In most cases, these two formats are functionally identical "raw" memory card dumps; the only difference is the file extension and how the emulator looks for them. How to Convert MCR to SRM
This is the native memory card format used by standalone emulators like ePSXe or DuckStation . It acts as a virtual 128KB memory card that can hold multiple game saves. mcr to srm converter
This is the "Save RAM" format used by RetroArch and its various Libretro cores (like Beetle PSX or PCSX-ReArmed). In most cases, these two formats are functionally