Electronics and Communication Engineering - Digital Electronics

1. 

Assertion (A): A demultiplexer can be used as a decoder.

Reason (R): A demultiplexer can be built by using AND gates only.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true

Answer: Option C

Explanation:

Demultiplexer requires NOT gates also in addition to AND gates.


2. 

Assertion (A): The output of a NOR gate is equal to the complement of OR of input variables.

Reason (R): A XOR gate is a universal gate.

A. Both A and R are correct and R is correct explanation of A
B. Both A and R are correct but R is not correct explanation of A
C. A is true, R is false
D. A is false, R is true

Answer: Option C

Explanation:

XOR gate is not a universal gate.


3. 

The number of bits in ASCII is

A. 12
B. 10
C. 9
D. 7

Answer: Option D

Explanation:

ASCII is a 7 bit code.


4. 

4 bit 2's complement representation of a decimal number is 1000. The number is

A. + 8
B. 0
C. - 7
D. - 8

Answer: Option D

Explanation:

(a) and (d) both are option, But there is meaning to represent a positive number in 2's complement form, we take complement representation for negative number only. Therefore most appropriate number is "-8".


5. 

In a D latch

A. data bit D is fed to S input and D to R input
B. data bit D is fed to R input and D to S input
C. data bit D is fed to both R and S inputs
D. data bit D is not fed to any input

Answer: Option A

Explanation:


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