Keyboard Ghosting Test: Anti-Ghosting and N-Key Rollover

Put a flat hand on the keyboard so 4–8 keys go down at once, lift it, and repeat about 15 times, or drum your fingers across the letters. The keyboard sends each change with its next report, so the gaps between those key events step in whole polling intervals.

Press several keys at once to start.

Gaps between key events up to 10 ms, in 0.25 ms steps. A 1000 Hz keyboard makes peaks at 1, 2, 3 ms; 125 Hz at 8 ms.

Press any key 20 times or more, at your own pace. Each press is timed from the moment the browser received it until the page’s code for the next frame runs, just before the browser draws the key lit up.

Press a key to start.

Included: the operating system and browser passing the key on, the page handling it, and waiting for the next animation frame. Not included: the switch and its debounce, the USB polling interval, and the time the browser and display take to draw and show the frame. That end-to-end input lag needs a high-speed camera or a light sensor on the screen.

Hold down a key (or a few) and shake, tap, twist or lift the keyboard for 10–20 seconds. A held key that loses contact for a moment sends a release and a new press a few ms later: that’s a drop. Keys held under 0.4 s, or re-pressed after another key, count as typing.

Hold a key down to start.

Press as fast as you can: the timer starts with your first press and stops on its own. Every press counts once; a key you hold down and let repeat doesn’t.

Press any key to start.

Hold A, press D while you keep holding A, let go of D, then of A. Then try it the other way round: hold D, press A. The tester reads the key events your keyboard sends and names how it resolves the two opposite keys. W/S and the left and right arrows work too.

• AD
• WS
• Arrow LeftArrow Right

Hold one key of a pair, then press the other.