Janardan Rai Nagar Rajasthan Vidyapeeth 2006 B.Tech Computer Science and Engineering DIGITAL ELECTRONICS  Question Paper
JRN Rajasthan Vidyapeeth University
COMPUTER SCIENCE ENGINEERING
SEMESTER 3
DIGITAL ELECTRONICS
Model Question Paper
BSAE4BSCO4BSE4BSET4BSAE9BSCO9BSE9BSET9 DIGITAL ELECTRONICS
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)

Q.1 What is flipflop? Explain RS flip flop ?

examples. ?

Q.3 Short note on Half adder ?


a) ExclusiveNOR gate.
b) NAND gate
c) NOT gate
Group B (25 Marks)
Answer any three questions (Questions 6 is compulsory)

Q.6 Short note on full adder ?

Q.7 Prove that the largest 4digit octal number when subtracted from the larger
3 digit hexadecimal number yields zero in decimal ?

Q.8 Briefly explain why a ripple counters maximum usable clock frequency decreases
as more flipflops are added to the counter to increase its MODnumber why is
maximum usable clock frequency in case of a synchronous counter independent of clock
frequency ?

Q.9 Convert
a) (176.F)_{16} to Decimal.
b) (110011)_{2} to Hexadecimal
c) (19.25)_{10 }to binary.

_{ }
Group C (25 Marks)
All Questions are Compulsory.
Q.11 Fill in the blanks ( each question carry 2 marks)
1. A 4 bit parallel adder can add ___________.
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 EXOR is __________.
Q.11 Multiple choice question. (Each question carry 2 marks)
1. Minimum number of flipflop 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 flipflop.
2.If all inputs of exclusive gate are one output is _________.
_ _ _ _
3. A B + AB = A
4.In JK flipflop when J =1 and K=1 , output toggles.
5.In negative logic, logic 1 represents low voltage.
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Earning: Approval pending. 