UNI
T1BASI
CCOMPUTERORANI
ZATI
ONANDDESI
GN
Comput
eror
gani
zat
ioni
sconcer
nedwi
tht
hest
ruct
ureandbehav
iouroft
heasseen
byt
heuser
.Itdeal
swi
thcomponent
sandconnect
ionsi
nthesy
stem.Comput
er
Or
gani
zat
iont
ell
sushowexact
lyal
ltheuni
tsi
nthesy
stem ar
ear
rangedand
i
nter
connect
ed.
Comput
erAr
chi
tect
urei
sconcer
nedwi
tht
hewayhar
dwar
ecomponent
sar
e
connect
edt
oget
hert
ofor
m acomput
ersy
stem.I
tact
sasani
nter
facebet
ween
har
dwar
eandsof
twar
e.I
thel
pust
hef
unct
ional
i
tiesoft
hesy
stem.
Basi
coper
ati
onalConcept
s
Toper
for
m agi
vent
askanappr
opr
iat
epr
ogr
am consi
sti
ngofal
i
stofi
nst
ruct
ionsi
s
st
oredi
nthememor
y.I
ndi
vi
duali
nst
ruct
ionsar
ebr
oughtf
rom t
hememor
yint
othe
pr
ocessor
,whi
chexecut
est
hespeci
fi
edoper
ati
ons.Dat
atobest
oredar
eal
so
st
oredi
nthememor
y.
Exampl
es:
-AddLOCA,
R0
Thi
sinst
ruct
ionaddst
heoper
andatmemor
ylocat
ionLOCA,t
ooper
andi
nregi
ster
R0& pl
acest
hesum i
ntor
egi
ster
.Thi
sinst
ruct
ionr
equi
rest
heper
for
manceof
sev
eral
steps,
1.Fi
rstt
hei
nst
ruct
ioni
sfet
chedf
rom t
hememor
yint
othepr
ocessor
.
2.Theoper
andatLOCAi
sfet
chedandaddedt
othecont
ent
sofR0
3.Fi
nal
l
yther
esul
ti
ngsum i
sst
oredi
nther
egi
sterR0
PREPAREDBYSAHALAKIJAIBHARATHCOLLEGE,
1
PBVR
,Theabov
efi
gur
eshowshowt
ememor
yandpr
ocessorcanbeconnect
ed.Iaddi
ti
on
t
oALUandcont
roluni
tthepr
ocessorcont
ainst
heno.ofr
egi
ster
susedf
orsev
eral
pur
poses.
ThePC (
Progr
am Count
er)cont
ainst
hememor
yaddr
essoft
hei
nst
ruct
iont
o
beexecut
ed.Dur
ingexecut
ion,t
hecont
ent
soft
hePCar
eupdat
edt
opoi
ntt
othe
nexti
nst
ruct
ion.Ev
eryt
ime t
hatan i
nst
ruct
ion i
sto be execut
ed,
the pr
ogr
am
count
err
eleasesi
tscont
ent
stot
hei
nter
nal
busandsendsi
ttot
hememor
yaddr
ess
r
egi
ster
.
Ther
egi
ster
sMARandMDRf
aci
l
itat
escommuni
cat
ionwi
tht
hememor
y.TheMAR
(
Memor
yAddr
essRegi
ster
)hol
dst
headdr
essoft
hel
ocat
iont
oorf
rom whi
chdat
a
ar
etobet
ransf
err
ed.Ascanbeseenf
rom t
hef
igur
eabov
e,t
heconnect
ionoft
he
MARt
othemai
nmemor
yisone-
wayoruni
dir
ect
ional
.
TheMDR(
Memor
yDat
aRegi
ster
)cont
ainst
hedat
atobewr
it
tenorr
eadoutoft
he
addr
essedl
ocat
ion.Dur
ingt
hef
etchoper
ati
on,t
heMDRcont
ainst
hei
nst
ruct
iont
o
beexecut
edordat
aneededdur
ingexecut
ion.I
nwr
it
eoper
ati
on,
MDRt
hedat
atobe
wr
it
teni
ntot
hemai
nmemor
y.
TheI
R(I
nst
ruct
ionRegi
ster
)cont
ainst
hei
nst
ruct
iont
hati
sbei
ngexecut
ed.Bef
ore
t
heI
Rexecut
est
hei
nst
ruct
ioni
tneedst
obedecodedf
ir
st.Assoonast
hecont
ent
oft
he MDR i
str
ansf
err
ed t
othe I
R,t
he decodi
ng pr
ocess commences.Af
ter
decodi
ng,
execut
ionoft
hei
nst
ruct
ionwi
l
ltakepl
ace.
Then-gener
alpur
poser
egi
ster
sR0t
oRn-1i
susedf
orst
ori
ngt
empor
aryv
alues
PREPAREDBYSAHALAKIJAIBHARATHCOLLEGE,
2
PBVR
, Letusconsi
dersomeoper
ati
ngst
eps.
1.Pr
ogr
amsr
esi
dei
nthememor
y&usual
l
ygett
heset
hrought
heI
/Puni
t.
2.Execut
ionoft
hepr
ogr
am st
art
swhent
hePCi
ssett
opoi
ntatt
hef
ir
sti
nst
ruct
ion
oft
hepr
ogr
am.3.Cont
ent
sofPCar
etr
ansf
err
edt
oMARandaReadCont
rolSi
gnal
i
ssentt
othememor
y.
4.Af
tert
het
imer
equi
redt
oaccesst
hememor
yel
apses,t
headdr
esswor
disr
ead
outoft
hememor
yandl
oadedi
ntot
heMDR.
5.Nowcont
ent
sofMDRar
etr
ansf
err
edt
otheI
R&nowt
hei
nst
ruct
ioni
sreadyt
obe
decodedandexecut
ed.
6.I
fthei
nst
ruct
ioni
nvol
vesanoper
ati
onbyt
heALU,i
tisnecessar
ytoobt
aint
he
r
equi
redoper
ands.
7.Anoper
andi
nthememor
yisf
etchedbysendi
ngi
tsaddr
esst
oMAR&I
nit
iat
inga
r
eadcy
cle.
8.Whent
heoper
andhasbeenr
eadf
rom t
hememor
ytot
heMDR,i
tist
ransf
err
ed
f
rom MDRt
otheALU.
9.Af
teroneort
wosuchr
epeat
edcy
cles,
theALUcanper
for
mthedesi
redoper
ati
on.
10.I
fther
esul
toft
hisoper
ati
oni
stobest
oredi
nthememor
y,t
her
esul
tissentt
o
MDR.
11.Addr
essofl
ocat
ionwher
ether
esul
tisst
oredi
ssentt
oMAR&awr
it
ecy
clei
s
i
nit
iat
ed.
12.Thecont
ent
sofPCar
eincr
ement
edsot
hatPCpoi
ntst
othenexti
nst
ruct
iont
hat
i
stobeex
ecut
ed.
I
nst
ruct
ionCodes
Ani
nst
ruct
ioncodei
sagr
oupofbi
tst
hati
nst
ructt
hecomput
ert
oper
for
ma
speci
fi
coper
ati
on.Acomput
eri
nst
ruct
ioni
sabi
nar
ycodet
hatdet
ermi
nest
hemi
cro
-
oper
ati
onsi
nasequencef
oracomput
er.Theyar
esav
edi
nthememor
yal
ongwi
th
t
hei
nfor
mat
ion.Eachcomput
erhasi
tsspeci
fi
cgr
oupofi
nst
ruct
ions.I
tisusual
l
y
di
vi
dedi
ntot
wopar
ts:
I
tconsi
stsof12bi
tsofmemor
ythatar
erequi
redt
odef
inet
headdr
essast
he
PREPAREDBYSAHALAKIJAIBHARATHCOLLEGE,
3
PBVR
T1BASI
CCOMPUTERORANI
ZATI
ONANDDESI
GN
Comput
eror
gani
zat
ioni
sconcer
nedwi
tht
hest
ruct
ureandbehav
iouroft
heasseen
byt
heuser
.Itdeal
swi
thcomponent
sandconnect
ionsi
nthesy
stem.Comput
er
Or
gani
zat
iont
ell
sushowexact
lyal
ltheuni
tsi
nthesy
stem ar
ear
rangedand
i
nter
connect
ed.
Comput
erAr
chi
tect
urei
sconcer
nedwi
tht
hewayhar
dwar
ecomponent
sar
e
connect
edt
oget
hert
ofor
m acomput
ersy
stem.I
tact
sasani
nter
facebet
ween
har
dwar
eandsof
twar
e.I
thel
pust
hef
unct
ional
i
tiesoft
hesy
stem.
Basi
coper
ati
onalConcept
s
Toper
for
m agi
vent
askanappr
opr
iat
epr
ogr
am consi
sti
ngofal
i
stofi
nst
ruct
ionsi
s
st
oredi
nthememor
y.I
ndi
vi
duali
nst
ruct
ionsar
ebr
oughtf
rom t
hememor
yint
othe
pr
ocessor
,whi
chexecut
est
hespeci
fi
edoper
ati
ons.Dat
atobest
oredar
eal
so
st
oredi
nthememor
y.
Exampl
es:
-AddLOCA,
R0
Thi
sinst
ruct
ionaddst
heoper
andatmemor
ylocat
ionLOCA,t
ooper
andi
nregi
ster
R0& pl
acest
hesum i
ntor
egi
ster
.Thi
sinst
ruct
ionr
equi
rest
heper
for
manceof
sev
eral
steps,
1.Fi
rstt
hei
nst
ruct
ioni
sfet
chedf
rom t
hememor
yint
othepr
ocessor
.
2.Theoper
andatLOCAi
sfet
chedandaddedt
othecont
ent
sofR0
3.Fi
nal
l
yther
esul
ti
ngsum i
sst
oredi
nther
egi
sterR0
PREPAREDBYSAHALAKIJAIBHARATHCOLLEGE,
1
PBVR
,Theabov
efi
gur
eshowshowt
ememor
yandpr
ocessorcanbeconnect
ed.Iaddi
ti
on
t
oALUandcont
roluni
tthepr
ocessorcont
ainst
heno.ofr
egi
ster
susedf
orsev
eral
pur
poses.
ThePC (
Progr
am Count
er)cont
ainst
hememor
yaddr
essoft
hei
nst
ruct
iont
o
beexecut
ed.Dur
ingexecut
ion,t
hecont
ent
soft
hePCar
eupdat
edt
opoi
ntt
othe
nexti
nst
ruct
ion.Ev
eryt
ime t
hatan i
nst
ruct
ion i
sto be execut
ed,
the pr
ogr
am
count
err
eleasesi
tscont
ent
stot
hei
nter
nal
busandsendsi
ttot
hememor
yaddr
ess
r
egi
ster
.
Ther
egi
ster
sMARandMDRf
aci
l
itat
escommuni
cat
ionwi
tht
hememor
y.TheMAR
(
Memor
yAddr
essRegi
ster
)hol
dst
headdr
essoft
hel
ocat
iont
oorf
rom whi
chdat
a
ar
etobet
ransf
err
ed.Ascanbeseenf
rom t
hef
igur
eabov
e,t
heconnect
ionoft
he
MARt
othemai
nmemor
yisone-
wayoruni
dir
ect
ional
.
TheMDR(
Memor
yDat
aRegi
ster
)cont
ainst
hedat
atobewr
it
tenorr
eadoutoft
he
addr
essedl
ocat
ion.Dur
ingt
hef
etchoper
ati
on,t
heMDRcont
ainst
hei
nst
ruct
iont
o
beexecut
edordat
aneededdur
ingexecut
ion.I
nwr
it
eoper
ati
on,
MDRt
hedat
atobe
wr
it
teni
ntot
hemai
nmemor
y.
TheI
R(I
nst
ruct
ionRegi
ster
)cont
ainst
hei
nst
ruct
iont
hati
sbei
ngexecut
ed.Bef
ore
t
heI
Rexecut
est
hei
nst
ruct
ioni
tneedst
obedecodedf
ir
st.Assoonast
hecont
ent
oft
he MDR i
str
ansf
err
ed t
othe I
R,t
he decodi
ng pr
ocess commences.Af
ter
decodi
ng,
execut
ionoft
hei
nst
ruct
ionwi
l
ltakepl
ace.
Then-gener
alpur
poser
egi
ster
sR0t
oRn-1i
susedf
orst
ori
ngt
empor
aryv
alues
PREPAREDBYSAHALAKIJAIBHARATHCOLLEGE,
2
PBVR
, Letusconsi
dersomeoper
ati
ngst
eps.
1.Pr
ogr
amsr
esi
dei
nthememor
y&usual
l
ygett
heset
hrought
heI
/Puni
t.
2.Execut
ionoft
hepr
ogr
am st
art
swhent
hePCi
ssett
opoi
ntatt
hef
ir
sti
nst
ruct
ion
oft
hepr
ogr
am.3.Cont
ent
sofPCar
etr
ansf
err
edt
oMARandaReadCont
rolSi
gnal
i
ssentt
othememor
y.
4.Af
tert
het
imer
equi
redt
oaccesst
hememor
yel
apses,t
headdr
esswor
disr
ead
outoft
hememor
yandl
oadedi
ntot
heMDR.
5.Nowcont
ent
sofMDRar
etr
ansf
err
edt
otheI
R&nowt
hei
nst
ruct
ioni
sreadyt
obe
decodedandexecut
ed.
6.I
fthei
nst
ruct
ioni
nvol
vesanoper
ati
onbyt
heALU,i
tisnecessar
ytoobt
aint
he
r
equi
redoper
ands.
7.Anoper
andi
nthememor
yisf
etchedbysendi
ngi
tsaddr
esst
oMAR&I
nit
iat
inga
r
eadcy
cle.
8.Whent
heoper
andhasbeenr
eadf
rom t
hememor
ytot
heMDR,i
tist
ransf
err
ed
f
rom MDRt
otheALU.
9.Af
teroneort
wosuchr
epeat
edcy
cles,
theALUcanper
for
mthedesi
redoper
ati
on.
10.I
fther
esul
toft
hisoper
ati
oni
stobest
oredi
nthememor
y,t
her
esul
tissentt
o
MDR.
11.Addr
essofl
ocat
ionwher
ether
esul
tisst
oredi
ssentt
oMAR&awr
it
ecy
clei
s
i
nit
iat
ed.
12.Thecont
ent
sofPCar
eincr
ement
edsot
hatPCpoi
ntst
othenexti
nst
ruct
iont
hat
i
stobeex
ecut
ed.
I
nst
ruct
ionCodes
Ani
nst
ruct
ioncodei
sagr
oupofbi
tst
hati
nst
ructt
hecomput
ert
oper
for
ma
speci
fi
coper
ati
on.Acomput
eri
nst
ruct
ioni
sabi
nar
ycodet
hatdet
ermi
nest
hemi
cro
-
oper
ati
onsi
nasequencef
oracomput
er.Theyar
esav
edi
nthememor
yal
ongwi
th
t
hei
nfor
mat
ion.Eachcomput
erhasi
tsspeci
fi
cgr
oupofi
nst
ruct
ions.I
tisusual
l
y
di
vi
dedi
ntot
wopar
ts:
I
tconsi
stsof12bi
tsofmemor
ythatar
erequi
redt
odef
inet
headdr
essast
he
PREPAREDBYSAHALAKIJAIBHARATHCOLLEGE,
3
PBVR
