FetchExecuteZyklus

The Fetch-Execute Cycle, also known as the instruction cycle, is the fundamental process by which a computer's central processing unit (CPU) executes instructions. It is a repetitive sequence of operations that the CPU performs for each instruction in a program.

The cycle begins with the fetch phase, where the CPU retrieves the next instruction from memory. This instruction is identified by the program counter, a special register that holds the memory address of the next instruction to be executed. The fetched instruction is then loaded into the instruction register.

Following the fetch phase is the decode phase. During this stage, the CPU interprets the instruction to determine what operation needs to be performed and what data, if any, is involved. This interpretation involves understanding the instruction's opcode and any associated operands.

The execute phase is where the actual operation specified by the instruction is carried out. This could involve arithmetic or logical operations performed by the Arithmetic Logic Unit (ALU), data movement between registers and memory, or control flow changes like jumps or branches.

After execution, the cycle may involve a write-back phase, where the result of the operation is stored back into a register or memory. The program counter is then updated to point to the next instruction, and the cycle repeats, continuing the execution of the program until it is completed or interrupted. This continuous loop of fetching, decoding, and executing instructions is the core of how computers run software.