3.6.2. Execution of Programs in Computers

So one simple example I can say that now in general I can say that we are fetching the instruction then we are executing it after completion of the executing we are going to fetch the next instruction. So this is the way we are going to set up fetch and execute, but after fetching some instruction if we know that that instruction needs some data then we have to fetch this particular data from the memory.

In computing, the basic process for executing a program involves two main steps: fetch and execute. First, the computer retrieves an instruction from its memory (fetch). After fetching, it processes (executes) that instruction. Once this instruction is completed, the computer fetches the next instruction. If the fetched instruction requires additional information, typically data stored in the memory, the computer will take an extra step to access this data before executing the instruction.

Think of it like following a recipe while cooking. First, you read the next step of the recipe (fetching the instruction). Then, you perform the action, like chopping onions (executing). If the step requires more ingredients that you need to gather from the pantry (fetching data), you will go and get them before you can continue with the cooking.

So for that we are having this particular indirect cycle we are going to fetch the data from the memory and that data will be supplied to the execution unit and it is going to execute it completely.

Whenever an instruction fetched from memory depends on specific data, the computer enters an indirect cycle. During this phase, it retrieves the necessary data from memory before proceeding to execute the instruction. This ensures that the execution unit has complete information to perform the task accurately.

Imagine you're building a piece of furniture and you need to know the size of screws. First, you read the instructions (fetching the instruction). If the next step requires screws that are stored in a different box, you have to check the box and grab the screws (indirect cycle) before you can continue building.

Here we have shown another one which is written as our interrupt this thing basically related to handling input output devices when we are going to discuss about the I/O module at the time we are going to discuss about this particular interrupt.

Interrupts are signals indicating that an event needs immediate attention from the CPU. This can be triggered by I/O devices, like when a keyboard is pressed or a mouse is moved. The CPU can pause its current activities to handle the interrupt, ensuring timely processing of user inputs and device communications, which enhances responsiveness.

Think of a teacher in a classroom explaining a complex topic. If a student raises their hand with a urgent question (the interrupt), the teacher momentarily stops and addresses the student's query before returning to the lesson. This interruption allows for better engagement and understanding.

So this is the start and nowadays also we say that Charles Babbage is considered as a father of computing in most of the book you are going to have these things.

The narrative of computing technology began with pioneers like Charles Babbage, who is renowned as the father of computing for his conceptualization of the analytical engine, a precursor to modern computers, in the early 19th century. This acknowledgment underscores the historical significance of early computing innovations that laid the groundwork for advancements.

Imagine tracing the lineage of a giant family tree. At the very beginning, one ancestor, like Charles Babbage, represents the foundational figure who inspired generations to develop modern technologies, much like how the analytical engine influenced future computer designs.

Then we are having the concept of our programming how to program these things how to control this particular calculating devices.

Programming represents the means by which humans instruct machines to perform specific tasks. Early programming languages laid the groundwork for controlling the behavior of calculating devices, leading to the complex software systems we use today. Understanding these origins helps to appreciate the evolution of programming from basic commands to sophisticated languages.

Consider a conductor leading an orchestra. The conductor's score represents the programming that guides each musician (the computer components) on when and how to play their instruments, resulting in a cohesive musical performance (the executed program).

So we are having the issues how to give input to the computer how to put all the information in a computer so that computer can operative.

The history of computing also encompasses how data is input into computers and stored for processing. This evolution has seen the development of various methods, from punched cards to contemporary digital storage systems, demonstrating the importance of effective input mechanisms in the functionality of computers.

Think of a library where books (data) are checked in and out. Initially, this was done with physical cards (punched cards), but now it's mostly managed electronically. Just as effective library systems help people access books easily, efficient data input methods allow computers to manage and process information smoothly.

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