2.4.2. Instruction Cycle

Now, when we are going to execute the program we can say this is the instruction cycle already I have mentioned that one instruction cannot be done in one step we are having several step and complete collection of all those particular steps are known as my instruction cycle.

The instruction cycle is a fundamental concept in computer architecture that describes how a computer executes a program. It indicates that executing one single instruction requires multiple steps, and the complete set of these steps forms what we call the instruction cycle. This cycle allows the computer to carry out the instructions from a program in a systematic manner.

Think of the instruction cycle like the process of cooking a dish. You don't simply throw all the ingredients into a pot; instead, you follow a recipe step by step. For example, you first gather all your ingredients (fetching), then chop vegetables and mix them (executing), and finally, you serve the dish (completing the process). Each step is vital for making the final product.

In basic way what will happen I can say that instruction cycle consists of 2 steps one we talk about the fetch and second one is execute.

The instruction cycle primarily consists of two main steps: fetching and executing. In the fetching step, the computer retrieves the instruction from its memory. In the executing step, the computer performs the operations specified by that instruction. This sequential process allows the computer to methodically operate through complex tasks. Fetching gets the necessary information from memory, while executing is the action part where the computer does something with that information.

Imagine you are a librarian. When a student asks for a book (fetch), you go to the shelf to find it. Once you have the book, you might explain its contents (execute) or check it out to the student. The fetching of the book and then providing the information is similar to how a computer fetches and executes instructions.

First we have to bring this instruction from this main memory to the processor. So bringing the information from main memory to the processor is known as the fetching of the instruction...

The fetching of an instruction includes various actions, such as moving it from the main memory to the processor, where it can be executed. The execution phase involves performing tasks based on the fetched instruction, which may itself require fetching additional data. This can lead to a sequence of fetch and execute actions until all required operations for an instruction are completed.

Consider a chef preparing a multi-ingredient recipe. The chef first gathers all necessary ingredients (fetching them). Once all ingredients are on the counter, the chef starts cooking (executing). If a specific ingredient isn’t ready, the chef might need to fetch that from the pantry as well, demonstrating that the process can loop back if more information is needed.

…until and unless we are going to get the last instruction which may be end instruction or stop instruction at that particular point we will come out from this cycle and execution of this particular instruction is over.

The instruction cycle continues in a loop, fetching and executing instructions until all have been processed, including a specific 'end' instruction that signifies there are no more tasks. This structured flow is crucial for managing complex programs and ensures that the computer works efficiently.

Think of reading a book. You start at the beginning, read each chapter (instruction cycle), and continue until you reach the end of the book (stop instruction), at which point you've completed the reading. Just like you wouldn't jump to the end of the book without reading preceding chapters, computers sequentially process each instruction during the instruction cycle.

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