Notes:-Computer Fundamental & Basic Course (DOS)
-1-
Operating System: - Operating System manages the overall operation of the system and acts
as an interface between the user and hardware. Def- O.S. (Operating System) is a set of
software programs which provides an interface between the user and computer system.
Functions of O.S: - O.S. acts as a resource manager .The main functions of O.S. are:1 Memory Management Functions: - O.S keep track on memory size and allocate memory
when the process requests for it.
2. Process management Functions:-When there is some complex job or assignment then
O.S will handle it. It handles the job by assigning various or some jobs to processor. This
function of O.S is known as job scheduling. ”Job Scheduling is that in which a job is divided
into some time schedule and each part of job is done at various or different time by O.S.”
3 Device Management functions: - Computer is attached with various input and output
devices. These are control or handle by O.S. This Function of O.S. is known as device
management functions.
4 File Management functions: - In this function O.S. Helps you to store and retrieve them
whenever required.
5 User Interface: - “O.S. Provides interface between computer/system and user/human”.
Computer can under stands the language of 0’s and 1’s whereas human being can understand
English like language. So O.S. Convert human understandable language to machine level
language and vice-versa or machine level language to human level language (0’s, 1’s) to
human understandable language.
MS-Dos:-Ms-dos stands for Microsoft disk operating system. MS-Dos is the operating system
for the IBM’s personal computers and their compatibles. It was released in 1980, when IBM
launched its first personal computer.
Features of Dos: Single user O.S.
 Hierarchical fill structure.
 Supports only 80 xxx architecture personal computer.
 Memory access limits 640 kb.
Post : - (Power on set test):- When computer turn on it will check the memory and all
attached devices to it. If all the devices are working properly then it will process else it will stop
there. System beeps after it has found that each and every part is working properly .This
process is called POST.
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-2-
Boot Record: -After post control is transfer to boot record. The main functions of boot record
are:1. The number of bytes per sector.
2. Number of sectors per cluster, per track, per disk.
3. Number of slides.
4. The total number of sectors per disk.
5. The maximum number of entries that boot area can hold.
6. To check whether disk is bootable or not.
DOS Kernel :- “After boot record , the control is then transferred to another important phase
called DOS kernel, It is made up of two special Hidden system files namely I.O. SYS and
MSDOS.SYS “ . On receiving, the control from the Dos Kernel the computer reeds the
information changes the internal configuration or internal setting according to the needs of
user.
Shell: - After Dos kernel or after setting the computer to suit the user needs, the control is then
transferred to command interpreter or COMMAND.COM. The file gets loaded into the memory
of the computer and takes the control over whole of the computer.
This file is the command processor and I responsible for the interpretation and carrying
out instructions. It is also called Shell and Displays the system prompt (also called DOS).
If booting from hard disk , Then Prompt shows
C:\ >
If booting from Floppy disk , Then Prompt shows
A:\ >
on screen
on screen
DOS has got three portions:1 Initialization Portion: - The first portion is initialization portion and its main job is to look for
the existence of the file called AUTOEXEC.BAT. The Initialization portion is transferred to
COMMAND.COM and AUTOEXEC.BAT gets executed.
2 Resident Portion: - The Second portion is resident portion. The resident portion of
command.com stays in memory throughout. This is responsible for performing some basic
tasks such as error handling, loading and unloading of transient portion whenever required.
3 Transient Portion: - The third portion is transient portion. This portion contains instructions
for executing some commands which the user commonly uses. The commands which are
stored in transient portion of commad.com are called internal commands.
Booting Sequence:1 ROM start up portion checks and initializes the hardware.
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-3-
2 The ROM startup routine performs memory check to calculate the size of the memory that is
available on the computer, and if it working in a proper manner.
3 Boot strap portion of the ROM startup routine, loads disk boot strap program from the boot
sector of the disk into memory.
4 The disk boot strap program loads the file IO.SYS from the disk into the memory.
5 The SYSINT module of IO.SYS loads the file MSDOS.SYS into the memory.
6 MSDOS.SYS looks for the file config.sys in the root directory of the bootable disk and
executes. It loads command.com into memory.
7 COMMAND.COM executes AUTOEXEC.BAT from the bootable disk.
8 The transient portion of command.com finally displays the DOS Prompt, which is as C :\> if
boot from hard disk else A :\> if boot from floppy disk.
Structure of DOS: - An operating system is concerned with the allocation of resources and
services such as memory, processors, devices and information. The operating system includes
program to manage there resources such as a scheduler, memory management module, I/O
program and a file system.
DOS acts as an interface between software and the hardware. It is a type of System Software
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-4-
DOS WORKING: - User give instructions in English like language then O.S will convert this
into the machine readable form. Now System/Computer will in turn process it and will give
result in machine language. O.S will again convert it from machine language to human
readable form. So it acts as an interface between user and the hardware.
Booting: - When computer switch on, Firstly POST is performed. After testing if all the parts
are in working order, then control is transferred to boot record. From the boot record control is
transferred to DOS Kernel consisting of special file IO.SYS and MSDOS.SYS .After having
configuration from these file, it will search for command interpreter i.e. command.com .
If COMMAND.Com is in the floppy disk i.e. in A drive
Then
A :/>
is generated. ( called A prompt)
It is called booting from floppy disk
If there is no floppy is available in an A Drive. then it will search for
COMMAND.COM in C drive, on Finding it
C :/>
or
is generated. ( called A prompt)
It is called booting from Hard disk
___________ _______ _____ ___
If COMMAND.Com is in the Hard disk i.e. in C drive
Then
C :/>
is generated. ( called A prompt)
It is called booting from Hard disk
The whole procedure is called booting. There are two types of booting:1 Cold Booting: - If computer will shut down or switch of in a proper way and again switch on
the computer, booting will takes place and corresponding A :\> or C :/> is generated. This is
called cold booting
2 Warm booting: - By Pressing “Ctrl + ALT + DEL “keys simultaneously, Computer will be
restarted and this is called warm booting.
► Commands: - MS-DOS commands are written in English and are very easy to learn. The
whole working of are done by commands. Def – “All the commands are actually programs
created in high level language and get activated whenever user types the particular command
at the DOS Prompt”.
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
BHALLA INFOTECH
Computer & Information Technology Training Institute
-5-
Notes:-Computer Fundamental & Basic Course (DOS)
-6-
Bootable Disk: - A Disk which is used for booting is called Bootable Disk. A bootable disk
must contains three files
1. MSDOS.SYS
2. IO.SYS
3. COMMANDS.SYS
1 MSDOS.SYS:- This file is known as “DOS Kernel”. It acts like a link between the input-output
services and the application programs being run by the user.
2 IO.SYS:- IO stands for Input-Output. So this input-output system file of dos is responsible for
managing input-output devices attached to computer.
3 COMMAND.COM:- This is the MSDOS Command Processor. It contains all the internal
commands of MSDOS.
Pathname:-The Full name of a file or directory is also known as pathname.
Types of Commands:-DOS Commands are of two types: Internal Commands
 External Commands
1 Internal Commands: - These Commands do not require any specific files for being
executed and are brought into the memory as soon as computer is switched on.
Or
Dos commands for which the specifications are available within the shell (Command.com) .
For example: - DATE, TIME etc.
2 External Commands: - These are those commands which require certain special DOS files
for being executed. Whenever external commands are to be executed the file is first loaded
into memory and then executed.
Or
Dos commands for which specifications are not internally available in command.com
For example: - Format command specification in format.com, MD, RD etc.
Details:DOS internal commands:1 DATE: - date command is used for display the current system date and can be used to
modify the system date.
Ex: C:\>DATE <enter>
2 TIME: - Time command is used to display current system time or can be used to modify the
current system time.
Ex: C:\>TIME <enter>
3 CLS: - The CLS command is used for the clear the view or content of the screen. Once the
CLS command is executed, the DOS prompt is placed at the top left corner of the screen.
Ex: C:\>CLS <enter>
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-7-
4 DIR Command: - The DIR command displays the list of existing files on the disk (Hard
disk/CD/DVD/Floppy disk).
Ex: C:\>DIR <enter>
Five columns are open as:a) First column is the name of the file.
b) The Second column is the extension* of the file.
c) Third column show the size of each file in bytes.
d) The fourth column indicates the date on which
file was created or modified.
e) The last column indicates the time at which file
was created or modified.
Parameter: - DIR commands have four parameters.
A) /W: - This shows the list of contest of the disk by Width
wise.
Ex: C:\>DIR/W <enter>
*Extension: - By which computer and
user can understand the type of the
file. Extension must at right side of
the dot (.).
Ex: Taj.jpg here Taj is file name and
jpg is extension. Jpg represent a
photo/snap file .So file is a photo or
picture
B) /S: - The shows the list of contents of the disk with directory and contents of the sub
directories also. Ex: C:\>DIR/S
<enter>
C) /P: - List the contents of the disk by page wise.
Ex: - C:\>DIR/P <enter>
D) /O: - this shows the contents via any order. These are Many Subtypes :a) N: Sorts the file via alphabetic order [a-z].
Ex: C:\>DIR/O:N <enter>
b) -N: Sorts the files via descending order or reverse alphabet order [z-a].
Ex: C:\>DIR/O:-N <enter>
c)
E: Sorts the files via Extension with alphabet order [a-z].
Ex: C:\>DIR/O:E
<enter>
d) -E: Sorts the files by extension with reverse alphabet order [z-a].
Ex: C:\>DIR/O:-E
<enter>
e)
S: Arrange the files in ascending order by size.
Ex: C:\>DIR/O:S
<enter>
f) -S: Arrange the files descending order or in reverse order
Ex: C:\>DIR/O:-S
<enter>
g) D: Arrange the files on the basis of dates from lower date to higher date.
Ex: C:\>DIR/O:D
<enter>
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-8-
h) -D: Arrange the files on the basis of dates from higher date to lower date
or in
Revere order.
Ex:
C:\>DIR/O:-D
<enter>
5 Copy Con: - It is used to make a new file in command prompt. To end file press Ctrl+z .
Ex:
C:\>copy con 1.txt
<enter> and end with by press Ctrl+z
6 Type: - It is used to display the contents of a particular file.
Ex:
C:\>type 1.txt
<enter>
7 Copy: - Copy command will make exact copy of the file onto another file wit different name
or on another disk drive.
Ex: a) C:\>copy 1.txt 2.txt
<enter> .In this copy command copy the
content of 1.txt to 2.txt file.
b) C:\>copy 1.txt D:
<enter> .In this copy command copy the
1.txt file to D drive .
8 DEL/ERASE: - These commands are used for deleting the files from the disk.
Ex: C: \>DEL 1.txt
<enter>
9 RENAME: - Rename command changes the name of an already exiting file to a new name.
Ex: C:\>RENAME A.doc B.doc <enter>
10 Vol: -This command displays the disk volume label.
Ex: C:\>Vol
<enter>
11 VER: - the ver command display version of DOS running on the machine.
Ex: C:\ver
<enter>
12 Wild Card Character “*” and “?”: -Wild card character is used for match a particular ward
to all file names and extensions
or
we will be using wild card characters for specifying all file names and extensions.
Ex: -1) For all files
C:\>DIR *.*
//show all files with unlimited character length.
2) For specific file with some characters
C:\>DIR ??
// show only those folders with name length only
two character .

*
is used for select all files and folders.

?
is used for select one –one character name for files and folders.
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-9-
External Commands: - These are those commands which require certain special DOS files
for being executed.
Ex: For “Format” Command “Format.com” is first loaded into the
memory then “Format” command is run.
1) MD Command: - The MD or MKDIR command creates a subdirectory. This command
is to be followed by path and name of the subdirectory to be created.
Ex: C:\>MD folder1
<enter>
// we make a folder/directory with name “folder1”.
2) CD Command: - This CD or CHDIR command is used to change the current path and
change the name of the current directory.
Ex: C:\>CD folder1
<enter>
Now on prompt
C:\>folder1\
//Now we are in folder1 directory.
3) RD Command: - This RD or RMDIR is used to remove a subdirectory. (A subdirectory
can’t be removed if it is not emptied of files or if it contains subdirectories or files.)
Ex: C:\>RD Folder1
<enter>
// This will delete the folder “folder1”.
4) LABEL Command: - This label command is used to give a volume label to the floppy or
hard disk.
Ex: C:\>LABEL main <enter>
5) Prompt Command: - This command is used to change the system prompt.
Ex: C:\>prompt window <enter>
//Now on Prompt change instead of C :\> it will show window.
6) DELTREE: - This command deletes a directory and all its files and subdirectories and
deletes files in a directorg.
Ex: C:\>DELTREE D:\folder1
<enter>
7) XCOPY: - This command copies the directories as well as subdirectories. It is similar to
copy operation.
Ex:C:\>XCOPY *.*/s D: <enter>
// it copies of all files and folders of C
Drive into D drive.
8) FIND: - This command is used to search a specific string of text in a file or files.
Parameters: - string having four parameters.
1) / V: - Displays all the lines not containing the specific string.
2) / C: - Displays only the lines not containing the specific string.
3) / N: - Includes line numbers in the display.
4) / I: -Ignores case.
Ex: C:\>find/v “ABC” 1.txt
<enter> // it finds “ABC” string in 1.txt file
BHALLA INFOTECH
Computer & Information Technology Training Institute
Notes:-Computer Fundamental & Basic Course (DOS)
-10-
9) Edit: -This command Starts the DOS Editor (like notepad in window) by which we can
create, edit or make changes in file.
Ex: - C:\>EDIT
<enter>
10) ATTRIB Command: - Attrib commands changer or displays the attributes of a file. Files
can be read only, read-write, archived or not archived.
+ sets an attribute
- clears an attribute
R read only file attribute
A archive file attribute
S system file attribute
H hidden file attribute
Ex: C:\>attrib 1.txt +r <enter> // this makes this file read only
Remaining Commands:11) PATH Command
12) DISKCOPY Command
13) DISKCOMP Command
14) CHKDSK Command
15) DEBUG Command
16) DOSKEY Command
17) ECHO Command
18) FDISK Command
19) GOTO Command
20) GRAPHICS Command
21) HELP Command
22) MEM Command
23) MEMMAKER Command
24) MSAV Command
25) MSBACKUP Command
26) RESTORE Command
27) SORT Command
Batch Files: - Bath file are those files in which commands are processed in a batch i.e. it
contains one or more DOS commands for a sequence of operations. These are created by
copy con command. These files have extension “.bat”
Ex: C :\> copy con AA.bat
___________________________________________________
BHALLA INFOTECH
Computer & Information Technology Training Institute