1. The tiny decisions inside digital devices

A digital circuit works with signals that stand for two states, often described as 0 and 1. By sensing and changing those signals, a circuit can respond to a button press, compare information, or send a command. It is a physical system carrying out logical decisions.

Check what you understood with a short quiz.

Use what you learned in the previous lesson to solve real-world problems.

A logic gate follows a simple rule: for example, it might send an output only when two inputs are on. Connect many gates and their small decisions can add up to counting, choosing, and processing information. The surprising part is how much complexity can grow from a few basic rules.

Check what you understood with a short quiz.

Use what you learned in the previous lesson to solve real-world problems.

Circuits do more than calculate. Some hold information so a device can remember a setting; others control timing, read sensors, or drive a screen and speaker. The same ideas help a microwave run its timer, a car respond to a sensor, and a phone process a touch.

Check what you understood with a short quiz.

Use what you learned in the previous lesson to solve real-world problems.

Digital circuit designers plan and test the hardware behind processors, controllers, and custom electronic devices. Their work connects with computer engineering, robotics, product design, and research. A small starter project—such as wiring a button to control an LED—shows how a physical circuit can follow a rule.

Check what you understood with a short quiz.

Use what you learned in the previous lesson to solve real-world problems.

Review this chapter with practice based on your mistakes.