Digital electronics miscellaneous


Digital electronics miscellaneous

Digital Electronics

  1. To add two m-bit numbers, the required number of half adder is—









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    To add two m-bit numbers, the required no. of half adder is 2m–1.

    Correct Option: A

    To add two m-bit numbers, the required no. of half adder is 2m–1.


  1. Consider the following statements:
    A 4: 16 decoder can be constructed (with enable input) by:
    1. Using four 2: 4 decoders (each with an enable input) only
    2. Using five 2: 4 decoders (each with an enable input) only
    3. Using two 3: 8 decoders (each with an enable input) only
    4. Using two 3: 8 decoders (each with enable input) and an inverter.
    Which of the statements given above is /are correct?









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    4: 16 decoder can be constructed using
    ● Five 2: 4 decoders (each with enable input) and
    ● Two 3: 8 decoders (each with enable input) and an inverter

    Correct Option: C

    4: 16 decoder can be constructed using
    ● Five 2: 4 decoders (each with enable input) and
    ● Two 3: 8 decoders (each with enable input) and an inverter



  1. In addition of two binary variables A and B results into a SUM and a CARRY output. Consider the following expressions for the SUM and CARRY outputs.
    (1) SUM = A. B + A·B
    (2) SUM = A.B + B.A
    (3) CARRY = A. B
    (4) CARRY = A + B
    Which of the following expressions are correct?









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    NA

    Correct Option: B

    NA


  1. A 4 × 1 MUX is used to implement a 3-input Boolean function as shown in figure. The Boolean function F (A, B, C) implement is— A B A 1 F(A, B, C)











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    The given figure
    F (A, B, C) = B CA + B C.A + B.C.1. + BC.0
    or F (A, B, C) = B CA + BCA + BC.(A + A)
    or F (A, B, C) = AB C + A BC + ABC + ABC
    or F (A, B, C) = 100, 001, 110, 010
    or F (A, B, C) = Σ (1, 2, 4, 6)


    Correct Option: A

    The given figure
    F (A, B, C) = B CA + B C.A + B.C.1. + BC.0
    or F (A, B, C) = B CA + BCA + BC.(A + A)
    or F (A, B, C) = AB C + A BC + ABC + ABC
    or F (A, B, C) = 100, 001, 110, 010
    or F (A, B, C) = Σ (1, 2, 4, 6)




  1. Expression for Y (A, B, C) in figure, where A, B and C are Boolean variables is—











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    The given figure
    From above figure
    Y = A B.1 + AB.C + AB.0 + AB.C
    or Y = A B + ABC + ABC
    or Y = A B + BC (A + A)
    or Y = A B + BC


    Correct Option: C

    The given figure
    From above figure
    Y = A B.1 + AB.C + AB.0 + AB.C
    or Y = A B + ABC + ABC
    or Y = A B + BC (A + A)
    or Y = A B + BC