Re: [MiNT] update:WRITE_BOOT,ALLOW_TRP_CHG

[Paul Wratt <paul.wratt@gmail.com>]

On Sun, Oct 7, 2012 at 11:19 PM, Jo Even Skarstein <joska@online.no> wrote:
> On Sun, 2012-10-07 at 18:54 +1300, Paul Wratt wrote:
>
>> you misunderstand post reference. The hardware circuits in 99% of
>> keyboards can NOT detect/acknowledge more than 3 simultaneous
>> kepresses (keys pressed at the same time). 4+ keys can be pressed, but
>
> I'm afraid you're the one who's misunderstanding. What you're writing
> here is not correct. You can easily press 10+ keys simultaneously on a
> PS/2 keyboard, and all of them will be sent to the computer. However, in
> any keyboard with a foil/membrane matrix instead of PCB (which means -
> as you say - cheap keyboards) there is a phenomenon called "ghosting"
> which means that if you press three adjacent (in the matrix that is)
> keys simultaneously a fourth "ghost" keypress will be generated. Now,
> the keyboard controller might handle this or it might not. If not, the
> ghost keypress will be sent to the computer. If it does handle it, it
> normally does so by filtering out possible ghost keypresses, *NOT* by
> limiting the number of simultaneous keypresses to three.
>
>> This directly affects the result of any /dev/xkbd driver output, but
>> not what the driver can process.
>
> Correct. Contrary to what you write a couple of posts back this is
> completely irrelevant to the device driver. Ghost keypresses are unique
> for any keyboard matrix, and there is no way to detect or handle this in
> software. The only thing the programmer can do is to allow the user to
> select which keys to use. But this is *not* specific to PS/2 keyboards,
> but to all membrane/foil keyboards (like the Stacy, or my old
> Spectravideo, or my CPC6128, or my Amiga 600...) or even "quality"
> keyboards with PCB but no diodes.
>
> Jo Even
>
http://www.coolermaster.co.uk/product.php?product_id=6815

"The Trigger keyboard offers you the ability to press up to 6 keys
simultaneously ..."

that is a gaming keyboard