BCA 1st Semester
Digital Logics Board Question Paper 2021

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Tribhuvan university

Bachelor In Computer Application

Course Title: Digital Logics

Code No: CACS 103

Semester:I

2021

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: 453.35 - 321.17 using both 9's and 10's complement.

3.

Simplify given Boolean function in both SOP and POS using k-map where d represents don't care condition.
F (A, B, C, D) = ∏ (2, 3, 4, 5, 7, 9, 10) and ∏ d (0, 6, 11)

4.

Define combinational logic circuit. Design a full adder with its truth table, logic diagram and Boolean expression.

5.

Define Decoder. Design BCD to Decimal decoder with its block diagram, truth table, circuit diagram and mathematical expression.

6.

Explain basic gates and universal gate. Realize NOR gate as a universal gate.

7.

Explain clocked JK flip flop with logic diagram, truth table, characteristic table and excitation table.

8.

Differentiate between synchronous and asynchronous counter. Design 3-bit up ripple counter.

Group C

Attempt any TWO questions

[2x10=20]
9.

Explain PLA with its block diagram. Design a combinational circuit using a ROM that accepts a 3-bit number and generates an output binary number equal to the square of the input number with circuit diagram, truth table and block diagram.

10.

What is counter? Design a mod 7 synchronous counter with state table, state diagram, circuit diagram.

11.

Define multiplexer. Explain 4:1 multiplexer with its block diagram, truth table and logic diagram. Mention how a 4:1 multiplexer works like lower order multiplexer.