TRB PG Assistant - Flip-flops - RS, RST, JK, master–slave, ripple counters, decade counters, up–down counters, serial and parallel registers One Line Questions & Answers

1. Consider a 4-bit ripple counter counting up. If the current count is 1010 (binary), what will be the count after the next clock pulse? — 1011

2. What is the minimum number of flip-flops required to construct a counter that can count up to 15? — 4

3. How many flip-flops are minimally required to build a decade counter? — 4

4. What is the modulus of a standard 4-bit Ring Counter? — 4

5. What is the modulus of a decade counter? — 10

6. In a serial register, data is entered and retrieved: — One bit at a time

7. Edge-triggered flip-flops are preferred over level-triggered flip-flops because they: — Avoid the race around condition

8. In a D flip-flop, the output Q takes the value of the D input on the: — Rising edge of the clock pulse

9. A counter that counts in the sequence 000, 001, 010, 011, 100, 101, 110, 111, 000... is a: — Modulo-16 counter (or Binary counter)

10. When the mode select input of an up-down counter is HIGH, it typically counts: — Up

11. What additional control input is typically required for an up-down counter? — Mode select (Up/Down)

12. What is a common application of shift registers? — Data serialization and de-serialization

13. What is the advantage of a Johnson Counter over a Ring Counter? — Counts to a higher modulus using the same number of flip-flops

14. What is the fundamental characteristic of a flip-flop? — It can store only one bit of information.

15. What is the primary advantage of a JK flip-flop over an SR flip-flop? — It resolves the indeterminate state of the SR flip-flop.

16. What is the purpose of the 'master' in a master-slave flip-flop? — It receives inputs first and stores them.

17. In a JK flip-flop, when both J and K inputs are HIGH (1), what happens to the output on the clock edge? — It toggles.

18. Which type of flip-flop is the simplest bistable multivibrator? — RS Flip-Flop

19. Which counter design avoids the 'race around condition' by using edge-triggering? — Master-slave JK flip-flop counter

20. What is the main disadvantage of a ripple counter compared to a synchronous counter? — Lower speed

21. In a master-slave flip-flop, when does the 'slave' section get updated? — On the falling edge of the clock pulse.

22. In a parallel register, data is entered and retrieved: — All bits simultaneously

23. A universal shift register can perform: — Both serial and parallel shifts, and potentially rotations

24. In an SR flip-flop, what is the state when both S (Set) and R (Reset) inputs are HIGH (1)? — Invalid/Forbidden state

25. A SIPO register is commonly used for: — Serial to parallel conversion

26. What is a register primarily used for? — Storing a group of bits

27. What is the state table for an SR flip-flop with S=0 and R=0? — Q(next) = Q (no change)

28. What problem does the master-slave configuration primarily address in flip-flops? — Race around condition

29. Which type of counter uses flip-flops that are all triggered simultaneously by the clock pulse? — Synchronous counter

30. A Ring Counter is a type of: — Shift register

31. A counter that counts through a specific sequence of states, typically 0 to 9, is called a: — Decade counter

32. Which type of counter can count in both increasing and decreasing directions? — Up-down counter

33. In a parallel-in/parallel-out (PIPO) shift register, all bits are loaded and read out: — Simultaneously in one clock cycle

34. A PIPO register is useful for: — Temporary data storage where speed is critical

35. A PISO register is primarily used for: — Parallel to serial conversion

36. A Johnson Counter (or Twisted Ring Counter) is created by connecting the output of the last flip-flop to the ______ input of the first flip-flop. — Complement (inverted output)

37. Which register type allows data to be loaded in parallel and read out serially? — PISO

38. Which type of register allows data to be input and output simultaneously, one bit after another? — SISO (Serial-In, Serial-Out)

39. Which of the following is NOT a type of flip-flop? — XY

40. Which flip-flop is often used to implement a delay element in digital circuits? — D Flip-Flop

41. What is the 'race around condition' primarily associated with? — JK flip-flops operating in toggle mode with level triggering

42. Which counter type is most susceptible to glitches caused by propagation delays? — Ripple counter

43. A ripple counter is also known as a: — Asynchronous counter

44. Which input condition causes a T flip-flop to toggle its output state? — T = 1

45. What is the maximum frequency a ripple counter can reliably count at? — The clock frequency divided by the number of flip-flops

46. An RST flip-flop includes an additional input 'T' (Toggle). What happens when T=1? — The flip-flop toggles its output.

47. What is the primary function of the 'preset' and 'clear' inputs on many flip-flops? — To asynchronously set or reset the flip-flop's output

48. In a Ring Counter, how is the last flip-flop's output connected? — To the input of the first flip-flop

49. In a ripple counter, how is the clock input of each subsequent flip-flop connected? — To the output of the previous flip-flop

50. What does the 'T' in T flip-flop stand for? — Toggle

Flip-flops - RS, RST, JK, master–slave, ripple counters, decade counters, up–down counters, serial and parallel registers - One Line Questions