[Tfug] APM mechanisms

[John Karns]

On Dec 26, 2007 4:52 PM, Bexley Hall <bexley401 at yahoo.com> wrote:
> Hi,
>
> 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
> which lets me cram a dual NIC and a SCSI HBA
> into it (the dual NIC lets it act as my
> firewall and the HBA lets me attach external
> storage as well as tape backup, etc. as needed).
>
> 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 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.


> 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
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 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.

-- 
John