Glass panels: what OS?

I've been wondering...

What underlying OS do the various glass panels (Avidyne, Garmin, etc.)
use? It might actually make me think twice about buying a particular
system if I knew that (for example) it was Windows underneath.

I would think that the glass panel folks would be using one of the
real-time OS's that are designed for industrial applications, but I
don't know for a fact.

--
Bruce Horn, Chief Technical Officer, Marketocracy, Inc.