What is Disk Operating System DOS? Types of Commands in DOS

Disk Operating System DOS: This operating system is one of the most useful operating systems. This program can be operated ‘both through floppy or a hard disk. This operating system can understand the valid commands given by the user.

It accepts the command given by the user and controls it. The, functions of input/output, file-management, memory management etc. are included in the DOS.

The operating system in DOS is mainly in three files :

  • IO.SYs

IO.SYS and MSDOSSYS are collectively called BIOS (Biodirectional Input/output System).

FUNCTIONS OF Microsoft Disk Operating System DOS:

Disk operating system performs a variety of functions which are explained as:

  1. Controls the operations of hardware and software.
  2. Creation of the new files and deletion of old files. Also copies files.
  3. Formats floppy disks
  4. searches viruses on the system.
  5. Provides information on the monitor to the user.
  6. Gets list of all files.

Check Out:

What is Booting?

Booting means to start the computer so as to interact with it. When the computer is switched on, it searches COMMAND.COM file and other system files.

If computer is already set up to read these files from floppy disk, then it searches the required files first on the floppy drives. If these files are found on the floppy, it starts MS-DOS from there.

If search is unsuccessful and there is any floppy in the drive, an error message appears on the screen.

  • “Non-System disk on disk error”
  • “Replace and press any key when ready”

In such a case, remove the floppy from the floppy drive and press any key or enter key.

Now the system searches for required files on the hard disk. If these files are found there than it performs self tests and gives a beep (sound).

When the system starts MS-DOS from the floppy drive, it shows the DOS-prompt as under:


When it starts MS-DOS from the hard disk, it shows the DOs-prompt as under:


The process of starting the computer in the above way is called cold booting.

Sometimes, the computer does not give response due to some reasons and in that case you can restart it by pressing Ctrl + Alt + Del Keys. The process of starting the computer using these keys is called warm booting.

DOS Commands

DOS Commands are of following two types:

  1. Internal commands
  2. External commands

The detail of these commands is being given below


These commands are in-built commands which are loaded in the computer memory when it boots up :

Examples of Some Internal DOS-Commands are :

  1. DIR
  2. DEL
  3. TYPE
  4. COPY
  5. TIME
  7. CLS
  8. DATE
  9. CD
  10. VOL
  11. PROMPT


External Commands are loaded in memory of computer additionally.

Examples of some external Commands are given below:

  1. CHK DSK
  4. PRINT
  6. MEM
  7. TREE
  9. XCOPY
  10. EDIT
  12. MOVE

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