Điện Tử - Cơ Sở Thiết Kế Mạch - Design Trên Máy Tính (Phân 2) part 15 ppt

c\sit'(
X(:.):::::
'I')
then
Y(3)<,,'\':
SLI1c
::::::
S:L
l'I:-,c
Y(2)<=='\':
S\
k
:.:::::S2;
end if;
Nluf
v,:IY.
trong
ch\.f(mg
ni\\"
Chl\llg
la
dJ
dna
I"a
l'hlfng
plutong
ph;ip
tlhl
hlnh
ht'Ja
diu

trllC \':1 chll'c
n:mg
clla
tlhl-l'ng
ll1adl
h)glC
cn
belli -
dL'
mach
11-;
In,ill \'il ctic
mach
111:ill
hI"
'ill' dl.lllg
nhCl'IlS
C,ill
tnil- ,:0' h,in
tnl1l~
ng()l\
n~211
VI
IDL.
2~1
Wli
t(lp
1.'110
chliong 7
I.

Hay
m{)
l<l
hanh
vi
ella b9
mil
hoa
16
- 4 bang ng6n
ngH
VHDL.
2.
M()
td.
cau truc va chuc nang clla h¢ dcm
thu~n
- nghich. dong
hI).
mil
:"JilCD
bAng
ngon
ngfr
VHDL.
.).
M6
til
e{iu
truc

Vii
chu'e nang
ella
b9 dcm kh6ng dong
hQ.
modul
10
hang
ng(m
ngO'
VIIDL
4.
.\tl{)
ta
cAu
true va ehuc nang eua b¢
dem
d~t
l';li
tn.mg
thai hang
ng60
ngiI
VHDL
5. M6
tii
eflu
truc
va
ehtrc

Ili.lng
eua
hQ
delll nhj phan khong ddng
hQ
bil.ng
ng{)!l
ngO'
VHDL
6. M6
t{l
cau true va ehue nang eua
ll1<;teh
cQng.
In1
ma
bu
2
biUlg
ng6n
ngfr
VllDL
7.
M(l
t,1
eAu
true
va
ehCfe
lliing eua mach cQng, trif

mil
bil I h:wg
ng{m
llgiJ
VHIlL
8.
,\1{)
Iii
dIU
true
\'01
ehere
n~lng
eLla
1l1i lCh
e(lng, trir
mIT
BCD
bang ng6n
ngu'
VHDL
lJ.
.~1l'1
ti.l
cAli
true
\';l
ehCrc
Jl(mg
cua

mi;leh
el)og 2 s6 nhj
ph<1n
8
hit
hilllg
ngon
ngiJ
VIIDL
10.
M{)
tii
eau true va ehu'c
ni.lng
clla
m<~eh
cc;>ng
nhanh 2
so
nhj ph,l/l 8 hit
bAng
ngon
ngiJ
V
HDL
11. M6
ta
du
truc va
chLrC

nang eua cac
mi.lch
th
hqp,
Ihlfc
hi¢n
de
bicu
there
to;ln hoc, logic bang ngon
ngiJ
VHDL.
242

~~
z
CHUONG VIII.
CAC
PHUONG
PHAP
KIEM
TRA
LOI
M~CH
LOGIC
Trong
chuang
nay
chung
t6i trinll bay

I11QI
,6
phuong
phap
phat hl¢n cac
lui
cua
cac
m~ch
lOgic.
Vi~c
phal
hi~n
loi
du\'·
thl,rC
hi¢n
dl,l'a
V~IO
cac
hQ
gl{\
Iri Ihu
nghi¢m
phat hi¢n l6i. d d,ly vi¢c phat
bl~n
C[IC
lui Ihiet
ke
co

the
th~fC
hi~n
tren
cac
m6
hinh
bi~u
dien bimg cac
ng6n
ngu·
m6
hinh
!loa phan dmg.
Dl(~U
nay
dong
tn(lt
viii
tro
quan
h·9ng
trnng
qua
trlnh
s,ln xu[it va l;un
gl<.llll
dLfC:K
chi phi
ki~111

Ira. Trong chuc1ng
nilY
cilling loi
trIp
Irung
Chll
yeu vilo
de
phuo·ng
phap
pil{).1
hi~n
llli
\,:1
1,.10
b()
gI<'t
Iri Ihu nghi¢m
cho
cac
1l1i).ch
tel
hqp. Doi voi nhiJng
111'.ICh
tw.ln
It.l",
do
eu
che '
ho

~t
d(mg
pink
t".IP
cua
chullg
nen \'i¢c ph,it hi¢n loi
c!trq·c
11H.((;
hi¢n
dua
trell nhling
phuong
ph,ip
pht."l"c
1~.lr
han
doi v6i
de
m<'.lch
t6
heyp
\";1
"Un1
ra ngn:li khu6n kho cuon sach nay.
§8.1. C,ic
1116
hinh
liii logic

mli
to{\ll
ph,-!I
hi9n
1l1J
Irong eac
l1li.\cb
lOgic
Iii
bai
toan
xac d)nh so
do
logic
duqc
thkt
ke
thl,l'c
hi~n
dU<;1C
cac
chuc
nang
da de
ra.
D~
gii.li
qUYCI
bai
tOtin

nay
ehung
ta
can
phili
X<l.y
dl}"ng
ma
hlnh
cua
m~Kh
logic
nhu
mQI
d6i
tuqng
kie'm Ira, sau do xfty
dl,l'ng
phuong phap phat hi¢n loi
V~I
cuoi
cung
la
xuy dl!ng
m6
hll1h loi
(eo
nghitl la
chi
ra

dU<jc
cac
d~c
trung
cua
loi
).
Ta
da
thfty rang
thea
'luan
diem
phan
10i li
1l1i lch
dL!<l
vao
hm~t
d(mg clla
chung,
eac
nwch
l6gic
dU(jc
chia
thanh thanh
d.c
m,~eh
to

hqp
va
cae
m,~ch
tU

11l
11,1'.
N1Hf
ta
uJ.
Ihi.ly
trong cae ml!c tru6c.
tren
quan
dic'm
ve
hOi.~1
d9ng,
cae
m'.lch
If)
h0P duqc the' hi¢n
(}
eh6
t1"<;lng.
thai clla
dc
duu ra d
1119i

tho-i
diem
Ihai
gian
dU(jc
xac
djnh
hoan
toan
bing
de
tn.lI1g
thai
cua
cac
u[iu
\'~\o
tai
cung
m()1
th0i di6m.
Nc~u
xe\
t)"ei1
quan
diem
diu
Irue, trong cac
mi lch
to

h(."ip
hoan
toan
khong
chua
cac
vong tin
hi~u
phi.ln
hoi. Neu xet Iren
khia
c<.mh
pIliit hi¢n l6i,
ca.c
I11~ch
t6
hQ"p
lit
nhiJng doi tuqng nghien
euu
kha
dem
gi~\.n.
N6u xci
tre:n
quan
diem hanh vi, lrong
hm~t
c1Qng
cua

cac
lTH.lch
turin
It.!
xual
hi~i1
cac
tr<;lng
Ihai ben trong;
con
xel tren
quan
diem
c[iu
true,
ellC
nweh
nay
con
chua
cae
\long
phan
h6i.
Dieu
do lam
cho
\'i¢c phat
hi~n
loi

trong
de
m,!-ch
luan
It.!
la
mot
bili
Io<in
v6
eung
phuc
ti).p.
Ck
h<)
I1h6·
\'a
d.c
b<)
vi
xu
ly
ve
ly
thuyc~1
cling Ihu¢e
nhc5m
cae
1l1<.lch
lufin tl!,

nhung
VI
so
lU<jng
de
tn~ng
Ihai trong
CUi.1
chung
n1"t
16n,
do
d6, n6i
243
chung.
dc
Ill'.ICh
Illty
kh(lI1g
Ih~
x":·p
\"ao
nh6m c,ie
111<.lch
lu:in
Iy
Vrfi
nhCl"tlg
d:ll"
diem kh;tc

hi~t
nlHr
\'(1)'
\'l'i
crlu
truc
\,;1
h~U1h
\'i.
\'i~c
pil,l\
hil'l1
Ibi
ch'ij
\'(1'1
ciie
h(l
nh6'
\'~l
hr)
vi
XLt"
I~'
c,ln phili tinh den
dc
d,k
lnrng
n"la
chung
\'(~

]ll,~ll
cau
Ink
\'~l
h~l1lh
\'i,
I\hu
\';)y
chLing
ta !hfly dmg
kh(lI1g
Ihc
cr'l
plut"rmg
ph;ip chung
ell:
ph;i\
hi~'1l
!<;i
Imng
dc
m',tch 16gic.
De
co Ih6
Ihy-c
hien
dUCK
cr)!l,!!
\'i~'c
d6

lit
dn
ph,l]
lUi!
chon
GtC
phl!o'ng ph,ip ph,i!
l1ien
I(li
linb
tefi
de
d~\c
Int"ng
ella
m,.tch.
M()I
hil.l
loan quan Irqng. xual Illen klli
X\ly
clL.rng
de
pl1urmg.
ph(lp
ph:11
hi~'1]
[('\i
!i"1
il,ra
chon

di~1l1
(1.)1
eho
de
lin hi¢u Ihll nghicill
\'~I
d,c
dicm quan
,,;il
Ibfch hqp.
Tnt'()'c
d{IY.
khi
kicill
tra e;lc
111i,lch
lllgic
pln"t"c
lap. ehelllg la
lju;m
",at
de
tIll hicll Ih(mg qua
C<lC
dicm nul bcn Irnng ell;l
Ill,lCh.
KIll
merc
d()
11ch

ho'p ella
111;.1cl1
1,-mg
knl{Si
Jllu'e
nlll( lrung
de
Ill;.lch
LSI. \'i¢c
(t(ll
1111":'1
hi
\"'l(:m
tra
de
llUt
ben lrong
1ll<,le[J
Ir(')'
Ill'n
phll"C
I'.lp
llO'll
nhicll,
Dil:U
d6
L:lln
"htl \'ll'l'
d'.ll
\';l

quan
",;il
de
tin Ju¢u
Ihtl"
nghl¢m
t:.,11
nlllIng
dicm hill
k~'
Cll,1
m;'\L"h
In')"
nen
\,(l
dlllg kh()
kh[\I1
\'tl
Ilhi~u
kllJ
kh(mg the
Ihll'l'
hl¢n
n(~!.
:.JIm
\'~Iy.
pIllIon!,'.
ph:lp
ph:11
hi¢n

Itli
d(ii
\'6i
nhCmg
1ll<,ICh
LSI
chi
dut,1'e
"it'
dUllg
c;ic eh:m
\';10
\';1
eh:1ll
ra eua mach.
Khi
Lll)
tich hop ella
ll1ill"h
limg
Ill"
LSI
den VLSI.
Iy
l~
gILt',\
-;6
Iw.mg
eh:ln
hCII

IIgo;li
eLla
1ll;.lch
\';1
",6
IUr1ng
plwll
Ill'
Irell tlllh Ihe
h;11I
(l:tn
~':J;'lnl.
<-lICU
d6
Ellll
e!.to
h~li
10:ln ph;il hiell
101
d(ii
\'()"i
nhLrng
111.,lel1
VLSI
!rl)'
n":n
phCl"e
lilp
ho'll
lllticll

:-'0
\'r1'i
\"~'e
ph;11
hicn
It)]
eho
CitC
Ill,teh LSI. Vice t;lnt!
lllere
d()
11cl1
h(fp
ell,\
m;,lcll
elw
phl~]1
:,\,'\y
dl,rng
nhCrIlf!,
mach
co
chel"e
nang
phC!'e
1',lp.
\'1
ell.1
niH!'
Ciic

jl()
\'1
Xl]'
I~'.
dil:lI11;IY
1~1l11
t,-l1lg
cit)
pllll'c
t;.I]1
clla
h~\J
to,in phill hien
k)i.
Vil'l'
tlill
r,\
de
phuong ph'lp gi:li
lIlIy":·t
bi:li
loan ph,il
hi":n
loi
I~I
cilia
f.cho;i
cllO
\ ll'e
Ih~rc hi~ll

d,c
mach
VLSI
\'~l
d611g
\'ai
trl)
H)
cllllg quail
tf(.lllg
l!'Ung
thtli
d:'li
ella
de
m.,leh
VLSI
VI
1ll:.H,:h
dn
c1l1\iC
klC:1ll
tra
1;\
m',leh h'lgie, nen la gl,l thie'l dlllg khi trong
m;.teh
c6
161.
maeh vttn
Ihl,J'c

11l¢n
de
ehuc
n(mg
nhu
m(':l!
mach
j(lgJC,
Cic
lr'lJ
thoa lllail dicll ki¢n
n~ly
dCli
dune gqi
Ii:I
cal'
It'll
16g1C.
eic
J()]
I()gie bic'lI
lu~n
,inh hu'bng
eua
c,ie
16i
\'(11
I)'
len h;mh \'i ella
de

h~
Ihong
c1lfriC
m(l
hlnh h6a.
VI
trong qua trlnh
llH'l
hinh h6a cae ph:in
Ill'
mach chung
1<1
I,ieh hi¢t Gic
chue
Il;tng logic
vi\
hi\nh
vi
Ihi)'i
gian. eho nell
\<1
si:
ph{m
ellia
dc
I()i
Ihi:lIlh
de
nh61ll loi sall:
NhOIl1

cac
I(ii
.lnh
hUtI'llg
tti"i
c1nl'c
n,ln~
lliglc
O'liI
ph ill
Ill':
i'<hl)l1l
dc
\(')i
anh
hUllng
t6i d()
tre
tin
hi~u
eli
qU'I
ph:in
Ill'.
Cac
j{l[
10<,11
n;IY
sc
;'mh

hU<1'ng
16i
Ih(Ji
gJan linh to.tn clla
ph;Ul
Ilf
\';\ do
LIt)
cling tlnh hUlmg
k~i
W;:11l
m'.H.:h.
Kill
\<1
m()
1,1
dc
16i
\',~I
I~'
nlHf
elic
i6i
logic. la sc dunc
llil(il1g
Iu-i
diem
niH!"
sall:
Thlr

nll[l\
lao
hili
10,\.n
ph[11J
lich Ibi IHlth;:ll1h
hill
10(111
l(lglC
110'11
Iii
hi\i
tmlll
\,[11
I)'. Dit'll n:l)' lilln
dl)
phCre
tilP
ella
h~1l
Imin gl;im
\'1
nhlcLl
j(li
\',-Jt
I}
kh,te nhau
co
Ihe:
du'c:)"c

mo hlnh h6a hilng cling m(ll I\\i
IllgJC
ThCf
hal
1;:1
m<)1
,,6
I(li
Illgic
I["('f
nell
khllllg
phu
thUllC
\';10
Clll1g
llgh~
Iheo
nghla: Ct:lllg
Im)1
lllO hlnh
k,i
dl
Ihd su'
dung
trong
nhicll c{mg
ngh¢ khac nhau. Do d6
dc
phuong philp kicm Ira \'i:1

ehu;in
dual]
(hfl.K x{\y
d~fng
eho
molmo
I1lnh
loi
sc
khlmg
thay
dOl
nga:,-"'
ce'l
khi
(6
s~r
Ihay
(bl
\'e
eong
ngh¢.
Thlr ha
Iii
cae
b()
gi<.t
tr\
thLi'
nghicm dc'

ph<.il
hien ei\c
16i
16glC
c6 the
(hrl)'C
sif (h.lIlg d6i \'6i
d.e
10)
V{lt
ly
co
h:mh
\'1
tmill'. maeh Child
hO;1ll
lnilll
elLfO'c
hieu
ro
hO(lC
qu.\,
piJCl'e
1' lp
de
e6 the ph,ln lich.
Mc)t
1110
hlnh
!oi

eo
th~
Iii
11111
hlnh
fin
hoi.le
ml)
hll1l1
\U'(lng
I11mh.
;\1()
hlnh
lbi
tu'('H1~
minh
dc
(tjnh m6t kh()ng gian
It)i,
[r(Jng
d{l
ILlng
lc'li
dw:c
xcie
djnh dQc
1(lp,
\'i:\
do
(k,

loi
SC
phfll1
lich
co
the dU\ie
X(IC
djnh
m()1
deh
tLfo'ng
minh. Tren tiurc
Ie'
ml1
hlnh
!t)1
1Lro-ng
111illh
Cll
the
clLnJC
1110'
rlm):!
Illy
nllJ(:~n
ph,'li
(him h.lo
du'Oc
kfeh tlur6e ella kh()\lg
gian

101
killing
qUit
16'11.
1\16
hlnh
h\i
an
xfly (hrng khong gian loi btlllg
(('tcll
;(i\c
dinh
c{l
IVa
Chl)ll
e:tc loi
IU)'
theo
mClc
d(l
quan
[,till
Cilll
ycu
lhl)ng
qu,1
c(tc
tinh
chill clla ehling.
~(yu

cho
tnr{J"c
16i
IO~iC
vit
m(J
hlnh mach,
vc
n~uycn
l~'.
Chlltlg
la
~;:
x(le
djnh
dUl.iC
chCfC
nang
logic ella
ll1Hch
\'6i sv ton
t,li
cLla
Illi
nily lrong lllach.
l\lnr
\'(Iy,
qu,\.
lrlnh
ml)

h!nh
ho.1
l(li
lien quan
1l1,~1
11110.':'1
16i
loa I
Ill\'l
hinh
1l1',lCh
dang
slr
(h.mg.
Tuy theo
Il1l1
hinh
1l1;.leh
CitC
Itli
logic
C(')
the
dUl.~C
chia
.so
hl) Ihimh
de
loai salt:
C

ic
I(,i
ehrq'c
xac djnh gan lien
vl-)i
1l1()
hlnh
cril'
trllC ehrnc
gO!
Iii
Ule
Itli
e[tll
Irue
.•
;\nh
lllf6ng ella e,ic
16i
du
truc
let
1~\Ill
1I1~ly
(k)!
"lX
lien
kc't
"ilia

de
111;lnh
philil
mi.lch.
Cll
III
I duq'c
X,-IC
djllh
gtm
lien \'6i
1Il()
hlllh Clllk nfmg
eLla
1ll'.lcil
duoc
g(.)j
1:\
c(le It,i
chCrc
nfl11g.
Vi
elL.1.
,'mil
hu('mg ella
c(lC
!6i
clnk
2 l5
nimg

c6
the lam Ihay
deli
hang ehun
Iy
cua
thanh
philn
mi Ich
hO~IC
dan
t6'i
vi¢c
cam
cae
phep toan tren thanh ghi.
;-"1i~e
du cae loi
ngau
[lhien
h04C
loi
cJc)1
hi~n
co
mi~1
tllLJOng
xuyen
trong
mi H.:h,

\'i¢c
ma
hlah
hoa
nhfrng
li'li
do yeu
cau
cae dfr li¢u Ihong ke
\'~
s,!
xUil1
hicn
thea
Xi.lc
suat
cua
chung.
l\'hO"ng
dO"
li~u
nay can thlet de
Xi.lc
d!nh
s6
l[in
kiem
If a
mQt
deh

dqc
I~p
can
I~p
L.li
de"
cl,fc
d~\i
hoa
)i.ae
suilt phat
hi~n
nhO"ng
loi chi
xU<lt
hi¢n
viii
Ian trang
111".lch
v6i nhOng gia tri tht'r
nghi¢Jl1.
Thong
thuang
chung
ta kh6ng
c6
dfiy dll
nhung
thong
lin

vc
m~lI
thong ke.
do
cJ6
doi vai
nhO"ng
cJ(>1
bi6n hm)e
xuAt
hien
kh6ng
thu'ang xuycn.
lot
nhUt
Iii.
sti
<.iI;lllg
dc
phuang
phiip kiem ngl1J¢m
In;J."c
tuyen. Tmng. glao
trlnh nay
chung
ta chi nghien
cCru
16i
cac
h,i

thuimg
tl""l!c.
Neu
khang
duqc
nhk
16i
m(lt
cach
lLro'ng
minh,
chung
ta giii thiet dIng
t".li
mot
thai
ditm
thai gian, trong
m<'.lch
chi
c6
nhieu nhal
lu
nH)[
16i.
VI¢C
Iillll
dan
gian hoa
bili

to{lI1
pld!
hi¢n
16i
hang
gi::i
thiet
ve
1M
dun
Ie
dw1C
bi¢n minh
bai
chi(/II flwc
1.:/£"111
'Fa
r/II(/f/lg xI/yell. Chien IWlc
kitm
tra thuimg
xuyen
co
the"
duqe
phat hicu
nhU
sau:
chung
ta
can

kie:m tra h¢ Ih6ng m()t
each
tilliang
xuycn
sao
cho
xac suat xual hi¢n nhieu
han
mOl
loi
giCi"a
hai
Hin
kiclll tra lien tiep
lu
du nh6.
Do
do
neu khoi.lng thai gian
hO'!t
d¢ng
eua
m,.teh
cang
l6"n,
ta sc
co
nhieu khu nang
g~p
tru'ong

hqp
xuat hi¢n nhicu
16i
trong
nwch
mot
lue. Tren
thI!C
te
van
XUi.lt
hi en nhung IrLiang
hqp
ma chien luvc
ki~m
Ira tlmong
xuycn
khong
du
de
ngan
ch~1l
twong
hqp
trong m'.lch
Cll
thc
xuat
hi~n
nhieu

loi
m9t
hic.
NhO"ng
truong
hqp
e6
Ihe:
xuAt
hi¢n
nhieu
hern
HH)t
loi trong
mi lch
co
the
iiI:
Cac lai
\,(It
Iy
c6
the:
XU;!I
hi¢n
tmng
llwch
giil"a
hat
][in

kicm
Ira
Et.
Trong
nhfrng loi
v~tt
15'
do,
m(H
saloi
c6
tht
tuong (rng vai nhicu loi
logic.
Dicu
nay
c6
khu mlng
x<1.y
ra
16n
cloi
veii
nhOng
mi.lCh
co
d(>
tfch hqp
cao
trong

do
nhieu
loi \';)t
Iy
c6
Ih~
.lnh
huang
toi he
1l1~lt
tinh the tren do
e6
1119t
so
cac thanh ph[lll nwch.
Trong
nhO"ng
mqeh
mai
duqc san mii't, thl trong nhung Ian thlr diiu
nhCi"ng
loi kcp
e6
the xuat
hi~n.
Trong
tlUang
hqp
nhO"ng
phep

IlIti
khong
phat hi¢n duqc het nhOng
Uii
don Ie, tai bat
ky
hie nuo,
n1,!-eh
co
tM
chua
nhung loi
chua
duvc
plli.it
hi¢1l
(loi
,1n).
Nhfrng loi an nay, khi
xu,Yt
hi¢n nhfrllg loi
dO'n
Ie
thu
hai giua hai
IiIn
ki~m
tra, sc
I<;tO
fa

nhieu
I<.\i
kcp trong
1l1i.lch.
Tuy
\,~ly.
mi~e
du
lrong
1l1i.lch
e6
the xuat hi¢n nhicu
16i
dtlng thai,
nilU"ng
nhCi"ng
h9 gia trj thti nghi¢m
dung
de
phat
hi~n
cae loi
don
JC
e6
the
dung
de'
246
tim

nhung
16i
kep.
Sa
dl
co
the'
thl!C
hien duqc
nhu
v~y
Iii.
do Irong ph:ill [6n
d.c
truang
hqp. nllll)lg hJi
Up
("()
the>"
(iI(I("
plllft
hifll
klli kit"rn
IIg!ti~;m
!Hillg
nhifng b(j
gici
tri tJllt
nghi¢m
thie

l
!
ki"
clIO
vi?'("
phdt hi¢1I lIill7ng
IrSr
dan
{c'IWp
tlulnh
//ii
kc'p
I/()i
frhl.
~6i
chung.
cdc nUl Mllh
irS!
("(Ill
{nie
giu
thie!
rc1n;.;:
("{II-
rliiillir
pli,/'n
khollg
("()
J/ii
WI

eM
co
nl1l711g
dlf(llIg
kh
n6i
ellling
/d
("()
the"
("(J
/r~I.
Cic
I()]
c1~c
trtfng do
dc
duang
ket noi
t<).o
nen
thuang
lu:
ngan
m<;lch
ho{!C
he)'
mach.
Cae
lOi

ngcln
mfJeh
(
ch~p
m<).ch
) la nhfrng
16i
xual hil'n klli
nhung
duang
truyen khong
duqc
phep lien ket
bj
ch(lp.
Vi
duo
lrang nhicll
cong
ngh~.
si! ngan
m<;lch
giua
day
dat
ho~e
ngu6n
voi cae
dUll"ng
lin

hi~u
e6
the lam
eho
dUC1ng
tin hi¢u bj
ch~lp
c6
muc di¢n
the
eo
dinh.
Khi
do
16i
logic
tuang
ung vai si!
Ch~IP
mi.~ch
sc bao
g6m
nhCi"ng
tin
hi¢u
nh,~n
nhung
gia tfj
e6
dinh \·E{O.l

f.
Nhung
16i
nay
dmyc
goi
Iii.
nhling loi
hang
so
va
(1trqc
ky'
hi¢u
Iii.
S-(/-\'.
Sl! ch(lp nweh
giLra
iwi
dUC1llg
till hi¢u
thuang
sinh ra nhfrng ham 16gic
mai
vu
dltq"C
goi
I~I
d.e
Ibi

bac
d1,u.
Tuang
ung vai
nhung
ham
logic
dUQ'c
sinh ra
do
ch~p
mi.lch, chung ta phan
bi~t
16i
bil.C
d.u
AND
va
16i
bac
Ci."iu
OR.
Cae
LOi
IIllJch hir la ket
qua
CLla
si! dlit
dc
ket noi.

Trang
nhieu
eang
~
~~~:nLJ
'I
d,e
dU"<!ng
lin ,
hleu
b,
nghel1~,
nghe
n
nhanh
r ,
.,
Innh
ttl.
Loi
ho-
mach:
a)
16i
her
ml.lch
ddn;
b)
16i
her

mach
kep.
ngh~.
s\!
h6
m~ch
tfcn nhGng
(hrCing
lin
hi~u
mot ehieu \'oi
nx)1
nhanh phan
ky
se lam
eho
dUC1ng
tin
hi~u
'laO do trd thanh
bj
ngat
vii
nh(m
IllOt
gia
tr~
logic
eo
djnh

(
nhu
lren hlnh
8.la
) va do
d6
Iren
duang
tin hi¢u
nay
xuat
hi¢n mot loi hung
so
.\'-(1-1'.
Nhling loi nay
cung
co
th~
la
ket
qUii
clla nhung
16i
Vi.}t
I)'
ben trong
phan
tt! dieu khien
duang
tin

hi~u.
Neu chung ta kh6ng
ki~m
tra
gii.l
tr! trcll hai
duu
cua
duong
tin hi¢u thl
khong
the
ph{\ll
bi¢t
duqc
hai
tn1C1ng
hqp noi Iren.
Nhu
v~y
chung ta th:iy rang,
mot
loi
logic
dan
Ie.
VI
dl,l
nhu
loi htmg

so
nh~n
gii.l
tr! a E
{O,
I)
tren
dul':mg
tin hi¢u i
co
the:
bieu dien cae loi
v~t
Iy
hoan toan
kh.:ic
nhau:
16i
do
duong
tin hi¢u i bi ngat:
16i
do
duang
tin
hi~u
i
bj
ch~p
voi ngu()n

ho~c
dal; bat
ky
mOl
16i
V~lt
Iy
ben trong
phan
IU
e6
dUC1ng
tin
hi~u
i
I~l
dau fa
va
16i
nay lam
eho
duemg tin hi¢u i luon
giG'
gia trj bang
(I.
247