Welcome to lesson two how a program works. She's in Python. So this is a very basic conversation that we're going to have about how a program actually works. And this is how all programs work, not necessarily Python, but again, we're using Python for the class. So, again, welcome to lesson two. And let's get started.

When a program is running on your computer, the CPU has to be able to understand the instructions it's being given in order to be able to process those instructions. So a CPU can only understand instructions that are written in machine language though, so we can't do machine language the computer has to translate that for us. Other programming language has been invented so that that process can be done for you. The CPU performs simple operations on pieces of data so it reads the data. It can Add it, subtract it multiply, it divides numbers, you can understand instructions written in machine language. And each CPU has its own instruction set.

So if even if it might be the same brand, if it is a different kind of CPU, it could still have its own instruction set. So I think it's important to mention here, what that really means is so safe, for example, that you're going to go to the store and you see a computer and you say, Oh, this one's only $200. And it has an Intel Celeron in it. Yeah, I'm gonna get this computer, you buy the computer, you go home, you load up some games, and all it does is crash and just really cannot handle the games. And that is because the Celeron processor is not built with the same instruction set. As the I five for example, the I five has a larger instruction set in it.

That's why it's more expensive. It can do more So the Celeron really isn't meant for things like gaming or whatever it is that you want to do that is graphics intensive or process intensive. Okay, so a CPU must perform many operations in order to complete a calculation. Whenever a user opens a program, that program must be copied from secondary memory to ram, each time the CPU executes it. So looking at that from the user level, if you're sitting at the computer and you open Microsoft Word, that program is copied into the secondary memory Ram. Remember, Ram will die if the computer shuts off and you will lose all of your memory in RAM and so that's why we want to constantly back up the programs that we're working on.

If you're working in it for a long period of time and you know, somebody has a power cord and automatically goes off, you could lose all of your work. And again, that's Cause it is stored in RAM when the program is actually running. The CPU program cycle is to fetch, decode and execute. So basically what happens here is the CPU will fetch, it'll read the next instruction from memory into the CPU, then it's going to decode it. So the CPU is going to decode that fetch an instruction. It's going to figure out what those instructions are and then the CPU will execute that instruction.

So now that you know how a program actually works, and what kind of memory it uses in order to work, think about this. These programs must be written in code, somebody has to know how to do the code for the program. Well, we call these programs languages. I'm going to tell you very quickly here that there are different types of languages. There is an assembly language, there is an assembler, and an assembly language uses mnemonics. So mnemonics are short words, where they get instructions instead of binary numbers.

So it's a little bit easier, we can actually give it instructions instead of trying to remember everything in binary. And assembler translates the assembly language for machine language for execution by that CPU, and so it gets all translated. So one of the reasons that we call it languages is because it is its own language. Obviously, you're not going to go out and learn Chinese in a day if you're not native to that language. So it's going to take some time, it's going to take some repetition, be patient with yourself, and you will get all these concepts down. So in programming, there are two types of languages.

There is a low level language and a high level language, a low level language is close to machine language. So again, machine language, we have our zeros and our ones and our binary. A high level language simplifies the program process. So there's no need to know how the CPU works or how it writes. So it's much more intuitive and much easier to handle. So now we know the different types of languages.

So what kind of programs do we use to handle those kinds of languages in order to write those programs? Well, there's two different kinds. There's a compiler and there's an interpreter, a compiler actually translates the high level language into machine language. So the machine language programs can be executed at any time and interpreter translates and executes the instructions in the high level language. Python is a great example of an interpreter it interprets one instruction at a time. And there is no separate program that has to run in order to see what happens.

So in Python, when we practice our programs, we can write the program and we can run the program and then see what those results are to check it for accuracy. Did a look at that now you've finished lesson two. So in lesson three, we're going to go on to learn how to program in Python. So we want to make sure that we're going to download Python we're going to learn how to install it and we're going to learn how to actually use the program Python. Now remember, when you're learning these, these concepts are not the easiest thing to understand. do realize that You're not going to understand everything at once you've got to earn a little bit at a time.

And as you learn a little bit at a time, it'll slowly ingest and this happens with, with everyone, like there's very few people that can sit down in a programming language and just get it all all at once. So be repetitive go over things and over things and over things. And that's the great thing about having the lessons where it's a movie because you can stop it, you can rewind it, you can rewatch it, you can do it over and over again. And I think that is super, super helpful. And again, remembering my class, you have a lifetime to be able to go back in and check this class out. So please enjoy yourself.

Please learn please let me know if there's anything further that I can do. Thank you. Let's move on to the next lesson.