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How saves sync

RomMBat sends your saves, save states and playtime to RomM, so another device paired to the same account can carry on where you left off. You do not have to do anything for it to happen.

What goes up

  • In-game saves, the ones a game makes itself, such as a battery save on a cartridge.
  • Save states, with their screenshot. See Save states.
  • Saves an emulator keeps as a folder per game, such as a PSP game's save data.
  • A PlayStation 2 game's memory card, once you have given that game its own card. See Memory cards.
  • How long you played. See Playtime.

When it happens

RomMBat syncs saves each time you open EmulationStation and each time you quit it, and again at the start of every sync. It runs in the background, with no window, and never while a game is starting. Nothing is sent while you play: it goes up the next time you quit EmulationStation.

A save another device made comes down when you open EmulationStation. If you have already started that game by then, RomMBat does not write under it: the save waits and lands the next time you quit EmulationStation. A save that reaches RomM while EmulationStation is sitting open comes down the next time you open it (#155).

Away from the server

Playing offline loses nothing. Saves and playtime wait on this device and go up the next time it can reach RomM. The main menu's Waiting to upload row counts what is still waiting.

When a save is deleted in RomM

Deleting a save in RomM takes it out of the emulator's folder on the next sync, and the sync summary says it was removed. A copy is kept in emulators/rommbat/replaced/, so nothing is lost for good. A save you changed here since it went up is sent again instead of removed.

When both sides changed

If a save changed here and on another device since they last agreed, RomMBat keeps both and asks you which one to use. Nothing is overwritten meanwhile. See Conflicts.

Changing emulator

Each emulator keeps its saves in its own place and its own format, and RomMBat syncs each one as it is, without converting it. So when you switch a system to another emulator, your progress comes with you only if the new emulator reads the same save file as the old one. Otherwise the game starts from whatever save the new emulator has, and your old save is usually still there when you switch back. A few emulators use the same file name as another but a different format, so one refuses the other's save or writes over it. Each system's page under Platforms says which of its emulators share a save, and which clash.

The standalone Mednafen opens a save under the game's plain file name before its own. Where it cannot read the save another emulator keeps under that name, Mesen's on the Master System and the PC Engine, mGBA's on the Game Boy Advance and mGBA's on the Game Boy for a game with the smallest save chip, such as Final Fantasy Adventure, RomMBat leaves that save on the server for a game that runs under Mednafen on this computer. The sync summary counts it as left on the server, for an emulator other than the one this device runs, and it arrives on the next sync after you switch the game to the emulator that wrote it.

To change a system's emulator, open Game settings in EmulationStation's main menu, then Per system advanced configuration, and pick the system.

What does not sync

Some saves cannot be tied to one game, such as a memory card every game shares. RomMBat never guesses: it leaves them where they are and reports them, with the reason. To see that report, run rommbat-agent saves in a terminal. It lists what is on this device, what has gone up, what cannot go up and why, and what is waiting on you.

Which emulators have had their saves tested is on Platforms.

When something looks stuck

The background sync writes what it did to emulators\rommbat\logs\background.log, since it has no window. rommbat-agent flush runs the same pass on the spot and shows what it does.