Execution of a Complete Instruction An instruction is a set of instructions that tell the processor how to perform a specific task. When the processor re...
An instruction is a set of instructions that tell the processor how to perform a specific task. When the processor receives an instruction, it interprets it and prepares its internal hardware to execute the task. This involves reading the instruction's details, finding the necessary data and resources, and then performing the task according to the instructions.
Execution is the process of carrying out these steps:
Fetch: The processor retrieves the instruction from memory. This is like a librarian searching for a book in a library.
Decode: The instruction is read and understood by the processor's decoder. This involves breaking down the instruction into its components and figuring out what to do.
Execute: The processor performs the instructions by accessing the necessary data and resources, and then carrying out the required tasks. This could involve performing calculations, accessing memory locations, or controlling the flow of data.
Store results: Once the task is completed, the result is stored in a designated memory location. This is like the book being placed on a shelf in the library.
Let's use an example to illustrate the execution of an instruction:
Imagine you have an instruction to add two numbers, A and B. The processor would follow these steps:
Fetch the instruction from memory.
Decode the instruction to understand that it adds A and B.
Execute the instructions by accessing the values of A and B from memory.
Perform the addition and store the result in a temporary location.
Store the result in the memory location associated with the instruction.
Key points to remember:
Execution is a sequential process that follows the instruction's steps.
It involves reading, understanding, and executing the instructions.
Each instruction is executed by the processor in a specific order.
The execution of an instruction can take multiple machine cycles