating system starts when you turn on your computer. A boot sector virus replaces the disc's original boot sector with it's own, and loads the virus into memory. Once the virus gets into the memory it spreads to other discs.

File Infector                      A File Infector virus code to the file that run programs. So, the virus gets activated whenever you run program that spreads to other program file.

Trojan Horse                     A Trojan Horse is disguised as a legitimate program when you run a program. Now when you run the program infected by Trojan Horse virus, your computer may be damaged. Files or dockets with a Trojan Virus may not be recovered.

Microsoft Word is a very powerful, advanced, useful and widely implemented Word Processing software which is developed by Microsoft Corporation, USA. It consist every kinds of Word Processing features like, Creating, editing, formatting, saving and printing documents, checking the correct spellings and grammar, searching antonyms and synonyms, working with newspaper columns, creating and formatting tables, adding footnotes and endnotes, page numbers, symbols, bookmarks, comments, inserting pictures, objects (e.g. Video clips, audio clips, PowerPoint Presentations, equations, Auto CAD drawings etc.), table of contents and index etc. It extension is DOC.

In spite of above mentioned features, there are many other fascinating features in WinWord, which helps us to furnish a document (report, letter, essay, thesis etc.) in such a way that we can produce the professional outlook. Now-a-days, WinWord is considered as the best Word Processing Software.

TO OPEN MS WORD

Ä  Click on START MENU

Ä  Choose PROGRAM

Ä  Choose MS OFFICE, or, Select Microsoft Word 2000/xp

          OR,

Ä  Click on START MENU

Ä  Choose RUN

Ä  Then a dialogue box appear as shown below