Page 91 - Computer science 868 Class 12
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9. There are ………………… output lines in hexadecimal to binary encoder.
a. 16 b. 8
c. 4 d. 2
10. Which is not a correct MUX?
a. 4 × 1 MUX b. 8 × 1 MUX
c. 16 × 1 MUX d. 12 × 1 MUX
B. Fill in the blanks:
1. The boolean expression of a two-variable XNOR gate represented by variables A and B is ………………… .
2. The gate produced by combining two NOR gates in series is ………………… .
3. ………………… is the expression of the sum term of a half adder.
4. AND, OR, NOT are called ………………… gates.
5. XOR gate produces 1 for ………………… combinations of 1 as input.
6. A 9 B is equivalent to ………………… .
7. A full adder can be obtained by joining two ………………… and an OR gate.
8. AND gate is 1 when ………………… its inputs are 1.
9. When the antecedent and consequent of a proposition is interchanged, the resulting proposition is called ………………… .
10. The carry term of a full adder is ………………… .
C. Answer the following questions:
1. Distinguish between:
(i) NAND and NOR gate (ii) Encoder and Decoder
(iii) Decoder and Multiplexer (iv) AND gate and OR gate
(v) Half adder and Full adder
2. A logical circuit is given:
?1?
A
?3?
?4?
?2?
B
C
Write the Boolean expression for:
(i) ?1? (ii) ?2? (iii) ?3? (iv) ?4?
3. In the given logic circuit, write the Boolean expression for:
(i) ?1? (ii) ?2? (iii) ?3?
?1?
A ?3?
B ?2?
C
4. (i) Draw the truth table and logic gate diagram for an Octal to Binary encoder.
(ii) What is Multiplexer? State an application of a Multiplexer. Also, draw the logic diagram of a 4 × 1 Multiplexer.
(iii) Define Half Adders. Draw the circuit diagram and the truth table for a Half Adder. [ISC 2015]
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Computer Hardware 89

