# Annamalai University Question Paper December 2014 B.Sc.Electronic Science:Digital Electronics

Annamalai University question paper december 2014
B.Sc. DEGREE EXAMINATION December 2014
(ELECTRONIC SCIENCE)
(THIRD YEAR)
(PART-III)
720. DIGITAL ELECTRONICS
Time: Three hours Maximum: 100 marks
SECTION – A
(5×4=20)
1. What is the advantage of using Hexadecimal systems? Covert 7C9 hex to
decimal?
2. Distinguish weighted and non-weighted codes.
3. Find the sum of minterms for function.
f(A,B,C,D)=AC
4. Explain SOP forms expressions.
5. Draw and explain a binary half adder.
6. Write short note on shift registers.
7. Explain the working of T-flip flop.
8. What are the drawbacks of variable resistor D/A convertor?
SECTION – B
(5× 16=80 )
9. What are the unique features of Boolean Algebra? State and prove
Demorgan’s theorem for any elements.
10. Implement the following Boolean expression using NAND gate only
i) y = A+ B C+AC and ii) y = (A+ B).( A+C)
11. Explain briefly K-map for four variable switching function with necessary
theory and table.
12. Draw and explain a 2’s complement adder and subtractor.
13. Explain a full subtractor circuit and find out it’s output. Show that how
it is realised using two half subtractors.
14. Draw and explain the working of clocked R-S flip flop using NAND gates.
15. Draw a 4-bit binary ripple counter and explain its working.
16. Explain briefly the binary ladder D/A converter and mention their