Where is the data/saved files/workdata for "Primavera P6 Professional R8.3"?

Member for

16 years 3 months

default database pmdb

Member for

7 years 6 months

So, any ideas how to recover my plans from within the 'database' ?

Member for

20 years 6 months

8.3 didn't use SQLite so it would've been saving to a database, not to a single *.db file like P6 R17 now does.