Lab 4: PS/2 Mouse Packets

Generated folder: labs/mouse/

Lab 4 extends the i8042 controller idea to the auxiliary PS/2 mouse. The mouse reports packets containing button state, movement deltas, sign bits, and overflow flags.

The important change from Lab 3 is that one device event is now naturally a group of bytes. If you lose synchronization, every following byte can be misread until the parser finds the beginning of a packet again. That makes the mouse a compact but serious protocol exercise.

Start with why pointing devices changed interfaces, then study the mouse controller path and the rules for packet parsing. After completing the implementation tasks, compare this older PS/2-shaped stream with modern pointer input.

TIP

Mouse input is the first lab where losing one byte can corrupt every following interpretation until you resynchronize.