Convert & Align 128KB Save Files (.sav to .srm) on MiSTer and OnionOS — Pokémon Unbound

Transferring saves between the MiSTer FPGA GBA core and handheld retro emulators running OnionOS or muOS requires manual raw block alignment.

1. 128KB FLASH Memory Alignment Issues

Pokémon Unbound uses the FLASH_1M (128 Kilobytes / 131,072 bytes) save format to accommodate over 800 Pokémon entries and quest logs. If you import a save file that is not exactly 131,072 bytes, the MiSTer FPGA GBA core or OnionOS cores will flag it as corrupted and format the save partition, erasing all progress.

RetroArch cores sometimes append metadata headers at the end of save files, rendering them slightly larger than 128KB, while standalone systems expect pure RAW binary saves.

2. Save File Conversion Guide

To convert and normalize a GBA save file across any platform:

1. Navigate to your emulator's physical save location (see table below) and locate your save file.
2. Check the file size. If it is not exactly 131,072 bytes, open a web browser and go to Save File Converter.
3. Upload your save file. Set the output console to Gameboy Advance and force the size dropdown to 128kB.
4. Download the raw save file, rename it to match your ROM name precisely, and append the appropriate extension (.sav or .srm) required by your target device.

3. Multi-Platform Save Paths