The MS-DOS comes alongwith some BATCH commands that are executed directly by COMMAND.COM and are always available to the operator and may be entered from any DOS prompt. These commands are called Internal commands because they can be executed without putting DOS diskette in the computer as long as COMMAND.COM is in the computer memory. Internal commands include batch commands, BREAK, CHKDIR, MKDIR, DIR, RMDIR, CLS , PATH, RENAME, DATE, TIME , COPY and ERESE etc.
The components of MS-DOS:- MS-DOS consists of four separate components-
(i). Basic I/O Interface
(ii). File and disk manager
(iii). The Disk Bootstrap
(iv). Command processor
(i).The basic input/output software (BIOS) or IO.SYS:-This is the interface between the heart of the operating system and the I/O capabilities of the computer. It means to enhance communication between the computer and the peripherals attached.
        BIOS has fundamental routines that control the keyboard, video display, disk drive and other peripherals of the computer without BIOS your computer will not be able to communicate with and control those devices. The system handles every character that is typed or displayed, printed and received or sent through the communication adapters. BIOS is probably located at two places. A part of it may be in ROM but majority is no a disk file called IO.SYS or MS DOS.SYS where ROM.BIOS exists. IO.SYS is largely an interface between the file and disk manager and the computers ROM-BIOS
            Every peripheral talks to the computer eithet one character at a time or in groups of characters called BLOCKS.
(ii). File and disk manager or MS DOS.SYS:- MS DOS.SYS is the program containing the code for the file management and disk buffering management capabilities of MS-DOS. Is also contains the code for the various utility functions that MS-DOS provides for programs.
(iii). The disk boostrap:- It is found on the first sector of every MS-DOS (bootable) diskette and on the first sector of the partition allocated to MS-DOS on a hard disk. It is put there by format command.
          When we turn on the computer, the process of loading and starting the operating system is called Booting which is done through Boot strap loader program.
(iv). The command processor (COMMAND.COM):- The COMMAND.COM is the command processor which is a program that sends the system prompt to the display and looks at the interprets the characters typed at the keyboard. We communicate with command processor and it tells the DOS as to what to do. It has several built in functions or sub programs which handle most common tasks for DOS like copying files, displaying a list of files on the disk and running programs.

➡VERIOUS INTERNAL COMMANDS ARE:-
1.CLS:- CLS command is used to clear the screen leaving only a MS-DOS prompt.
Syntext:- c:/>CLS
2. VER:- Version common print the MS-DOS version number.
Syntext:- c:/>VER
3. VOL:- Volume command displays the specified drives volume label and serial number if exist.
Syntext:- c:/>VOL[drive:]
4. TIME:- This command allows to enter and change the time.
Syntext:- c:/>TIME
5. DATE:- This command displays the current date.
Syntext:- c:/>DATE
6.COPYCON:- The purpose of this command is to create a file. The file created by this command can not be modified.
Syntext:- c:/> COPYCON file name. Extansion
Example:- Ram is a good boy
^z (cantrolz)
7. DIR:- It displays the list of directive and file on the screen.
Syntext:- c:/>DIR
8. TYPE:- The purpose of this command is to view the contents of the text.
Syntext:- c:/>type file name.extantion
9. RENAME (REN):- It is used to rename an old file with new file name.
Syntext:- c:/>REN old file name new file name
10. DEL (EREAS):- This command deletes specifised file from the directory.
Syntext:- c:/>DEL filename extantion
11. MKDIR (MAKE DIRECTORY):- This command is used to make a directory or sub directory.
Syntext:- c:/>MD\directory name
c:/>MD\sub directory name
Now if user wants to create a sub directory pooja in sunita directory
C:/>CD\sunita enter
C:/>C\sunita>MD pooja
12. CHDIR:- This command is used to change the directory from the work directory to that one which you spaciable.
Syntext:-C:/>CD\perent directory
C:/>CD\sub directory
C:/>CD..
13. RMDIR (RD) Remove directory:- This command is used to remove a directory or sub directory.
Syntext:- C:/>RD(Root directory)
C:/>RD(Sub directory)
14. PATH:- The purpose of this command is to sets or resets the sequence of directories to be searched for executable files. There are tree options for setting or path.
A. To set the path:-c:/>PATH=drivename:\directory.
B. To see the path:- c:/>path_
C. To remove the path:- c:/> path;
15. COPY:- The command copy one or more files to another locations.
Syntext:-C:/>copy source path Target path
16. PROMPT:-This can changes the MS-DOS command prompt.
Syntext:- c:/>prompt