The Central Processing Unit (CPU) is composed of several key components that work together during the fetch-execute cycle. Understanding the roles of these components is crucial for understanding how a computer processes data and instructions.
Role/Purpose: The ALU performs all arithmetic and logical operations. During the execution phase of the fetch-execute cycle, the ALU performs the operation required by the instruction.
Function in Fetch-Execute Cycle: If the instruction is an arithmetic or logical operation, the ALU receives the data, processes it as required, and returns the result.
Role/Purpose: The Control Unit directs the operations of the processor. It manages the fetch-execute cycle by decoding the instructions and controlling how data moves within the CPU.
Function in Fetch-Execute Cycle: During the decode phase, the CU interprets the instruction and signals the necessary components to act, such as telling the ALU what operation to perform.
Role/Purpose: The cache is a small-sized, high-speed memory located inside the CPU. It stores frequently used data and instructions to speed up the access time.
Function in Fetch-Execute Cycle: The cache provides quick access to frequently used data and instructions. During the fetch phase, if the data or instruction is found in the cache, it speeds up the process significantly.
Role/Purpose: Registers are small, high-speed storage locations directly within the CPU. They temporarily hold data that is being used during the execution phase.
Function in Fetch-Execute Cycle: Registers temporarily hold data, instructions, and addresses. For example, during the fetch phase, the Program Counter (PC) register holds the address of the next instruction, and the Memory Address Register (MAR) holds the address of where to fetch data from.