Important Digital Logic and Design Short Questions
Chapter: 35
Question 1:
What is the role of start and stop bits in asynchronous serial data transmission?
Answer:
Start and stop bits are used to indicate the beginning and end of a character, ensuring proper synchronization and separation of characters.
Chapter: 35
Question 2:
Describe the function of a Parallel In/Serial Out shift register.
Answer:
It converts parallel data into serial data, allowing multiple bits to be shifted out one at a time.
Chapter: 35
Question 3:
How does a keyboard encoder work with a shift register?
Answer:
A keyboard encoder scans the keys using a shift register-based ring counter to identify which key is pressed and encodes this information.
Chapter: 35
Question 4:
What is the difference between an active-high and an active-low output in PLD?
Answer:
Active-high outputs are asserted when high voltage is applied, while active-low outputs are asserted when low voltage is applied.
Chapter: 35
Question 5:
Explain the significance of the dot extension '.CLK' in logic descriptions.
Answer:
The '.CLK' extension indicates that the register device is clocked, meaning it changes state on a clock edge.
Chapter: 35
Question 6:
How is a Parallel Input/Parallel Output 8-bit Register configured in ABEL?
Answer:
It is configured by declaring pin assignments and specifying logic equations for data input and output, with inverted outputs as needed.
Chapter: 35
Question 7:
What does the 'SHLD' signal do in a 4-bit Parallel In/Serial Out shift register?
Answer:
The 'SHLD' signal controls whether parallel data is loaded into the register or serial data is shifted out.
Chapter: 35
Question 8:
What is the function of the 'One Shot' in the keyboard encoder circuit?
Answer:
The 'One Shot' generates a pulse to handle key press events, ensuring that the key code is properly stored and processed.
Chapter: 36
Question 9:
What is the role of D flip-flops in a 3-bit Up/Down Counter?
Answer:
D flip-flops store the current state and determine the next state of the counter based on the input X and current state.
Chapter: 36
Question 10:
How is the next state determined in a 3-bit Up/Down Counter?
Answer:
The next state is determined using D flip-flop inputs and Boolean expressions derived from the current state and the control input X.