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Electronics and Communication Engineering - Digital Electronics

Exercise : Digital Electronics - Section 2
1.

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

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

Both A and R are correct and R is correct explanation of A
Both A and R are correct but R is not correct explanation of A
A is true, R is false
A is false, R is true
Answer: Option
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.

Both A and R are correct and R is correct explanation of A
Both A and R are correct but R is not correct explanation of A
A is true, R is false
A is false, R is true
Answer: Option
Explanation:

XOR gate is not a universal gate.

3.
The number of bits in ASCII is
12
10
9
7
Answer: Option
Explanation:

ASCII is a 7 bit code.

4.
4 bit 2's complement representation of a decimal number is 1000. The number is
+ 8
0
- 7
- 8
Answer: Option
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
data bit D is fed to S input and D to R input
data bit D is fed to R input and D to S input
data bit D is fed to both R and S inputs
data bit D is not fed to any input
Answer: Option
Explanation:

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