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Important Digital Logic and Design Short Questions

Chapter: 17
Question 1:
How is a Decimal-to-BCD Encoder used in a telephone keypad?
Answer: A Decimal-to-BCD Encoder converts the decimal digit pressed on a telephone keypad into its corresponding BCD code, using pull-up resistors to detect key presses.
Chapter: 18
Question 2:
What is a 2-input, 4-bit multiplexer?
Answer: A 2-input, 4-bit multiplexer like the 74X157 has two sets of 4-bit inputs and one 4-bit output. It selects one of the input sets to connect to the output based on the select input.
Chapter: 18
Question 3:
How does the select input work in a 2-input, 4-bit multiplexer?
Answer: The select input in a 2-input, 4-bit multiplexer determines which of the two input sets (A or B) is routed to the output.
Chapter: 18
Question 4:
What does the G pin do in a 2-input, 4-bit multiplexer?
Answer: The G pin is an active-low enable pin that enables or disables the multiplexer. When G is low, the multiplexer is enabled.
Chapter: 18
Question 5:
How is an 8-input multiplexer formed?
Answer: An 8-input multiplexer is formed by connecting two 4-input multiplexers with a NOT gate and OR gate. The select input decides which multiplexer is active.
Chapter: 18
Question 6:
What role does a 2-to-4 decoder play in a 16-input multiplexer?
Answer: The 2-to-4 decoder in a 16-input multiplexer selects one of the four 4-input multiplexers based on its input, allowing selection from 16 different inputs.
Chapter: 18
Question 7:
How can a 2-input, 8-bit multiplexer be implemented?
Answer: A 2-input, 8-bit multiplexer is implemented by connecting two 4-bit multiplexers. The select inputs and enable pins of both multiplexers are connected together.
Chapter: 18
Question 8:
What is the primary use of multiplexers?
Answer: Multiplexers are primarily used to route data from multiple sources to a single destination, functioning as data routers, logic function generators, and more.
Chapter: 18
Question 9:
How does a parallel to serial converter work using a multiplexer?
Answer: A parallel to serial converter uses an 8-to-1 multiplexer to convert 8-bit parallel data into serial data, transmitting one bit at a time over a single wire.
Chapter: 18
Question 10:
What is the difference between Common Anode and Common Cathode 7-segment displays?
Answer: In a Common Anode display, all anodes are connected together and require a positive voltage to light up. In a Common Cathode display, all cathodes are connected together and need to be grounded to light up.