What’s inside of my computer?

What's inside of my computer? Chapter 2

Now, we’re going to look at what’s inside of our computer.

If this seems daunting or unnecessary, bear with me! I promise it’s neither of those things, as we will only go through the basic, but crucial components.

So what are those components?

  1. Storage (Hard Drive / SSD)
  2. Memory (RAM)
  3. Processor (CPU)

These are the bare minimum that you need in a typical computer. There’s also this big thing called the motherboard, in which they are all connected so that they can communicate with each other. It’s through this motherboard that everything else communicates too (screen, keyboard, mouse, speakers, etc.). That’s all you need to know about the motherboard.

Now let’s look into the three components a bit deeper.


The storage device is where all the data is stored. This is usually in the form of a hard disk drive (HDD) or a solid-state drive (SSD). The difference between the two is that the HDD has a little disk continuously spinning inside, whereas the SSD doesn’t have any moving parts. Instead, it’s all electronics. Since there are no moving parts inside an SSD, it’s much faster than an HDD.

A storage device has a really big capacity, since it needs to hold every single file and program in your computer, including your operating system! All these files stay in this storage device even when the computer shuts down and no more electricity flows into it.


The memory, also called Random-Access Memory (RAM), is another component that holds data like the storage device. There are however 3 big differences:

  1. It has a much smaller capacity than the storage device.
  2. You can access and change its data much faster than on the storage device.
  3. You lose all the data on it when you stop feeding it electricity.

Now, you might be thinking: What is the purpose of this memory if I already have a storage device?

The answer is simple. The computer’s objective is to process data. To do that, the computer moves the data from its storage place to the processor. After it processes the data, it needs to write the result back to the storage place.

The problem with only using a storage device is that it’s slow. There is a balance between the data transfer speed and the capacity of any storage device. This is why we need a much smaller, but much faster, component: the memory. However, to get the high speed, the memory needs to be volatile, which means that it once the computer shuts down, you lose everything on it.

This is why it’s important to shut your computer properly, since your OS copies important things from the memory back to the storage device.


The processor, or CPU, is the component that works with the data. It can do things like arithmetic and comparing values. These operations might seem so basic for doing things like running a video game or displaying things on a screen, but we need to remember that an average processor can now do over a billion of operations per second! The exact number for your computer can be checked by looking for your CPU’s clock rate.

Processors usually have multiple things called cores. This means that the processor actually has multiple copies of itself, so if you have a quad-core processor with a clock rate of 2 GHz, you actually have 4 processors that can each do 2 billion operations per second!

In order for the processor to process data so fast, it needs to have a rapid access to it. To make that happen, whenever you open a program up, it gets copied from the storage device to the RAM. This allows the processor to quickly access and modify data of a program you’ve opened. Then, whenever you close that program, its data is copied back from the RAM to the storage device, so that you don’t lose newly updated data when your computer shuts down.

Of course, since your OS is also a program, it’s the first program that gets copied from your storage device to your RAM when you turn on your computer.

As you can imagine, there are many more parts inside of our computers that play in this game of data transferring and processing. We don’t need to understand them all, and the ones that we should know, well, we don’t need to know them yet!

Next: Chapter 3 – What is code?

If you want to start from the beginning of the series, go to chapter 0.

By Radu

Software Engineer and Computational Scientist graduated from the Technical University of Munich. Worked at Shopify, DRW and Ubisoft.

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