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Keeping up with Logitech n-key rollover keyboards

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pex:
This is just all part of working for the cause...
Posted on their forum:

http://forums.logitech.com/logitech/board/message?board.id=hardware&thread.id=6217

No responses yet.  I know there is anecdotal references to n-key rollover on SOME runs of the G11/G15, however it is important to note that they advertise, if anything, 'anti-ghosting' rather than 'anti-blocking'...since I'm not big on the science yet, I'd say this is an incomplete reference to n-key rollover (which is also a term companies have used, even if incorrectly.)

In other news, I contacted cherrycorp.com (AGAIN!) for n-key rollover answers.  I don't believe they responsed last time.

IBI:
I've never heard of a logitech keyboard being advertised with anti-ghosting/anti-blocking/n-key rollover though, do you have a link to that?

Also, don't logitech's keyboards tend to have printed keys?

I got a reply from cherry UK stating that as far as they're aware the G80-3000 didn't have 'Full Alpha N-key rollover'. He did mention cherry had thought about plans for making a gaming keyboard directly, but that any plans for that were shelved for the forseeable future, and advised me to look at the Raptor-gaming K1 and K2 which may have full n-key rollover.

karlito:
G15 does not support N-Key rollover. It supports 6 keys down + modifiers and that's it.  As far as I can remember it doesnt even come with a PS/2 adapter and it does not work with a PS/2 adapter (at least the ones I have).

pex:
Cherry has a huge line of keyboards and I have seen some that mention "alpha n-key rollover", which sounds incredibly silly to me but nonetheless I see it mentioned.

"Full" and "Alpha" are not terms that are acceptable together.  "Full" means the whole keyboard, and "Alpha" means the letters.  "Full Alpha" would be redundant and is never the question we should be asking unless that's all we ever expect to need.

Alpha n-key rollover is certainly something I'd never want to support with my buck.  It sounds quite stop-gappish to me.

I am searching for manufacturer references from both Logitech and Cherry to validate my claims...I'll post when I find them.


--- Quote from: karlito;3771 ---G15 does not support N-Key rollover. It supports 6 keys down + modifiers and that's it.  As far as I can remember it doesnt even come with a PS/2 adapter and it does not work with a PS/2 adapter (at least the ones I have).
--- End quote ---

It sounds to me like the 6 key issue is USB-related (although no matter how big the USB buffer is, we should expect that all our presses would show up, right?) as long as it is consistent with all key combinations.  It would surprise me significantly if the G15 couldn't use the PS/2 interface for keyboarding only, and I would find it unfathomable if it couldn't do it with an appropriate driver.

IBI:

--- Quote from: pex;3772 ---
It sounds to me like the 6 key issue is USB-related (although no matter how big the USB buffer is, we should expect that all our presses would show up, right?) as long as it is consistent with all key combinations.
--- End quote ---


I think it's written into the specifications. Quote from them:

"The keyboard must report a phantom state indexing Usage(ErrorRollOver) in all array fields whenever the number of keys pressed exceeds the Report Count. The limit is six non-modifier keys when using the keyboard descriptor in Appendix B. Additionally, a keyboard may report the phantom condition when an invalid or unrecognizable combination of keys is pressed. "

It's here if anyone feels like reading it in full.


--- Quote from: karlito;3771 ---G15 does not support N-Key rollover. It supports 6 keys down + modifiers and that's it.
--- End quote ---


Hmm, I thought the phrase 'n-key rollover' was a handy way of refering to keyboards that supported more keys than usual but weren't full n-key rollover? If the G15 is proper 6-key rollover then I'm really surprised logitech aren't shouting about it.


--- Quote from: pex;3772 ---Cherry has a huge line of keyboards and I have seen some that mention "alpha n-key rollover", which sounds incredibly silly to me but nonetheless I see it mentioned.

"Full" and "Alpha" are not terms that are acceptable together.  "Full" means the whole keyboard, and "Alpha" means the letters.  "Full Alpha" would be redundant and is never the question we should be asking unless that's all we ever expect to need.

Alpha n-key rollover is certainly something I'd never want to support with my buck.  It sounds quite stop-gappish to me.

I am searching for manufacturer references from both Logitech and Cherry to validate my claims...I'll post when I find them.
--- End quote ---


I've seen mention of Alpha/Full n-key rollover on cherry keyboards too, and I've had people who sell them tell me they've been told that the keyboards have full n-key rollover. However, I've never found reference to it on the cherry site. I wonder if the full/alpha n-key rollover on the G80 is a special order and the normal ones don't have them?

And yes 'Full Alpha N-key rollover' does sound absurd, but that's what the reply I got refered to it as.

I don't think Alpha n-key rollover is stop-gappish. It sounds as if it's for a specific requirement, maybe unicode character entry or multi-lingual writing or something similar. I'd agree that for a general purpose keyboard Full is the way to go.

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