Phase 0: How Computers Actually Work · ~35 minutes · Python

What a Computer Actually Does

A computer never understands what you meant. It only ever does exactly what you said.

Real-world application: Correctly distinguishes 'the computer is confused' from 'I gave it a precise, wrong instruction' — the mental model everything else in this course builds on

What you will learn

Explain what a bit and a byte are, and what it means for a program to be 'instructions plus data'
Describe the difference between RAM (memory) and disk (storage) in terms of what survives a restart
Trace the fetch-execute cycle at a level that explains why a computer can only do one precise thing at a time
Run a Python program on this page and correctly predict the output of a second one before running it

Introduction

Type: Learn
Languages: Python
Prerequisites: None — true zero background
Time: ~35 minutes

Objective

Learning objectives

Explain what a bit and a byte are, and what it means for a program to be "instructions plus data"
Describe the difference between RAM and disk in terms of what survives a restart
Trace the fetch-execute cycle at a level that explains why a computer only ever does one precise thing at a time
Correctly predict the output of a small Python script before running it

What you'll do

Read the lesson, then in the Build section near the end, run three tiny Python programs right on this page. There is nothing to install.

Ask Python to read the byte 01000001 as a number, and then as a letter.
Predict what a four-line program prints, then run it to check.
Move one line on purpose, run it again, and write one sentence explaining why the output changed.

Unlock the full lesson

You've read the first 2 sections. The rest of this lesson covers The Problem, Build, Check Yourself, Key Terms & Next — plus a hands-on lab, quiz, and project artifact.

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