Machine Instruction Cycle

What is the role of the Arithmetic and Logic Unit (ALU) in the CPU?

• It controls the clock through the control unit.

• It is responsible for calculations such as addition, multiplication, and logic such as AND and OR.

• It stores the memory address that holds the next instruction to be read.

• It holds the data that has just been read or is about to be stored in a memory location.

What does the Program Counter (PC) do?

• It stores the current instruction during the time it is being processed.

• It holds the memory location address that is about to be written or read from.

• It stores the value of the current index being accessed.

• It stores the memory address that holds the next instruction to be read and increments/changes the program counter from one instruction to the next.

What is the function of the Memory Address Register (MAR)?

• It holds the data that has just been read or is about to be stored in a memory location.

• It stores the current instruction during the time it is being processed.

• It holds the memory location address that is about to be written or read from.

• It stores the value of the current index being accessed.

What is the purpose of the Index Register (IR)?

• It holds the memory location address that is about to be written or read from.

• It stores the value of the current index being accessed and is used when accessing array variables.

• It stores the memory address that holds the next instruction to be read.

• It holds the data that has just been read or is about to be stored in a memory location.

What is the first step in the fetch decode execute cycle?

• The value from the program counter is copied to the MAR

• A request is made to retrieve the data from the memory location

• The content of the memory location is sent via the Data Bus to the MDR

• A check for interrupts is made

What is the purpose of the CIR in the fetch decode execute sequence?

• It stores the value of the program counter

• It decodes the value of the instruction

• It sends a request to retrieve data from memory

• It checks for interrupts

At what point in the fetch decode execute sequence is a check for interrupts made?

• After the program counter is iterated

• Before the data is moved to the accumulator

• After the data is moved to the accumulator

• Before the value of the CIR is decoded

According to the note, when can the program counter be iterated in the fetch decode execute cycle?

• Only after the loop starts again

• Before the data is fetched from memory

• At any point after the data is accessed from the memory location

• Only before the CIR is decoded

In the fetch decode execute cycle, what is the role of the Memory Data Register (MDR)?

• It holds the memory location address that is about to be written or read from.

• It stores the data that has just been read or is about to be stored.

• It contains the memory address of the next instruction.

• It stores the current instruction during processing.

What is the primary function of the accumulator in the fetch-execute cycle?

• To store the address of the next instruction to be fetched

• To temporarily hold the data fetched from memory or the result of arithmetic/logical operations

• To decode the instruction fetched from memory

• To control the flow of data within the CPU