Tribhuvan University
Bachelor of Computer Application
Semester 1 · TU Board 2026
Course Title: Digital Logic (CACS103)
Full Marks: 60Pass Marks: 24Time: 3 hours
Group B
Attempt any SIX question.(6 × 5 = 30)
- 2.5
What is 2's complement? Subtract (10110)₂ − (01011)₂ using 2's complement method.
Answer comingAlso asked in 2022, 2021, 2019, Model question
- 3.5
Define Half Adder and Full Adder. Design a Full Adder circuit with its truth table, Boolean expressions, and logic diagram.
Answer comingAlso asked in 2026, 2022, 2021
- 4.5
Explain D flip flop with characteristics table, equation and logical circuit.
- 5.5
Design full adder with truth table logical expression and logical circuit.
Answer comingAlso asked in 2026, 2022, 2021
- 6.5
What is a Decoder? Explain a 2:4 Decoder with its block diagram, truth table, and logic circuit.
Answer comingAlso asked in 2023, 2022, 2021, 2020, 2019
- 7.5
Prove De Morgan's second theorem (A · B)' = A' + B' using a truth table. Also realize a basic AND gate using NAND gates only.
- 8.5
What is shift register? Explain different types of shift register.
Answer comingAlso asked in Model question
Group A
Attempt all the questions.(10 × 1 = 10)
- 1.1
a. What is the 2's complement of (10110100)₂? b. Convert (9F)₁₆ to decimal. c. What is the difference between a latch and a flip-flop? d. Write the Boolean expression for an Ex-NOR gate. e. What is a min-term? Give an example for three variables A, B, C. f. What is synchronous counter? g. What is a Full Adder? Write its sum output expression. h. What is the purpose of a multiplexer? i. What is register? j. What is a Ripple counter? State one disadvantage.
Group B
Attempt any SIX questions.(6 × 5 = 30)
- 2.5
What is 2's complement? Subtract (10110)₂ − (01011)₂ using 2's complement method.
Answer comingAlso asked in 2022, 2021, 2019, Model question
- 3.5
Define Half Adder and Full Adder. Design a Full Adder circuit with its truth table, Boolean expressions, and logic diagram.
Answer comingAlso asked in 2026, 2022, 2021
- 4.5
Explain D flip flop with characteristics table, equation and logical circuit.
- 5.5
Design full adder with truth table logical expression and logical circuit.
Answer comingAlso asked in 2026, 2022, 2021
- 6.5
What is a Decoder? Explain a 2:4 Decoder with its block diagram, truth table, and logic circuit.
Answer comingAlso asked in 2023, 2022, 2021, 2020, 2019
- 7.5
Prove De Morgan's second theorem (A · B)' = A' + B' using a truth table. Also realize a basic AND gate using NAND gates only.
- 8.5
What is shift register? Explain different types of shift register.
Answer comingAlso asked in Model question
Group C
Attempt any TWO questions.(2 × 10 = 20)
- 9.10
Minimize the following function using K-Map and Tabulation method respectively F(A,B,C,D) = Σ m(0,1,4,5,8,9,11)
- 10.10
Design a 3-bit synchronous up counter using T flip-flops. Show the state diagram, state table, excitation table, Boolean expressions for inputs, and the complete logic diagram.
- 11.10
Design a combinational circuit with three inputs (X, Y, Z) and three outputs (A, B, C). When the binary input (X, Y, Z) is 0, 1, 2 or 3, the binary output is one greater than the input. When the binary input is 4, 5, 6 or 7, the binary output is one less than the input. Write the Truth Table for the inputs and outputs. Simplify the resulting expressions for A, B and C outputs (use algebra or maps).
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