DOS Basic Concepts

DOS- Software that operates the computer system.

• Purpose- File management, Disk management


• When we switch ON the system, DOS automatically loads on RAM if it is working as operating system.


• It is saved in the file named "COMMAND.COM" .


• Its supporting programs are saved in some hidden file i.e. IO.SYS & MSDOS.SYS. The group of these programs are known as bootable program. When it loads on memory. That process is known as 'booting'.

Functions of DOS

• operates computer hardware


• Configuration setting- setting of all the hardware components, after that microprocessor able to establish connection


• Directory management- make directory on disk


• File management- make, read, write, copy, print, rename, delete file


• Disk management- manage free space on disk, format disk etc.

Working of DOS :
a.) Boot Record- The record read by ROM first in booting process.
b.) IO.SYS- It simply resets all devices and disk.
c.) MSDOS.SYS- It links all the application programs with io.sys.
d.) COMMAND.COM- Also known as command processor. It reads the commands and do work according to that.

If error occurs in booting process :
Error- Bad or missing command interpreter
It means there is no bootable program present in disk.

Priority :
1. Floppy
2. Hard disk
3. USB drive

File naming :
" firstname.extension"
e.g. sun.text (text file)
Rules for naming a file:
1.) Can use
a) A,B,C,.........,Z & a,b,c,.........,z
b) 0,1,2,........,9
c) @, #, $, %, (, )
2.) Can't use
a) Blank space, "," (comma), Backspace, "."
b) Reserve words- AUX, COM1, COM2, COM3, COM4, LPT1, LPT2, LPT3, NUL, PRN
c) Punctuation marks- ^, *, =, +, [, ], :, ", \,, /, ?, <, >

File extension :
.exe- executable file
.com- command file
.sys- sytem file
.bat- batch file
.bak- backup file
.doc- document file
.dbf- database file
.wk3- worksheet file