Notes Bel Sample Paper| preparation material for computer Science students-Part 3/June 2011

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 Notes Bel Sample Paper|preparation material for computer Science students-Part 3

Today I am going to post Questions on Digital Electronics.
Let's Start preparation for BEL_Exam26 june 2011_CS

Guys, As we all know that BEL is going to take test on 26 june 2011.

I have posted Bel Sample Paper|questions on COMPILER DESIGN and COMPUTER NETWORK lastly.

Bel Sample Paper|Digital Electronics
1.The NAND gate output will be low if the two inputs are
(A) 00 (B) 01
(C) 10 (D) 11

Answer:(D) 11
Explanation:The NAND gate output will be low if the two inputs are 11
X(Input) Y(Input) F(Output)
0 0 1
0 1 1
1 0 1
1 1 0

2.The decimal equivalent of hex number 1A53 is
(A) 6793 (B) 6739
(C) 6973 (D) 6379

Answer:(B) 6739
Explanation:The decimal equivalent of Hex Number 1A53 is 6739
(Conversion from Hex Number to Decimal Number is given below)
1 A 5 3 Hexadecimal
16³ 16² 16¹ 16° Weights
(1A53)16 = (1X16³) + (10 X 16²) + (5 X 16¹) + (3 X 16º)
= 4096 + 2560 + 80 + 3
= 6739

3.The Gray code for decimal number 6 is equivalent to
(A) 1100 (B) 1001
(C) 0101 (D) 0110

Answer:(C) 0101
Explanation:The Gray code for decimal number 6 is equivalent to 0101
(Decimal number 6 is equivalent to binary number 0110)
0 1 1 0 changed as gray code:0 1 0 1

4.The digital logic family which has minimum power dissipation is
(A) TTL (B) RTL
(C) DTL (D) CMOS

Answer:(D) CMOS
Explanation:(CMOS being an unipolar logic family, occupy a very small fraction of silicon Chip area)

5.The 2’s complement of the number 1101101 is
(A) 0101110 (B) 0111110
(C) 0110010 (D) 0010011

Answer:(D) 0010011
Explanation:The 2’s complement of the number 1101101 is 0010011
(1’s complement of the number 1101101 is 0010010
2’s complement of the number 1101101is 0010010 + 1 =0010011)

6.Which of the following is the fastest logic
(A) TTL (B) ECL
(C) CMOS (D) LSI

Answer:(B) ECL
Explanation:ECL is the fastest logic family of all logic families.
(High speeds are possible in ECL because the transistors are used in difference
amplifier configuration, in which they are never driven into saturation and thereby the storage time is eliminated.

7.Which of the memory is volatile memory
(A) ROM (B) RAM
(C) PROM (D) EEPROM

Answer:(B) RAM
Explanation:RAM is a volatile memory
(Volatile memory means the contents of the RAM get erased as soon as the power
goes off.)

8.In a JK Flip-Flop, toggle means
(A) Set Q = 1 and Q = 0.
(B) Set Q = 0 and Q = 1.
(C) Change the output to the opposite state.
(D) No change in output.

Answer:(C) Change the output to the opposite state.
Explanation:In a JK Flip-Flop, toggle means Change the output to the opposite state.

9.In digital ICs, Schottky transistors are preferred over normal transistors because of their
(A) Lower Propagation delay. (B) Higher Propagation delay.
(C) Lower Power dissipation. (D) Higher Power dissipation.

Answer:(A) Lower Propagation delay
Explanation: Lower propagation delay as shottky transistors reduce the storage time delay by preventing the transistor from going deep into saturation.

10.Which of following are known as universal gates
(A) NAND & NOR. (B) AND & OR.
(C) XOR & OR. (D) None.

Answer:(A) NAND & NOR.
Explanation:NAND & NOR are known as universal gates, because any digital circuit can be realized completely by using either of these two gates.
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