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Important Digital Logic and Design Short Questions

Chapter: 22
Question 1:
What is the function of select inputs in a Quad 1-of-4 MUX?
Answer: The select inputs determine which one of the four inputs will be sent to the output for all multiplexers.
Chapter: 22
Question 2:
Why is the GAL20V8 device used instead of the GAL16V8 for the Quad MUX?
Answer: The GAL20V8 is used because it has enough pins to implement the Quad MUX, while the GAL16V8 does not.
Chapter: 22
Question 3:
How many input and output pins does the GAL20V8 device have?
Answer: The GAL20V8 device has 12 input pins, 2 special function inputs, and 8 input/output pins.
Chapter: 22
Question 4:
What does the Boolean expression for Aout in a Quad 1-of-4 MUX represent?
Answer: The Boolean expression Aout = !S1 & !S0 & A0 # !S1 & S0 & A1 # S1& !S0 & A2 # S1 & S0 & A3 selects the input A0, A1, A2, or A3 based on the select inputs S1 and S0.
Chapter: 22
Question 5:
What is the significance of the truth table in the Quad 1-of-4 MUX?
Answer: The truth table shows how different combinations of select inputs (S1, S0) map to specific outputs (Aout, Bout, Cout, Dout).
Chapter: 22
Question 6:
What is a sequential circuit in digital electronics?
Answer: A sequential circuit is a type of digital circuit that includes memory elements to store past inputs and outputs.
Chapter: 22
Question 7:
Why are memory elements important in an ALU?
Answer: Memory elements are needed in an ALU to store intermediate results and inputs/outputs for arithmetic operations.
Chapter: 22
Question 8:
What is the primary difference between combinational and sequential circuits?
Answer: Combinational circuits do not store state and produce outputs based solely on current inputs, while sequential circuits use memory elements to store state.
Chapter: 22
Question 9:
How does an S-R latch change state?
Answer: An S-R latch changes state based on the set (S) and reset (R) inputs. The combination of these inputs determines the output state Q and its complement Q.
Chapter: 22
Question 10:
What happens when both S and R inputs of an S-R latch are 0 in NAND-based latches?
Answer: Both Q and Q outputs are invalid when both S and R inputs are 0, as they should be complements of each other.