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ECE :: Digital Electronics

  1. An AND gate has two inputs A and B and one inhibit input 3, Output is 1 if

  2. A.
    A = 1, B = 1, S = 1
    B.
    A = 1, B = 1, S = 0
    C.
    A = 1, B = 0, S = 1
    D.
    A = 1, B = 0, S = 0

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  3. The greatest negative number which can be stored is 8 bit computer using 2's complement arithmetic is

  4. A.
    - 256
    B.
    - 128
    C.
    - 255
    D.
    - 127

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  5. A JK flip flop has tpd= 12 ns. The largest modulus of a ripple counter using these flip flops and operating at 10 MHz is

  6. A.
    16
    B.
    64
    C.
    128
    D.
    256

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  7. The basic storage element in a digital system is

  8. A.
    flip flop
    B.
    counter
    C.
    multiplexer
    D.
    encoder

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  9. In a ripple counter,

  10. A.
    whenever a flip flop sets to 1, the next higher FF toggles
    B.
    whenever a flip flop sets to 0, the next higher FF remains unchanged
    C.
    whenever a flip flop sets to 1, the next higher FF faces race condition
    D.
    whenever a flip flop sets to 0, the next higher FF faces race condition

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  11. A 12 bit ADC is used to convert analog voltage of 0 to 10 V into digital. The resolution is

  12. A.
    2.44 mV
    B.
    24.4 mV
    C.
    1.2 V
    D.
    none of the above

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  13. For the truth table of the given figure Y =

  14. A.
    A + B + C
    B.
    A + BC
    C.
    A
    D.
    B

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  15. A full adder can be made out of

  16. A.
    two half adders
    B.
    two half adders and a OR gate
    C.
    two half adders and a NOT gate
    D.
    three half adders

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  17. If the functions w, x, y, z are as follows.
    w = R + PQ + RS ,
    x = PQR S + PQR S + PQ R S


    Then

  18. A.
    w = z x = z
    B.
    w = z, x = y
    C.
    w = y
    D.
    w = y = z

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  19. The output of a half adder is

  20. A.
    SUM
    B.
    CARRY
    C.
    SUM and CARRY
    D.
    none of the above

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