Disk Operating System
What is Dos?
DOS stands for Disk Operating System.
DOS (Disk Operating System) was the first widely-installed
operating system for personal computers.
DOS controls the computer’s hardware and provides
an environment for programs to run.
This system program must always be present when
working with your computer.
Dos is a single user operating system. Single user
operating system is most popular in microcomputer
upto mid of 1990s.It is also called DOS because it is
store on a disk of a computer.
Major Task Of a DOS
The major tasks the DOS must carry out are:-
To control input and output devices.
To enable user to load and execute program.
To maintain an orderly system of data on the disk.
DOS has three important or special files are :-
BAT (batch files)
COM (command files)
EXE (executable files)
DOS consist of a series of a program designed to
control the computer resources.
DOS commands have three parts: File name,
Mostly these commands consist of regular English
word like words.
For example ERASE,COPY,DEL,PRINT etc.
Types of DOS Commands
There are two types of DOS commands.
DOS Internal Commands.
DOS External Commands.
DOS Internal Commands
DOS internal commands are stored in the
DOS internal command are loaded automatically
into the memory (RAM) when you start your
These includes the simpler and common commands
that are needed on regular basis.
Internal commands are the part of COMMAND.COM
Some DOS Internal Commands
Some DOS internal command are:-
CLS – CLS command is use for clear the screen.
VER – Display the DOS version number.
VOL –Displays the volume label and serial
TYPE –Display the contents of a text.
Exit –Exit the command processor
DOS External Commands
Second type of DOS Commands is External
DOS External Command required less frequently.
These are reside on disk.
Loaded automatically into memory (RAM) only
Some DOS External Commands
Some DOS External Commands are:-
CHKDSK – Check the validity of disk and reports
the total space, number of files and
amount of free space.
COMP – Compare the content of two sets of
COMMAND – Starts the command processor.
SYS –Creates a bootable drive.