APM.

[Oleg Gusev]

> If they do, they might be sending charging status over
> the serial line.  The designers might have assumed
> that when is A/C is on then the batteries are
> charging.

I'm wondering where is this "intelligent" circuitry. If you
will look at the motherboard picture, you can see the
chips responsible for the battery charging. The battery has
4 pins, so you can be right.
Every six seconds you get the Ser1 interrupt, and should 
read 48 bytes (my guess was that these are actually 24 of
16bit values, but it can be a mistake and some of them are 8bit) 
and interpret them in some way. The ac_line 
status can be guessed from these independently from the
GPB5 pin that i'm using right now. Then you should decide
which of the exponential curves to take, calculate the
logarithm, and make a linear regression to estimate the
remaining time, etc. If the curve goes up, then you are charging.
Honestly, i don't undestand why HP can't provide this information.
Maybe somebody should ask them politely :)

 Oleg.