[SGVLUG] Calling the brightest of cal tech and other nerds!

Tom Emerson osnut at pacbell.net
Sat Dec 23 09:52:27 PST 2006


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My turn to weigh in on the discussion...

Dustin Laurence wrote:
> On Fri, Dec 22, 2006 at 05:06:39PM -0800, Donald E Gibbs wrote:
> 
>> Every time you spark the case you reset.  Okay.  The question was
>> asked why this happens.  Why doesn't the enclosure protect the
>> internals.
> 
> Unless you have an idea of what might be unusual in this situation, I
> think the discussion is esoteric already.
> 
> To cut even more to the chase, part of the question is "why is this
> acting differently than other machines?"  I don't recall ever hearing of
> other machines rebooting under similar conditions.

Actually, I believe he said it "shuts down", NOT "reboot", but that's
only a matter of semantics.

in the lightning-fast pace of computer evolution, you might not have
noticed that for the last three or four years or so, computers don't
have "the big red switch" anymore -- (for those to young to know what
I'm talking about, the original "power" switch on IBM PC's was indeed a
"big red switch", approximately 1" wide with a throw of 3/4" or more.)
Instead, the (supposed) "power" switch is a soft-switch that goes to the
MOTHERBOARD, not the POWER SUPPLY, and essentially generates a signal on
some trace/line related to the PSU which (as John K. surmised) tells it
to turn off (or on, as the case may be)

my guess, similar to the magic/more-magic switch(*), is that touching
the case does indeed cause a "signal" to be induced on the "power
supply" line to the MB, which in turn instructs the system to shut off.
 I /suspect/ you can mitigate this somewhat by changing the BIOS such
that the "power switch" needs to be held for 4 seconds before shutting
off (similar to many laptops)

Tom

(*) I'm impressed, Dustin -- you've related that story a few times at
the after-after meeting (streetside on Lake...) but never knew it had
been committed to an actual website...

- --
Top o' the Blog: latest Suse install in the least likely of places
http://osnut.homelinux.net/mtblog/ya_index.html
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