OT?: AF 447 and avionics software

["Alex R. Mosteo" <alejandro@mosteo.com>]

I'm sure most of us are following the news on this issue. I just read an 
article where an 'expert' questions "damn computers". Particularly this 
quote:

"In these fly-by-wire systems, one never really knows if one has checked out 
all possible combinations of events to make sure that the computer properly 
reacts,"

http://www.time.com/time/world/article/0,8599,1902421,00.html

Frankly I know nothing about the aviation standards for software/computer 
use, but I suspect it is somewhat more strict than "one never really knows". 
I mean, surely you can't test everything, but I guess one can be reasonably 
confident on the system design!

Now, there's a trend forming pointing to the ADIRU [1] unit, because of 
recent incidents like the Qantas flight mentioned in the article. I'm not 
sure there's really verified reasons to point to it yet but, trying to stay 
on topic:

I think Airbus is mainly Ada, right? Do you know some good place to read 
about its software systems?

What about these ADIRU units, are they delivered to Airbus by some provider 
or are of their own built?

[1] http://en.wikipedia.org/wiki/Air_Data_Inertial_Reference_Unit