[Tfug] APM mechanisms

[Bexley Hall]

Greetings!

--- John Karns <johnkarns at gmail.com> wrote:

> On Dec 26, 2007 4:52 PM, Bexley Hall
> <bexley401 at yahoo.com> wrote:
> > I have a Compaq Presario 3020 (?) that I am
> > currently using as my DNS/TFTP/SMTP/whatever
> > server.  It's a Pentium 166 (?) class machine.
> > Nothing spectacular.  Except, it has two slots

[snip]

> > But, the *biggest* win is an attached LCD display
> > which saves me the hassle of having to make room
> > for a monitor *or* run it headless and have to
> > drag out a monitor when/if it dies, etc.
> >
> > The box runs NetBSD 3.1 (quite nicely).  *But*,
> > the damn LCD backlight is *always* on!  :<
> 
> I have an old Dell Inspiron 8100 with an nVidia card
> that won't
> respond to the xset command to turn off the

Hmmm... my xset has no such "feature" (unless it
hides under a different name/description).  While
I don't run X on that box (I use the display just as
a text console when things have bit-the-shed).  But,
if it *did*, I could scan the sources to see *how*
it is trying to do so...

> backlight.  After some
> fishing around, I found a work-around for it.  I'll
> have to take a
> look at the script I implemented it in to see what
> the command is.  It might be of use to you.

Excellent!  I can always DL the source of xset
from whatever distro you are using to see what's
under the hood...

> > So, with all this as background information,
> > my question is:
> >
> > How does APM work on these boxes?
> 
> I spent some time tracing through some of the APM
> related issues of
> the laptop and OS (Ubuntu 5), but it didn't seem to
> lead me to a

<grin>  Ever notice how piss-poor the documentation
on open-source projects is?  :>  (FWIW, PostgreSQL
really stands out as an exception, here)

> solution.  It gets rather contorted for some
> machines which date back
> to that period (ca. 2000 - 2001), due to the fact
> that some of them
> (at least the Dells) tried to put a foot in both
> camps by implementing
> parts of both ACPI and APM support in the BIOS, but
> didn't adhere to
> strictly to the standards of one / both of the

Yes, I think that's the case.  And, I think it was a
typical MS inspired hack vs. a well thought out
"feature".

> specs.  My take on it
> at the time was the backlight control was more
> dependant on the quirks
> of the video card BIOS than the machine BIOS.

Hmmm... this is an oddball design.  IIRC, the video
card is *almost* off-the-shelf but modified to
talk to an LCD instead of external monitor (though
I think the external monitor connector is still
present... perhaps wired in parallel, etc.)

Thx!
--don


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