BCA 1st Semester
Digital Logics Model Question 2026 - Tribhuvan University (TU) Model Question 2026

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Tribhuvan University

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Bachelor In Computer Application

Course Title: Digital Logics

Code No: BCA 103

Semester: I

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

Candidates candidates must answer the question in their own words as far as possible.

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

Group A (Very Short Questions) Attempt all questions.

[10 × 1 = 10]
1.

a. Define analog signal.
b. What is a binary number system?
c. What is the need for complement?
d. Define a Gray code. Find gray code of 1011010
e. What is a Boolean algebra? How is it different from Binary System?
f. What is a basic logic gate?
g. Define a combinational circuit.
h. What is the race around condition?
i. What is a register?
j. Define a counter.

Section "B"

Group B Attempt any SIX questions.

[6 × 5 = 30]
2.

Convert the following:
a. (101101)₂ to decimal
b. (45)₁₀ to binary

3.

Subtract 23 from 18 using both 1's and 2's complement method.

4.

Simplify Boolean expressions using K-Map
F(A,B,C)=Σ(0,2,4,6) and d= Σ(1,3,)

5.

Describe the working of half adder with logic diagram.

6.

Explain multiplexer with applications.

7.

Explain bidirectional shift register.

8.

Explain different types of flip-flops (RS, JK) with truth table.

Section "C"

Group C Attempt any TWO questions.

[2 × 10 = 20]
9.

Write the steps for designing a combinational circuit. Design a 4-bit magnitude comparator and explain its working principle.

10.

A JK flip-flop is subjected to continuous clock pulses and both J and K inputs are HIGH.
a. Explain what happens in a simple JK flip-flop.
b. Explain how a Master-Slave configuration resolves this issue.
c. Illustrate your answer using a timing diagram

11.

Design a 4-bit binary counter using JK flip-flops.
a. Show logic diagram
b. Explain counting sequence
c. Analyze timing behavior