Osmania University (OU) 2007 B.E Computer Science LOGIC AND SWITCHING AND THEORY - Question Paper
Code No. 4211/N
FACULTY OF ENGINEERING B.E. 2/4 (CSE) I Semester Suppl. Examination May/June - 2008 Subject: Logic and Switching Theory
Time : 3 hours ] [Max. Marks : 75
Note : Answer all questions of Part-A.
Answer five questions from Part-B.
PART - A (25 marks)
1. NOR gate is called a universal gate. Justify the statement with an example. 2
2. Convert the hexadecimal number ABC 9 into its decimal and octal equivalents.
2
3. What is the advantage of Karnaugh map approach to simplification of boolean expressions over the algebraic approach ? 3
4. Design and draw a circuit for odd parity generation for an eight bit data. 3
5. Distinguish between a decoder and demultiplexa. 2
6. Draw the circuit diagram of a binary full adder after designing the logic circuit with logic gates. 3
7. Write the excitation table of J-K flip-flop. Derive a D type flip-flop using J-K flip-flops. 3
8. Write a VHDL code for a 2:4 decoda. 2
9. What is a hazard ? Give the example of a combinational circuit with a hazard. . . 3
c
10. Explain how a function can be symmetric with a suitable example. 2
PART - B (5><10=50 marks)
11. (a) Given that C = A B + AB; show that A = B C + BC.
(b) Prove that the sum of all minterms of a 3 variable Boolean functions is equal to 1
(c) Determine the canonical sum form for
XA, B, C) = C + (A + B)(A + B) 3+4+3
12. Design a full adder circuit using look ahead carry generator, 10
13. (a) Design a 5 * 32 decoder using only 3 x 8 decoder modules. Assume that
each 3x8 decoder has one active low enable input and one active high input.
(b) Draw the circuit diagram and explain the functioning of 3 * 8 multiplexer.
14. Design a sequential synchronous counters that follows the sequence 0, 2, 4, 7,
5, 1. Use JK flip-flops and NAND gates to realize the counter. 10
15. (a) Determine whether the following function is symmetric:
Ax, y, z) - 2(0, 2, 3, 4, 5, 7) '
If so, find the variables of symmetry.
(b) Find the contact realization for the following function :
AP, Q, R, S) - Z(3, 7, 8, 9, 13).
How many springs are likely to be used ? 5+5
16. Simplify the following function using tabular method.
AA, B, C, D, E, F, G) = (20, 28, 38, 39, 52, 60, 102, 103, 127). 10
17. Write short notes on : 4+3+3
(a) Symmetric relay contact networks
(b) Essential prime implicant
(c) Multilevel logic design.
C-169/500
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| Earning: Approval pending. |
