Important Digital Logic and Design Short Questions
Chapter: 28
Question 1:
What is the role of the NOR gate in a truncated Mod-7 counter?
Answer:
The NOR gate helps determine when to reset the counter to a preset value once it reaches the terminal count.
Chapter: 28
Question 2:
How does a cascaded 12-bit counter work with initial counts and reloading?
Answer:
The 12-bit counter is loaded with an initial count and reloaded to this value upon reaching the maximum count, allowing larger counts.
Chapter: 28
Question 3:
What configuration is used for a 74HC163 to implement a Mod-9 counter?
Answer:
The 74HC163 is configured with logic gates to reset the counter to 0000 upon reaching the count 1001.
Chapter: 29
Question 4:
What is the main difference between a down-counter and an up-counter?
Answer:
A down-counter counts in descending order and is implemented by connecting the Q0 and Q1 outputs with an AND gate to the complementary outputs of the flip-flops.
Chapter: 29
Question 5:
How does the UP/DOWN input affect the counting direction of an Up-Down Counter?
Answer:
Setting the UP/DOWN input to logic 1 makes the counter count upwards, while setting it to logic 0 makes it count downwards.
Chapter: 29
Question 6:
What are the main components of the 74HC190 4-bit Up/Down Counter IC?
Answer:
The 74HC190 has parallel data inputs (D0 to D3), data outputs (Q0 to Q3), a CLOCK signal, an active-low LOAD input, an active-low CTEN counter enable input, a D/U input for counting direction, a MAX/MIN output, and an RCO (Ripple Clock Output).
Chapter: 29
Question 7:
How is a digital clock implemented using counters?
Answer:
A digital clock uses a 50 Hz signal divided to 1 Hz by a counter, with further divide-by-60 counters for seconds and minutes. The hours are counted using a decade counter and a flip-flop for 12-hour representation.
Chapter: 29
Question 8:
What is the purpose of the RCO (Ripple Clock Output) in the 74HC190 counter?
Answer:
The RCO output goes low when the counter reaches terminal counts 1001 (counting up) or 0000 (counting down) and can be used to cascade multiple counter ICs.
Chapter: 29
Question 9:
How can glitches in a counter decoder circuit be minimized?
Answer:
Glitches can be minimized by using the strobing method, where the decoder outputs are enabled only during the positive half of the clock signal to avoid glitches occurring during the negative half.
Chapter: 29
Question 10:
What does the term "glitch" refer to in digital counters?
Answer:
A glitch refers to short, unwanted pulses or noise that occur due to propagation delays in counters and decoders, causing incorrect or erratic output states.