N-key rollover, or ” NKRO ,” is a feature of high-end keyboards that detects all keystrokes no matter how many keys you press simultaneously. This ensures that each keystroke is recorded and that “ghosting” can be removed, with the possibility of the extra keystroke being registered when multiple keys are pressed simultaneously.

In a basic keyboard , electrical connections that range from base of the keys to keyboard output (typically a USB connection ) can intersect. If you press multiple keys at the same time, then the keyboard registers some keystrokes but not all. Ghosting occurs when data are combined with two or more keystrokes and register input with a key if you do not press.

Most keyboards have some level of rollover, meaning they support multiple simultaneous keystrokes. For example, an inexpensive keyboard may have 5-key rollovers, but others may also have 8-key rollovers. This type of rollover is called “x-key rollover” where x is equal to the number of keys that can be simultaneously pressed and recorded.

N-key rollover means that there is no limit to how many keys can be pressed and recorded at once. This feature is typically found in high-end keyboards, such as gaming keyboards that are used in eSports. Here, gamers often press a lot of keys at once when they are playing video games, so it is important to register for the keyboard all the input accurately.

This USB interface initially only supports 6 simultaneous keystrokes plus 4 modifier keys only. Such simultaneous keystroke limits are not found in modern USB interfaces.

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