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SPPU Computer Engineering (Semester 3)
Digital Electronics and Logic Design
May 2017
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary

Solve any one question from Q.1(a,b,c) &Q.2(a,b,c)
1(a) Implement the expression using a 8:1 multiplexer $f(a, b, c, d)=\sum m(0, 2, 3, 6, 8, 9, 12, 14).$
4 M
1(b) What is the difference between combinational and sequential circuits?
2 M
1(c) Simply the following logic function using the Quine -McCluskey minimization technique: $Y(A, B, C, D)=\sum m(0, 1, 3, 7, 8, 9, 11, 15)$
6 M

2(a) Explaiin in detail look ahead carry generator
6 M
2(b) Design Mod-24 counter using 7490
2 M
2(c) Design a sequence detector using MS J-K flip-flop sequence is 1101.
4 M

Solve any one question from Q.3(a,b,c) & Q.4(a,b)
3(a) Draw ASM chart for 2-bit UP counter using multiplexer controller method.
8 M
3(b) List any two medeling style of VHDL
2 M
3(c) Compare concurrent and sequential statement in VHDL
2 M

4(a) Design 4 input and 6 output combinational circuit using PLA. The input variables are A,B, C and D:
Y1 = ∑m(0, 3, 5, 6, 9, 10, 12, 15)
Y2 = ∑m(0, 1, 2, 3, 11, 12, 14, 15)
Y3 = ∑m(0, 4, 8, 12)
Y4 = &summ (0, 2, 3, 5, 7, 8, 12, 13)
Y5 = ∑m(0, 1, 3, 4, 5, 6, 11, 13, 14, 15)
Y5 = ∑m (1, 2, 6, 8, 15).
6 M
4(b) Draw block diagram of PLA device and explain.
6 M

Solve any one question from Q.5(a,b,c) & Q.6(a,b)
5(a) Explain characteristics of digital Ics (any four).
4 M
5(b) Explain operation of TTL NAND gate.
6 M
5(c) Explain TTL open collector.
3 M

6(a) What is addressing mode? Identify and Justify addressing modes of the following 8051 instructions:
i) MOVX A, @DPTR
ii) MOVC A, @ A+PC
iv) MOV DPTR, #2550.
6 M
6(b) What is microcontroller? Distinguish between microcontroller and microprocessor.
7 M

Solve any one question from Q.7(a,b,c) &Q.8(a,b)
7(a) Explain CMOS inverter.
4 M
7(b) Why wired logic is not possible in CMOS operation.
4 M
7(c) Explain trisate logic.
5 M

8(a) Explain the physical structure and significances of all I/O ports of 8051 microcontroller.
7 M
8(b) Give significance of the following pins in 8051:
i) PSEN#
ii) EA#/ VPP
iii) ALE
iv) TxD
v) INTO#
vi) RST.
6 M

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