AetherSX2 reads this BIOS file to boot games exactly as a real console would. Without it, you will be staring at a black screen or an error message reading: "Cannot open BIOS image."
Finding the correct 4MB BIOS for AetherSX2 is the most important step in setting up PS2 emulation on Android. Without this system file, the emulator cannot boot games. ⚡ What is the AetherSX2 BIOS 4MB File? aethersx2 bios 4mb
However, Sony owns the copyright to the BIOS code. Therefore, emulator developers cannot legally distribute the BIOS file with their app. Instead, the emulator acts like a shell, and you—the user—must provide a "dump" of the BIOS extracted from a physical PS2 console you own. AetherSX2 reads this BIOS file to boot games