Classical

Digital Logic - Combinational Circuits

61:  

 The number of two input multiplexers required to construct a 210 input multiplexer is,

A.

31

B.

10

C.

127

D.

1023

 
 

Option: D

Explanation :


62:  

 The full adder adds the Kth bits of two numbers to the

A.

difference of the previous bits

B.

sum of all previous bits

C.

carry from ( K - 1 )TH bit

D.

sum of previous bit

 
 

Option: C

Explanation :


63:  

 In the following question, match each of the items A, B and C on the left with an approximation item on the right

 

A. Shift register can be used              1. for code conversion

B. A multiplexer can be used             2. to generate memory slipto select

C. A decoder can be used                  3. for parallel to serial conversion

                                                                 4. as many to one switch

                                                                  5. for analog to digital conversion

A.

A   B   C

1   2   3 

B.

A   B   C

3   4   1

C.

A   B   C

5   4   2

 

D.

A   B   C

1   3   5

 
 

Option: B

Explanation :


64:  

 A full-adder is a logic circuit which can add two single order bits plus a carry in from a previous adder. Its incomplete truth table is given in the table below. The missing entry in the outputs for SUM and CARRY out are 

Input

Outputs

A

A

B

Cin

Sum

CarryOUT

0

0

0

0

0

0

0

0

0

1

1

0

0

0

1

0

1

0

0

0

1

1

0

1

1

1

0

0

1

0

1

1

0

1

0

1

1

1

1

0

0

1

1

1

1

1

?

?

 

A.

0 0

B.

0 1

C.

1 0

D.

1 1

 
 

Option: D

Explanation :


65:  

Extremely low power dissipation and low cost per gate can be achieved in:

A.

MOS ICs

B.

C MOS ICs

C.

TTL ICs

D.

ECL ICs

 
 

Option: B

Explanation :




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