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Important Digital Logic and Design Short Questions

Chapter: 36
Question 1:
What is the Boolean expression for D2 in a 3-bit Up/Down Counter?
Answer: D2 = Q2Q1Q0X + Q2Q1Q0 X + Q2Q0 X + Q2Q1X + Q2Q1Q0
Chapter: 36
Question 2:
How does the 3-bit Up/Down Counter handle an asynchronous clear?
Answer: When the asynchronous clear signal is active (0), all outputs (Q2, Q1, Q0) are reset to 0 regardless of the X input.
Chapter: 36
Question 3:
What are the main states in the elevator control system?
Answer: The main states are Wait 1 (W1), Close 1 (C1), Up (U), Wait 2 (W2), Close 2 (C2), and Down (D).
Chapter: 36
Question 4:
What is the output of the elevator system when in the Up state?
Answer: In the Up state (U), the output is Door=1 (closed), Motion=1 (moving), and Dir=0 (up).
Chapter: 36
Question 5:
When does the elevator transition to the Wait 2 state?
Answer: The elevator transitions to Wait 2 (W2) when it arrives at the second floor and is waiting with the door open.
Chapter: 36
Question 6:
How does the elevator system respond to the Open button in the W1 state?
Answer: If the Open button is pressed in the W1 state, the system remains in Wait 1 (W1) with the door open, regardless of other inputs.
Chapter: 36
Question 7:
What is the purpose of the State Diagram in the elevator control system?
Answer: The State Diagram defines how the elevator transitions between states based on inputs like requests and sensors, and controls the elevator's operation.
Chapter: 36
Question 8:
How is the direction of movement controlled in the elevator system?
Answer: The direction is controlled by the DIR output signal, which is set based on the current state and requests from different floors.
Chapter: 37
Question 9:
How can the number of input latches be reduced in the elevator system?
Answer: By storing REQ1, FLOOR1, and OPEN button outputs on one latch, and REQ2, FLOOR2, and OPEN button outputs on another latch, thus simplifying Boolean expressions and reducing latch count.
Chapter: 37
Question 10:
What is the Boolean expression for setting the SR1 latch in the elevator system?
Answer: The Boolean expression for setting the SR1 latch is REQ1 + FLOOR1.DIR + OPEN.DIR.