24059940 operating system copy

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Operating SystemOperating System


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A special system software that acts as an intermediary bthe computer hardware.Provides an environment in which the user can execute

convenient and efficient manner.

Operating System

User

Operating System

Hardware

Ex amples of OS: Windows, MS-DOS, Linu x , Uni x


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OperatingOperating SystemSystem

Thu s t he main goals for an Operating system are:

y Make comp u ter

co

nvenient to use ( h ides Hardwaredetails)

y Utilize reso u rces in effi c ient manner


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Operating SystemOperating System

Computer hardware

Operating System

User

Application Software


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Functions Functions of O/S of O/S

1. Process Management 2. Memory Management 3. Deadlock Handling

4. File Management 5. I/O Management 6. Protection & Security 7. Job scheduling 8. Interpretation of commands and instructions.9. Co-ordination of compilers and, assembler, programs and other

s/w of computer system.


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Functions Functions of O/S of O/S

10. Production of error messages.11. Maintenance of internal time clock and log system usage for all

users.12.

Provides easy communication between the computer system and users.13. Resource Allocator 14. Intermediary 15. Executes application software 16. Memory management 17. CPU Scheduling


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CATEGORIES OF OPERATING SYSTEMS CATEGORIES OF OPERATING SYSTEMS

Operating systems can be categorised by t henumber of users t hey s upport as well as by t heir level of sop h istication.

Th ree categories are broadly recognized:-1. D eskt o p O/S :

Designed to s upport a single user or a smallwork gro up of users.

2 . D epartmental O/S :S upports from a few dozen to a few hu ndredusers.


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CATEGORIES OF OPERATING SYSTEMS CATEGORIES OF OPERATING SYSTEMS

3 . E nterprise O/S :Generally s upports t housands of users andtransactions sim u ltaneo usly.Offers t he greatest f unctionality, followed by

departmental operating systems, and t hendesktop operating systems.Th e user interface is t he least sop h isticated onenterprise operating systems.


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D eskt o p Operating SystemD eskt o p Operating System


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Desktop Operating SystemDesktop Operating Systemy

Supports a single user or a small group of users.y Some examples of the operating systems in this categoryare:-

1. M S-DOS :One of the original operating systems for the IBM PCand its clones.A non-graphical, line oriented, command-drivenoperating system, with a relatively simple interface but

not a friendly user interface.It was not capable of multitasking.It has now been almost totally replaced by GUI

products such as Windows 95, Windows 98, Windows2000 and Windows XP.


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D esktop Operating SystemD esktop Operating System

2. Windows 3.1y I t is a transition windowing system between

MS-DOS and Windows95, Windows 98 and

Windows 2000.y I t is not actually an operating system, but aGUI that operates with, and e x tends thecapabilities of MS-DOS


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3. Windows 95y The first of a series of products in the Windows operating

systems that provides a GUI by using icons to provide instantaccess to common tasks.

y It is a 32-bit operating system that features multitasking,networking, and Internet integration capabilities.

y It also offers plug-and-play capabilities by enabling the operatingsystem to recognize new hardware and install the necessarysoftware (device drivers) automatically.


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Desktop Operating SystemDesktop Operating System4 . W

indow

s 98Offered minor refinements, b ug fixes, anden hancements to windows 95.

5 . W ind ow s NT

A n operating system for h igh -end desktops andworkstations.It provides t he same GUI as Windows 95, 98, and2000.

Has more powerf u l m u ltitasking, and memorymanagement capabilities.It is pop u lar in networked systems in b usinessorganizations.


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8 . IBM s OS/2 Operating Systemy A 32-bit operating system t hat s upports m u ltitasking,

and s upports networked applications.9. M a c int o sh Operating Systemy F or A pple M acintos h microcomp u ters.y Is a 32-bit operating system t hat feat u res

mu ltitasking and powerf u l grap h ics capabilities.


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10. U nixy Provides many sophisticated desktop features,

including multiprocessing and multitasking

techniques.y Is valuable to business organizations because it can be used on many different sizes of computers (different hardware: non Intel and Intel processors).

y Was popularized by Sun Microsystems.


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Desktop Operating SystemDesktop Operating System11. L

inuxy A powerf u l version of Unix .y Completely free of c harge.y It offers m u ltitasking, virt ual memory management, and

TCP/IP networking.y Originally written by Lin us Tovalds at t he University of

Helsinki in 1991.y He t hen released t he so urce code to t he world.y

Like Unix, it r uns on m u ltiple hardware platforms.y Is becoming widely used by Internet service providers.y Th e clearing house for Lin ux information on t he Internet may

be fo und at www.lin uxhq .com


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Desktop Operating SystemDesktop Operating System

1 2 . J ava Operating Systemy Is designed for hand- held prod ucts and

network comp u ters.y S uns java operating system exec u tes

programs written in Java lang uage wit hou t theneed for a traditional operating system.

y It is designed for Internet and Intranetapplications and embedded devices.


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D epartmental Server OperatingD epartmental Server OperatingSystemsSystems


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Th e major departmental server operating systemsinclude:-

y Unixy

Windows N T server y IBM s OS/2 Warp Server y Novell NetWarey IBM s OS/400


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Although some of these are also desktop OS, all can serveas departmental server OS because of their:-

y Strong scalabilityy Reliabilityy Backupy Security26y Fault tolerancey Multitaskingy Multiprocessingy TCP/IP networkingy Network management


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E nterprise Operating SystemsE nterprise Operating Systems


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E nterprise OperatingE nterprise OperatingSystemsSystems

The major enterprise operating systems include:

y IBMs MVS (Multiple Virtual Storage)y

IBMs VM (Virtual Machine)y IBMs VSE (Virtual Storage Extended)y Digital Open VMS (Virtual Machine System)


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E nterprise OperatingE nterprise OperatingSystemsSystems

E nterprise operating systems s upport:

y Sec u re electronic commerce

y M u ltiple conc urrent users

y Large (terabyte) databases

y M illions of transactions per day.


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Types o f O/STypes o f O/S

M u ltitasking

M u ltiprogramming

Time s haring

M u ltiprocessing


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MUL TITASK ING O/SMUL TITASK ING O/S

Executing more than one task concurrently.Execution of two or more tasks/programs by one user

concurrently on the same computer with one central processor.For example, the user may be running one program andsimultaneously listening to a music file.


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Mul tiprogramming OperatingMul tiprogramming OperatingSystemSystem

Refers to concurrent execution of different users programs on a machine with a single processor.It is the execution of two or more programs concurrentlyon a multi-user operating system.The processor spends a certain amount of time executingeach users program. As the processor works much

faster, it seems as though all the programs are being runat the same time.


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Time SharingTime Sharing Operating SystemOperating System

Round-Robin processing of programs for several users.

A single comp u ter processes t he tasks of several users at different locations based on t heconcept of time slicing between t he users.

24059940 operating system copy

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