Lab 3: Keyboard And i8042

Generated folder: labs/kbd/

Lab 3 moves from periodic events to human input. A key press is not a character; it is a device event that may arrive as one or more scancode bytes. This distinction is important. Characters belong to text input, keyboard layouts, modifiers, and application policy. Scancodes belong to the device stream.

In this lab you work below the text-input layer so that you can understand how a system first learns that a physical key changed state. That knowledge is useful for games, editors, shells, debug consoles, and any final project that needs responsive controls rather than occasional line-based input.

Read why keyboards are controller streams, then study the keyboard controller and the rules for scancode parsing. After that, compare interrupts and polling, learn the small set of KBC commands used by the lab, and combine keyboard input with timer events in multiple devices. The implementation tasks collect the required functions, and the final page compares this model with modern keyboards.

TIP

Treat the keyboard as a byte stream first. Turn bytes into application actions only after the low-level parser is correct.