Keyboard Hardware - Simultanous Keypresses (maybe off-topic)

[HaBaLeS]

Hi,

this is not really a LWJGL Question, but maybe someone here knows the answer.

I was playing with Keyboard Class and the Event System. I wrote a simple Test which shows which keys are pressed. With this test i noticed i can only press a limited amount of keys simultaniously. Thats what excactly i expected. The strange thing is the maximum numbers of keys i can press differs regarding which keys i press!?!?

For Example:

F1 + F2   --> no other F Key accepted but some of the "normal keys"
F2 + F3 +F4 --> is working with no problem

or:

asdf + jk is working (6 keys seems to be the absolute maximum)
asdf + gh -> gh is not working

So my question is:
Does anyone know whats the reason for this (i estimate its the Keyboard Hardware wireing)? And is there a Specification describing this behavior ?


Greetings &
  a Happy new Year

HaBaLeS

[NateS]

Any two keys besides ctrl, shift, and alt are fine. More than that and various hardware reacts differently. They call it "ghosting". You can buy special keyboards like the SteelSeries 7G Keyboard that don't have the problem:
http://www.amazon.com/SteelSeries-64022-7G-Keyboard-Black/dp/B000W6IY6O/ref=dp_cp_ob_e_title_0
They also make a model called 6G that supports up to any 8 keys at once. Of course, you can never rely on users to have this kind of hardware.

[bobjob]

http://en.wikipedia.org/wiki/Rollover_(key)