By the way, something unusual in neogeo...

[Tux]

I had this happen lately : while testing irrmaze, it didn't have any soft dips, which is a bug, I think almost all the neogeo games have some softdips except some prototypes. The backup ram was full but it's supposed to rotate the games inside once it's full. For some reason, mine didn't rotate anything anymore. I might have done something wrong with it, some testing gone bad maybe, but the bios doesn't display any error for that, it's just that any new game can't create a new slot in the backup ram, and it had some consequences on the game play, it had some strange settings because of that, no instructions, no display of the credits at the bottom of the screen, but except that the game seemed to work fine.

I don't know why the games didn't rotate anymore, I kept a backup of it for now.

Fixing it is easy anyway, either delete the file savedata/neogeo.saveram, or go into the bios, hardware tests, when arriving at the stage where it tests the backup ram the unibios proposes to reset it if you press a+b+c, it's equivalent to deleting the file so it will be re-created next time.

I just tested with a new backup ram, loaded more than 8 games, and this time they rotate normally... There is probably a bug somewhere, but for now I don't know exactly what happened... ! Maybe it's linked to switching from aes to mvs in the unibios, not sure, just an idea...

Edited November 14, 2021 by Tux

[Tux]

After some tests, in normal play the backup ram is "locked" at the end of each frame, meaning it can be saved or removed without problem.

The only place I found where it's not the case is in the service mode ! Here the card is left unlocked, maybe it's how I saved mine at a wrong time.
Anyway I added some test to prevent that, the emu now displays a message box to warn if the backup ram is still unlocked and refuses to save it in this case. I'll see how it goes, but it's probably better this way.
I could fix the stuck backup ram manually by removing a duplicated entry, I just removed the 1st one, and it was back to normal again...
The format is documented here : https://wiki.neogeodev.org/index.php?title=Backup_RAM (it was byteswapped when saved by raine, I changed that so that you can edit it more easily in a hex editor in this kind of case, it's able to read the byteswapped format of course but it will save differently now).