How Diode Isolation Prevents Ghosting in Mechanical Keyboards
In basic membrane keyboards, keys are wired in a grid of rows and columns. When three keys forming a rectangle in the circuit matrix are pressed simultaneously (e.g. W, S, and A), current backfeeds across the shared column trace, making the keyboard controller believe a fourth phantom key (D) is pressed.
To prevent this "ghosting", budget keyboards simply block the third key from registering (Key Jamming). Gaming keyboards place an individual diode on every switch, ensuring electrical current only flows in one direction and enabling true N-Key Rollover (NKRO).