Embedded Systems-8051 Microcontroller
-
Upload
tansnvarma -
Category
Documents
-
view
38 -
download
0
Transcript of Embedded Systems-8051 Microcontroller
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 1/47
8051 MICROCONTROLLER
EMBEDDED SYSTEMS
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 2/47
Introduction
CPU
General-
Purpose
Micro- processor
RAM ROM I/O
Port
TimerSerial
COM
Port
Data Bus
Address Bus
General-Purpose Microprocessor System
CPU for Computers
No RAM, ROM, I/O on CPU chip itself
!ample: Intel"s !#$, Motorola"s $#%!%
Many chips on mother"s &oar'
General-purpose microprocessor
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 3/47
RAM ROM
I/O
PortTimer
Serial
COM
PortMicrocontroller
CPU
A smaller computer
On-chip RAM, ROM, I/O ports(((
!ample:Motorola"s $#)), Intel"s #%*), +ilo"s +# an' PIC )$
A sinle chip
Microcontroller .
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 4/47
Microprocessor
CPU is stan'-alone, RAM,
ROM, I/O, timer are separate
'esiner can 'eci'e on theamount of ROM, RAM an'
I/O ports(
e!pansie
ersatility
eneral-purpose
Microcontroller
0 CPU, RAM, ROM, I/O an'
timer are all on a sinle chip
0 fi! amount of on-chip ROM,RAM, I/O ports
0 for applications in 1hich cost,
po1er an' space are critical
0 sinle-purpose
Microprocessor s( Microcontroller
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 5/47
)( meetin the computin nee's of the tas2 efficiently an' cost
effectiely
0 spee', the amount of ROM an' RAM, the num&er of I/O
ports an' timers, si3e, pac2ain, po1er consumption
0 easy to upra'e
0 cost per unit
4( aaila&ility of soft1are 'eelopment tools
0 assem&lers, 'e&uers, C compilers, emulator, simulator,
technical support
5( 1i'e aaila&ility an' relia&le sources of the microcontrollers(
6hree criteria in Choosin a Microcontroller
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 6/47
Block Diagram
CPU
On-cip
RAM
On-cip
ROM !or
program
code
" I/O Ports
Timer #
Serial
PortOSC
Interrupt
Control
$%ternal interrupts
Timer &
Timer/Counter
Bus
Control
T%D R%DP# P& P' P(
Address/Data
Counter
Inputs
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 7/47
Feature 8051 8052 8031
ROM (program space in b!es" #$ 8$ 0$ R%M (b!es" 1&8 &5' 1&8
Timers & &
I)O pins & & &
Seria* por! 1 1 1
In!err+p! so+rces ' 8 '
Comparison o! te )#*& +amil, Memers
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 8/47
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 9/47
Pin Description o! te )#*&
P7IP/Cer'ip
1234567
891011121314151617181920
40393837363534
33323130292827262524232221
P1.0P1.1P1.2P1.3P1.4P1.5P1.6
P1.7RST
(RXD)P3.0(TXD)P3.1
(T0)P3.4(T1)P3.5
XTAL2XTAL1
GND
(INT0)P3.2
(INT1)P3.3
(RD)P3.7(WR)P3.6
VccP0.0(AD0
)P0.1(AD1)P0.2(AD2
)P0.3(AD3)P0.4(AD4)P0.5(AD5)
P0.6(AD6)P0.7(AD7)
EA/VPP ALE/PROG
PSENP2.7(A15)P2.6(A14
)P2.5(A13
)P2.4(A12
)P2.3(A11)P2.2(A10)P2.1(A9)P2.0(A8)
8051
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 10/47
Pins o! )#*&(
'/")
RS6( pin 8): reset
It is an input pin an' is actie hih( normally lo1) (
6he hih pulse must &e hih at least 4 machine cycles(
It is a po1er-on reset(
Upon applyin a hih pulse to RS6, the microcontroller
1ill reset an' all alues in reisters 1ill &e lost(
Reset alues of some #%*) reisters
9ay ): Po1er-on reset circuit
9ay 4: Po1er-on reset 1ith 'e&ounce
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 11/47
Pins o! )#*&(
(/")
/A( pin 5)): e!ternal access
6here is no on-chip ROM in #%5) an' #%54 (
6he /A pin is connecte' to GN7 to in'icate the co'e is
store' e!ternally(
/PSN & A: are use' for e!ternal ROM(
;or #%*), /A pin is connecte' to <cc(
=/> means actie lo1(
/PSN( pin 48): proram store ena&le
6his is an output pin an' is connecte' to the O pin of the
ROM(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 12/47
Pins o! )#*&(
"/")
A:( pin 5%): a''ress latch ena&le
It is an output pin an' is actie hih(
#%*) port % proi'es &oth a''ress an' 'ata(
6he A: pin is use' for 'e-multiple!in the a''ress an'
'ata &y connectin to the G pin of the ?@:S5?5 latch(
I/O port pins
6he four ports P%, P), P4, an' P5(
ach port uses # pins(
All I/O pins are &i-'irectional(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 13/47
;iure @-4 aB( 6A: Connection to #%*)
2
(#p+
1
(#p+
XTAL2
XTAL1
GND
Usin a uart3 crystal oscillator
9e can o&sere the freuency on the 6A:4 pin(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 14/47
;iure @-4 &B( 6A: Connection to an !ternal Cloc2
Source
N
EXTERNALOSILLATOR
SIGNAL
XTAL2
XTAL1
GND
Usin a 66: oscillator
6A:4 is unconnecte'(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 15/47
!ample .
;in' the machine cycle for
aB 6A: D ))(%*84 ME3
&B 6A: D )$ ME3(
Solution.
aB ))(%*84 ME3 / )4 D 84)($ 2E3F
machine cycle D ) / 84)($ 2E3 D )(%#* µs
&B )$ ME3 / )4 D )(555 ME3F
machine cycle D ) / )(555 ME3 D %(?* µs
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 16/47
R$S$T alue o! Some )#*& Registers.
####DPTR ###0SP
####PS1
####B####ACC
####PC
Reset alueRegister
RAM are all 2ero3
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 17/47
Po1er-On RS6 1ith 7e&ounce
EA/VPP
X1
X2RST
Vcc
10 !"
8.2 #
30 $"
9
31
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 18/47
Pins o! I/O Port
6he #%*) has four I/O ports
Port % ( pins 54-58): P%( P%(%~ P%(?) Port )( pins )-#) : P)( P)(%~ P)(?) Port 4( pins 4)-4#): P4( P4(%~ P4(?) Port 5( pins )%-)?): P5( P5(%~ P5(?) ach port has # pins(
Name' P%( (D%,),(((,?) , P)(, P4(, P5(
!: P%(% is the &it %( :S) of P% !: P%(? is the &it ?(MS) of P%
6hese # &its form a &yte(
ach port can &e use' as input or output &i-'irectionB(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 19/47
Registers
A
R%
R)
R5
R@
R4
R*
R?
R$
7PE 7P:
PC
7P6R
PC
Some #%*) )$-&it Reister
Some #-&itt Reisters of
the #%*)
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 20/47
Some Simple Instructions
MO dest4source 5 dest 6 source
MO A470'8 5A60'8
MO A4 79r9 5A6:r9 OR 0'8
MO R"47;'8 5R"6;'8
MO B4#+<8 5B6te content o! +<9t ,te o! RAM
MO DPTR470;("8
MO DP=47("8
MO DP8470;8
MO P&4A 5mo> A to port &
?ote &.MO A470'8 @ MO A40'8
A!ter instruction MO A40'8 te content o! 0'9t ,te o! RAM ill replace in Accumulator3
)#); )#*&MO A=40'8 MO A470'8
MO A=49r9 MO A479r9
MO B40'8
MO A=4EBF MO A40'8
?ote '.MO A4R( G MO A4(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 21/47
ADD A4 Source FADAHSOURC
A77 A,$ FADAH$
A77 A,R$ FADAHR$
A77 A,$ FADAHJ$K or ADAHR$
%DD %,0-. /%%20-.3
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 22/47
S$TB it 5 it6&
C=R it 5 it6#
S6 C F CLD)
S6 P%(% F&it % from port % D)
S6 P5(? F&it ? from port 5 D)
S6 ACC(4 F&it 4 from ACCUMU:A6OR D)
S6 %* Fset hih 7* of RAM loc( 4%h
?ote.
C:R instruction is as same as S6
i(e.
C:R C FCLD%
ut follo1in instruction is only for C:R.
C:R A FAD%
it A''ressa&le
Pae 5*8,5$%
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 23/47
SUBB A4source 5A6A-source-CH
S6 C FCLD)
SU A,R* FADA-R*-)
ADC A4source 5A6AsourceCH
S6 C FCLD)
A7C A,R* FADAHR*H)
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 24/47
D$C ,te 5,te6,te-&
I?C ,te 5,te6,te&
INC R?7C A
7C @%E F J@%KDJ@%K-)
CP= A 5&9s complement!ample.
MO< A,**E FAD%)%)%)%) :%). CP: A
MO< P),A
ACA:: 7:AL
SMP :%)
?OP J R$T J R$TI
All are li2e #%#$ instructions(
CA::
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 25/47
A?= - OR= - R=
AMP:.MO< R*,#8E
AN: R*,%#E
RR K R= K RRC K R=C A
AMP:.
RR A
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 26/47
Structure of Assembly
language and Running an8051 program
OR4 0.
MO R5,6&5.
MO R7,6#.
MO %,60
%DD %,R5
%DD %,61&..ERE S9M: .ERE
END
7I6OR
PROGRAM
ASSM:R
PROGRAM
:INR
PROGRAM
OE
PROGRAM
Myfile(asm
Myfile(o&
Other o& fileMyfile(lst
Myfile(a&s
Myfile(he!
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 27/47
Memory mapping in 8051
ROM memory map in 8051 family
%%%%E
%;;;E
%%%%E
);;;E
%%%%E
?;;;E
#?*)
A6#8C*)#?*4
A6#8C*4
4%
7S*%%%-54
8% 32%
from Atmel Corporationfrom 7allas Semicon'uctor
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 28/47
RAM memory space allocation in te 8051
?;E
5%E
4;E
4%E
);E
)?E)%E
%;E
%?E
%#E
)#E
%%EReister an2 %
)Stac2 (Register Bank 1
Reister an2 4
Reister an2 5
it-A''ressa&le RAM
Scratch pa' RAM
8051 Flag bits and te !S"
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 29/47
8051 Flag bits and te !S"register :S; Regis!er
CL AC ;% RS) O<RS% P--
CHPS9(?Carry flag
ACPS9($ Auxiliary carry flag
--PS9(* Available to the user for general purpose
RS&PS9(@ Register Bank selector bit 1
RS#PS9(5 Register Bank selector bit 0
OPS9(4Overflow flag
--PS9()User define bit
PPS9(% arity flag !et"Reset odd"even parity
RS& RS# Register Bank Address
% % % %%E-%?E
% ) ) %#E-%;E
) % 4 )%E-)?E
) ) 5 )#E-);E
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 30/47
Instructions that Affect Flag Bits:
N&' X c*+ , 0 &- 1
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 31/47
E<amp*e
MO %,68.%DD %,6&-.
8 00111000&- 00101111 ==== ==============
'7 01100111CY0 %C1 :1
E<amp*eMO %,688.%DD %,6>.
88 10001000> 10010011 ==== ============== 11B 00011011
CY1 %C0 :0
E<amp*eMO %,6>C.%DD %,6'#.
>C 10011100'# 01100100 ==== ============== 100 00000000
CY1 %C1 :0
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 32/47
Addressing Modes Imme'iate
Reister
7irect Reister In'irect
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 33/47
Immediate Addressing Mode
MO< A,$*E
MO< A,"A"
MO< R$,$*E
MO< 7P6R,45@5E
MO< P),$*E
!ample .
Num U 5%
Q
MO<R%,NumMO< 7P6R,'ata)
Q
ORG )%%E
'ata).'& =IRAN>
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 34/47
Register Addressing ModeMO< Rn, A FnD%,((,?
A77 A, Rn
MO< 7P:, R$
MO< 7P6R, A
MO< Rm, Rn
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 35/47
Direct Addressing Mode
Althouh the entire of )4# &ytes of RAM can &e accesse' usin 'irecta''ressin mo'e, it is most often use' to access RAM loc( 5% ?;E(
MO< R%, @%E
MO< *$E, AMO< A, @ F MO< A, R@
MO< $, 4 F copy R4 to R$
F MO< R$,R4 is inali' T
S+R register and teir address
MO< %%E, $$E F MO< A,$$E
MO< %;%E, R4 F MO< , R4
MO< #%E,A F MO< P),A
it A''ressa&le Pae 5*8,5$%
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 36/47
Register Indirect Addressing Mode
In this mo'e, reister is use' as a pointer to the 'ata(
MO< A,Ri F moe content of RAM loc(9here a''ress is hel' &y Ri into A
iD% or ) B
MO< R),
In other 1or', the content of reister R% or R) is sources or taret in MO<, A77 an' SU
insructions(!ample.
9rite a proram to copy a &loc2 of )% &ytes from RAM location stertin at 5?h to RAMlocation startin at *8h(
Solution.
MO< R%,5?h F source pointer
MO< R),*8h F 'est pointer
MO< R4,)% F counter
:). MO< A,R%
MO< R),A
INC R%
INC R)
7N+ R4,:)
ump
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 37/47
On-Cip ROM Access
6his mo'e is 1i'ely use' in accessin 'ata elements ofloo2-up ta&le entries locate' in the proram co'eBspace ROM at the #%*)
MO<C A,AH7P6R
AD content of a''ress A H7P6R from ROM
?ote.ecause the 'ata elements are store' in the proramco'e B space ROM of the #%*), it uses the instructionMO<C instea' of MO<( 6he =C> means co'e(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 38/47
!ample.
Assumin that ROM space startin at 4*%h contains =Eello(>, 1rite a proram to transfer the &ytes into RAM locations startin at @%h(
Solution.
ORG %
MO< 7P6R,ML7A6A
MO< R%,@%E
:). C:R A
MO<C A,AH7P6R
+ :4
MO< R%,A
INC 7P6R INC R%
SMP :)
:4. SMP :4
F-------------------------------------
ORG 4*%E
ML7A6A.7 =Eello>,%
N7
?otice te ?U== caracter 4#4 as end o! string and o e use te L instruction todetect tat3
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 39/47
!ample.
9rite a proram to et the ! alue from P) an' sen' !4 to P4, continuously (
Solution.
ORG %
MO< 7P6R, 6A)
MO< A,%;;E
MO< P),A
:%).
MO< A,P)
MO<C A,AH7P6R MO< P4,A
SMP :%)
F----------------------------------------------------
ORG 5%%E
6A). 7 %,),@,8,)$,4*,5$,@8,$@,#)
N7
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 40/47
MU: V 7I<
MU= AB 5WA D AX
MO< A,4*E
MO< ,$*EMU: A F4*EX$*ED%88
FD%E, AD88E MU= AB 5A D A/, D A mo'
MO< A,4*
MO< ,)%
MU: A FAD4, D*
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 41/47
Stack in te )#*&
6he reister use' to accessthe stac2 is calle' SPstac2 pointerB reister(
6he stac2 pointer in the#%*) is only # &its 1i'e,1hich means that it canta2e alue %% to ;;E(
9hen #%*) po1ere' up,the SP reister containsalue %?(
?;E
5%E
4;E
4%E
);E
)?E
)%E
%;E
%?E
%#E
)#E
%%EReister an2 %
)Stac2 (Register Bank 1
Reister an2 4
Reister an2 5
it-A''ressa&le RAM
Scratch pa' RAM
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 42/47
!ample.
MO< R$,4*E
MO< R),)4E
MO< R@,%;5E
PUSE $
PUSE )
PUSE @
%E
%AE
%8E
%#E
Start SPD%?E
4*
%E
%AE
%8E
%#E
SPD%#E
;5
)4
4*
%E
%AE
%8E
%#E
SPD%#E
)4
4*
%E
%AE
%8E
%#E
SPD%8E
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 43/47
=OOP and LUMP Instructions
D9N?
;ri!e a program !o c*ear %CC, !@enaAA !o !@e acc+m+*a!or !en !ime
So*+!ion
MO %,60/
MO R&,610
%4%IN %DD %,60
D9N? R&,%4%IN4 /repea! +n!i* R&0 (10 !imes"
MO R5,%
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 44/47
Oter conditional #umps
+ ump if AD%
N+ ump if A/D%
7N+ 7ecrement an' ump if A/D%
CN A,&yte ump if A/D&yte
CN re,'ata ump if &yte/D'ata
C ump if CLD)
NC ump if CLD%
ump if &itD)
N ump if &itD%
C ump if &itD) an' clear &it
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 45/47
CL?$ 4 L?C
$%ercise.
9rite a proram that compare R%,R)(
If R%YR) then sen' ) to port 4,
else if R%ZR) then sen' %;;h to port 4,else sen' % to port 4(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 46/47
$A%% &nstructions
Another control transfer instruction is the CA::
instruction, 1hich is use' to call a su&routine(
=CA==Nlong call
In this 5-&yte instruction, the first &yte is the opco'e
an the secon' an' thir' &ytes are use' for the
a''ress of taret su&routine( 6herefore, :CA:: can
&e use' to call su&routines locate' any1here 1ithin
the $@ &yte a''ress space of the #%*)(
7/18/2019 Embedded Systems-8051 Microcontroller
http://slidepdf.com/reader/full/embedded-systems-8051-microcontroller-5696fa137ed90 47/47
ACA== Nasolute call
ACA:: is 4-&yte instruction in contrast to :CA::,1hich is )5 &ytes( Since ACA:: is a 4-&yte instruction,the taret a''ress of the su&routine must &e 1ithin 4
&ytes a''ress &ecause only )) &its of the 4 &ytes are use'for the a''ress( 6here is no 'ifference &et1een ACA::an' :CA:: in terms of sain the proram counter onthe stac2 or the function of the R6 instruction( 6he only'ifference is that the taret a''ress for :CA:: can &e
any1here 1ithin the $@ &yte a''ress space of the #%*)1hile the taret a''ress of ACA:: must &e 1ithin a 4-
&yte rane(