Operating System
Operating System
•
• A special system software that acts as anA special system software that acts as an
intermediary between a user of a computer and the intermediary between a user of a computer and the computer hardware.
computer hardware. •
• Provides an environment in which the user canProvides an environment in which the user can execute programs/applications in a convenient and execute programs/applications in a convenient and efficient manner. efficient manner.
Operating System
Operating System
User User Operating System Operating System Hardware HardwareExamples of OS: Windows, MS-DOS, Linux, Unix Examples of OS: Windows, MS-DOS, Linux, Unix
Operating System.
Operating System.
Thus the main goals for an
Thus the main goals for an Operating system are:Operating system are: •
• Make computerMake computer convenientconvenient to use (hides Hardwareto use (hides Hardware details)
details) •
Operating System
Operating System
Computer hardware Computer hardware Operating System Operating System User User Application Software Application SoftwareFunctions
Functions
of O/S
of O/S
1
1.. PrProocceesss s MMaannaaggeemmeenntt 2
2.. MMememoorry y MMaannaaggememenentt 3 3.. DDeeaaddlloocck Hk Haannddlliinngg 4 4.. FFiille e MMaannaaggeemmeenntt 5 5.. II//O O MMaannaaggeemmeenntt 6
6.. PrProottecectitioon n & & SeSeccururitityy 7
7.. JJoob b sscchheedduulliinngg 8.
8. IntInterperpretretatiation on of of comcommanmands ds and and insinstrtructuctionions.s. 9.
9. CoCo-o-ordrdininatatioion of con of compmpililerers ands and, ass, assememblblerer,, programs and other s/w of computer system. programs and other s/w of computer system.
Functions
Functions
of O/S
of O/S
10.
10. ProductProduction of error mession of error messages.ages. 11.
11. Maintenance of Maintenance of internal time internal time clock and logclock and log system usage for all users.
system usage for all users. 12.
12. Provides easy Provides easy communication between communication between thethe computer system and users.
computer system and users. 13. Resource Allocator
13. Resource Allocator 14.Intermediary
14.Intermediary 15.
15. ExecuExecutes applicates application softwartion softwaree 16.
16. MemorMemory manay managemegementnt 17.CPU Scheduling
CATEGORIES OF OPERATING CATEGORIES OF OPERATING
SYSTEMS SYSTEMS
Operating systems can be categorised by Operating systems can be categorised by the number of users they support as well as the number of users they support as well as by their level of sophistication.
by their level of sophistication.
Three categories are broadly Three categories are broadly
recognized:-1
1.. DDeesskkttoop p OO//SS:: •
• Designed to support a single user or aDesigned to support a single user or a small work group of users.
small work group of users. 2
2.. DDeeppaarrttmmeennttaal l OO//SS:: •
• Supports from a few dozen to a fewSupports from a few dozen to a few hundred users.
CATEGORIES OF OPERATING CATEGORIES OF OPERATING
SYSTEMS SYSTEMS 3
3.. EEnntteerrpprriisse e OO//SS:: •
• Generally supports thousands of usersGenerally supports thousands of users and transactions simultaneously.
and transactions simultaneously. •
• Offers the greatest functionality, followedOffers the greatest functionality, followed by departmental operating systems, and by departmental operating systems, and then desktop operating systems.
then desktop operating systems. •
• The user interface is the least The user interface is the least
sophisticated on enterprise operating sophisticated on enterprise operating systems.
Desktop Operating
Desktop Operating
System
System
Desktop Operating
Desktop Operating
System
System
•
• Supports a single user or a sSupports a single user or a small group of users.mall group of users. •
• SoSome me exexamamplples es of of ththe e opopereratatining sg sysystetems ms in in ththiiss category
category are:-1
1.. MMSS--DDOOSS:: •
• OnOne oe of tf the he ororigigininal al opopereratatining sg sysystetems ms fofor tr the he IBIBMM PC and its clones.
PC and its clones. •
• A nA nonon-g-graraphphicicalal, l, linine oe oririenenteted, d, cocommmmanand-d-drdrivivenen operating system, with a relatively simple
operating system, with a relatively simple interface but not a friendly user interface. interface but not a friendly user interface. •
• It It wawas s nonot t cacapapablble e of of mumultltititasaskikingng.. •
• It It hahas ns now ow bebeen en alalmomost st tototatalllly y rereplplacaced ed by by GUGUII products such as Windows 95, Windows 98,
products such as Windows 95, Windows 98, Windows 2000 and Windows XP.
Desktop Operating
Desktop Operating
System
System
2
2.. W
Wiin
nd
do
ow
ws 3
s 3..1
1
•
• It is a transition windowing system
It is a transition windowing system
between MS-DOS and Windows95,
between MS-DOS and Windows95,
Windows 98 and Windows 2000.
Windows 98 and Windows 2000.
•
• It is not actually an operating system,
It is not actually an operating system,
but a GUI that operates with, and
but a GUI that operates with, and
extends the capabilities of MS-DOS
extends the capabilities of MS-DOS
Desktop Operating
Desktop Operating
System
System
3 3.. WWiinnddoowws s 9955 •• The first of a series of products in the Windows The first of a series of products in the Windows operating systems that provides a GUI by using operating systems that provides a GUI by using icons to provide instant access to common tasks. icons to provide instant access to common tasks. •
• It is a 32-bit operating system that featuresIt is a 32-bit operating system that features
multitasking, networking, and Internet integration multitasking, networking, and Internet integration capabilities.
capabilities. •
• It also offers plug-and-play capabilities byIt also offers plug-and-play capabilities by
enabling the operating system to recognize new enabling the operating system to recognize new hardware and install the necessary software
hardware and install the necessary software (device drivers) automatically.
Desktop Operating
Desktop Operating
System
System
4 4.. WWiinnddoowws s 9988 •• Offered minor refinements, bug fixes, andOffered minor refinements, bug fixes, and enhancements to windows 95.
enhancements to windows 95. 5
5.. WWiinnddoowws s NNTT •
• An operating system for high-end desktops andAn operating system for high-end desktops and workstations.
workstations. •
• It provides the same GUI It provides the same GUI as Windows 95, 98,as Windows 95, 98, and 2000.
and 2000. •
• Has more powerful multitasking, and memoryHas more powerful multitasking, and memory management capabilities.
management capabilities. •
• It is popular in networked systems in It is popular in networked systems in businessbusiness organizations.
Desktop Operating
Desktop Operating
System
System
6 6.. WWiinnddoowws s 22000000 •• Microsoft changed the name of the upgrade of Microsoft changed the name of the upgrade of Windows NT 5.0 to Windows 2000.
Windows NT 5.0 to Windows 2000. •
• This operating system has added security features. This operating system has added security features. •
• Runs on multiprocessor computers.Runs on multiprocessor computers. •
• Offers added Internet and Intranet functionality.Offers added Internet and Intranet functionality.
7.
7. WiWindndowows s CE CE (C(Comompapact ct EdEdititioion)n)
•
• Is a 32-bit operating system designed for hand-heldIs a 32-bit operating system designed for hand-held PCs, and wireless communication devices.
Desktop Operating
Desktop Operating
System
System
8.
8. IBIBM’M’s Os OS/S/2 O2 Opeperaratiting ng SySyststemem •
• A 32-bit operating system that supportsA 32-bit operating system that supports multitasking, and supports networked multitasking, and supports networked applications.
applications. 9.
9. Macintosh Operating SystemMacintosh Operating System •
• For Apple Macintosh microcomputers.For Apple Macintosh microcomputers. •
• Is a 32-bit operating system that featuresIs a 32-bit operating system that features multitasking and powerful graphics
multitasking and powerful graphics capabilities.
Desktop Operating
Desktop Operating
System
System
10.Unix
10.Unix
••
Provides many sophisticated desktop
Provides many sophisticated desktop
features, including multiprocessing and
features, including multiprocessing and
multitasking techniques.
multitasking techniques.
••
Is valuable to business organizations because
Is valuable to business organizations because
it can be used on many different sizes of
it can be used on many different sizes of
computers ( different hardware: non Intel and
computers ( different hardware: non Intel and
Intel processors).
Intel processors).
Desktop Operating
Desktop Operating
System
System
11 11.. LiLinunuxx •• A powerful version of Unix .A powerful version of Unix . •
• Completely free of charge.Completely free of charge. •
• It offers multitasking, virtual It offers multitasking, virtual memory management, andmemory management, and TCP/IP networking.
TCP/IP networking. •
• Originally written by Linus Tovalds at Originally written by Linus Tovalds at the University of the University of Helsinki in 1991.
Helsinki in 1991. •
• He then released the source code to the He then released the source code to the world.world. •
• Like Unix, it runs Like Unix, it runs on multiple hardware platforms.on multiple hardware platforms. •
• Is becoming widely used by Is becoming widely used by Internet service providers.Internet service providers. •
• The clearinghouse for Linux information on the Internet The clearinghouse for Linux information on the Internet may be found at www.linuxhq.com
12.
12.Java OperJava Operating Systeating Systemm
•• Is designed for hand-held products and networkIs designed for hand-held products and network computers.
computers.
•• Sun’s java operating system executes programsSun’s java operating system executes programs written in Java language without the need for
written in Java language without the need for aa traditional operating system.
traditional operating system.
•• It is designed for Internet and Intranet applications andIt is designed for Internet and Intranet applications and embedded devices.
embedded devices.
Desktop Operating System
Desktop Operating System
Departmental Server
Departmental Server
Operating
Operating
Systems
Systems
The major departmental server operating The major departmental server operating
systems systems include:-•
• UnixUnix •
• Windows NT serverWindows NT server •
• IBM’s OS/2 Warp ServerIBM’s OS/2 Warp Server •
• Novell NetWareNovell NetWare •
• IBM’s OS/400IBM’s OS/400
Departmental Server Operating
Departmental Server Operating
Systems
Systems
Departmental Server Operating
Departmental Server Operating
Systems
Systems
Although some of these are also desktop OS, Although some of these are also desktop OS, all can serve as departmental server OS
all can serve as departmental server OS because of
because of their:-•
• Strong scalabilityStrong scalability • • ReliabilityReliability • • BackupBackup • • Security26Security26 •
• Fault toleranceFault tolerance •
• MultitaskingMultitasking •
• MultiprocessingMultiprocessing •
• TCP/IP networking TCP/IP networking •
Enterpris
Enterprise
e Operating
Operating
Systems
Enterprise Operating
Enterprise Operating
Systems
Systems
The major enterprise operating systems include: The major enterprise operating systems include:
•
• IBM’s MVS (Multiple Virtual Storage)IBM’s MVS (Multiple Virtual Storage) •
• IBM’s VM (Virtual Machine)IBM’s VM (Virtual Machine) •
• IBM’s VSE (Virtual Storage Extended)IBM’s VSE (Virtual Storage Extended) •
Enterprise Operating
Enterprise Operating
Systems
Systems
Enterprise operating systems support: Enterprise operating systems support: •
• Secure electronic commerceSecure electronic commerce •
• Multiple concurrent usersMultiple concurrent users •
• Large (terabyte) databasesLarge (terabyte) databases •
Types of O/S
Types of O/S
• • MultitaskingMultitasking • • MultiprogrammingMultiprogramming •• Time sharing Time sharing •
MULTITASKING O/S
MULTITASKING O/S
•
• Executing more than one task concurrently.Executing more than one task concurrently. •
• Execution of two or more tasks/programs byExecution of two or more tasks/programs by one user concurrently on the same computer one user concurrently on the same computer with one central processor.
with one central processor. •
• For example, the user may be running oneFor example, the user may be running one program and simultaneously listening to a program and simultaneously listening to a music file.
Multiprogramming
Multiprogramming
Operating System
Operating System
•
• Refers to concurrent execution of different users’ programsRefers to concurrent execution of different users’ programs on a machine with a single processor.
on a machine with a single processor. •
• It is the execution of two or more programs concurrently onIt is the execution of two or more programs concurrently on a multi-user operating system.
a multi-user operating system. •
• The processor spends a certain amount of time executing The processor spends a certain amount of time executing each user’s program. As the processor works much faste each user’s program. As the processor works much faster,r, it seems as though all the programs are being run at t
it seems as though all the programs are being run at thehe same time.
Time Sharing
Time Sharing Operating
Operating
System
System
•
• Round-Robin processing of programs for severalRound-Robin processing of programs for several users.
users. •
• A single computer processes the tasks of A single computer processes the tasks of
several users at different locations based on
several users at different locations based on thethe concept of time slicing between the users.
Multiprocessing
Multiprocessing Operating
Operating
System
System
•
• Simultaneous processing of two or moreSimultaneous processing of two or more
programs by multiple computers or processors programs by multiple computers or processors linked together to perform work
linked together to perform work simultaneously.simultaneously. •
• This can involve processing of instructions from This can involve processing of instructions from different programs or different instructions
different programs or different instructions within the same program simultaneously. within the same program simultaneously. •
• Implemented using concepts of parallelImplemented using concepts of parallel processing.
Real Time
Real Time Operating System
Operating System
•
• an operating system that guarantees a certain capabilityan operating system that guarantees a certain capability within a specified time constraint
within a specified time constraint •
• Such applications include embedded systems and Such applications include embedded systems and scientificscientific research equipment.
research equipment. •
• ProProvidevides facils facilitiities whies which, if usch, if used proped properlyerly, guara, guarantenteee deadlines can be met.
deadlines can be met. •
• Uses Uses specialspecialized sized scheducheduling ling algoritalgorithms hms in oin order trder to proo providevide the real-time developer with the
the real-time developer with the tools necessary to producetools necessary to produce deterministic behavior in the final
deterministic behavior in the final system.system. •
• An RTOS is valued more for how quickly and/or predictablyAn RTOS is valued more for how quickly and/or predictably it can respond to a particular event
it can respond to a particular event •
• An early example of a large-scale real-time operatingAn early example of a large-scale real-time operating
system was the so-called "control program" developed by system was the so-called "control program" developed by American Airlines and IBM for the Sabre Airline Reservations American Airlines and IBM for the Sabre Airline Reservations System.
