Well sometimes the books are wrong. Digifant I came before Digifant II. In fact
if you check the wiring diagrams for a golf/Digifant II and Vanagon/digifant I
you will see that they are almost identicle. Digifant II just has additions (no
changes) when compared to digifant I

Anyway I have opened up a digifant I box and it uses a really cheap 8 bit
processor. This limits the resolution that it can adjust and measure things like
mixture, timing and temperature. Consider that many of todays car ECU's have 32
bit brains.

The older L-Jetronic in 75-79 loafs used an analog computer that was capable of
measuring and controlling to much finer levels but they were not without
problems either.