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# Janardan Rai Nagar Rajasthan Vidyapeeth 2006 B.Tech Computer Science and Engineering DIGITAL ELECTRONICS - Question Paper

Tuesday, 14 May 2013 09:05Web

JRN Rajasthan Vidyapeeth University

COMPUTER SCIENCE ENGINEERING

SEMESTER 3

DIGITAL ELECTRONICS

DR

Model Question Paper

#### Time : 3 hrs Maximum marks : 75

Instruction:

1. Question paper is divided into Group A, Group B and Group C

2. Each Group is 25 Marks

3. Figure to the right in bracket indicates marks.

4. Good Handwriting is expected

5. Assume suitable data if necessary.

Group A (25 Marks)

Answer any three questions (Question 1 is compulsory)

 (5)

Q.1 What is flip-flop? Explain R-S flip flop ?

 (10)

Q.2 Explain Gray code? Explain conversion of binary to gray code and gray to binary with

examples. ?

 (10)

Q.3 Short note on Half adder ?

 (10)

Q.4 Write all gates and explain any two gates in detail ?

 (10)

Q.5 Short note on

a) Exclusive-NOR gate.

b) NAND gate

c) NOT gate

Group B (25 Marks)

Answer any three questions (Questions 6 is compulsory)

 (5)

Q.6 Short note on full adder ?

 (10)

Q.7 Prove that the largest 4-digit octal number when subtracted from the larger

3- digit hexadecimal number yields zero in decimal ?

 (10)

Q.8 Briefly explain why a ripple counters maximum usable clock frequency decreases

as more flip-flops are added to the counter to increase its MOD-number why is

maximum usable clock frequency in case of a synchronous counter independent of clock

frequency ?

 (10)

Q.9 Convert

a)   (176.F)16 to Decimal.

c)   (19.25)10 to binary.

 (10)

Q.10. What are registers? Explain shift register ?

Group C (25 Marks)

All Questions are Compulsory.

Q.11 Fill in the blanks ( each question carry 2 marks)

2.   (110)2+ (110)2 = ( ________) 8

3.   Excess 3 of (15)10 is _________.

4.   OR gate is expressed by logical expression y = _________.

5. Equation of EX-OR is __________.

Q.11 Multiple choice question. (Each question carry 2 marks)

1.      Minimum number of flip-flop needed to construct a BCD counter is

a)      4

b)      1

c)      10

d)      none

2.      The base of decimal number is _________.

a)      8

b)      2

c)      10

d)      none of the above

3.      distributive law is A(B+C) = __________.

a)      AB + C

b)      (A + B)

c)      AB+AC

d)      NONE

4.      In general multiplexer has the output lines __________.

a)      2

b)      1

c)      3

d)      none of the above

5.      1 byte is equal to _________nibbles .

a)      1

b)      2

c)      3

d)      4

Q.11 True or false (each question carry 1 marks).

1.combinational circuits are designed using gates and flip-flop.

2.If all inputs of exclusive gate are one output is _________.

_ _ _ _

3. A B + AB = A

4.In JK flip-flop when J =1 and K=1 , output toggles.

5.In negative logic, logic 1 represents low voltage.

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