On Sat, Dec 01, 2001 at 12:52:45AM -0500, der Mouse wrote:
> > I haven't a clue about this "n-key rollover" thing.  I only own
> > [...].  None of them have key repeat problems.
> 
> "repeat" != "rollover".
> 
> > Is this a USB ailment?
> 
> Perhaps.  More likely it's a cheap-keyboard ailment.

[...]

> I don't know if this is a USB thing, a Mac thing, an Apple thing, or
> just that that particular keyboard design had had corners cut.

I doubt it has to do with USB.  (As you said, it has to do with the key-
switches, not the way the data is sent over the wire.)  You may have just
had a cheap keyboard.

Apple has always had a spec for their ADB keyboards, and I think the Apple
USB ones continue the spec.  Certain keys (the modifier keys and a few
others like space and delete) must be recognized at all times.  Of the
others, you can have two down at a time.  I guess this would be two-key
rollover with a few extras.  The Mac OS keyboard routines are written
around this spec.  And it would also explain why all the magic startup
key combinations have only two letters (O and F, P and R, etc.)

This is probably in Inside Macintosh or on Apple's Web site.

On my keyboard I can actually get keypresses for more than two keys at once,
but not every combination works (some give keyboard errors).  There's
probably some kind of pattern in terms of the switch matrix (like I can
hold down any number of keys if they are in the same row, but not if they
are in different rows -- or whatever, I'm just guessing).

Really, I don't want to mess around with this stuff.  Keyboards are so
simple, the technical design should be about perfect by now.  Obviously
economics is interfering.

Incidentally, "ion " often comes out as "ionn ".  It's getting on my nerves.
I wonder if our keyboard driver is aggravating this problem, because it
handles keyboard errors differently than the Mac OS driver?  Unfortunately
I can't repeat the problem when I'm typing slowly,  But I know it's not
my typing.

-- Derek