🎯 Checkpoint: the secret language
Why: Lock in the secret: everything the machine holds is numbers in switches.
Unlocks: The last piece — how a pile of switches makes decisions.
Quick stop — nothing new here. In four lessons you uncovered a secret most people never learn: a machine that seems to hold photos, songs and messages actually holds only numbers, and each number is only a row of on/off switches. Before the final section, let's make sure that chain is solid in your head. If a question stumps you, replaying its lesson takes five minutes.
| Thing on your screen | Really stored as | The trick |
|---|---|---|
| A number | A row of on/off switches | Binary — each switch doubles: 1, 2, 4, 8… |
| A letter | A number | A shared code book (Unicode) — A is 65 |
| A picture | Three numbers per pixel | Red, green, blue — each 0 to 255 |
| Everything above | Bytes | One byte = 8 switches = a number from 0 to 255 |
Deep down, how many different things can ONE switch (one bit) remember?
What exactly is a byte?
The machine stores the letter A. What does it actually put in memory?
A single pixel in a real photo stores…
Chain complete: photo → pixels → numbers → bytes → switches. When someone says “it's all just ones and zeros”, you now know exactly what they mean — and how the trick works. One question remains: how does a pile of switches decide anything? That's the final section.