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ARM ARCHITECTURE ANDORGANISATION

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Introduction to 16/32 bit processors

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ARM and RISC

• ARM stands for Advanced Risc Machines

What is RISC?

  RISC (reduced instruction set computer) is amicroprocessor that is desined to perform a sma!!er

number of t"pes of computer instructions so that it

can operate at a hiher speed (perform more mi!!ionsof instructions per second# or MI$S)%

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&'AR'S *& RISC

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RISC Architecture

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ARM

Components+

• Arithmetic Logic Unit

• Booth multiplier

• Barrel hi!ter

• Control unit

•

Regiter "le

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ARM ARC,I'CR'

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1.Arithmetic LogicUnit (ALU) 

•

he A- has t.o 32bits inputs%he first comes from the

reister fi!e .hi!e the other comes

from the shifter% A- outputs

modif" the status reister f!as%

• he 0bit output oes to the 0

f!a as .e!! as the Cout oes

to the C f!a% hi!e the most

sinificant bit actua!!" represents

the S f!a# the A- output is

 *Red to et the f!a%

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2.Booth multiplier

• he mu!tip!ier has three

32bit inputs% A!! theinputs come from the

reister fi!e% he

mu!tip!ier output is on!"the 32 !east sinificant

 bits of the product%

• he mu!tip!ication starts

.henever the start input

oes active% he output fin

oes hih .hen finishin%

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3.Barrel shifter

• he barre! shifter has a 32bit input to be shifted%

his input is comin from the reister fi!e or it

cou!d be immediate data% he shifter has other

contro! inputs comin from instruction reister%

•  Shift fie!d in the instruction contro!s theoperation of the barre! shifter% his fie!d

indicates the t"pe of shift to be performed

(!oica! !eft or riht# arithmetic riht or rotate

riht)%

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• he amount b" .hich the reister shou!d be shifted is

contained in an immediate fie!d in the instruction or it

cou!d be the !o.er 6 bits of a reister in the reister fi!e%

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4.Control unit: 

• &or an" microprocessor# contro! unit is the heart of

the s"stem% It is responsib!e for the s"stem operationand so the contro! unit desin is the most important

 part in the .ho!e desin%

• Contro! unit is usua!!" a pure combinationa! circuit%

he processor timin is a!so inc!uded in the contro!unit%

• Sina!s from the contro! unit are connected to

ever" component in the processor to supervise its

operation%

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$eature o! ARM%Architecture