Page 316 - FUNDAMENTALS OF COMPUTER

NPP

316 Fundamentals of Computers NPP

That means in each case the output is AV… ha ~ma AmCQ>nwQ> A H$m nyaH$ àmá hmo ahm h¡Ÿ&
complement of A.
That means if one input of XOR gate is AWm©V² XOR JoQ> Ho$ EH$ BZnwQ> na 1 {X`m OmE Vmo
fixed at 1 then it inverts other input. It works as dh Xygao Ho$ {bE NOT JoQ> H$m H$m`© H$aVm h¡ Am¡a `{X
NOT gate. But if the other input is fixed at zero EH$ BZnwQ> na eyÝ` {X`m OmE Vmo BgH$m AmCQ>nwQ> A
its output would be A ⊕ 0 = A. Thus, it does not ⊕ 0 = A hmoJmŸ& AV… `h BÝdQ>© Zht H$aVm h¡Ÿ& `h XOR
invert. This gate can be used as a controlled
invertor with a control signal INVERT. JoQ> Ho$ EH$ BZnwQ> na {Z`§ÌU {g¾b INVERT XoH$a Cgo
{Z`§{ÌV NOT JoQ> H$s Vah H$m_ _| bo gH$Vo h¢…
INVERT A

When INVERT = 1, then only it will work `{X INVERT = 1 h¡ Vmo AmCQ>nwQ> A hmoJm AÝ`Wm
as NOT gate. Using four such XOR gates, a 1's A hmoJmŸ& AV… Mma Eogo JoQ>m| H$mo {_bmH$a EH$ Mma {~Q>m|
complement circuit can be drawn which is H$mo 1's H$m°påßb_|Q> XoZo dmbm {Z`§{ÌV n[anW ~Zm
controlled: gH$Vo h¢&

INVERT

Controlled
Inverter

The output X 3 X 2 X 1 X = A 3 A 2 A 1 A 0 O~ INVERT = 1 Vmo X X X X =
0
3
0
1
2
only when INVERT = 1 else we get X X X X A A A A AÝ`Wm X X X X = AA A A A
= A A A A 0 3 2 1 0 3 2 1 0 3 2 1 0 3 2 1 0
2
3
1
3.46 2's Complement Circuit 3.46 2's H$m§ßbr_|Q> n[anW
2's complement of a binary number can be {H$gr ~mBZar g§»`m Ho$ 1's H$m°påßb_|Q> _| EH$
obtained by adding 1 to its 1's complement i.e. Omo‹S>H$a 2's H$m°påßb_|Q àmá {H$`m Om gH$Vm h¡ Ÿ& AWm©V²;
A 3 A 2 A 1 A + 1 = 2's complement of AA A A A 0
3
2
1
0