The CPU (Central Processing Unit) is the core component of a computer responsible for carrying out instructions from programs. It performs the fetch-decode-execute cycle to process data and run applications.
🧠 Basic Operation of a CPU: The Fetch-Decode-Execute Cycle
Fetch
- The CPU fetches (retrieves) an instruction from memory (RAM).
- The address of the instruction is held in the Program Counter (PC).
- The instruction is loaded into the Instruction Register (IR).
Decode
- The Control Unit (CU) decodes the instruction to understand what action is required.
- It identifies the operation (e.g., addition, comparison) and which data or registers are involved.
Execute
- The Arithmetic Logic Unit (ALU) or Floating Point Unit (FPU) executes the instruction.
- This could involve performing a calculation, moving data, or making a decision (e.g., branching).
Store (optional step)
- The result may be stored back in a register or in memory (RAM).
🧩 Main Components of the CPU
- Component Description
- Control Unit (CU) Directs operations of the CPU and coordinates activities.
- Arithmetic Logic Unit (ALU) Performs arithmetic (add, subtract) and logic (AND, OR) operations.
- Registers Small, fast storage areas for immediate data (e.g., accumulator, program counter).
- Cache Small, high-speed memory within the CPU to store frequently used data.
- Buses Pathways that carry data, addresses, and control signals between CPU and other parts.
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