initially posted the same question in the NVRAM thread but started a dedicated topic here

I have successfully installed FM1608 DIP chips in my WPC games

I was messing around with my GQ-4x4 programmer to read/write those chips and tried to restore my previous highscores from before installing them (would be nice to somehow keep them)
Was not very successful so far. I managed to change the name and the highscores but I could only modify them such that the checksum is not changed-otherwise the default names get restored from the EPROM.
screenshot from the BSD code with the highscores and names is attached

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 checksum is located nor would I know how to calculate a correct checksum

dumped my BSD RAM files there:
https://drive.google.com/drive/folders/1zenDT35G-a03-qtLoSGPwVrBEXCerT73?usp=sharing
one is 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´

Would be interesting where the correct checksum has to be entered in?
How is that checksum calculated?

Did anyone else successfully mess around and managed to restore their personal highscores via writing them to the NVRAM?
Any ideas/hints welcome-I do not have much knowledge on those kind of things but keen to mess around and lern...

the only related info I found was that but was not very helpful to me: https://github.com/mattvenn/ds2604-sram-driver

my initial post with some ideas is here: https://pinside.com/pinball/forum/topic/nvram-experience/page/14#post-6588833

I would prefer not to have to mess around with installation of PinMAME...in the worst case I try to redo my highscores with the glass off

ram (resized).png

sounds like a wild hack-but too late as the battery buffered RAM is already unsoldered and has lost its memory

Finally I found a way how to restore the highscores on my WPC games after installing NVRAM
I´m not an expert in those things but as I figured out how it works I thought I will do a quick summary-don´t blaim me for any badly explained/described details

quick writeup:

!!! Do this at your own risk! Don´t mess around with changing random parameters in the RAM file-might mess up or destroy your game !!!

-used the GQ-4x4 programmer with the DS1225Y profile together with the FM1608 DIP NVRAM chips
-take pictures/note down your highscores before removing batteries or your SRAM chip
-install FM1608 in the (optionally temporary installed ZIF) socket in your WPC MPU board
-power up the game. It will show "factory settings restored". Set date and time. You can also set your preferred other adjustments now or later on-does not matter
-pull the FM1608 and read the data with the GQ-4x4 programmer. Save that file and keep it to be able to mess around with the data
-you will get something like that (default RAM file from my FT)
ft gc (resized).jpg
lets start with the grand champion:
Grand champion here is "CRL" (yellow) with a score of 300.000.000 (red). Just modifying those numbers will not work as they are ´protected´ by a checksum (blue) which is located just after the score. After entering your own Grand campion initials and highscore one has to recalculate this specific "GC"checksum (there is plenty of checksums for various adjustments-see github reference)
- how to recalculate (here GC) checksum:
- open a hex calculator (here the one that comes with windows) and set "hex" and "word" accordingly
calc (resized).JPG
start with "FFFF" and subtract the hex numbers for the initials and score (here it is: FFFF - 43 - 52 - 4C - 03 - 00 - 00 - 00 - 00) which results in FF 1B.
Put the recalculated checksum (here FF1B) at the corresponding address

-similar procedure for the other 4 highscores.
they are located just before the GC
ft gc and hs (resized).jpg
It is starting with 1.place "MDR" followed by "MAX", "JWS" and "CG " with scores from "250.000.000" down to "175.000.000"
Enter your own 3 digit initials and your highscores accordingly. Afterwards one has to recalculate the "HS"checksum.
Procedure as above except that the string is longer: FFFF - 4D - 44 - 52 - 02 - 50 - (00 - 00 - 00) - 4D - 41 - 58 - 02 - 25 - (00-00...) - 4A - 57 - 53 - 02 - (00...) - 43 - 47 - 20 - 01 - 75 - (00..)- The result is "FBA7" which has to be entered right after the last highscore (in pink) and before the initials of the GC

-some example after the GC and highscore #3 are restored (my initials are "HAR" followed by my personal highscores). Note the recalculated checksums:
ft scores (resized).JPG

-write the modified file to your FM1608 DIP NVRAM chip and install it in your game
-power up and see if you have successfully restored your personal highscores. If you did a mistake with the checksums the factory settings and default scores (read from ROM) get restored

!!! Do this at your own risk! Don´t mess around with changing random parameters in the RAM file-might mess up or destroy your game !!!

some hints:
-the location (addresses) of the array for the highscores and GC might differ from game to game but they seem to be always close to the end of the file.

-for some additional champion like "biggest liar" or "rock boat champion"on fish tales we could not clearly figure out the structure (although it looked obvious-seems the initials are not part of the checksum there) . I restored them by playing a game with the glass off
For TZ for the LOTZ champion I was able to restore it-can´t remember the details-think it was a 8bit checksum

references: found some details about the structure of the RAMfile here: https://github.com/tomlogic/pinmame-nvram-maps
Also the guy sharing that info was very helpful and pointed me in the right direction to get it done