An operating system is a set of specialized programs, which coordinate the activities, resources, and operations of it are various hardware peripherals. It is heart of the computer system software.
DOS: Among other operating system MS-DOS is the most common single task (only one task at a time) operating system in use today in personal computers. It is a production of Microsoft Inc. USA. Similarly DOS developed by IBM (International Business Machine) is known as PC DOS.
BOOTING: It is a process by which a computer loads an operating system software (e.g. MS-DOS) from secondary storage media (e.g. Floppy Diskette or Hard Disk) into the main memory of computer and gets ready to accept data, commands and instructions.
Or
It is a process for making the computer ready for working.
Booting is of two types:
Cold Booting: Starting the computer by switching on the main switch (Power) of system unit or starting a cold computer is called Cold Booting.
Warm Booting: Re-booting the computer, which is already been started.
This can be done in two ways:
Press "Reset" button available on your system unit.
Press Ctrl + Alt + Del keys in Keyboard at a time.
When the machine is switched on, a number of steps are undertaken before the system is ready. The steps are:
The system does the POST [Power On Self Test], where the system automatically checks the memory, the devices like the KEYBOARD, VDU, MOUSE (if attached), the disk drives are so on and if any discrepancy is detected, relevant messages are displayed on the screen.
Searches for the booting files i.e. IO.SYS, MSDOS.SYS & COMMAND.COM from the drive, which was set up in BIOS.
On finding the booting files, it first loads the IO.SYS file, which shall look after all, inputs to the system and outputs form the system. Then it loads MSDOS.SYS that looks after the disk operations, and lastly COMMANA.COM is loaded which is to ensure the execution of the commands.
Before loading COMMAND.COM the system searches a very import yet optional file called CONFIG.SYS, the function of this file is to configure the system according to the user's specification.
After COMMAND.COM is loaded the system again searches for another important file AUTOEXEC.BAT and if found, system executes it.
Now when all files are loaded, the system provides the user with a PROMPT on the screen. The prompt looks like A:> or C:>. Only when the prompt appears on the screen we know that the system is ready functioning.
Files: Every DATA and PROGRAM in the computer system is stored in the form of Files. The files in DOS have two parts namely Base name and extension. A base name has maximum of eight characters whereas extension can have a maximum of 3 characters. Filename and Extension must be separated by a period (.) not by space. It must be a single. No empty space allowed in between.
Program Files: They are the files having some special instructions stored in them, which executes and provides the instructed output when they run. Files with the extension like EXE, BAT, SYS and COM are the examples of program files.
Data Files: They are the files which are just used to store data and records in them. They do not execute and are shared by the program files when a program needs to get the required data. These files may or may not have extensions. All the files without the extension like that of the program files are the data files.
Command: A command is a request or instruction to the computer, which when feeded in the computer through input device is process and implemented by computer accordingly. They are of two types:
Internal or In-Built-Up Command:
All internal commands are associated with COMMAND.COM file and it is loaded while booting and remains in Computer's Main Memory (RAM) until we you turn off the CPU. So, whenever you issue an internal command it runs immediately.
Following are the MS-DOS internal commands:
CLS Clear the screen.
Example: CLS
DATE It allows users to view and reset the system date.
Example: DATE
TIME It allows users to view and reset the system time.
Example: TIME
COPY CON It allows users to create and save a file under the given name. It is the worst word-processing command, which does not allow us to modify and print the contents. [Note: Do not use the following extension BIN, SYS, COM, EXE].
Example: COPY CON Ramesh.txt
Dear Girish
How is your computer class is going?
See you soon
F6, [saves & exits to command prompt].
or
CTRL + C [exits to command prompt without saving]
TYPE It allows users to view content of the given file.
Example: TYPE Ramesh.txt
REN or RENAME It allows users to change the name of a file.
Example: REN Ramesh.txt Ramesh1.txt
Or
RENAME Ramesh.txt Ramesh1.txt
DIR It allows us to view the contents (e.g. files and directories/folders) of current path.
Examples:
a) DIR Displays the content of current directory, continuously.
b) DIR/P Displays the content of current directory, pausing between the pages.
c) DIR/W Displays only the name of the directory in width format.
d) DIR/L Displays in lowercase.
e) DIR *.EXE Displays only those files having EXE extension.
[Note: Here '*' is called a "Wild Card". It is used to represent nothing, one or more unknown characters while specifying the filename and extension.]
f) DIR P*.EXE Displays only those file starting with letter 'P' and having extension "EXE".
g) DIR R???.* Display file name starting with 'R' having 4 characters. Extension any.
[Note: the "?" (a question/what/interrogative sign) is also a wild character represents either nothing or one unknown character when we use it in filename or extension.]
h) DIR > PRN Send the directory list to the printer.
DIR > file1 Save the list of directory in to file named file1.
DEL It allows us to erase one or more unwanted files.
Example: DEL file1
VER Displays the version/ edition/generation of MS-DOS being currently used.
Example: VER
VOL It helps us to know the volume label (i.e. name) of a floppy diskette or hard disk.
Example: VOL
Directory / Folder Maintenance:
What is Directory?
A directory is just like a folder of a cabinet (or room of a house) utilized to store the similar type of files. As it is used to store the systematically, it helps us to search for a particular file in a very short period.
Example C:\Users\Rama\Data
Where C: = Drive name or Root Directory of drive C.
Users = Directory or Folder.
Rama = Sub-directory or sub-folder.
Data = Sub-directory of Sub-folder.
\(Back slash) = sign is used to separate the drive name, folder, subfolder and filename.
So any directory created in Root Directory of any drive is called a "Directory or Folder".
Any directory created inside a directory is called "Sub-Directory or Sub-Folder".
Root directory, Directory and Sub Directory are the relative term.
MD Creating a directory, or Make Directory.
Example: MD LETTER Creates directory called LETTER.
CD Changing Directory.
CD.. Coming out from current directory.
CD\ Coming to root directory.
CD letter Going inside the directory called letter.
RD Remove Directory.
[Note: the Directory to be removed must be empty, the command should be issued outside from the directory to be removed.]
PROMPT: Changes the appearance of MS-DOS prompt.
Example: PROMPT $P$D$G {P=path, D=Date, G= Greater than sign}
PATH: Establishes or shows or remove the searching path (drive & directory) for executable program file.
Example: PATH C:\WINDOWS Establish the searching path as WINDOWS.
PATH Display current path.
PATH; Clears the current path.
COPY: It is used to make the duplicate of one or more files.
Example: COPY C:\file1 A:\file2 Copy file1 form C: to A: and change name as file2.
COPY file1 + file2 + file3 Newfile Merging three file together and put it into Newfile.
C: A: Changing the Drive.
Example: C: A: change working drive from C: to A:.
External Command.
All the MS-DOS commands except those mentioned above are the external commands. It runs slower than internal command. It is stored in secondary storage devices. They are specially designed for some specific purpose.
1.CHKDSK: Check the status of a disk and displays a status reports. It can fix the problems but is not much reliable.
Example: CHKDSK C: Run check disk on C: drive.
2.SCANDISK: Checks disks for damages, and repairs them, if needed. It is more reliable and recommended command to fix the disk and file errors.
Example: SCANDISK C: Run scandisk on C: drive.
3.ATTRIB: Displays or changes file attributes.
Any file has certain specific characteristics or qualities that define the nature of the file; this in turn determines the access of the file. The Attributes available under DOS are R, A, H and S.
R [Read-Only file attribute] The file with this attribute can be displayed or read only but cannot be modified in any way or neither can they be deleted.
A [Archive file attributes] With this attributes, we can mark the files. The MSBACKUP, XCOPY and RESTORE commands can copy only those files marked with this attributes.
S [System file attributes] it designates a file as a system file. Files with I this attributes cannot be seen, edited and run.
H [Hidden file attributes] the files with these attributes are not normally displayed in directory listings, such file cannot be edited, deleted by can be run, if we know their names.
+ Set an attributes.
Remove an attribute.
Example: ATTRIB Displays attributes of all files in current directory.
ATTRIB +R Nepal Assign read only attributes to file called Nepal.
4.DELTREE: Deletes a directory and all the subdirectories and files in it.
Example: DELTREE C:\temp Delete directory called temp.
[Be sure to use this command before you use it. It can be mishandle to create problems]
5.DISK COPY: Copies the contents of one floppy disk to another. It is duplicating the floppy diskette. [Note: A hard disk can not be disk copied.]
Example: DISK COPY A: B: Make B:duplicate copy of A:
6.DOSKEY: Loads the DOSKEY program into memory. It will allow us to recall old command recently used.
Example: DOSKEY Starts storing old command now unwands.
7.EDIT: It is a powerful MS-DOS text editor, which allows us to create, edit, save, open, duplicate and print a TEXT file.
Example EDIT Gita.txt Create text file called Gita.txt and allows us to edit.
8.FORMAT: A new disk, including a hard disk, must to prepare before it is used for the first time. This step is called formatting.
Example: FORMAT A: It formats a floppy drive.
9.LABEL: Creates, changes, or deletes the volume label of a disk. User can give a name to each disk, which will be stored internally as information. This name is known as volume label.
Example: LABEL Displays the volume label and serial number of the disk in current drive, if they exist. Then it prompts you to enter the new volume label (not longer than 11 characters) or delete the existing volume label.
10.MORE: Displays one screen of output at a time. This command is commonly used too view long text files.
Examples: DIR | MOREDisplays the directory listing one screen at a time. Press a key to see the next screen. This command does the same function of DIR/P .
11.MOVE: Moves files to the drive and directory you specify. It also renames files and directories.
Example: MOVE A:\HARI.TXT C:\DATA\SITA.TXT Moves the file named HARI.TXT from drive A into the DATA directory on drive C and in the same time renames the file to SITA. TXT.
12.SYS: Copies MS-DOS system files (IO.SYS & MSDOS.SYS) and command interpreter (COMMAND.COM) to a disk you specify.
Example: SYS A: Copies the system files and files and command interpreter from current drive into the disk on drive A.
13.UNFORMAT: Restores a disk erased by the FORMAT command or restructured by the RECOVER command.
Example: UNOFROMAT A: Restores the formatted disk in drive A without listing all the files and sub _ directories.
14.XCOPY: Copies directories, subdirectories and their files (expect hidden and system). The XCOPY command first loads the specified directories and files into RAM as much as it can hold and after then, copies them from RAM to target drive &folder. So xcopy is faster than COPY command (The COPY command copies one file at one time from source to target location however RAM has the sufficient spaces to hold more files)
Examples: XCOPY A: B:/S/E Copies all the files and sub -directories (including the empty sub-directories) from the disk in drive A to the disk in Drive B.
15.TREE: This command is needed usually since a disk can have numerous directories and sub directories and all of them filled with files, so at times it becomes really difficult to locate particular file or group of files. This command graphically displays the directory structure.
Example: TREE C: Displays the names of all sub-directories on the disk C:.
16.PRINT: Prints the contents of MS-DOS Text File. This command can print in the background if you have an output device connected to your system serial or parallel ports.
Examples: PRINT COW Sends the contents of Cow to the computer.
17.DISKCOMP: Compares the contents of two floozy diskettes. This command performs the track-by-track comparisons. It determines the number of sides and sectors per track to compare based on the format of the first disk you specify.
Example: DISKCOMP B: A: Compares the disk in drive B with the disk in drive A.
18.SORT: Sorts input and writes results to the screen, a file, or another device.
Examples: SORT/R Sorts the paragraphs/records of MAILLIST.TXT in reverse order and then displays the output on screen
19.MSD: The MSD (Microsoft Diagnostic Tool) command provides detailed technical information about your computer.
Example: MSD Runs the Microsoft Diagnostics tool, analyzes the computer and then, displays different headings. You can choose the desired heading to view the corresponding technical information. Press F3 to quit from Microsoft Diagnostic tool.
20.MEM: Displays the amount of used and free memory in your system. It displays the information about allocated memory areas, free memory areas and the programs currently loaded into memory.
Example: MEM
Checks and then displays the amount of used and free memory in your system.
Memory Type Total Used Free
Conventional 640k 144k 496k
Upper 91k 91k 0k
Reserved 384k 384k 0k
Extended (XMS) 15.269k 273k 14.996k
Total Memory 16.384k 892k 15.492k
Total under 1 MB 731k 234k 496k
HELP: Starts MS-DOS help on MS-DOS commands.
Example: HELP Displays the MS-DOS help table of contents. From the table of contents, you can choose the desired command topic you want to view. HELP CHKDSK Displays the help about CHKDSK command.
FAST HELP: When used alone, displays the list of all MS-DOS commands and gives a brief explanation of each. The information about the FAST HELP command displays in similar to, but less detailed than, the information found in MS-DOS help. OR The FAST HELP along with the any MS-DOS command, provides help information about that.
Example: COMMAND /? Displays help information on that command.
