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Date:      Sun, 18 Oct 1998 22:27:32 -0700 (PDT)
From:      Jim Shankland <jas@flyingfox.com>
To:        clash@tasam.com, kpielorz@tdx.co.uk
Cc:        hardware@FreeBSD.ORG
Subject:   Re: ATX boards and restart after power failure
Message-ID:  <199810190527.WAA28219@biggusdiskus.flyingfox.com>
In-Reply-To: <009c01bdfb0d$04650d80$f10408d1@bug.tasam.com>

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When we discussed this subject a week or so ago (ATX boards that don't
have a BIOS or other switch to cause them to boot up automatically
when power is restored after a power failure), I said I'd summarize
briefly what I've learned.  So:

It's polymorphically perverse.  Some boards have BIOS settings; there
was one report of a motherboard with a jumper you could add or remove.
Many Socket7 ATX boards have neither.  One suggested fix was to ground
the power supply's PS-ON line; this worked on the Tyan S1572
motherboards we've been using, so that's our solution for now.
However, I'm told by the hardware guys that it did *not* work on the
Asus P5A board they evaluated.  There were also reports that jumpering
the "soft power on" button that the user is supposed to push works on
some boards.  It didn't work for us, with the two boards mentioned
above.  Finally, it is possible to design a simple circuit that
simulates pushing the soft-power-on button for half a second or so
when power is applied.  We haven't attempted this.  (I suppose there's
a market for a solenoid gadget that you velcro to the front of your
computer, and that presses the "on" button briefly when the machine
is powered up.)

It's alleged that none of this is a problem on Pentium II boards.

The other conclusion I've reluctantly reached is that people
who design motherboards for a living seem to be muttonheads.

Many thanks to those who responded with suggestions and information.

Jim Shankland
Flying Fox Computer Systems, Inc.

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