Disk Operating System (DOS) was the first widely installed operating system for personal computers. DOS controls the computer's hardware and provides an environment for programs to run. It has important files like BAT, COM, and EXE. DOS commands allow the user to control computer resources and come in internal and external types. Internal commands are stored in COMMAND.COM and loaded automatically, while external commands reside on disk and load only when needed. Some examples of commands are CLS, VER, TYPE, and CHKDSK.

1. Disk Operating System
PRESENTED
BY
RIZWAN AKRAM

2. 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.

3. 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.

4. 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.

5. DOS Files
DOS has three important or special files are :-
BAT (batch files)
COM (command files)
EXE (executable files)

6. DOS Commands
DOS consist of a series of a program designed to
control the computer resources.
DOS commands have three parts: File name,
parameters, switches.
Mostly these commands consist of regular English
word like words.
 For example ERASE,COPY,DEL,PRINT etc.

7. Types of DOS Commands
 There are two types of DOS commands.
DOS Internal Commands.
DOS External Commands.

8. DOS Internal Commands
DOS internal commands are stored in the
COMMAND.COM file.
DOS internal command are loaded automatically
into the memory (RAM) when you start your
systems.
These includes the simpler and common commands
that are needed on regular basis.
 Internal commands are the part of COMMAND.COM

9. 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
(COMMAND.COM Program).

10. DOS External Commands
 Second type of DOS Commands is External
command.
DOS External Command required less frequently.
 These are reside on disk.
 Loaded automatically into memory (RAM) only
when needed.

11. 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
files.
COMMAND – Starts the command processor.
SYS –Creates a bootable drive.

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