Re: N-key rollover keyboards

[Dmitry Alexandrov]

Alan Davis <alan3davis@gmail.com> wrote:
> On Sun, Aug 2, 2020, 10:04 Dmitry Alexandrov <dag@gnui.org> wrote:
>> FWIW, N-key rollover is not really about USB or protocols; itʼs about 
>> circuit of the keyboard.
>>
>> It does matter, when you reconfigure modifiers in a human-friendly way, that 
>> is move one of the ‘controls’ (normally, the left one) closer to ‘space’ — 
>> under your thumb — (ctrl:swap_lalt_lctl setxkbmap(1) -option or equivalent).
>>
>> Then, on many ordinary keyboards few combinations, that are in use in Emacs, 
>> are indeed get ‘ghosted’.  And M-C-b with inner M- and C- is a very likely 
>> variant.
>>
>> Two-key chords can never be affected, of course.
>
> 'ghosted'?

Yes.  https://www.bing.com/search?q=key+ghosting

> Does this mean these apparently problematic combinations require N-key 
> rollover?

No, not necessary.  Much cheaper redesign of a circuit would suffice.

> I am also using org-mode with several multiple-key chords.  I cannot remember 
> any instance where these have been a problem.

So, evidently, either your keyboards are not affected or youʼve just never 
bumped into affected chords.  Do an exhaustive check, if you are concerned:

        (while t
          (let ((key (read-key)))
            (message "%s: ok\n" (format-kbd-macro (vector key)))
            (when (eql ?\C-g key) (keyboard-quit))))

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