N-key rollover (NKRO) & key ghosting
Also searched as: nkro · n-key rollover · key rollover · 6kro · key ghosting · anti-ghosting · rollover
What it means
N-key rollover (NKRO) means every key you hold registers at the same time, no matter how many. Older or cheaper keyboards have a limit — often '6-key rollover' — and beyond it extra presses get dropped or 'ghost,' which is why a key sometimes does not fire when you are already holding several.
More detail
It matters when a game asks for several keys at once — sprint + strafe + crouch + ability, fighting-game inputs, or rhythm games — where a non-NKRO board can swallow a press at the worst moment. Most modern gaming keyboards are NKRO (or at least anti-ghost the common gaming cluster); some have a switch between a 'full NKRO' and a '6KRO' compatibility mode, so it is worth confirming yours is in the full mode. …
In the Blackbook
The deeper explanation continues inside the app. The Blackbook publishes its verdicts here — the full write-ups stay in the book, on your rig, next to your own measurements.
The Compy Blackbook holds 191 graded entries like this one, judged against your hardware — and every change it does make is reversible, with the receipt to prove it.
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