The document provides an overview of DOS (Disk Operating System) and various operating systems including Windows, Linux, and Unix. It explains the booting sequence and the role of BIOS, as well as the types of files and important command files in DOS. Additionally, it defines internal and external DOS commands with examples.

1. DOS
(Disk Operating System)

2. Operating System
 DOS
 Windows
 LINUX
 UNIX
 etc...

3. What is DOS ?
 Single user operating system.
 CUI (Character User Interface)

4. Booting Sequence
 Basic Input Output System (BIOS)
 BIOS automatically looks for the PC’s master
computer program, first in the A: drive, if a
floppy drive is loaded, otherwise in the C: drive.

5. What is FILES?
 Data files.
 Program files.
 Sub Directory files

6. Every file name has two parts
 File name
 Extension

7. Various Versions of DOS

8. Important files in DOS
 IO.sys
 MS-DOS.sys
 COMMAND.com

10. What are DOS command?
 Internal command
 External command

11. Internal Commands
 Cls
 Dir
 Copy
 Del
 Ren
 Type
 Cd
 Md
 Rd
 undelete,
 Erase
 Date
 Time
 Ver
 Prompt
 Break
 Vol
 Pause

12. External Commands
 Diskcopy
 Xcopy
 Format
 Label
 Mem
 More
 Tree
 deltree
 lock
 Unlock
 Scandisk
 Diskcomp
 Chkdsk
 copy con
 Mode
 Fdisk
 attrib
 Move