Thanks for all info. I find it cumbersome that giving useful answers is so difficult... also the answers to the initial question seem to be logically correct. It's like the old programmers joke when being asked to do A or B and the logical correct answer given is YES...
So the result is now: Virus TI has a backup battery and it is placed in a battery holder that makes exchange possible without soldering...?... if you are a qualified can opener... LOL
Concerning the non volatile 'Rom' memory - that could be an EEPROM, Flash or similar.. but that does not really matter much for the user.