Every computer — your phone, your laptop, a supercomputer — does everything with one incredibly simple trick, repeated billions of times: flipping tiny switches on and off. This site shows you that trick, step by step, with your own hands on the switches.
Switch → Gate → Gate → Answer. That's the whole idea. Let's build it up piece by piece.
Meet the transistor: a switch smaller than a speck of dust that another wire can flip on or off. This is the only building block a computer has.
2Wire two transistors in a row and you get AND. Wire them side by side and you get OR. See the actual transistors, not just a black box.
3Now treat those wired-up bundles as single boxes — a tiny decision-maker. Click the inputs and watch AND, OR, NOT, and XOR gates think.
4A switch only knows two states: off and on. It turns out that's enough to write any number, using nothing but 0s and 1s.
5The payoff: chain gates together into an "adder" and watch two numbers get added in front of your eyes, one carry at a time.
6The twist: computers don't really subtract. Flip every bit, add one, and run it through the exact same adder you just built.
7Binary's multiplication table has only two facts: anything × 0 is 0, anything × 1 is itself. Watch that turn into a full product.
8Long division, binary-style: bring down a bit, see if the divisor fits, subtract if it does. Repeat. That's it.
9Zoom out: from a 1944 computer built out of 3,500 clicking relay switches to a modern CPU with billions of transistors doing the exact same trick.
No background needed. If you've never opened up a circuit or written a line of code, this is for you. Every idea here builds on the last one — start at Chapter 1 and click through.