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MS-DOS, also known simply as DOS, was developed to run single-user, stand-alone desktop computers. When the personal computer market exploded in the 1980s, MS-DOS was the standard operating system delivered with millions of these machines. In many ways, MS-DOS exemplifies early operating systems because it manages jobs sequentially from a single user

 Internal and External Commands

The commands that are a part of resident DOS are known as internal commands. Because they are always in internal memory, DOS always knows where to find them. Also, it does not have to load them from disk storage into internal memory before it can execute them. To use one of these commands, all you ever have to do is to enter the command name at the command prompt. 

If a command isn't in resident DOS, it's called an external command. Each of these commands is stored in a disk file called a command file. On a MS¬DOS system, the names of command files always have an extension of COM or EXE. Usually, these command files are stored in the DOS directory on one of the drives of your Pc. .

Internal commands

1.DIR command to display a list of the names of files stored on a diskette in the current drive, another drive, or a hard drive

DIR /P command (Pause switch) to display directory listings/filenames one screen at a timeDIR /W command (Wide switch) to display directory listings/filenames in five columns

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Syntax

C:\> Dir

2. MD : This command is used to create a folder/directory in the DOS Syntax :

C:\> MD foldername

3. CD command to change from one directory to anotherC:\> CD foldername

4. CD.. command to change to the directory above the current directory

C:\> CD..5. CD\ command to change from the current directory to the root directory6. Copy con: This command is used to create thefile

C:\> copy con filename

----------------type data

Ctrl+z (to save files) or F6

7. DEL command to delete a file or a group of files;

C:\> del filename

8. COPY command copies the contents of a file (called the source file) and produces a new file (called the destination, or target, file). You can copy files to the same diskette, a different diskette, and a hard drive or other storage media using a different or the samefilename

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c:\> copy srcfile destfile

9. MOVE command moves one or more files to another drive, directory, or drive and Directory c:\> move srcfile dest

10. type: command to view the contents of a file.

C:\> type filename

11. Ren – this command is used to rename the name of a file

C:\> ren oldname newname

2. External Command

1. FORMAT command to prepare a diskette for use on a computer system. The Format

capacity switch allows for formatting double-density diskettes in high-density or extrahighdensity disk drives and high-density diskettes in extra-high density drives. Changinga default drive by specifying the name of the drive to be used as the new default drive

C:\> Format directoryname

2. DISKCOPY command used to make duplicates copies of a diskette[DOS command]/? Help switch to obtain help information on any DOS command

3. DEFRAG command, a DOS utility that optimizes directories and eliminates or reduces

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File fragmentation.4. BACKUP command backs up an entire hard drive, a directory, a

group of files, or aSingle file onto a set of backup diskettes or other storage media

5. RESTORE command restores an entire hard disk, a directory, a group of files, or a single

file from a set of backup diskettes or other storage media

6. DELTREE command deletes a directory tree, all of its subdirectories, and all files in the

specified directories7. XCOPY command copies a directory and its subdirectories and

files, a group of files, orA single file to another disk or other storage media