Digital Logic and Design MCQs with Answers
Practice important Digital Logic and Design MCQs with answers and explanations.
Chapter: 35
Q721:
How is the test vector used to specify a logic 0 output when the Clear input is logic 0?
A. By setting all inputs to 1
B. By setting the Clear input to 0
C. By setting the clock signal
D. By setting the enable signal
Correct Answer:
B
Chapter: 36
Q722:
What type of flip-flop was used in the original 3-bit Up/Down Counter?
A. D flip-flop
B. T flip-flop
C. SR flip-flop
D. JK flip-flop
Correct Answer:
D
Chapter: 36
Q723:
In the 3-bit Up/Down Counter, what input controls the counting direction?
A. Clock
B. Clear
C. X input
D. Q0 input
Correct Answer:
C
Chapter: 36
Q724:
Which equation defines the D1 input in the 3-bit Up/Down Counter?
A. D1 = Q1Q0X
B. D1 = Q0 ⊕ Q1 ⊕ X
C. D1 = Q2Q0X
D. D1 = Q0Q1X
Correct Answer:
B
Chapter: 36
Q725:
What state does the elevator system start in according to the state diagram?
A. Up State
B. Close 1 State
C. Wait 2 State
D. Wait 1 State
Correct Answer:
D
Chapter: 36
Q726:
What does the ABEL statement [Q0, Q1, Q2].CLK = clock define?
A. Synchronous reset
B. Asynchronous reset
C. State change on clock
D. Clock initialization
Correct Answer:
C
Chapter: 36
Q727:
What is the output of the elevator system in the Up State (U)?
A. Door=0, Motion=0, Dir=0
B. Door=1, Motion=0, Dir=0
C. Door=0, Motion=1, Dir=1
D. Door=1, Motion=1, Dir=0
Correct Answer:
D
Chapter: 36
Q728:
Which state represents the elevator waiting with the door open on floor 2?
A. Close 2 State (C2)
B. Wait 1 State (W1)
C. Wait 2 State (W2)
D. Down State (D)
Correct Answer:
C
Chapter: 36
Q729:
The _____________ input overrides the ________ input
A. Asynchronous, synchronous
B. Synchronous, asynchronous
C. Preset input (PRE), Clear input (CLR)
D. Clear input (CLR), Preset input (PRE)
Correct Answer:
A
Chapter: 36
Q730:
The essential difference between synchronous and asynchronous counters is that the synchronous counters ________.
A. Use a clock pulse to control changes
B. Do not use a clock pulse to control changes
C. Operate at varying speeds
D. Are used for special applications
Correct Answer:
A
Chapter: 36
Q731:
In the Down State (D), what direction does the elevator move?
A. Up
B. Down
C. Stationary
D. Both
Correct Answer:
B
Chapter: 36
Q732:
What happens when the Clear input is set to 0 in the 3-bit Up/Down Counter?
A. The counter increments
B. The counter decrements
C. The counter is reset to 000
D. The counter stays unchanged
Correct Answer:
C
Chapter: 36
Q733:
Which statement best describes the function of the Clock signal in the elevator system?
A. Controls door open time
B. Controls floor requests
C. Controls state transitions
D. Controls direction of movement
Correct Answer:
C
Chapter: 36
Q734:
What is the purpose of the ARRIVE signal in the elevator system?
A. Indicate door is closed
B. Indicate elevator is on floor
C. Indicate door is open
D. Indicate motion has stopped
Correct Answer:
B
Chapter: 36
Q735:
How many states are there in the elevator's state diagram?
A. 4
B. 5
C. 6
D. 7
Correct Answer:
C
Chapter: 36
Q736:
What is the output signal configuration in Close 1 State (C1)?
A. Door=0, Motion=0, Dir=0
B. Door=1, Motion=0, Dir=0
C. Door=1, Motion=1, Dir=1
D. Door=0, Motion=1, Dir=1
Correct Answer:
B
Chapter: 36
Q737:
In the state diagram, which state does the elevator move to after Wait 1 State (W1)?
A. Close 2 State (C2)
B. Up State (U)
C. Down State (D)
D. Close 1 State (C1)
Correct Answer:
D
Chapter: 36
Q738:
How is the next state for Q2 determined in the 3-bit Up/Down Counter?
A. By X input only
B. By Q1 and Q0 inputs
C. By a combination of Q2, Q1, Q0, and X
D. By Clock signal only
Correct Answer:
C
Chapter: 37
Q739:
How many latches are used to store the external inputs in the modified elevator control circuit?
A. Two
B. Three
C. Four
D. Five
Correct Answer:
A
Chapter: 37
Q740:
What does the DIR variable indicate in the elevator system?
A. Motion direction
B. Current floor
C. Door status
D. Request type
Correct Answer:
B