[Tfug] OT - PC Autostart Hardware

[Bexley Hall]

Hi, Jim,

> I know there's lots of hardware lurkers out there, so
> here's a HW question.  I use network power switches to
> allow me, or an automated process, cycle power to a PC. 
> These things are not cheap, and they are one more piece of
> equipment to keep track of and fiddle with (and get
> lost/stolen).  Are there internal PC power supplies that can
> be triggered to do a power cycle from a process running on
> that same PC?  I have a PC that also houses a GPS receiver,
> and when things hang my first hack-fix is to force a reboot,
> and I'd like to have a second level of response wherein
> I cycle power to the whole box.  Does such a power supply
> exist, and what about SW to drive it?

I had to think about this to figure out what was so
"special" about your requirement...

Obviously, you can power *down* most modern PC's
"on command" (you may need to be root and/or hack the
kernel if you want an arbitrary process to be able to do this
EVEN IF THE SYSTEM IS HUNG)

The trick, of course, is to get the powered down machine
to power back *up* after power has been removed!  ;-)

It seems like this should be easy to do with a little
hardware hack external to the machine.  In essence, you want
to be able to cause the power button to be "pushed" *after*
you have "shutdown" the system.

You should be able to attach an open-drain output of a
one-shot to the power button and trigger it from some
"convenient" output available on the machine (an unused
signal on a serial port, parallel port, etc.).  I suspect
you could also just trigger it on "falling Vcc" (i.e.,
whenever the system shuts off, have it turn itself back
on *regardless* of the actual cause! -- This would require
the presence of a "real" power switch to be able to turn the
machine off "for good"). 

Unfortunately, this requires a (minor) mod to the hardware
so its not a "portable" solution...