N-Key Rollover and 6-Key Rollover in Mechanical Keyboards: What's the Difference

Whether it's playing a fast-action game, typing all-important documents, working on complex computer codes, or many other tasks, it is important and efficient to have all the keypresses on your keyboard registered accurately.

You see, when typing on a keyboard, only one key is pressed at any given time. It is then released before the next key press. However, there are many cases when keys are pressed together such as very rapid typing or pressing modifier keys together with character keys. In some cases, the keyboard fails to register these key presses, causing some unwanted issues.

Mechanical keyboards with N-key rollover and 6-key rollover issues attempt to solve this "ghosting" problem. How? That's what we're going to discuss in this article.

Defining Key Ghosting

Key ghosting is one of the most peculiar and annoying problems of keyboards, particularly old, cheap, or low-quality keyboards. Key ghosting occurs when single keys are pressed at the same time. When this happens, some of the keys may not register as a character or an action on the monitor. In some cases, the output is abnormal; an unwanted character called a phantom key may appear. In other cases, an unintended action may be executed. This weird glitch is referred to as key ghosting. 

Why does this happen? It's all in the keyboard's circuitry.  Each key in a keyboard is positioned in a certain row and column. When the key is pressed, an electrical circuit is created between its assigned row and column. The keyboard controller detects this signal, registers it as a keystroke, and sends the signal to the CPU for processing. 

Sometimes, multiple keys are pressed simultaneously due to fast typing, combos for certain actions in computer games, or as a combination of pressing a legend key and a modifier key (e.g. Shift or Control keys). When this happens, the keyboard computer may be unable to detect and process the keystrokes. The device may become confused and register a keypress that you did not make.

Mechanical keyboard manufacturers design their products to avoid combinations that commonly result in ghosting. However, the more unusual or complex the combination of keys, the more likely that this flaw will occur. While ghosting doesn't usually affect everyday use, it becomes a significant concern in high-performance activities such as gaming or specialized typing tasks where multiple keys are often pressed simultaneously.

Difference Between N-Key and 6-Key Rollover Keyboards

To reduce key ghosting, many mechanical keyboards have an anti-ghosting feature called a key rollover. A keyboard with a key rollover feature has a different circuit design or incorporates diodes under each key to isolate individual key presses, preventing the occurrence of ghosting. Thus, these keyboards can accurately register each keystroke.

Mechanical keyboards with key rollover features are categorized based on their rollover capability. The most common ones are N-key rollover (NKRO) and 6-key rollover (6KRO). There is a third one called 2-key rollover, but this is not worth it if you're eyeing a keyboard with key rollover features.

N-Key Rollover (NKRO)

With keyboards with N-key rollover (NKRO), you can press all keys at the same time, and each key press is individually registered. You won't experience ghosting or key-blocking issues no matter what. 

You can do even the most complex key combinations without missing keystrokes.

6-Key Rollover (6KRO)

With keyboards with a 6-key rollover (6KRO) rollover feature, you can press up to 6 keys at the same time without experiencing ghosting. This feature is often found in mid-range mechanical keyboards.  

Exceeding the Rollover Limit on a Keyboard

There may be times when you need to press more keys concurrently than your keyboard's rollover limit permits. When you exceed the rollover limit, several things can happen. 

1. Key Blocking: Some of your key presses may not register at all. The keyboard fails to detect additional key presses.
2. Ghosting: Unintended key presses are registered. Additional characters may appear on the monitor. Commands which you did not mean to make may be executed.
3. Input Lag: Simultaneous key presses can cause delays between pressing a key and its corresponding character or action on the computer. 

Importance of Key Rollover

Key rollover and anti-ghosting are important features in keyboards, especially if you need precise and rapid input. 

1. Accurate Input: Every keystroke is accurately detected and transmitted to the computer. This precision is essential for gaming, programming, and typing where accurate input is important.
2. No More Ghosting: Key rollover and anti-ghosting functionality eliminate ghosting issues, allowing users to execute complex key combinations without errors.
3. Improved Gaming Performance: In gaming where split-second reactions and precise inputs are important for winning or accomplishing a mission, key rollover or anti-ghosting can make a significant difference. Gamers can do complex maneuvers and combinations without worrying about missed or misinterpreted keystrokes. This leads to better performance and gameplay experience.
4. Efficient Typing: Key rollover and anti-ghosting ensure a smoother and more responsive typing experience. Users can type rapidly without concerning themselves with input errors.

Conclusion

N-Key rollover keyboards are superior to 6-Key rollover keyboards when it comes to anti-ghosting. You would need this feature if you are an avid competitive gamer or a fast typist. If accuracy and speed are important in your tasks, an n-key rollover keyboard should be your first choice.