Electronics and Communication Engineering - Digital Electronics

21. 

Assertion (A): Decoder is not a combinational circuit.

Reason (R): Every memory element of semi conductor form has a decoder.

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 B

Explanation:

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22. 

In 8085 microprocessor, in order to enable RST 5.5, RST 6.5 and RST 7.5 interrupts, which of the following instruction are needed?

A. EI only
B. SIM only
C. EI and SIM both
D. None

Answer: Option C

Explanation:

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23. 

A retriggerable one shot is one which

A. can be triggered only once
B. has two quasi stable states
C. can not be retriggered till the complete pulse appears at output
D. can be retriggered while the output is being generated

Answer: Option D

Explanation:

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24. 

A(A + B) =

A. A
B. A B
C. AB
D. AB

Answer: Option C

Explanation:

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25. 

For the K map in the given figure, the simplified expression is

A. xl x2 x4 + x2 x4 + x1 x3
B. x2 x4 + x2 x4 + x1 x3
C. x1 x2 x4 + xl x2 + x3 x4 + x2x4
D. x1 x2 + x2 x3 + x3x4

Answer: Option B

Explanation:

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