B CompE Bachelor of Computer Engineering Digital Logic and Circuit Design 1 — Questions and Answers
Question 1: Which logic gate produces an output of 1 only when all inputs are 1?
- OR gate
- AND gate (Correct answer)
- NAND gate
- XOR gate
Correct answer: AND gate
An AND gate outputs 1 (HIGH) only when all of its inputs are simultaneously 1; otherwise it outputs 0.
Question 2: What is the decimal equivalent of the binary number 1011?
- 9
- 10
- 11 (Correct answer)
- 12
Correct answer: 11
Binary 1011 = 1x8 + 0x4 + 1x2 + 1x1 = 8 + 0 + 2 + 1 = 11 in decimal.
Question 3: Which of the following is a minimization technique for Boolean expressions?
- De Morgan's Theorem
- Karnaugh Map (K-map) (Correct answer)
- Shannon's Theorem
- Venn Diagram
Correct answer: Karnaugh Map (K-map)
A Karnaugh Map (K-map) is a visual method for simplifying Boolean expressions by grouping adjacent minterms.
Question 4: What type of logic circuit has its output depend only on the current inputs with no memory?
- Sequential Circuit
- Combinational Circuit (Correct answer)
- Finite State Machine
- Flip-flop
Correct answer: Combinational Circuit
A combinational circuit produces outputs determined solely by current inputs, with no feedback or memory elements.
Question 5: Which flip-flop sets output Q=1 on S=1,R=0, and resets Q=0 on S=0,R=1?
- D Flip-Flop
- JK Flip-Flop
- SR Flip-Flop (Correct answer)
- T Flip-Flop
Correct answer: SR Flip-Flop
The SR (Set-Reset) flip-flop sets Q to 1 when S=1,R=0 and resets Q to 0 when S=0,R=1; the S=R=1 state is invalid.
Question 6: What is the output of an XOR gate when both inputs are equal?
- 1
- 0 (Correct answer)
- Depends on the input values
- Undefined
Correct answer: 0
An XOR gate outputs 0 when both inputs are the same (both 0 or both 1) and outputs 1 only when inputs differ.
B CompE Bachelor of Computer Engineering Digital Logic and Circuit Design 1
Which logic gate produces an output of 1 only when all inputs are 1?