On 22 Jan 2012 at 15:07, Mouse wrote:
  But when using a keyboard as a multi-button input
device that happens
 to have lots of buttons, which (for example) many games do, it's far
 less clear.  It would not surprise me to see rollover requirements go
 as high as nine or maybe even ten in extreme cases; certainly when
 playing the piano I need N-key rollover for N above 6 - fortunately my
 piano, unlike most computer text keyboards, is designed for that sort
 of thing.  (It's an electronic piano, not a mechanical one, but a
 pretty good one as such things went when I bought it; it definitely
 supports N-key rollover for N well over 6.) 
I believe I mentioned music keyboards as an exception, as in the
ancient Casio WK-1200 sitting at my right elbow here, which could
probably render the Tom Turpin style of playing (i.e. sit on the
keyboard, or so it was reported) just fine.
--Chuck