Code No.: 207
FACULTY OF ENGINEERING
B.E. II/IV Year (CSE) I Semester (Main) Examination, November/December 2008
LOGIC AND SWITCHING THEORY
Time: 3 Hours] [Max. Marks: 75
Answerall questions of Part A.
Answer any five questions from Part B.
Part A - (Marks: 25)
1. What are universal gates? Explain the reasons that are called universal gates. 3
2. Simplify the following Boolean expression. 2
F (A, B, C) = AB + A + B + BC
3. Distinguish between canonical forms and standard forms of Boolean equations. 2
4. Implement x + yz + yz using NOR gates. 2
5. Distinguish between a combinational and sequential logic circuit. Draw the block
diagram of a sequential circuit. 3
6. Draw the diagram of a full adder circuit using two half adders and other logic
7. What is a hazard in combinational network? 2
8. Draw the excitation table for a J-K flipflop. 2
9. Realize a contact network with minimum number of contacts for SO,'I,3 (A, B, C, D). 3
10. Explain the concept of glitches when combinational circuits are used in
conjunction with ripple counters. Give a suitable example. 3
Part B - (Marks: 5 x 10 = 50)
11. (a) Prove that the sum of all min. terms of a 3 variable Boolean function is equal
(b). Convert the following sum of product form to a product of sum form.
- - -
F (A, B, C) = ABC + ABC + ABC
(c) Convert the decimal number 5678 to its hexadecimal equivalent. 3+4+3
12. (a) Simplify the function using Karnaugh map
f(A, B, C, D) = L (0, 4, 5,7, 8, 9, 13, 15)
with minimum number of literals.
(b) Distinguish between a prime implicant and essential prime implicant. 6+4
13. (a) Distinguish between a decoder and encoder.
(b) Design a priority encoder with 8 inputs and 3 outputs and draw the circuit
14. (a) Distinguish between a register and a latch.
(b) Convert an SR flipflop to JK flipflop and draw the logic diagram. 2+8
15. (a) Determine whether the function F (A, B, C) = L (0, 2, 3, 4, 5, 7) is symmetric
and variables of symmetry.
(b) Design a mod-5 asynchronous counter and draw the concerned waveforms.
16. Design a BCD to decimal decoder utilizing the don't care combinations. Draw
the relevant diagrams. 10
17. Write brief notes on : 3+3+4
(a) Parity generator
(b) Binary multiplier
(c) Relay contact network.