BCA 1st Semester
Digital Logics Board Question Paper 2019

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Tribhuvan university

Bachelor In Computer Application

Course Title: Digital Logics

Code No: CACS 103

Semester:I

2019

Full Marks:60 Pass Marks:24 Time:3 hours

Candidates are required to answer the question in their own words as far as possible.

Group A
Group B
Attempt any SIX question.
[6x5=30]
2.

Subtract: 1010.110 - 101.101 using both 2’s and 1’s complement.

3.

Simplify (using k-map) the given Boolean function in both SOP and POS using the don't care condition if: f(A, B, C, D) = ℼ(0,1,3,7,8,12) ℼ d(5,10,13,14).

4.

Define decoder. Draw logic diagram and truth table of 3 to 8 line decoder.

5.

Define ROM. Implement the following combinational logic function using ROM:

A1 A0 | F1 F2
        0  0  |  1  0
        0  1  |  0  1
        1  0  |  1  1
        1  1  |  1  0

6.

What are the drawbacks of clocked RS Flip Flop? Explain the operation of JK Flipflop along with its circuit diagram and characteristic table.

7.

What is T-Flip Flop? Explain clocked JK Flip-Flop with its logic diagram and truth table.

8.

Design MOD-7 counter with state and timing diagram.

Group C

Attempt any TWO questions

[2x10=20]
9.

Define PLA. Design PLA circuit with given function.
F1(A, B, C) = Σ(3,5,6,7)
F2(A, B, C) = Σ(0,2,4,7)
Design PLA Program table also.

10.

Distinguish between sequential and combinational logic with example? Discuss the design procedure of combinational logic.

11.

A sequential circuit with two D flip flops, A and B, two inputs x and y, and one output z, is specified by the following next state and output equations.
A(t + 1) = x'y + xA
B(t + 1) = x/B + xA
z = B
1.Draw the logic diagram.
2.Derive the state

3.Derive the state diagram.