Operating System
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Operating System
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What is an operating system?
It is a set of program that provide
an
interface between hardware, software
and users and manages all the resources
and provide platform where user can
execute all application/program easily.
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Basic function of operating system
Operating
System
Device configurationControls peripheral devices connected to the computer
File managementTransfers files between main memory and secondary storage, manages file folders, backup of file ,recovery of file, protection of file.
Memory managementAllocation and deallocation of memory space.
Decide which process load onto memory when memory
Space become available.
Interface platformProvide the interface b/w hardware, software and users.
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Common Operating System Network Operating System
UNIX / Linux / MS Windows2000 Server
Desktop Operating System MS Windows 9X/Me / Mac OS / DOS
Mobile Operating System Palm OS and Pocket PC
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Types of Operating System
Batch processingReal time processingTime sharing processing
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Batch Processing System
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Real Time Operating system
•Immediate response is needed.•For example
anti-missile defense systemairplane landing control systeminterrupt error in computer system
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Time Sharing Operating System
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Good Operating System
efficient time spent to execute its programs
should be shortsmall in size
memory occupied should be as small as possible
reliable
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Special Features of OS
multi-taskingmulti-programmingparallel processingbufferingspooling
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Multitasking
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Multiprogramming
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Parallel Processing
Job 1
Job 2
Job 3
Job 4
Job 1
Job 2
Job 3
Job 4
CPU 1 CPU 2 CPU 1
time
with multiprocessing
Time
Without multiprocessing
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Spooling
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Components of operating system
Kernel: Core components of the OS Process scheduler
Determines when and for long each process executes
Memory manager Determines when and how memory is allocated
to processes Decides what to do when main memory is full
File system Organizes named collections of data in
persistent storage Networking
Enables processes to communicate with one another
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Who is going to attack?
There are various types of intrudersNaïve Users – These are kind of people who have a long nose and have nothing to do. They know less but keep on checking out places for other people’s data (Mails etc.).Skilled Users – These are people like inquisitive students who are more or less skilled and try out ways to access things they are not meant to just for fun or to learn.Purposeful Intruders – These people do nasty jobs on purpose – e.g. Hacking the Military Data of enemy nation, Hacking confidential data of the rival company, etc.
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Some well known security threats
Viruses Trojansworms
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Some ways to tackle intruders
Passwords – Good passwords – Mixture of numbers, letters of different case is a good security measure. Passwords ideally should not carry any personal information. These steps make it difficult to guess passwords.Periodically changing passwords – Some systems allow us to specify passwords and specify some period within which the password will have to be changed.Recursive Passwords – This is a technology in which each time a password is used, it is re-encrypted or changed automatically. The user is given a list of passwords for a period of time. If that list is secured, the user’s data is secured.
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References :
Operating system book by galvin www.wepapers.com www.pucomp.org www.authorstream.com
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