Page 92 - Computer science 868 Class 12
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5. How is a decoder different from a multiplexer? Write the truth table and draw the logic circuit diagram for a 3 to 8 decoder and
explain its working. [ISC 2019]
6. (i) What is an Encoder? Draw the Encoder circuit to convert A-F hexadecimal numbers to binary. State an application of a Multiplexer.
(ii) Differentiate between Half Adder and Full Adder. Draw the logic circuit diagram for a Full Adder. [ISC 2018]
7. What is a Multiplexer? How is it different from a decoder? Draw the circuit diagram for a 8 : 1 Multiplexer. [ISC 2017]
8. Derive a Boolean expression for the logic circuit given below and reduce the derived expression, using Boolean laws.
A
B
9. Derive a Boolean expression for the logic circuit given below and reduce the derived expression, using Boolean laws.
A'
B
C
D'
E Y
F
G'
10. Draw the logic circuit diagram of the following Boolean expression using AND, OR and NOT gates.
(i) (A+B)'.C'+ (A+B+C)' (ii) (P'+Q'+R').(P+Q+R)
(iii) (A+B').(B'+C).(C'+A) (iv) X.Y'+Y.Z'+Z.X'
(v) (A'.B+A.B') .(A'.B'+A.B)
11. Draw the logic circuit diagram of the following expression using NAND gate only.
(i) A'.B'.C'+ A.B.C (ii) (X+Y).(X+Y'+Z)
(iii) X'.Y + X.Y' (iv) (X+Y+Z).X'.Y'
(v) A.B + A.C'+ B.C
12. Draw the logic circuit diagram of the expression given in 11 using NOR gate only.
D. Assertion and Reasoning Based Question.
Assertion: Multiplexer is a combinational circuit that selects a single output from a set of inputs.
Reason: Multiplexer has ‘n’ input lines and maximum 2n output lines.
(a) Both Assertion and Reason are true, and Reason is the correct explanation for Assertion.
(b) Both Assertion and Reason are true, but Reason is not the correct explanation for Assertion.
(c) Assertion is true and Reason is false.
(d) Assertion is false and Reason is true.
9090 Touchpad Computer Science-XII

