Page 303 - FUNDAMENTALS OF COMPUTER

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NPP Number System, Boolean Algebra and Logic Circuits 303

B . A + . B . A The combination of these two gates Ho$ AÝXa Ho$ n[anW H$mo EH$b JoQ> H$s ê$n _| Xem©`m Om
enclosed in the dotted box can be considered as gH$Vm h¡Ÿ& Bg JoQ> H$mo XNOR JoQ> H$hVo h¢Ÿ& BgH$m
a single gate. This gate is called XNOR gate g§Ho$V Bg àH$ma h¡-
whose symbol can be drawn as:

A

B A.B + A.B = AOB

The output of XNOR gate will be the BgH$m AmCQ>nwQ> XOR Ho$ AmCQ>nwQ> H$m H$m°påßb_|Q>
complement of output of XOR gate: The truth hmoVm h¡Ÿ& BgH$s gË`-Vm{bH$m Bg àH$ma go ~ZmB© Om
table can be drawn as:
gH$Vr h¡…
Truth Table: 2-input X-NOR

A B Y
0 0 1

0 1 0
1 0 0

1 1 1
The output of XNOR gate is 1 for similar {H$gr Xmo BZnwQ>m| dmbo XNOR JoQ> _| `{X A = B hmo Vmo
inputs and is Zero for dissimilar inputs. AmCQ>nwQ> 1 hmoJm AÝ`Wm hmo Vmo 0 hmoJmŸ& Bg{bE BgH$m Cn`moJ
Therefore this gate can also be utilized as a ^r Xmo {~Q>²g Ho$ H$ånoaoQ>a Ho$ ê$n ‘| {H$`m Om gH$Vm h¡Ÿ&
comparator of two bits.
The output of XNOR gate is Zero for odd gmW hr `{X BZnwQ> _| 1 H$s g§»`m {df_ h¡ Vmo
number of 1’s in the input and the output is 1 AmCQ>nwQ> eyÝ` hmoJm VWm g_ Ho$ {bE 1 hmoJmŸ& AV…
for even number of 1s. Therefore this gate is XNOR JoQ> H$m Cn`moJ ^r no[aQ>r MoH$a d no[aQ>r
also used in parity checker and parity OZaoQ>a _| hmoVm h¡Ÿ&
generators.
3.38 XNOR Gate Properties & use in computer
Property Use
Compares two Bits; output is 1 for similar bits else it is zero. Comparator
Checks parity; output is one for even parity and zero for odd parity Parity checker &
binary number parity Generator
3.38 XNOR JoQ> Ho$ JwU VWm H$åß`yQ>a _| Cn`moJ
JwU Cn`moJ

Xmo {~Q>m| H$s VwbZm H$aVm h¡Ÿ& `{X `o g_mZ h¡ Vmo AmCQ>nwQ> 1 AmVm h¡ AÝ`Wm H§$noaoQ>a
AmCQ>nwQ> 0 AmVm h¡Ÿ&