Classical

Digital Logic - Combinational Circuits

56:  

 What logic function is performed by the circuit shown below?
Nand gate circuit

A.

Ring counter

B.

Ripple counter

C.

Full adder

D.

Half adder

 
 

Option: D

Explanation :

Here total 7 NAND gates are present  and in half adder one AND and one EX-OR gate are required.
In turn  one EX-OR gate can be built by 5 NAND
where as one AND gate can be built by 2 NAND  gates
so this is  diagram of half adder. So the answer is (D).


57:  

What is the Boolean expression for the following circuit?

or gate circuit

A.

F(A, B) = ( A + B' ) . ( B + A' )

B.

F( A, B ) = 1 ( Tautology )

C.

F( A, B ) = ⊕ ( inconsistency)

D.

F ( A, B ) = A ⊕  B ( A exclusive OR'ed with B)

 
 

Option: A

Explanation :

 Ans is  A as  input to 1st OR gate is A, and B' so output   of 1st OR gate is (A+B')
In the same way output  for 2nd OR gate is (A'+B)
So Final output will be (A+B'). (A'+B) 


58:  

 In the circuit shown below, which logic function does this circuit generate?

Logic-Circuit

A.

AND

B.

NOR

C.

NAND

D.

OR

 
 

Option: D

Explanation :


59:  

Output of the following circuit is

Logic Circuit

A.

0

B.

1

C.

x

D.

x'

 
 

Option: A

Explanation :

Truth Table for XOR

XOR Truth Table


60:  

A small dot or circle printed on top of an IC indicates

A.

Vcc

B.

Gnd

C.

Pin 14

D.

Pin 1

 
 

Option: D

Explanation :




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