WMS games run a checksum on their nvram contents, sometimes down to the individual adjustment/audit, sometimes on groups of adjustments. They've been doing this back into the system 7 era.

If WPC does it the same way as system 11, the adjustments get one checksum, and each audit (which includes the hstd, even though it's not an 'audit') has their own. If the checksum doesn't match on an audit, when you are scrolling through them, it puts 'Error' on the display.

I guess it could be called a check byte? Integrity byte?

thanks guys for the quick responses and slochar for showing me where the actual highscores are hidden.....so obvious but I missed them

As stated above I can modify the name and/or the highscore such that the checksum is not changed-otherwise the default names and scores get restored from the EPROM..so there seems to be some kind of checksum/controlbyte or whatever

I did also do a file compare after entering the grand champion score but there were so many differences that I can not figure out where that controlbyte is located nor would I know how to calculate a correct controlbyte

dumped my BSD RAM files there:
https://drive.google.com/drive/folders/1zenDT35G-a03-qtLoSGPwVrBEXCerT73?usp=sharing
one ist the original and the other is the one after achieving the Grand champion with a score of 448.970.080 and entering the name `HGR´

Yes, that is what I mean by "corruption check". I knew they did that for the adjustments, just figured they didn't bother with the score table, as it's not critical data and can be easily reset.

I think they did it for the scores because if you beat some ludicrously low random score, you'd get free credits and the operator would never buy your brand again.

Gottlieb system 80 had a crude version of this, where they store every nvram nibble 3 times and they all have to agree, or if 2/3 of them agree, the 3rd one gets set to that value.

thanks for the input, but don´t want to mess that thread up-created a separate topic: https://pinside.com/pinball/forum/topic/restoring-writing-own-highscores-to-nvram#post-6591485

Has someone successfully used the FM1608 on a Capcom (pinball magic) instead of the zeropower M48Z08 ?
I assume it is working-pinout also the same
Just wanted to have a confirmation before installing one

I can confirm that the FM1608 NVRAM is working as expected on my Capcom pinball magic

I figured out how to restore my personal highscores and write it to the NVRam chip
details here: https://pinside.com/pinball/forum/topic/restoring-writing-own-highscores-to-nvram#post-6623391