156. The main drawback of digital system is that—

1. 1. It is difficult to design

   
   
   

   2. It is not a precise system

   
   
   

   3. The real world is mainly analog

   
   
   

   4. Digital circuits are prone to noise

   
   
   

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1. View Hint View Answer Discuss in Forum

   The main drawback of digital system is that the real world is mainly analog.

   Correct Option: C

   The main drawback of digital system is that the real world is mainly analog.

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157. Modulo-2 addition is represented by—

1. 1. f = AB + BA

   
   
   

   2. f = AB + A B

   
   
   

   3. f = AB

   
   
   

   4. f = AB + A' B + BC

   
   
   

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1. View Hint View Answer Discuss in Forum

   Modulo-2 means, f = A ⊕ B = AB + BA.

   Correct Option: A

   Modulo-2 means, f = A ⊕ B = AB + BA.

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158. Simplify (X + Y) (X + Y)

1. 1. X

   
   
   

   2. Y

   
   
   

   3. X + XY

   
   
   

   4. X (1 + Y)

   
   
   

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1. View Hint View Answer Discuss in Forum

   Given expression
   F = (X + Y) (X + Y)
   or F = X + XY + YX + Y Y
   or F = X (1 + Y) + YX + 0
   or F = X + YX
   or F = X (1 + Y) = X
   Hence alternative (A) is the correct choice.

   Correct Option: A

   Given expression
   F = (X + Y) (X + Y)
   or F = X + XY + YX + Y Y
   or F = X (1 + Y) + YX + 0
   or F = X + YX
   or F = X (1 + Y) = X
   Hence alternative (A) is the correct choice.

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159. With reference to the exclusive OR gate with many inputs, consider the following statements—
     1. Even parity input words produce a low output
     2. If the inputs are two, the output is high only when the inputs are different.
     3. The gate recognised only words of even parity
     4. Odd parity input words produce a low output The only true statements are—

1. 1. 1, 2

   
   
   

   2. 3, 4

   
   
   

   3. 1, 3

   
   
   

   4. 2, 4

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: A

   NA

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160. Which of the following can be used as an inverter?

1. 1. AND gate

   
   
   

   2. OR gate

   
   
   

   3. NOR gate

   
   
   

   4. None of these

   
   
   

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1. View Hint View Answer Discuss in Forum

   NA

   Correct Option: C

   NA

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