Control Unit MCQs – T4Tutorials.com

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1. : What is the primary function of the Control Unit (CU) in a CPU?
(A) To perform arithmetic operations
(B) To manage data storage
(C) To fetch, decode, and execute instructions
(D) To handle input/output operations

2. : Which component of the Control Unit is responsible for generating control signals?
(A) Arithmetic Logic Unit
(B) Register Unit
(C) Control Register
(D) Control Logic

3. : How does the Control Unit interact with the Arithmetic Logic Unit (ALU)?
(A) By providing control signals to execute arithmetic operations
(B) By storing results in memory
(C) By managing input/output operations
(D) By decoding instructions

4. : What role does the Instruction Register (IR) play in the Control Unit?
(A) It holds the current instruction being executed
(B) It stores data temporarily
(C) It manages memory addresses
(D) It generates control signals

5. : How does the Control Unit determine the next instruction to execute?
(A) By using the Program Counter (PC)
(B) By fetching data from memory
(C) By storing intermediate results
(D) By performing arithmetic operations

6. : What is the function of the Program Counter (PC) in the Control Unit?
(A) To keep track of the address of the next instruction to execute
(B) To store the current instruction
(C) To manage data transfer
(D) To generate control signals

7. : Which unit within the Control Unit is responsible for decoding instructions?
(A) Decoder Unit
(B) Arithmetic Unit
(C) Register Unit
(D) Logic Unit

8. : How does the Control Unit handle branching instructions?
(A) By updating the Program Counter with the branch address
(B) By executing arithmetic operations
(C) By storing results in the accumulator
(D) By generating control signals

9. : What type of signal does the Control Unit send to the ALU for an addition operation?
(A) Control signal
(B) Data signal
(C) Address signal
(D) Status signal

10. : Which part of the Control Unit is responsible for timing the execution of instructions?
(A) Clock signal generator
(B) Data Bus
(C) Address Bus
(D) Memory Unit

11. : How does the Control Unit manage the execution of a loop in a program?
(A) By using the Program Counter to repeatedly execute instructions
(B) By storing the loop instructions in memory
(C) By performing arithmetic operations
(D) By managing input/output operations

12. : What is the role of the Control Unit in handling interrupts?
(A) It suspends the current execution and transfers control to the interrupt service routine
(B) It manages data transfer between devices
(C) It performs arithmetic calculations
(D) It updates memory addresses

13. : How does the Control Unit coordinate with memory during instruction execution?
(A) By sending address and control signals to memory
(B) By performing arithmetic operations
(C) By managing input/output operations
(D) By storing data in the register

14. : Which component within the Control Unit helps in executing conditional instructions?
(A) Instruction Decoder
(B) Arithmetic Logic Unit
(C) Program Counter
(D) Memory Address Register

15. : What happens when the Control Unit encounters a jump instruction?
(A) It updates the Program Counter to the target address
(B) It performs a subtraction operation
(C) It stores data in the accumulator
(D) It generates a carry signal

16. : How does the Control Unit handle a halt instruction?
(A) It stops the execution of instructions
(B) It stores results in memory
(C) It performs a logical shift
(D) It manages data transfer

17. : What role does the Control Unit play in pipelined processing?
(A) It manages instruction stages to improve CPU performance
(B) It performs arithmetic calculations
(C) It handles input/output operations
(D) It stores intermediate results

18. : Which control signal is responsible for reading data from memory?
(A) Read Signal
(B) Write Signal
(C) Address Signal
(D) Data Signal

19. : How does the Control Unit execute a subroutine call?
(A) By saving the return address and jumping to the subroutine
(B) By performing arithmetic operations
(C) By managing input/output operations
(D) By updating the memory address

20. : What is the purpose of the instruction decoder within the Control Unit?
(A) To interpret and decode the instruction for execution
(B) To store intermediate results
(C) To manage data transfer
(D) To generate control signals

21. : How does the Control Unit interact with the status flags?
(A) It checks status flags to determine the outcome of operations
(B) It performs arithmetic operations
(C) It stores results in memory
(D) It handles input/output operations

22. : What does the Control Unit do when it receives a reset signal?
(A) It initializes the Program Counter and other registers
(B) It performs a bitwise operation
(C) It manages data transfer
(D) It executes arithmetic operations

23. : How does the Control Unit handle direct memory access (DMA) operations?
(A) By coordinating with the DMA controller to transfer data directly between memory and peripherals
(B) By performing arithmetic operations
(C) By storing results in the accumulator
(D) By updating the Program Counter

24. : What is the role of the Control Unit in executing a logical operation?
(A) To send control signals to the ALU for logical operations
(B) To perform arithmetic calculations
(C) To manage memory addresses
(D) To store intermediate results

25. : How does the Control Unit manage multiple instruction cycles?
(A) By controlling the fetch, decode, and execute phases in sequence
(B) By performing simultaneous operations
(C) By storing instructions in memory
(D) By managing data transfer

26. : Which register within the Control Unit holds the address of the next instruction to be executed?
(A) Program Counter
(B) Instruction Register
(C) Memory Address Register
(D) Data Register

27. : How does the Control Unit ensure that instructions are executed in the correct sequence?
(A) By incrementing the Program Counter after each instruction
(B) By performing arithmetic operations
(C) By managing memory access
(D) By handling input/output operations

28. : What is the purpose of the Control Unit’s timing signals?
(A) To synchronize the operations of the CPU
(B) To perform arithmetic operations
(C) To manage data storage
(D) To handle input/output operations

29. : How does the Control Unit handle an unconditional branch instruction?
(A) By updating the Program Counter with the new address
(B) By storing the current instruction in memory
(C) By performing a logical shift
(D) By managing data transfer

30. : What is the function of the Control Unit in relation to memory read and write operations?
(A) It generates the necessary control signals to perform read and write operations
(B) It performs arithmetic calculations
(C) It manages input/output operations
(D) It stores intermediate results

31. : How does the Control Unit handle instruction pipelining?
(A) By managing overlapping instruction execution stages
(B) By performing simultaneous operations
(C) By storing results in memory
(D) By handling data transfer

32. : What happens in the Control Unit during the decode phase of instruction execution?
(A) The instruction is decoded into a form that can be executed
(B) Data is transferred to memory
(C) Arithmetic operations are performed
(D) The Program Counter is updated

33. : How does the Control Unit handle interrupts in a multi-tasking environment?
(A) By prioritizing and managing multiple interrupt requests
(B) By performing arithmetic operations
(C) By storing intermediate results
(D) By updating memory addresses

34. : What is the function of the Control Unit in executing an input/output operation?
(A) To generate control signals for managing I/O devices
(B) To perform arithmetic calculations
(C) To manage memory addresses
(D) To store data temporarily

35. : How does the Control Unit manage the execution of a loop?
(A) By repeatedly executing instructions based on the loop counter
(B) By storing the loop instructions in memory
(C) By performing arithmetic operations
(D) By handling input/output operations

36. : Which component within the Control Unit is responsible for instruction fetch operations?
(A) Program Counter
(B) Instruction Register
(C) Memory Address Register
(D) Arithmetic Logic Unit

37. : How does the Control Unit interact with the system clock?
(A) It uses clock signals to synchronize the timing of operations
(B) It performs arithmetic calculations
(C) It manages memory access
(D) It handles data transfer

38. : What is the purpose of the Control Unit’s microinstructions?
(A) To provide detailed control signals for each step of instruction execution
(B) To perform arithmetic operations
(C) To manage memory addresses
(D) To handle input/output operations

39. : How does the Control Unit handle conditional branch instructions?
(A) By evaluating condition codes and updating the Program Counter accordingly
(B) By performing arithmetic operations
(C) By storing the branch address in memory
(D) By generating control signals for data transfer

40. : What is the role of the Control Unit in handling a software interrupt?
(A) To transfer control to the interrupt handler routine
(B) To perform arithmetic operations
(C) To store intermediate results
(D) To manage data transfer

41. : How does the Control Unit execute a hardware interrupt?
(A) By saving the current state and jumping to the interrupt service routine
(B) By performing arithmetic operations
(C) By managing input/output operations
(D) By updating memory addresses

42. : What is the function of the Control Unit during the execute phase of instruction execution?
(A) To carry out the operation specified by the decoded instruction
(B) To store data in memory
(C) To perform a logical shift
(D) To manage input/output operations

43. : How does the Control Unit coordinate with the memory unit during instruction execution?
(A) By sending address and control signals for fetching and storing data
(B) By performing arithmetic calculations
(C) By managing input/output operations
(D) By storing intermediate results

44. : What is the role of the Control Unit’s instruction cycle?
(A) To perform the sequence of fetching, decoding, and executing instructions
(B) To manage data transfer
(C) To perform arithmetic operations
(D) To handle input/output operations

45. : How does the Control Unit manage the execution of complex instructions?
(A) By breaking down complex instructions into simpler micro-operations
(B) By storing results in memory
(C) By managing input/output operations
(D) By performing arithmetic calculations

46. : Which component within the Control Unit updates the Instruction Register?
(A) Fetch Unit
(B) Decode Unit
(C) Execute Unit
(D) Control Logic

47. : How does the Control Unit handle multiple stages of instruction execution?
(A) By managing each stage of the instruction cycle in a pipelined manner
(B) By performing arithmetic operations simultaneously
(C) By storing instructions in memory
(D) By managing input/output operations

48. : What is the purpose of the Control Unit’s timing signals in relation to the system clock?
(A) To synchronize the execution of instructions with clock cycles
(B) To perform arithmetic calculations
(C) To manage memory addresses
(D) To handle data transfer

49. : How does the Control Unit interact with the CPU’s registers?
(A) By managing data flow to and from the registers during instruction execution
(B) By performing arithmetic operations
(C) By managing input/output operations
(D) By storing intermediate results

50. : What happens during the fetch phase of the instruction cycle?
(A) The Control Unit retrieves the next instruction from memory
(B) Data is transferred to memory
(C) Arithmetic operations are performed
(D) The Program Counter is updated

51. : What is the role of the Control Unit in a pipeline with multiple execution units?
(A) To schedule instructions to various execution units and manage data flow
(B) To perform arithmetic operations
(C) To manage memory addresses
(D) To handle input/output operations

52. : How does the Control Unit deal with cache coherence in multi-core processors?
(A) By managing consistent data access across multiple cores
(B) By performing arithmetic calculations
(C) By storing results in memory
(D) By handling input/output operations

53. : What is the function of the Control Unit in handling out-of-order execution?
(A) To manage the execution of instructions in an order different from the program sequence for performance
(B) To perform arithmetic operations
(C) To manage memory addresses
(D) To handle data transfer

54. : How does the Control Unit manage speculative execution?
(A) By executing instructions before their actual necessity is confirmed to improve performance
(B) By performing arithmetic calculations
(C) By managing memory addresses
(D) By handling input/output operations

55. : What is the role of the Control Unit in handling context switching?
(A) To save and restore the state of a process during a context switch
(B) To perform arithmetic operations
(C) To manage memory addresses
(D) To handle data transfer

56. : How does the Control Unit ensure correct execution of instructions in a multi-threaded environment?
(A) By managing thread contexts and scheduling instructions appropriately
(B) By performing arithmetic operations
(C) By managing memory addresses
(D) By handling data transfer

57. : What is the function of the Control Unit’s branch target buffer?
(A) To predict the target address of branch instructions for faster execution
(B) To perform arithmetic calculations
(C) To manage memory addresses
(D) To handle data transfer

58. : How does the Control Unit manage instruction prefetching?
(A) By loading instructions into the cache before they are needed for execution
(B) By performing arithmetic operations
(C) By managing memory addresses
(D) By handling data transfer

59. : What is the role of the Control Unit in handling memory protection?
(A) To enforce access controls and prevent unauthorized memory access
(B) To perform arithmetic calculations
(C) To manage memory addresses
(D) To handle data transfer

60. : How does the Control Unit handle vector instructions in SIMD architecture?
(A) By managing the execution of instructions that operate on multiple data elements simultaneously
(B) By performing arithmetic operations
(C) By managing memory addresses
(D) By handling data transfer

Control Unit MCQs
By: Prof. Dr. Fazal Rehman | Last updated: June 19, 2025

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