Re: sometimes keyboard resets to default 6 chars a sec.

Riley Williams (rhw@MemAlpha.CX)
Fri, 21 May 1999 00:46:37 +0100 (GMT)


Hi Keith.

>> When this happens, it immediatly affects all consoles and X
>> terminals at the same time, and there doesn't seem to be a way
>> to reset this back to higher speeds (actually as fast as
>> possible) except by rebooting.

> kbdrate -r 30 -d 250, root only.

>> This phenomenon is rare (about once every 2 months), but only
>> seem to happen since kernel 2.2 (or just before), and I can't
>> reproduce it at will.

>> What I see is a brief light up of the keyboard leds like during
>> boot.

> Could be a dodgy keyboard or cable. I get exactly the same
> problem when I switch my screen, keyboard and mouse from one
> machine to another. Mind you that is through a 4 way switch and
> I suspect the switch itself is resetting the keyboard.

I also use a 4-way switch to switch keyboard, video and mouse, and
I've met this problem with it. The explanation is simple: multiway
switches come in two varieties, these being make-before-break and
break-before-make respectively, and for this application, it is VERY
important that break-before-make switches are used.

If, as appears to be the case with your box, make-before-break
switches have been used, then both the keyboard and mouse could get
reset when switching, depending on the precice signal levels on the
pins being switched from and to at each stage.

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html

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