> 1. Subtract DC bias count (= 128) from signal if > 128, subtract signal
> from bias count (= 128) if < 128.
Urk, I can't resist. You mean, something like this?

        btfss signal,7          ; if signal is 0-127
        comf signal,f           ; make it 255-128
        bcf signal,7            ; now subtract 128

Ahhhh... :)

OK, serious question: I need to implement VU-style indicator for music
playback device. It's just for decoration (feeping creaturism), so
accuracy is not terribly important, but obvious, maybe exaggerated,
bouncing LED is.

I was planning to sample about 8Khz and run thru simple IIR filter, the
output works the bargraph. But the RMS thread has gotten me thinking:
would this really do what I need? What exactly the heck is a Volume Unit
anyway? Is there an algorithm that makes more sense?

-- Rich