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Electronics and Communication Engineering - Digital Electronics

Exercise : Digital Electronics - Section 1
31.
Minimum number of 2-input NAND gates required to implement the function F = (x + y) (Z + W) is
3
4
5
6
Answer: Option
Explanation:

F = (x + y) (z + w) = xy.(z + w)

= xyz + xyw

= minimum no. of 2 input NAND gate.

32.
Which device has one input and many outputs?
Multiplexer
Demultiplexer
Counter
Flip flop
Answer: Option
Explanation:

Demultiplexer takes data from one line and directs it to any of its N output depending on the status of its select lines.

33.
A carry look ahead adder is frequently used for addition because
it costs less
it is faster
it is more accurate
is uses fewer gates
Answer: Option
Explanation:

In look ahead carry adder the carry is directly derived from the gates when original inputs are being added. Hence the addition is fast. This process requires more gates and is costly.

34.
The counter in the given figure is
Mod 3
Mod 6
Mod 8
Mod 7
Answer: Option
Explanation:

When counter is 110 the counter resets. Hence mod 6.

35.
In register index addressing mode the effective address is given by
index register value
sum of the index register value and the operand
operand
difference of the index register value and the operand
Answer: Option
Explanation:

4 = 22, in up scaling digit will be shifted by two bit in right direction.

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