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Which of the following CPU registers contains the address of the next instruction to be fetched from the main memory when the previous instruction has been successfully completed?

Which of the following CPU registers contains the address of the next instruction to be fetched from the main memory when the previous instruction has been successfully completed? Correct Answer Program Counter (PC)

Program counter:

  • A program counter is used to keep track of the execution of the program. It contains the memory address of the next instruction to be fetched.
  • The program counter contains the address of the next instruction to be fetched from the main memory when the previous instruction has been successfully completed.
  • The program counter also functions to count the member instruction.
  • As each instruction gets fetched, the program counter increases its stored value by 1.


Accumulator:

  • “Accumulator” is the most frequently used register to store data from memory. It is an indifferent number in the different microprocessors.
  • An Accumulator is a register for the short term, intermediate storage of arithmetic and logic data in a computerized CPU.
  • Intermediate results of an operation are progressively written to the accumulator, overwriting the previous value.

 

Memory Address Register:

  • The ‘MAR’ (Memory Address Register) is the CPU register that either stores the memory address from which data will be fetched to the CPU or the address to which data will be sent and stored.
  • MAR holds the address of the location to be accessed from memory.


Memory Data Register:

  • MDR (Memory Data Register) also known as MBR (Memory Buffer Register) is the register in a computer processor, or control processing unit, CPU, that stored the data being transferred to and from the immediate access storage.
  • When reading from the memory, data addressed by MAR is fed into the MDR and then used by the CPU. When writing to memory, the CPU writes data from MDR to memory location whose address is stored in MAR.

 

Confusion Things:

  • “Instruction Register” is the register that holds the instruction which is currently being executed.
  • The difference between stack pointer and the program counter is that the stack pointer is a register that stores the address of the last program largest in a stack while the program counter is a register that stores the address of the next instruction to be executed from the memory.

Related Questions

On a non-pipelined sequential processor, a program segment, which is a part of the interrupt service routine, is given to transfer 500 bytes from an I/O device to memory.     Initialize the address register     Initialize the count to 500 LOOP: Load a byte from device     Store in memory at address given by address register     Increment the address register     Decrement the count     If count! = 0 go to LOOP Assume that each statement in this program is equivalent to a machine instruction which takes one clock cycle to execute if it is a non-load/store instruction. The load-store instructions take two clock cycles to execute. The designer of the system also has an alternate approach of using the DMA controller to implement the same transfer. The DMA controller requires 20 clock cycles for initialization and other overheads. Each DMA transfer cycle takes two clock cycles to transfer one byte of data from the device to the memory. What is the approximate speedup when the DMA controller based design is used in place of the interrupt driven program based input-output?
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Consider the following statements in order to perform a write operation into a specified memory location, the MDR and MAR: 1. The word to be stored into the memory location is first loaded by the CPU into MDR. 2. The address of the location into which the word is to be stored is loaded by the CPU into MAR. 3. A write signal is issued by the CPU. Which of the above statements are correct ? 
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Consider the following two C code segment. Y and X are one- and two-dimensional arrays of size n and n × n respectively, where 2 ≤ n ≤ 10. Assume that in both code segments, elements of y are initialized to 0 and each element X[i] [j] of array X is initialized to i + j. Further assume that when stored in main memory all elements of x are in same main memory page frame. Code segment 1:                 //initialize elements of y to 0                 //initialize elements X[i] [j] of X to i+j                       for (i = 0; i < n; i++)                                 Y[i] += X[0] [i]; Code Segment 2:                 //initialize elements of Y to 0                 //initialize elements X[i] [j] of X to i+j                        for (i = 0; i < n; i++)                                 Y[i] += X[i] [0]; Which of the following statements is/are correct? S1: Final contents of array Y will be same in both code segments S2: Elements of array X accessed inside the for loop shown in code segment 1 are contiguous in main memory S3: Elements of array X accessed inside the for loop shown in code segment 2 are contiguous in main memory
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