Download BBA IInd SEMESTER EXAMINATION 2008-09

MCA I (First) Semester Examination 2011-12
Course Code:MCA105
Paper ID:0871105
Digital Electronics
Time: 3 Hours
Max. Marks: 70
Note: Attempt six questions in all. Q. No. 1 is compulsory.
1.
a)
b)
c)
d)
e)
f)
g)
h)
Answer any five of the following (limit your answer in 50
words).
(4x5=20)
Assuming sign-magnitude representation of binary numbers,
find decimal equivalent of (101100)2.
What is ASCII code? Discuss.
Draw logical symbol of NOR gate and write its truth table.
Draw logical symbol of Flip-Flop. What are the properties of
a Flip-Flop?
What are Encoders? Explain.
Draw half subtractor circuit using basic gates.
What is Asynchronous Counter? Give an example.
What is Register? What are its different types?
2. a)
b)
c)
d)
Convert (3A.2F)16 into binary number.
Convert (675.625)10 into octal number.
Subtract (2C)16 from (3F)16
Encode decimal number 46 to Gray code.
3. a)
Simplify the Boolean expression given below using Boolean
Theorems:
(5)
y  A B C  A BC  ABC  AB C
Minimize the four-variable logic function using K-Map: (5)
f ( A, B, C , D)  M (0,1, 2, 3, 5, 7,8, 9,11,14) .
b)
4. a)
b)
(2.5)
(2.5)
(2.5)
(2.5)
What is S-R Flip-Flop? Explain its working.
(5)
What is the restriction in S-R Flip-Flop? How to overcome it
using J-K Flip-Flop? Explain.
(5)
5.
Convert a J-K Flip-Flop to T Flip-Flop using conversion
design technique.
(10)
6.
Draw truth table for full adder circuit. Draw its logical circuit
using NAND gates.
(10)
7. a) Explain the operation of a 4-bit shift right register.
(5)
b) Write truth table and draw logic diagram of 2 to 4
decoder.
(5)
8.
Draw logic diagram and explain working of 4-bit
synchronous counter. Draw its timing diagram.
(10)