Quotes from roulishollandais:
"I know all that Chris Scott ! I am able to do substractions..."
Forgive me... But your posts are usually so cryptic that it is sometimes difficult for a simple soul like me to estimate your experience and knowledge of aeronautical matters in general, and glass cockpits in particular. You talk of an MD80 pilot course, and then you say you are a software professional. If you read my posts, you know exactly my experience in the context of Habsheim, but I know little of yours. So I have no alternative but to take your questions on face-value, and answer them as well as I can. I have also to consider other readers who may have less knowledge of altimetry than you. (By the way, I admire your courage in posting on an English-language forum, because I would not want to try a French-language one.)
"...please accept that we don't know how the pressure (total and static) are 'handled' by the software to appear as a graduated scale on the PFD on the glass cockpit."
That is true, but how many pilots of a/c with mechanical or electro-mechanical altimeters know the precise mechanism that drives the needles, or the chances of them misreading? In my case, altimeters had already become more and more sophisticated as my career gradually progressed from the DC-3/C-47 to the A310 and DC10. Pilots have to take many things on trust, unless and until they find a problem. The A310 of 1983 had a PFD and ND, on which we relied for most of our flight parameters, except altitude and VS. So the DMC and other links in the display system were not unprecedented in airline service. I was flying A320s before this accident, and experienced no altimeter indication problems that I was aware of.
We know that Capt Asseline had had a problem on a previous flight, in a descent over the Jura mountains, when the selected sub-scale settings had changed spontaneously. That later resulted in the a/c being lower than he intended. But, as far as I know, there is no suggestion or likelihood that the same fault happened at Habsheim, and the pilots had both set the QFE of 984 less than a minute before they levelled off at 61 ft. Therefore, it is most likely that the indications on the PFDs were precisely 808 ft lower than the pressure altitudes recorded by the DFDR.