<P> Rollover is the ability of a computer keyboard to correctly handle several simultaneous keystrokes . </P> <P> During normal typing on a conventional computer keyboard, only one key is usually pressed at any given time, then released before the next key is pressed . However, this is not always the case . When using modifier keys such as Shift or Control, the user intentionally holds the modifier key (s) while pressing and releasing another key . Rapid typists may also sometimes inadvertently press a key before releasing the previous one . Certain unusual forms of keyboarding require multiple keys to be pressed or held down simultaneously; for example, Braille2000 keying requires as many as six keys to be pressed at once analogous to the six dot keys of a Braille typewriter . Some computer games require keys (other than the usual modifier keys) to be held down while others are pressed and released . </P> <P> Certain high - end keyboards have "n - key rollover". This means that each key is scanned completely independently by the keyboard hardware, so that each keypress is correctly detected regardless of how many other keys are being pressed or held down at the time . </P> <P> Most music keyboards use isolation diodes in their keyboard matrix to implement full n - key rollover (sometimes abbreviated NKRO), making them immune to both key ghosting and key jamming . </P>

What does anti ghosting mean on a keyboard