This document provides information about the Disk Operating System (DOS), including its three main layers: BIOS, the DOS kernel, and the command processor. It describes the functions of each layer, with BIOS managing hardware devices, the kernel providing file management, memory management and other core functions, and the command processor serving as the interface between the user and DOS through built-in commands. The document also lists and explains some common DOS commands.

2. 1) Dos stands for DISK OPERATING
SYSTEM.
2) It is the most popular operating system
which was developed by Microsoft
Corporation of USA in early 1981.
3) It provides a set of commands that
enables you to access or manipulate
information on your disks, as well as
simply interacts with your computer.

3. MS-DOS is divided into three layers are:-
1) BIOS(Basic Input Output System)‫‏‬
2) Dos Kernel
3) The Command Processor (Shell)‫‏‬

5. This part of Dos is
supplied by the individual manufacturer of the
system. It contain a set of programs called
drivers that manage the following devices
attached to a computer system like screen,
printer, secondary storage devices, system
clock,
block device - a driver that is used for primary
bootstrap.
One part of BIOS is stored in a
read only memory(ROM).The remaining part of
BIOS is stored in a system file called IO.SYS file
resides on the boot disk.

6. It is a set of programs called system
functions which provide the following services :
a) File Management.
b) Memory Management.
c) Character Device (INPUT/OUTPUT)‫‏‬
d) Access to real time clock.
e) Basic networking function

7. The shell or command processor is
an interface between the user and the dos. It is
contained processor is an interface between the
user & the dos. It contained in a file called
command.com
It provides a standard set of
commands that gives users access to file-
management, device management, configuration
& miscellaneous functions, such as maintaining
and verifying the time and miscellaneous
functions, such as maintaining and verifying the
time and date.

8. 1) Internal commands
2) External commands

9. Internal commands are built into
the operating system as part of a file
called COMMAND.COM (or, on a 2000 or
XP machine CMD.EXE) . They are loaded
into memory whenever you switch on your
computer. When you type an internal
command, MS-DOS performs it
immediately.

10. • DIR
• TYPE
• COPY
• REN
• MD
• DEL
• CD
• RD
• DATE
• TIME
• VER
• VOL
• CLS
• PROMPT
• EXIT
• COPY CON

11. Files with extension COM or
EXE are external commands. Because
these commands are files, they are not
built into the operating system ( these are
the commands that alter between
versions of MS-DOS).

12.  COPY
 RESTORE
 ATTRIB
 LABEL
 BACKUP
 MODE
 SORT
 CHKDSK
 SCANDISK
 FIND
 PRINT
 DELTREE
 XCOPY
 REPLACE
 DISKCOPY
 SYS
 FORMAT

13. DATE COMMAND –
This command is used to display the
current date on the screen. we can also set the
date by using this command.
Syntax :-
c:> date
Example :-
c:> date [ dd/mm/yy]

14. This command is used to see the
current time or used to set the time.
Syntax :-
c:> Time
Example :-
c:> Time [hh/mm/ss]

15. This command is used to clear the
screen.
Syntax :-
c:> cls
Example :-
c:> cls

16. This command is used to see all or
specified files on the specified drive.
Syntax :-
c:>dir
or
c:>dir[drive:][pathname]
or
c:>dir[drive:][pathname][/p][/w]
Example -
c:>dir d/p
/P - Display page wise listings of directory.
/W – Display widthwise listing of directory.
/B – Displays a bare filename listing without size,date &
time information.
/L – Displays files information in lowercase.

17. Type command :-
Display the contents of specified file.
Syntax :-
c:>type <filename>
or
c:>type[drive:]<filename>
Example -
c:>type A: try.txt