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Course outline
  1. 01How a computer works
    1. 1.1What is a computer?(completed)
    2. 1.2The CPU: the brain(completed)
    3. 1.3Memory: RAM vs storage(completed)
    4. 1.4How the CPU and memory work together(completed)
    5. 1.5What happens when you turn on a computer(completed)
  2. 02How the Internet works
    1. 2.1What is the Internet?(completed)
    2. 2.2Addresses and names: IP and DNS(completed)
    3. 2.3Packets: how information travels(completed)
    4. 2.4Client and server: opening a website(completed)
    5. 2.5Inside a busy server(completed)
    6. 2.6Why this matters for AI(completed)
  3. 03Introducing the GPU
    1. 3.1What is a GPU?(completed)
    2. 3.2CPU vs GPU(completed)
    3. 3.3The GPU's own memory: VRAM(completed)
    4. 3.4How the CPU and GPU work together(completed)
    5. 3.5Why GPUs suit AI(completed)
  4. 04Tensors and models
    1. 4.1What is a tensor?soon
    2. 4.2What is an AI model?soon
    3. 4.3Training vs inferencesoon
  5. 05Splitting work across GPUs
    1. 5.1Why split work across GPUs?soon
    2. 5.2Data parallelismsoon
    3. 5.3Tensor parallelismsoon
    4. 5.4Pipeline parallelismsoon
    5. 5.5Expert parallelismsoon
    6. 5.6Which to use whensoon
  6. 06Serving LLMs with vLLM
    1. 6.1What is LLM serving?soon
    2. 6.2Meet vLLMsoon
    3. 6.3Serving a model with vLLMsoon

Lesson 1.1

What is a computer?

Every computer does three things: it takes something in, works on it, and gives something back.

beginner 3 min readChecked

In one line

A computer is a machine that takes something in, works on it by following instructions, and gives something back.

Real-life analogy

Think of a restaurant.

A customer gives an order (that is the input). The chef follows a recipe and cooks (that is the processing). A plate of food arrives at the table (that is the output).

We will keep using this restaurant through the whole course. In the next lessons you will meet the chef (the CPU), the counter (RAM) and the pantry (storage).

Where the comparison stops working: a chef can taste the food and improvise. A computer cannot. It only does exactly what its instructions say, nothing more and nothing less.

Diagram

1. INPUTKeyboard, mouse,touch, microphone2. PROCESSCPU followsinstructions3. OUTPUTScreen, speaker,printerStorage: keepsthings for laterLike a restaurant:order in, cooking,plate out
Input goes in, the CPU processes it, output comes out. Storage keeps things for later.

Step by step

So what makes something a computer? Is it the screen? The keyboard? The price?

None of those. A computer is defined by what it does, not by how it looks.

1. Input: something goes in

Input is anything you give the computer. You type on a keyboard. You tap a touchscreen. You speak into a microphone. A camera takes in a picture.

All of these turn something from the real world into information the computer can work with.

2. Process: the computer works on it

Next, the computer does something with that information. This part is done by a chip called the CPU, short for central processing unit. You can think of it as the computer’s brain.

The CPU follows instructions. An instruction is one tiny, exact step, like “add these two numbers” or “compare these two letters”. A program, such as a game or a web browser, is just a very long list of these instructions.

3. Output: something comes back

Finally, the computer gives you a result. Words appear on the screen. Music comes out of the speaker. A page comes out of the printer.

And storage: keeping things for later

There is one more piece. What if you want to keep your photo or your document for tomorrow? The computer saves it in storage, such as an SSD or a hard drive. We will look at storage, and its fast partner RAM, in lesson 1.3.

Computers are everywhere

Now look around you. Your phone takes touches in, processes them, and shows results. So does a smart TV, a games console, a car’s dashboard and a cash machine.

They are all computers, because they all follow the same pattern: input, process, output.

Key takeaways

  • A computer is any machine that takes input, processes it by following instructions, and gives output.
  • The CPU does the processing. A program is a long list of tiny, exact instructions.
  • Storage keeps your files for later.
  • Phones, laptops, TVs and game consoles are all computers.

Recap: an order comes in, the chef cooks, a plate goes out. A computer does the same with information: input, process, output.

Now you understand what a computer is and why a phone counts as one too. Next, we will meet the chef of our restaurant: the CPU.

Quick check

Pick an answer, then press Check answer. Nothing is recorded.

  1. You type a message on your phone and it appears on the screen. Which part is the output?
  2. Which of these is a computer?
  3. In our restaurant comparison, what is the processing step?

Sources

This lesson was checked against these pages.

  1. What Is RAM vs. Processor? · Intel
  2. What is a Central Processing Unit? · Arm
  3. What Is Computer and Laptop RAM and Why Does It Matter? · Intel