CH1.1 - Understanding OS2

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PRACTICAL APPROACHOF OPERATING SYSTEM

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Chapter 1.1:

Uner!tan"n# OS


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#

1.1 UN$ERSTAN$ING

OS

1.1.1 %hat "! OS&

1.1.2 H"!t'r( ') OS

$e*e+'p,ent1.1.- T(pe! ') OS


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1.1Uner!tan"n# OS

1.1.1 %hat "! OS&

An OS is a program that acts as an intermediarybetween a user of a computer and the

computer hardware Operating system goals:

Execute user programs and make solving userproblems easier.

Make the computer system convenient to use

An operating system uses the computerhardware in an ecient manner


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A computer system can be divided roughlyinto:

!. Harare " provides basic computingresources for the system

#. Operat"n# !(!te, " controls andcoordinates the use of the hardware among

the various application programs for thevarious users

$. App+"/at"'n! pr'#ra,! " de%ne the waysin which the system resources are used to

solve the computing problems of the users

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A!tra/t "e ') S(!te, C',p'nent!

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Operating System Main 'unctions

Re!'r/e a++'/at'r " manages andallocates resources

C'ntr'+ pr'#ra, " controls the execution ofuser programs and operations of ()O devices

3erne+ " the one program running at alltimes on the computer *along with the kernel+there are # other types of programs: systemprograms and application programs,

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(n general+ acomputer systemhas some resourceswhich may beutili-ed to solve aproblem. hey are Memory

0rocessor*s,

()O

'ile System

etc.

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he OS ,ana#e! the!e re!'r/e! ana++'/ate! the,to speci%c programs andusers.

1ith the management of the OS+ aprogrammer is rid of dicult hardwareconsiderations.

An OS pr'*"e! !er*"/e! for0rocessor Management

Memory Management'ile Management2evice Management3oncurrency 3ontrol

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1.1.2 H"!t'r( ') OS $e*e+'p,ent

'irst generation !4&5 6 !455

echnology: *a/, te! p+#'ar! 0rogramming: !ett"n# !',e !"t/he!

0rogramming language: ,a/h"ne +an#a#e

asks: ta+e! ') !"ne5 /'!"ne5 +'#ar"th,!

OS: n'ne

3omputer designer is: builder and

programmer and

operator and

sys admin 4

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Second generation !455 !475 echnology: Tran!"!t'r! 0rogramming: Pn/he /ar! 0rogramming languages: FORTRAN A!!e,+(

asks: S/"ent"6/ 3omputer: Ma"n)ra,e! OS: 7at/h !(!te,

8niversities started to buy computers

*millions 9, Separation between computer designers+

builders+ operators+ programmers andmaintenance personnel.

!

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Second generation !455 !475 echnology: Tran!"!t'r! 0rogramming: Pn/he /ar! 0rogramming languages: FORTRAN A!!e,+(

asks: S/"ent"6/ 3omputer: Ma"n)ra,e! OS: 7at/h !(!te,

8niversities started to buy computers

*millions 9, Separation between computer designers+

builders+ operators+ programmers andmaintenance personnel.

!!

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hird generation !475 " !4; echnology: IC! 0rogramming: Pn/he /ar!

0rogramming languages: FORTRAN A!!e,+( asks: S/"ent"6/ /',,er/"a+ 3omputers: I7M -805 $EC P$P!

OS: M+t"pr'#ra,,"n#9t",e!har"n#5 !p''+"n#

OSes 2eveloped: MULTICS (father of all modern OSes) UNIX (System V, BSD)

POSIX (y I!!!)

MINIX (y Tanena"m)

L#n"$ (der#%ed from MINIX) !#

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'ourth generation !4;60resent echnology: LSI

0rogramming: H"#h +e*e+

0rogramming languages: C9C5 ;a*a5

3omputer: PC

OS: %"n'!5 Ma/OS5 L"n<

3heap 03s

!$

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!.!.$ ypes of OS

a, ybride, Embedded

!&

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a= 7at/h

A batch system is one in which ?obs arebundled together with the instructionsnecessary to allow them to beprocessed without intervention.


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!7

1.1Uner!tan"n# OS

bring cards to (


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=T",e Shar"n#9Intera/t"*e

ime sharing is a logical extension ofmultiprogramming.

(n time sharing systems+ the 308executes multiple ?obs by switchingamong them+ but the switches occur so

freBuently that the users can interactwith each program while it is running.

(t reBuires an interactive computersystem providing direct communication

between user and the system !@

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/= Rea+>T",e

An OS that guarantees a certaincapability within a speci%ed timeconstraint.

his can be especially important inmeasurement and automation systems

where downtime is costly or a programdelay could cause a safety ha-ard.

E.g. industrial process control systemswhere each ?ob must be completed in

the speci%ed time. !;

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e= H(r"

A


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e= E,ee

An e,ee 'perat"n# !(!te,! is OSfor embedded computer system.

hese operating systems are designed tobe compact+ ecient+ and reliable for manyfunctions.

irtually all appliances that have a digitalinterface. E.g: watches+ microwaves+ 3=s+cars 66 utili-e embedded systems.

Some embedded systems include an

operating system. #

1.1Uner!tan"n# OS

CH1.1 - Understanding OS2

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