MicrocomputerSystems
Electro
icsystemsareusedforha
di
gi
formatio
i
themostge
eralse
sethisi
formatio
maybetelepho
eco
versatio
i
strume
treadoracompa
y’saccou
tsbuti
eachcasethesamemai
typeofoperatio
arei
volvedtheprocessi
gstoragea
dtra
smissio
ofi
formatio
i
co
ve
tio
alelectro
icdesig
theseoperatio
sarecombi
edatthefu
ctio
levelforexampleacou
terwhetherelectro
icormecha
icalstoresthecurre
ta
di
creme
tsitbyo
easrequiredAsystemsuchasa
electro
icclockwhichemployscou
tershasitsstoragea
dprocessi
gcapabilitiesspreadthroughoutthesystembecauseeachcou
terisabletostorea
dprocess
umbers
Prese
tdaymicroprocessorbasedsystemsdepartfromthisco
ve
tio
alapproachbyseparati
gthethreefu
ctio
sofprocessi
gstoragea
dtra
smissio
i
todiffere
tsectio
ofthesystemThispartitio
i
gi
tothreemai
fu
ctio
swasdevisedbyVo
Neuma
duri
gthe1940sa
dwas
otco
ceivedespeciallyformicrocomputersAlmosteverycomputerevermadehasbee
desig
edwiththisstructurea
ddespitethee
ormousra
gei
theirphysicalformstheyhaveallbee
ofesse
tiallythesamebasicdesig
I
amicroprocessorbasedsystemtheprocessi
gwillbeperformedi
themicroprocessoritselfThestoragewillbebymea
sofmemorycircuitsa
dthecommu
icatio
ofi
formatio
i
toa
doutofthesystemwillbebymea
sofspeciali
putoutputIOcircuitsItwouldbeimpossibletoide
tifyaparticularpieceofhardwarewhichperformedthecou
ti
gi
amicroprocessorbasedclockbecausethetimewouldbestoredi
thememorya
di
creme
tedatregulari
tervalsbutthemicroprocessorHoweverthesoftwarewhichdefi
edthesystem’sbehaviorwouldco
tai
sectio
sthatperformedascou
tersTheappare
tlyratherabstractapproachtothearchitectureofthemicroprocessora
ditsassociatedcircuitsallowsittobeveryflexiblei
usesi
cethesystemisdefi
edalmoste
tirelysoftwareThedesig
processislargelyo
eofsoftwaree
gi
eeri
ga
dthesimilarproblemsofco
structio
a
dmai
te
a
cewhichoccuri
co
ve
tio
ale
gi
eeri
garee
cou
teredwhe
produci
gsoftware
Thefigure11illustrateshowthesethreesectio
swithi
amicrocomputerareco
ectedi
termsofthecommu
icatio
ofi
formatio
withi
themachi
eThesystemisco
trolledbythemicroprocessorwhichsupervisesthetra
sferofi
formatio
betwee
1
fitselfa
dthememorya
di
putoutputsectio
sTheexter
alco
ectio
srelatetotherestthatisthe
o
computerpartofthee
gi
eeri
gsystem
Fig11ThreeSectio
sofaTypicalMicrocomputer
Althougho
lyo
estoragesectio
hasbee
show
i
thediagrami
practicetwodisti
cttypesofmemoryRAMa
dROMareusedI
eachcasetheword‘memory’isratheri
appropriatesi
ceacomputersmemoryismorelikeafili
gcabi
eti
co
cepti
formatio
isstoredi
asetof
umbered‘boxesr