Intros: 14 Topics Before the Levels

How an intro works

An intro opens before the level and consists of short steps: Experiment — you toggle switches on a mini-circuit and watch; Rule — the observation is put into words or a table; Transfer — the rule is checked on a new circuit; Why it matters — an example from real hardware. You cannot "fail" an intro: a wrong answer becomes a hint, not a barrier.

An intro can be closed at any moment and reopened later: the game remembers which topics you have seen. If the placement test confirms you know a topic, its intro is skipped automatically.

The fourteen topics

Topics follow the level order: each "Take the intro in the game" link opens the right level, and the level guide link opens a detailed walkthrough.

• The AND Gate: Two Switches and a Lamp — level 3. The lamp is on only when both switches are on — this is where the truth table comes from. Take the intro in the game · Level 3 guide
• Composing Gates — level 5. How to predict a chain of two gates without running the circuit: trace the signal gate by gate. Take the intro in the game · Level 5 guide
• Binary Counting: Build a Number from Lamps — level 6. Lamps weighted 1-2-4-8 build any number, and the extra one on overflow becomes a carry. Take the intro in the game · Level 6 guide
• Binary Addition and the Carry — level 7. The XOR-AND half adder, the full adder, and the carry that runs down the chain like a wave. Take the intro in the game · Level 7 guide
• The Bus and the 8-bit Word — level 8. Eight wires carry one number; on schematics the bundle is drawn as one thick arrow. Take the intro in the game · Level 8 guide
• Feedback Is Memory — level 10. A circuit that remembers a one after its input goes off: a ring of two gates stores one bit. Take the intro in the game · Level 10 guide
• The Clock and the D Flip-Flop — level 11. Q copies D only at the WRITE press: the clock edge is what keeps a processor predictable. Take the intro in the game · Level 11 guide
• The Register: a Byte of Flip-Flops — level 12. Eight D flip-flops sharing one clock capture a whole byte in one press and hold it until the next edge. Take the intro in the game · Level 12 guide
• The ALU and the Op Code — level 14. A number can be an order: the op code picks addition or subtraction, and an instruction fits one byte. Take the intro in the game · Level 14 guide
• Program as Data — level 18. ROM cells hold plain numbers; the program counter and the Harvard architecture are what make them instructions. Take the intro in the game · Level 18 guide
• Negative Numbers: Two’s Complement — level 25. A lit top bit is the minus sign: 11111011 reads as −5, and the processor gets the N flag for free. Take the intro in the game · Level 25 guide
• Concurrency: Code Is a Blueprint — level 30. Verilog lines never run one after another: every part of the blueprint works at once, and line order does not matter. Take the intro in the game · Level 30 guide
• Instantiation: from Blueprint to Part — level 34. A finished module joins a circuit in one line: .sum(s1) connects the blueprint’s port to your wire. Take the intro in the game · Level 34 guide
• generate-for: a Loop in Space — level 37. The loop draws eight flip-flop copies side by side, and all of them fire on the shared clock in one edge. Take the intro in the game · Level 37 guide