I took a college class that basically went over how computers work from like a physics level all the way up, and its layers upon layers upon layers of abstraction.
Like. At a fundamental level, there's a lot of complicated stuff that happens with physics, especially when things get really small but like. If we have a semiconductor, we can make a setup such that when the semiconductor is receiving power from one side, it allows more electricity to flow through the other side of it. Sort of like how you can stop a sink from flowing, but if you turn the valve, water can flow through again. We can call this a transistor.
Electrons don't really "flow" or "not flow", but based on how much flows through when the transistor when it is "powered" vs "unpowered" we can define some "level" of flow that we say is "on" and another which is "off". And as long as we respect that it takes time for the electricity to move and the superconductors to change their conductivity, ect ect, we can abstract away the physical reality of these things and be left with just, wires that are On, and wires that are Off.
We no longer care how semiconductors work, or how electrons work really. We just have a Transistor that toggles its state based on its input.
With the transistors then, we can arrange them in certain ways, which have certain properties. Maybe the first one, like a faucet, if its On then the output will be On also if it has power flowing through it. We can think about it like 2 inputs - the toggle, and the power flow - and one output - whether the resulting wire is On or Off. If we were to map all possible combinations, we would find that there's only One configuration where the output is on, when both inputs are also on! We can think about this as a kind of Gate that only allows water through when it's powered. We will call On "1" and Off "0".
We no longer care how transistors work. We just have a series of inputs, and a series of outputs.
Now we have a whole bunch of different gates we could use, that will have a different output depending on the arrangement of the two inputs! We label these with names, like "AND" for the gate above, or "OR" or "XOR" that all have different mappings and you can draw cute tables for these! You can then combine these into different bigger mappings that do more complex things. Maybe you have 16 inputs and 8 outputs, where the 8 outputs ends up being a representation equalling the 16 inputs added together. Maybe you combine lots of them to do multiplication, or shifting the numbers around, or whatever!
We no longer really care how gates work. We now just have these big boxes that have a designated Input of 1's and 0's, a function they do to those numbers, and an output of more 1's and 0's.
We connect these boxes together, because that way we could do more complicated arrangements. What if we want to add and *then* multiply? We need some way to sequence the events, so we will create a place to store the instructions we want to do in order, and another place that will read from those instructions based on a number. We start with instruction 1, then go to 2, ect all the way down the list until all the instructions are done. We can also make an instruction that changes what our current instruction is, so we can jump around our list too! We put a funny box whose job is to read the instructions and determine what they mean so it can process them in this order, and we call the lists of 00000000 and 11111111 that we give it "OP Codes" and define them.
We no longer care how the computer adds or multiplies. We only care that when we ask it to "multiply", that it gives us the right answer as a result.
We can now write lists of instructions for the computer to follow! The computer we now call it, is very smart and will follow the instructions exactly. However, it's still talking in 1's and 0's, which makes it hard to talk to and ask for what we want. We connect it to a screen, and we tell it which pixels make up the letter "A" and which ones make the number "3" and so on. And now, we can write a little program that allows us to type out these characters on our keyboard, and the computer renders them to the screen! We will write another program that converts our written instructions of "JUMP 0000" into the language of 1's and 0's the computer can understand.
We no longer care how the computer understands it as 1's and 0's. We just need to know what "JUMP" means, and how to chain the words together like puzzle pieces to make a program that the computer can use.
These instructions are still really barebones, and still a little hard to read. We have to remember where we are storing data so we can recall it back later, we have to remember where we are jumping to so we can make things work, it's sort of a hassle. Luckily, we can write a program to fix this, by writing a new layer on top that we will call a Programming Language, that will handle all of these interactions for us! This will make it smooth for us to write code.
We dont care how assembly works anymore. Depending on the language, we don't even care about where the data is stored or how it is stored on the computer, just that it is and we can use it.
Now, we are using our fancy new programming language to write code! Lets say we want to write code to play the game poker. We could just write all the script together, but that makes it hard to bugtest, to iterate on, ect. So we break the code into Steps. We create an Object for the Card, and we give it information about what kind of card it is. We then make a deck, that stores a number of "cards", and has various functions which do things like "Draw a Card" or "Shuffle". We don't need to know how the code that "shuffles" the deck works, we just know what shuffling means, we know we need to give it a deck to shuffle, and itll give us back a shuffled deck.
We now don't even care about how the code setting up the deck is like.
We have abstracted away to the point of like. Language. You want to play poker? Well you shuffle the deck, then you draw so many cards to each player, and then you see which player has the highest score, and they win!
It's like this all the way up to the biggest stuff. This is how rocks were tricked into thinking.
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