Operating system

K.HIMABINDU., M. Tech
OBJECTIVES
1. Assist the user to use the computer system CONVENIENTLY.
2. Enable the user to use the computer system and window EFFICIENTLY.
3. Assign the processors for performing tasks.
4. Allocate memory, managing memory and other storage areas.
5. Apply various command interpretations.
6. Schedule various jobs/tasks.
7. Establish priorities for different jobs.
8. Coordinate and manage peripherals devices.
9. Know input and out management.
10.Establish data security an integrity.

Definition of Operating System
• An operating system is a set of program files which controls the resources of the
computer system and allows the communication of hardware components of a
computer to the software components of the computer system. Operating systems
provides access to computer services which is possible only via working of both
the hardware components and the software components.
• User can interact with the operating system through Command Line Interface
(CLI) OR Graphical User Interface (GUI).
• Examples : CLI - DOS
GUI-Windows

Characteristics of OS
1. Single tasking or Multitasking
2. Single threading or Multithreading
3. Character based or Graphic user interface
4. Weak or Strong Security
5. 8,16,32 and 64 bits processed at a time
6. Portable and Non-portable Operating system
7. Proprietary and open operating systems

TYPES OF
Single User
Multi User
Multi Programming
Multi Process
Time Sharing
Real Time / On line
Batch Processing

Disk Operating System (DOS) is OS software which loads into computer memory and
performs tasks, manages secondary storages devices and maintains information on the
disk devices.
DOS is the first operating system which is used widely in personal computers. First version
of DOS called PC-DOS was developed for IBM by bill gates of Microsoft Corporation. Bill
gates retained rights for marketing a Microsoft version of DOS called MS –DOS.
DOS is a command line operating system and prompts user to enter commands. DOS is a
16-bit operating system and does not support multi users and multitasking.

Purpose:
Each time the computer boots up, DOS searches for a configuration system file and it uses the commands to configure the
system. DOS uses the commands in auto execution bat to further refine the way it starts the computer system. If the auto
execution boot is not set, the machine will be in default mode. This file is used to run programs automatically on start up. The
operating system causes all the commands in this file executed before the start up is completed. It coordinates the flow of
information between computer the disk, floppy or hard disk.

Types of Commands in MS DOS
1. Internal Commands (Loaded into PRIMARY Memory)
1.Dir – The command list out
all the directories.
a) Dir/p – To get directories
page wise
b) Dir/w- Width wise
c) Dir[drive]- To list out the
directories of another
directory.
d) Dir*.<extension>
e) Dir*.* - current directory
f) Dir com???.*
g) Dir/s – sub directories
2.MD Or MKDIR
3.CD<Directory Name>
4.RD<SUB-DIRECTORY NAME>
5.CD..
6. COPY<source
filename><destination file
name>
7.COPY CON<FILE NAME>
8. REN<Existing file
name><new file name>
9.DEL<file name>
10. PATH
11.PROMPT
12. VER
13. VOL
14. CLS
15. DATE
16. TIME
17. TYPE

Types of Commands in MS DOS
2. External Commands (Do not need to be loaded into MEMORY)
1.BACKUP C:
2.RESORE A:C:
3. ATTRIB<FILE Name>[+h] or [-h] or [+r] or [-r]
4.CHKDSK C
5.DISKCOPY A:B:
6.COMP A:B.COMI C:B.COM
7.DISKCOMP A:B:
8.FORMAT A:
9. PRINT<FILE NAME>
10. RECOVER<FILENAME>
11.REPLACE A:/*.*C:/STUDENTS
12. LABEL A:STUD
13. EDIT<FILE NAME>
14. FIND’’marks’’*.txt

WILDCARD CHARACTERS
A wildcard character is a special character or symbol that represents one or more other
characters. The most commonly used wildcard characters are the asterisk(*), which typically
represents zero or more characters in a string of characters, and the question mark(?), which
typically represents anyone character.
1.To find a directory by using ‘*’ - C:>dir BCOM*
2. To delete a file by using ‘*’ - C:>DEL *TXT
3.To find a file by using ‘?’ - C:>dir? BCOM
4. To delete a file or directory by using ‘?’ - C:>DEL ? Doc

A Computer Virus is a compute program that can copies itself and spread from one computer to another.
A computer virus is “a computer program usually hidden within another program that produces copies of itself and inserts
them into other programs or files, and then destroys data”.
Computer viruses are never naturally occurring; they are always man made. Once created and released, however, their
spread is not directly under human control.
Computer Virus

Symptoms of a Computer Virus
1. The computer runs slower
than usual.
2. The computer stops
responding or it locks up
frequently.
3. The computer crashes, and
then it restarts every few
minutes.
4. The compute restarts on its
own. Additionally, the
computer does not run as
usual.
5. Applications on the
computer do not work
correctly.
1. Disks or Disk drives are
inaccessible.
2. You cannot print items
correctly.
3. You see unusual error
messages.
4. You see distorted menus and
dialog boxes.
5. A program disappears from
the computer even though
you did not intentionally
remove the program

Different
Types of
ANTIVIRUS

Windows1.01, 1.02, 1.03, 1.04
Windows 2.03,2.10,2.11
Windows 3.0,3.1,NT 3.1,3.2, NT
3.5,3.51
Windows 95
Windows NT 4.0
Windows 98
Windows2000
Windows ME
Windows XP
Windows XP Professional X64
Windows Vista
Windows 7
Windows 8
Windows 8.1
Windows 10
Microsoft windows client versions.

Microsoft
windows
server
versions.

Icons in
windows
desktop
Application
Window
Document
Window

Basic Components of a Window

Window menu

CONTROL PANEL

Operating system

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