Paper 1: CPU Architecture Flashcards
What is the Von Neumann Architecture?
Data and instructions (Programs) are stored together in memory
This allows the computer to run different programs rather than just complete one type of task.
What does the Control Unit (CU) do?
Directs the flow of data inside the CPU and manages all CPU components
It tells them when to work.
What is the function of the Arithmetic Logic Unit (ALU)?
Carries out calculations and logical operations such as AND, OR, NOT and Binary shifts.
What is a Register in CPU architecture?
Memory that stores one piece of data, an Instruction or an address.
What does the Program Counter (PC) store?
The address of the next instruction in the cycle.
What is the role of the Memory Address Register (MAR)?
Stores the address currently in use by the CPU.
What does the Memory Data Register (MDR) store?
Stores Data fetched or to be written to memory.
What is the function of the Current Instruction Register (CIR)?
Stores the Current Instruction that has been fetched and the CPU is working on.
What does the Accumulator (ACC) store?
Stores the result of any calculations being carried out by the ALU.
What is the purpose of the Address Bus?
Sends the address of the memory to be accessed.
What does the Control Bus do?
Sends the signal to say what to do at the memory location, e.g., Store or Load.
What does the Data Bus contain?
Contains the data being sent or fetched from the memory location.
What is the fetch-decode-execute cycle?
The process used by the CPU to process program instructions and data.
What happens first in the fetch-decode-execute cycle?
The Program Counter is incremented.
What happens in the first stage of the 7 stages of the fetch-decode-execute cycle?
The memory address held in the program counter (PC) is copied into the memory address register (MAR).
What does the Control Unit signal after copying the address to the MAR?
It tells the processor to send a signal along the address bus to the memory address held in the MAR.
What occurs after the instruction or data is sent to the MDR?
If it is an instruction, it is copied into the Current Instruction Register (CIR).
What happens to the Program Counter after fetching an instruction?
The address in the program counter is incremented by one.
What is decoded by the Control Unit after fetching the instruction?
The instruction in the Current Instruction Register (CIR).
What is the last step in the fetch-decode-execute cycle?
Results of processing are stored in the accumulator (ACC).
True or False: The fetch-decode-execute cycle ends after one execution.
False.
Fill in the blank: The instruction has been completed, so the process returns to step ___ and repeats.
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