Disk Operating System

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Disk Operating System By Naman kumar navikunjan/1 Disk Operating System Operating System is a set of programs that is extremely important to activate and Co-Ordinate the activities of various hardware resources like the processor and Input/Output devices. In other words, Operating System controls the movement of information on in the Computer. OR An operating System is a collection of programs that manage System is to provide a basic set of computer instructions to manage the flow of information in the computer. The operating System forms the communication interface between the computer hardware, application software programs and the user. Computer Boot Process Post Boot Record Dos Kernel Device Drivers Config.sys Command.com Autoexec.Bat Dos prompt POST(Power - On Self Test) Whenever we switch on a PC a program called POWER-ON SELF TEST (POST) is executed from the ROM-BIOS(BASIC INPUT OUTPUT SYSTEM).It checks the hardware of the PC step by step and if it finds any error the PC will halt with an error massage displayed on the screen. If it does not find any error, it will enable the PC for further operation. OR The POST(POWER- ON SELF TEST) is a firmware which is always present in ROMBIOS of any PC and whenever the PC is switched "ON" the first program which is executed is POST. Basically POST is a series of programs which checks all the logic on the motherboard which contains the CPU and all the support chips, the base memory on the motherboard as well as on the expansion card and all the I/O devices that are connected with the PC. If the POST find any error or malfunctioning of the hardware, it has four different methods of indicating the error. (a) Display error massage as error code. (b) Output the different tomes (short or long) at the speaker. (c) Output the check points on Port A of programmable peripheral interface (PPI) (d) Display a detailed error message. With the help of the above error indicating methods, it becomes easy to locate and rectify the error that occurs in a PC. BOOT RECORD Once the POST performs the job of checking the computer and its attached devices, the control is then transferred to "BOOT RECORD". The main function of "BOOK RECORD" is to convey the following information which it requires to know to access information from disk. 1. 2. 3. 4. 5.

The The The The The

number of bytes per sector number of sectors per cluster, per track, per disk number of sides total number of sectors on disk maximum no. of entries that root area can hold

Disk Operating System By Naman kumar navikunjan/2 6.

The most important part of Boot record is to find out whether the disk is bootable or not. DOS KERNEL From the boot record the control is then transferred to the most important phase called DOS KERNEL.. DOS KERNEL is made up of two special hidden system files namely IO.SYS and MSDOS.SYS. DOS kernel works in tandem with COMMAND.COM for interfacing the computer, the user and the programs. IO.SYS IO.SYS provides the basic facilities for handling the input and output (I/O device) such as keyboard and the display on your terminal screen. MSDOS.SYS MSDOS.SYS is the control program that runs everything OR This is a program for Application program to use it contains special subprograms to make many commonly easy for programmer. CONFIG.SYS The CONFIG.SYS file is a text file that contains special commands. these commands configure your computer's hardware components. so that MS-DOS and applications can use them. When MS-DOS starts, it carries out the commands in the CONFIG.SYS file. Typically, the CONFIG.SYS file is located in the root directory of current drive. COMMAND.COM After setting the computer to suit the user's needs, the control is then transferred to "user interface" or "command interpreter" or COMMAND.COM This lie gets loaded into memory and then takes up the role of "policeman", who is on constant vigil to help out people in trouble. The command processor consists of four distinctly separate parts:(1) A RESIDENT PORTION resides on memory immediately after MSDOS.SYS & its data area. This portion contains the routines to process interrupts of Critical error handling Control break handling Terminate address. This includes displaying error messages and interpreting the reply Abort, Retry or lgnore. All the DOS error handling is done within this position of the command processor. (2) AN INITIALIZATION PORTION follows the resident portion. This section contains the Autoexec file processor setup. (3) THE TRANSIENT PORTION is loaded at the high end of memory which is command processor itself. It contains:All the internal command processors. The batch file process. Produces the system prompt. Accepts the keyboard commands & causes it to be executed. (4) THE LOADER PORTION loaded with a routine to load & execute external commands, i.e., files with the extension .COM and .EXE. This portion is at the highest end of memory and is invoked but the EXEC function called to load the program. AUTOEXEC.BAT An AUTOEXEC.BAT file lets you to run programs automatically when you start MS-DOS OR Some information you want to flash out when you start the computer. HOW TO (RE)BOOT COMPUTER (A) Set CPU button to ON. (B) Press Reset Button. (C) Press "CTRL+ ALT+ DEL" Guide lines for DOS command (1) You can type commands in uppercase or lowercase letter or a combination of both.

Disk Operating System By Naman kumar navikunjan/3 (2) Commands must be spelled correctly. Incorrectly spelled commands may result in a "Bad command or file name" message. (3) A colon (:) must be included when specifying a drive letter. (4) Commands are usually followed by one or more parameter. (5) To abort a command, press control and c (CTRL+C) and Control and Break (CTRL+BREAK) at the same time. (6) The DOS prompt consist of the default drive letter and the character ">" E.g.:C:\> (7) Commands start executing only after you press the ENTER key. WILD CARD CHARACTERS The wild card characters are used to restrict the scope of a DOS command to only those files which matches the pattern specified. There are two types of wild card :- "*" & "?" Where "*" can substitute a set of characters & "?" can only substitute a character at a particular position. DOS COMMANDS There are two types of DOS commands :1. INTERNAL COMMANDS 2. EXTERNAL COMMANDS 1. 2.

INTERNAL COMMANDS :- Internal Commands are those commands which get transferred into computer's memory. For e.g.:- DIR, COPY etc. EXTERNAL COMMANDS :- External Commands are those commands which don't get transferred into computer's memory. For e.g.:- XCOPY, FORMAT etc. INTERNAL COMMANDS

DATE This command is used to enter or change the date known to the system Syntax : DATE [mm/dd/yy ] Ex : c:> DATE TIME This command is used to enter or change the time known to the system. Syntax : TIME [ hh : mm:[ss[.xx]]] hh = 0 - 23 mm = 0 - 59 ss = 0 - 59 xx = 0 - 99 (hundredths of a second) Ex. : C:\> TIME CLS This command is used to clear the screen. Syntax : CLS Ex. : C:\> CLS VOL This command is used to see the volume label of the specified drive. Syntax : VOL [Drive name:] Ex. : C:\> VOL VER This command is used to see the MS - DOS version. Syntax : VER Ex. : C:\> VER

Disk Operating System By Naman kumar navikunjan/4 DIR This command lists the files and the sub directories in a directory except the hidden system files. Syntax:- DIR[drive:] [path ] [file name [.ext]] [/p] [/w] [/A] [/s] Ex.:- C\> DIR ( display all files) C:\> DIR NAME ( display only specified name) C:\> DIR/P (display pause wise) C:\> DIR/W (display width wise) C:\> DIR/A (display files with specified attributes ) C:\> DIR/S (display all files in a directory and all subdirectory) C:\> DIR ABC.*( display all files having name ABC) C:\> DIR ?.*( display all files having file name one character) MD ( MKDIR) This command is used to creates a directory in the specified disk. Syntax :MD [drive:] [path ] Ex. :C:\> MD RAJ CD (CHDIR) This command changes the DOS current directory of the specified directory OR displays the working directory. Syntax :CD [drive:] [path] Ex. :C:\> CD RAJ CD.. This command puts in the parent directory to the working directory. Ex. :C:\> ABC\RAJ> CD.. C:\>ABC> CD\ This command changes the current directory of the default drive to its root directory . Ex.:- C:\ABC\RAJ> CD\ C:\> RD (RMDIR) This command removes a directory from the specified disk. Syntax :RD [drive:][path] Ex. :C:\> RD RAJ RESTRICTION: Directory should be empty.  Hidden system directories can't be removed. REN This command is used to changes the name of the file specified in the first parameter to the name and extension given in the second parameter. Syntax :REN[drive:] [path] Ex. :C:\> REN RAJ.BAT NISHA.BAT DEL or ERASE This command is used to delete or erase a specified file(s). Syntax:-DEL [drive:] [path][p] Ex.:- C:\>DEL RAJ.BAT C:\> DEL*.BAT(deleted all files having extension .BAT) C:\> DEL*.*/P ( /P option is used for confirmation before deleting each file.)

Disk Operating System By Naman kumar navikunjan/5 TYPE This command displays the contents of a text file on the screen. Syntax:-TYPE [drive:] [path] Ex.:- C:\> TYPE RAJ.BAT C:\>TYPE RAJ.BAT >PRN If you wants to redirect the output a file, use filename instead of PRN. COPY This command is used to copies one or more files to another specified disks. Syntax :COPY [drive:] [path] [drive:] [path] Ex. :C:\> COPY RAJ.BAT NISHA .BAT NOTE :-

C:\> COPY RAJ .BAT+ NISHA .BAT JEETU.BAT C:\> COPY*.* A: PATH This command displays or sets a search path for executable files. Syntax :PATH [drive:] [path] ;[drive:] [path] Ex. :C:\> PATH A\;C:\ NOTE:-Type PATH; to clear all search- path settings and direct MS-DOS to search only in the current directory. Type PATH without parameters to display the current path. PROMPT This command set a new MS-DOS prompt. Syntax:- PROMPT "prompt string" Prompt can be made up of normal characters and the following special codes $Q --> =(equal sign) $$ --> $ (dollar sign) $T --> Current time $D --> Current date $P --> Current drive and path $V--> MS-DOS version number $N -->Current drive $G --> > ( greater -then sign) $L --> < (less- than sign) Type PROMPT without parameters to reset prompt to the default setting. EXTERNAL COMMANDS DOS KEY This command is loads the DOSKEY program into memory. The DOSKEY program recalls MS- DOS commands and enables you to edit command lines. Syntax :DOSKEY Ex :C:\> DOSKEY NOTE :- F7 key is used to display all command into the computer memory. F9 issued to select a line number. ALT+ F7 key is used to remove all the previous used command from its memory. DELTREE This command deletes a directory and all the files and subdirectories that are in it. Syntax :DELTREE [drive:] [path] <subdirectory name>or Ex. :C:\>DELTREE RAJ MOVE This command moves one or more files to the location specify . It can also be used to rename files and directories. Syntax :MOVE [drive:] [path] <source file>

Disk Operating System By Naman kumar navikunjan/6 Ex.

:-

C:\> MOVE RAJ. BAT NISHA.BAT

SCANDISK This command detects, diagnoses and repairs disk errors. It can repair both our file system (FAT) and physical disk, i.e. cross linked files, lost clusters, surface flaws etc. This is more useful than CHKDSK command. Syntax :SCANDISK [drive name:] Ex :C:\>SCANDISK A: EDIT This command starts MS-DOS editor, a text editor you can use to creates and change ASCII text files. Syntax :EDIT [drive:] [path] Ex :EDIT AUTOEXEC.BAT NOTE:- After using this command we get following MENUS:FILE

EDIT

SEARCH

OPTION

HELP

If you want to activate menu for doing the various types of job we have to select first character of that menu with ALT key. DISKCOPY This command copies the contents of the diskette in the source drive to the diskette in the target diskette is unformatted, during the copy the disk is formatted. Syntax :DISKCOPY <source drive name:> Ex. :C:\> DISKCOPY A: B: DISKCOMP This command is used to compares the contents of two floppy disks Syntax :DISKCOMP <source drive name:> Ex :C:\> DISKCOMP A:B XCOPY This command copies files, directories and their subdirectories. Syntax :XCOPY [drive:] [/P] [/S] [/E] Ex.

:-

C:\> XCOPY A *.*/S/E C:\> XCOPY A *.*/P NOTE :/S --> switches used to copies directories and lower level subdirectories unless they are empty. /P --> switches prompts you before copying each file to you let confirm whether you want to create each target file. /E--> switches copies any subdirectories even if they are empty. FORMAT This command formats a specified desk. Formatting analyzes the entire desk for any defective tracks. This command is also used to format all new desk before MS- DOS can use them. Syntax :FORMAT [drive:] [/S] [/4] [/U] [/Q] [/C] Ex. :C:\> FORMAT A /S/C/U NOTE:- /S--> This option is used to copy the operating system files. /4 --> This option is used to format a low density( DSDD) in a high density (1.2 MB) drive. /U --> This option is used to unformatting unsave. /Q --> This option is used to quick formatting. /C --> This option is used to correct the bad clusters.

Disk Operating System By Naman kumar navikunjan/7 SYS This command creates a startup desk by copying hidden MS-DOS system files and the MS-DOS command interpreter (COMMAND.COM) to the disk. Syntax :SYS < drive name:> Ex. :C:\> SYS A: LABEL This command creates, change or delete the volume identification label on a desk. Syntax :LABEL [drive:] [volume label] Ex :C:\>LABEL A:AKSHAT TREE This command graphically displays the structure of a directory. Syntax :TREE [drive name:] [/F] Ex :C:\>TREE A : RAJ/F NOTE:- /F option lists the full path of each directory and subdirectory on the specified drive. ATTRIB This command sets or resets the file attributes for a single file, for selected files in a directory or for all files in a directory level . It also display the attributes of a file. Syntax :ATTRIB [+R] [-R] [H][-H] [+A] [-A] [path] Ex. :ATTRIB +H RAJ.BAT NOTE:+H --> change specified file(s) to hidden. -H --> makes hidden file(s) visible again. +R --> change specifies file(s) to read only. -R --> change specifies file(s) to write only. +A --> sets the archive attribute of a file. -A --> clear the archive bit of the specified file. CHKDSK This command is used to checks the status of a disk and displays a status report. Can also fix disk errors. Syntax :CHKDSK [drive:] [/F] [/V] Ex. :C:\>CHKDSK A /F/V NOTE :- /F --> This option direct CHKDSK to fix errors found in a directory of FAT (File Allocation Table) /V --> This option display the name of each file in every directory as a desk is checked. WARNING:- Do not use CHKDSK with the /F switch when you are running windows. UNFORMAT This command is used to recover files from an accidental desk format. Syntax :UNFORMAT [drive name:] Ex :C:\>UNFORMAT A: UNDELETE This command is used to restores files that where previously deleted by using the DEL command. Syntax :UNDELETE [[drive:] [path] file name] Ex. :C:\> UNDELETE RAJ.BAT MODE This command sets operation modes for devices. Syntax :MODE n Ex. :C:\> MODE CO80 Where "n" specified one of the following values 40, 80, CO40, CO80, MONO. NOTE :40 --> indicate 40 characters per line. 80--> indicate 80 characters per line.

Disk Operating System By Naman kumar navikunjan/8 MONO --> specified a monochrome display adapter with a constant display width of 80 characters per line. MORE This command that reads data from the standard input device, sends one screen of data to the standard output device and then pause with the message ---MORE--Syntax :MORE NOTE :- The MORE command will not work if the disk is full or write protected because to hold input information until it is displayed. This command viewing long files. Ex. :C:\> TYPE RAJ.BAT | MORE C:\> MORE Ex. :C:\> FIND /C "TEXT" RAJ. BAT NOTE:/V Displays all lines NOT containing the specified string. /C Displays only the count of lines containing the string, but does not display the lines also. /N Displays line numbers with the displayed lines. /I Ignores the case of characters when searching for the string. “string” Specifies the text string to find. [drive:][path]filename Specifies a file or files to search. If a pathname is not specified, FIND searches the text typed at the prompt or piped from another command. SORT Sorts input and writes results to the screen, a file, or another device SORT [/R] [/+n] [[drive1:][path1]filename1] [> [drive2:][path2]filename2] [command |] SORT [/R] [/+n] [> [drive2:][path2]filename2] /R Reverses the sort order; that is, sorts Z to A, then 9 to 0. /+n Sorts the file according to characters in column n. [drive1:][path1]filename1 Specifies file(s) to be sorted [drive2:][path2]filename2 Specifies a file where the sorted input is to be stored. command Specifies a command whose output is to be sorted. SETVER This command causes DOS to supply a different version number to an application. It updates a table of application that require DOS to provide an earlier version number. We must load this table into memory by including the Command : DEVICE = SETVER.EXE in your CONFIG.SYS file. Syntax : SETVER [/D or Delete] Example : C:\>SETVER OLDGAME.EXE 3.3 C:\>SETVER/D OLDGAME.EXE BACKUP Both MSBACKUP (Backup for DOS) and Backup for Windows are used to copy your files to one or more backup diskettes for safekeeping. In this way, if you experience a disk drive failure or data error, you can restore your files from the backup media.

Disk Operating System By Naman kumar navikunjan/9 When we run backup first time, then we are prompted to perform a compatibility test. This ensures that Backup is setup properly for your computer. RESTORE This command restored files back to a fixed disk after they have been copied to floppy disks using BACKUP. This command available from DOS versions 2.00 through 5.00. Later versions of DOS include its own restore utility. Windows also uses same command. Q. Ans.

Write the commands to display and print the DOS files. Describe TYPE command to see file's content (With MORE command) Print May be taken through ">PRN" with Type command. "PRINT", an external command can also be used to print a text file. To do so type the command in following way :PRINT This command print from background. Also printing through "EDIT" command may be explain.

Q.

Describe the process of formatting of hard disk. What are the various formatting options available in MS-DOS. Make/Get a fresh set of floppies/ CDs of those operating system, want to install in Hard Disk later. That floppy/Cd should contain FORMAT Command. However, FORMAT command may be applied from the same disk too, but later above disks required. Then give the following command :FORMAT/U/S C: System prompts a warning about removing all data, Press "Y" and the formatting procedure starts. A counter appears as 1%, 2% ....100% and after 100% format completed. IF "/S" Option had been given then SYSTEM files will be transferred to Hard Disk. After it, system prompts for enter "Volumn Label". Either enter something upto 11 character or press enter for none and it will show a report about disk status, i.e. how many bytes the disk have, free bytes, used bytes by system files etc.

Ans.

Various options available in MS-DOS for formating is :To transfer system file after formatting. To does not save any unformatted information To check for bad cluster and if not repairable then mark it as bad area, that operating system does not write anything there later. /V:label To tell about volume label after formatting. /S /U /C -

Q. Ans.

Describe the command that you will use to analyse the directories, files and the file Allocation Table (FAT) on the designated drive and the process of generating a disk and memory status report. Scandisk command is used to analyse the directories, fiels and FAT etc. It is an utility software which was introduced in DOS 6.2. This utility detects, diagnoses, and repairs disk errors on both uncompressed and DoubleSpace compressed drives. Scandisk can repair both of our file system (File Allocation Table or FAT) and physical disk errors. Examples of file system errors are cross linked files and lost clusters. Physical disk errors include surface flaws. Scandisk also maintain a log of repairs, i.e. what it had done in his repairing process. Whenever Scandisk finishes checking our drive's file system, it asks us if we want to perform a surface scan. Surface Scan takes lot of time depending upon the size and speed of processor. It can be used as follows :-

Disk Operating System By Naman kumar navikunjan/10 Syntax Ex Q. Ans.

Q. Ans.

Q. Ans.

::-

SCANDISK [drive name:] C:\>SCANDISK A:

Describe the DEFRAG command. Write the command that will fully defragment drive C and arrange files in alphabetical order. File defragmentation occurs as files are read from and written back to your disk. Files are written randomly into available space. Therefore, part of a file may be written to one location on your disk. When another file is encountered on the disk the system searches for the next available space. This process continues until many of your files become fragmented, which slows down read and write operations. The DEFRAG program is used to collect the files back into contiguous disk sectors. This speeds up file access and therefore can noticeably improve program performance. With the introduction of DOS 6.2, DEFRAG makes use of extended memory. This feature enables DEFRAG to defragment larger disks containing many more files and directories. Type simply DEFRAG at command prompt followed with drive name. A menu driven program appears from which we can select various options. To Defrag the files of Drive C: we have to do following thing. C:\> DEFRAG C: Defragmentation starts. From the coming menu using TAB key goto Sort option and choose Name radio buttom and press enter to start defragmenting. It is a good idea to use SCANDISK before DEFRAG command. Describe the command that will compare the contents of one file with the another file and displays the first ten differences between them. COMP and FC commands are external DOS commands that compares the contents of two specified files. Both of these commands perform similar operations. The most notable use of the COMP command is to compare one or more copies of a file to the original file to verify an exact reproduction. This is the quickest way to ensure a good quality file copy. If you suspect copy problems, you may wish to use COMP or FC each time you make a copy of a file just to be safe. You can also use the COMP and FC commands to locate differences in ASCII text files. This lets you go directly to the area of change for a visual comparison. Following is the function of FC command :FC [/A] [/C] [/L] [/LBn] [/N] [/T] [/W] [/nnnn] [drive1:][path1]filename1 [drive2:][path2]filename2 FC /B [drive1:][path1]filename1 [drive2:][path2]filename2 /A Displays only first and last lines for each set of differences. /B Performs a binary comparison. /C Disregards the case of letters. /L Compares files as ASCII text. /LBn Sets the maximum consecutive mismatches to the specified number of lines. /N Displays the line numbers on an ASCII comparison. /T Does not expand tabs to spaces. /W Compresses white space (tabs and spaces) for comparison. /nnnn Specifies the number of consecutive lines that must match after a mismatch. What is the purpose of ECHO command in a batch file? This command is used to turns off or on all the commands to display on screen after using it. We can use this command on command prompt and in a Batch file too. At the command prompt when we type "ECHO OFF", then command prompt disappears from the screen. However we can give instructions through

Disk Operating System By Naman kumar navikunjan/11 DOS commands, but command prompt remain hidden. Again when we apply "ECHO ON", it appears. In the Batch file when we use "ECHO OFF", then instructions after it does not show on screen, only their results are shown. We can also use it to show any message on screen as "ECHO <Message>" in batch file. To get a blank line in our batch file report we have to give "ECHO.". In a batch file this command is used to show any message, creating menus etc. Q. Ans.

Describe the purpose of FDISK command in DOS. The FDISK command is an external DOS command that prepares a fixed (or hard) disk for use. This command is available with DOS versions 2.00 and later. It is used to organize your fixed disk into partitions, which allocates disk space to separate usable areas. Each partition is assigned a logical drive letter, like C, D and E when more than one partition is used on a single disk device. Because the maximum amount of disk space addressed by DOS versions released prior to 4.01 was 32 megabytes, it was necessary to be familiar with partitioning strategies offered b the FDISK command in order to organize disk drives having storage capacities in excess of the 32-megabyte barrier. Smaller disks are normally given a single DOS partition. The FDISK command is used after your fixed disk has received a low-level format. Performing this procedure erases all stored data. Therefore, if your hard disk is already formatted, then use it carefully. Partitions created with FDISK command is generally used to keep two or more operating system in each partition. Sometimes, people also make partition in disk to keep different types of data in different drives. So that when one partition standing any problem than another can be use. Suppose that operating system and application programs may be keep in Drive C and working data in Drive D. Songs or games may be keeep in Drive E and so on.

Q.

How is MSBACKUP command an improvement over the BACKUP command? BACKUP command is used with fixed disk systems using DOS versions 2.00 through 5.00. Later it changed into MSBACKUP command. BACKUP command was a charater based command in which a user remembered lot of switches but MSBACKUP command is a menu driven command, so now a user can select their choices from menu to take backup. Backup is an external command used to copy files automatically from a fixed disk to floppy disks. BACKUP lets you copy selected files, all files in a specified directory or every file on the fixed disk. It also lets you copy only those files that have been changed or created from last backup. If the files being copied exceed the capacity of the target floppy disk, BACKUP prompts you to change disks and then to continue the process. MSBACKUP if using, then first of all a compatibility test will be performed. The compatibility test is used to tell the Backup program about your system and user can configure the backup as per his requirement. Through MSBACKUP command a user can also verify backup data and compare the data with original data.

Ans.

Q. Ans.

Explain the purpose of the RECOVER command? The RECOVER command is an external command available on DOS versions 2.00 and later. It is used to recover one or more files from a defective disk. Assume that you are experiencing problems reading or copying a file named LETTER.TXT in drive B. You suspect data errors. You may be able to recover the file using the command RECOVER B:LETTER.TXT. The bad data is often omitted by eliminating a bad disk sector from the file. If recovery is successful, you may be able to recreate the discarded data,

Disk Operating System By Naman kumar navikunjan/12 which is preferable to having to recreate an entire file. You should be aware that recovered files often have extra data at the end. This can be deleted using a standard ASCII word processors. Be sure to check the end of the file and eliminate any added "Garbage" as required. Q. Ans.

What is the function of SUBST command? The SUBST command was introduced in DOS versions 3.10. The command word SUBST is an abbreviation for substitute. It is an external command that lets you assign a disk drive designator to a drive and file path of your choice. If you have a subdirectory designated as C:\DOS\UTIL, you can use SUBST to shorten this notation to a single disk drive letter. For example, the command SUBST E: C:\DOS\UTIL return E: => C:\DOS\UTIL lets you use E: as a shorthand form for the notation "C:\DOS\UTIL". This shows you current substitution settings. You can see a file directory of C:\DOS\UTIL with DIR E:. A substitution setting is disconnected with SUBST E:/D. This cancels the drive and/or pathname relationship associated with E:.

Q.

Explain the Redirecting command Input and Output? The internal and external DOS commands normally take their input from the keyboard (standard input device) and display their output on the screen (standard output device). However, you can instruct the DOS to accept input from a source other than the keyboard and send output to a destination other than the screen by redirecting and piping. Redirecting Input To accept input from a source other than the key board, a less-than symbol (<) is used. The symbol is placed just before the input source. eg : C:\> label < input.txt Redirecting Output To send output to a destination other than the screen, enter a greater-than (>) in the command line. The symbol is placed just before the output destination. You can also redirect output of the DIR command to a file. eg : C:\> dir > Rajeev C:\> dir > prn Adding Output (Appending) If you want to add the new data to the end of an existing file, enter two greater-than symbols in the command line. eg : C:\> Dir/s >> Rajeev Redirecting command Input and Outpur eg : C:\> SORT < NAMES > LIST This command sorts the contents of file "NAMES" alphabetically and stores it in a file named "LIST". Q.

How is MS-DOS Organised? Describe what is I/O system, the Command Processor and Utilities in MS-DOS. Ans. MS-DOS is an operating system developed by Microsoft Corporation. MS-DOS is a large collection of different types of files among which minimum four files are compulsory for MS-DOS, i.e. IO.SYS, MSDOS.SYS, COMMAND.COM & DRVSPACE.BIN. Other files such as TREE.COM, EDIT.COM etc. are additional files which is necessory when we use External command of DOS. IO.SYS, MSDOS.SYS, CONFIG.SYS, HIMEM.SYS, RAMDRIVE.SYS etc. are those files who control the Input and Output devices of computer, i.e. how a user instruct the computer and how the operating system control different part of the computer. Standard input and output devices are controlled by IO.SYS and MSDOS.SYS. Other

Disk Operating System By Naman kumar navikunjan/13 devices such as printer, scanner, mouse, CD-Drive etc. are controlled by there Device Drivers which is loaded through CONFIG.SYS or AUTOEXEC.BAT. The DOS command processor or the command interpreter is contained in the COMMAND.COM program. This essential program controls the prompt, error messages, other messages, DOS environment etc. Some utilities program such as FORMAT, SCANDISK, DEFRAG etc. are used to enhance the power of the Disk Operation System. These program is used to repair the disk and organise it so it can work fast.

Disk Operating System By Naman kumar navikunjan/14 Q.

What are hierarchical directories? Illustrate a structure of a hierarchical directory. Ans. We can store number of files on our disk. But if all the files will be stored on same location then searching a file will become much more lengthy. So, we keep all the files in some folders. These folders may also contain sub-folder and so on. These folders are used to keep related files together. System of storing files on disks, in

which files are stored in folders and folders can contain other folders are known as hierarchical directories. Following is the example of a hierarchical directory :-

Disk Operating System By Naman kumar navikunjan/15

Additional Knowledge of DOS BATCH FILE Batch files are ASCII text files that store a series of commands that are later automatically executed line-by-line when you run the file. It’s Extension should always be .BAT. A batch file may include following elements :DOS commands Program names Batch language commands Command line and environmental variables Different commands used in a Batch file are :@ - Turns off the display of command followed by @. Echo - Turns off or on all the commands to display on screen after using it. Pause - Prompts to strike any key to continue... Call - Runs a second batch file and returns to the batch file from which it was called. 5. Goto

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