Understanding ignition timing

Hello, I'm trying to better understand the Rotax ignition system.

I understood that there were 2 cases.

- The old engines equipped with the 966871 flywheel and no soft start.
The ignition at start and up to 650 rpm, the advance is 4° and then the advance is 26°.

- The new ones, (around 2013, I can't find precisely), equipped with the flywheel 966872 and the soft start.
In this case the CDI receives an impulse via the 12V of the starter relay, and delays the ignition by 3° for 4 to 8s before returning to an advance of 26°.

What I don't understand is how on the old version of the CDI it changes the advance to 650rpm.

And why use a time delay on new CDI ?

I understand that the 912 engine is made to run around 5000 rpm, at lower rpm it doesn't run very smoothly.

Can we say that the old CDI are analog and the new ones contain an eprom or something like that?

 
I have some pictures for those who are interested of the contents of an old open CDI.

Thanks in advance 

Jean Sébastien