GROL Digital Logic and Microcomputers 2 — Questions and Answers
Question 1: What is the output of an XNOR gate when both inputs are logic 1?
- Logic 0
- Logic 1 (Correct answer)
- High impedance
- Undefined
Correct answer: Logic 1
An XNOR gate outputs logic 1 when both inputs are the same (both 0 or both 1).
Question 2: Which Boolean expression represents De Morgan's theorem applied to the expression NOT(A AND B)?
- NOT(A) AND NOT(B)
- NOT(A) OR NOT(B) (Correct answer)
- A OR B
- A AND B
Correct answer: NOT(A) OR NOT(B)
De Morgan's theorem states NOT(A AND B) = NOT(A) OR NOT(B).
Question 3: A NAND gate with all inputs tied together functions as which logic gate?
- AND gate
- OR gate
- NOT gate (inverter) (Correct answer)
- XOR gate
Correct answer: NOT gate (inverter)
Tying all NAND inputs together makes it behave as a NOT gate, outputting the complement of the single input.
Question 4: In a sum-of-products (SOP) Boolean expression, terms are combined using which operation at the top level?
- AND
- OR (Correct answer)
- NOT
- XOR
Correct answer: OR
In SOP form, product (AND) terms are summed (OR'd) together at the top level.
Question 5: What is the hexadecimal equivalent of binary 1010 1111?
- A9
- AF (Correct answer)
- BF
- AE
Correct answer: AF
Binary 1010 = hex A and binary 1111 = hex F, so 10101111 = AF in hexadecimal.
Question 6: Which type of logic circuit has outputs that depend only on the current inputs, with no memory or feedback?
- Sequential logic
- Combinational logic (Correct answer)
- Synchronous logic
- Asynchronous logic
Correct answer: Combinational logic
Combinational logic circuits have outputs determined solely by present inputs, with no stored state.
Question 7: What is the two's complement representation of -7 in an 8-bit system?
- 10000111
- 11111000
- 11111001 (Correct answer)
- 01111001
Correct answer: 11111001
To get two's complement of 7 (00000111): invert bits to get 11111000, then add 1 to get 11111001.
GROL Digital Logic and Microcomputers 2
What is the output of an XNOR gate when both inputs are logic 1?