| 1. | The output Y of a 2-bit comparator is logic 1 whenever the 2-bit input A is greater than the 2-bit input B. The number of combinations for which the output is logic 1, is ? | |
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4
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6
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8
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10
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Report Question| 2. | A 1-bit full adder takes 20 ns to generate carry-out bit and 40 ns for the sum bit. What is the maximum rate of addition per second when four 1-bit full adders are cascaded ? | |
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10^7
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1.25 x 10^7
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6.25 x 10^6
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10^5
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| 3. | Which one of the following statements correctly defines the full adder? An adder circuit ? | |
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having two inputs used to add two binary digits. It produces their sum and carry as input
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having three inputs used to add two digits plus a carry. It produces their sum and carry as output
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used in least significant position when adding two binary digits with no carry-in to consider, it produces their sum and carry as outputs
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having two inputs and two outputs
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| 4. | Which one of the following statements is not correct ? | |
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A full adder can be constructed using two half-adders and an OR gate
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Two four bit parallel adders can be cascaded to construct 8-bit parallel adder
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Ripple carry adder has addition time independent of the number of bits
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Carry look ahead is used to speed up the parallel addition
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| 5. | For a binary half-subtractor having two inputs A and B, the correct set of logical expressions for the outputs D (= A minus B) and X (= borrow) are ? | |
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D=AB+ A’B, X = A’B
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D=A’B+ AB’ + AB, X= AB’
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D=A’B + AB’, X = A’B
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D=AB+ A’B’, X= AB’
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| 6. | Which of the following circuits come under the class of sequential logic circuits? 1. Full adder 2. Full subtracter 3. Hall adder 4. J-K flip 5. Counter Select the correct answer from the codes given below: ? | |
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1 and 2
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2 and 3
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3 and 4
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4 and 5
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| 7. | Two 2's complement numbers having sign bits 'x' and 'y' are added and the sign bit of the result is 'z'. Which Boolean function indicates the occurrence of the overflow ? | |
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xyz
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x’y’z’
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x’y’z + xyz’
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xy + yz+zx
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| 8. | The equivalent name for multiplexer is ? | |
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multi
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data encoder
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data selector
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demux
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| 9. | A multiplexer is a combinational logic circuit used to perform the operation ? | |
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AND-AND
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AND-OR
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NOR-OR
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XOR-NAND
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| 10. | How many input and output required for demultiplexer ? | |
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one input and one output
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number of selection inputs and one output
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one input and many output
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None of the above
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