Every PS2 emulator, including ARMSX2, NetherSX2 and PCSX2, asks for a BIOS file the first time you open it. Without it, no game will start. This guide explains what the BIOS is and how to get it the legal way: by copying it from your own PlayStation 2.
What is the PS2 BIOS?
The BIOS is the PS2’s built-in system software: the startup screen, the memory card browser and the code games rely on. Emulators recreate the PS2’s hardware, but they still need Sony’s BIOS to boot games. It’s a single file of about 4 MB, usually named something like SCPH-xxxxx.bin after the console model.
The BIOS is copyrighted by Sony. Downloading it from a website isn’t legal, which is also why emulators can’t include it. The legal way is to dump (copy) it from a PS2 you own. Any model works, including the slim.
What you need
- A PlayStation 2 (fat or slim, any region).
- A way to run homebrew on it, such as a FreeMcBoot memory card, or the FreeDVDBoot or OpenTuna exploits.
- A USB stick formatted as FAT32 (older PS2s may not read big or very new sticks; 4–16 GB works best).
- A BIOS dumping homebrew. The PCSX2 team recommends biosdrain, which is free and open source (on GitHub).
Dump the BIOS in 5 steps
- Copy biosdrain to the USB stick. Download the
biosdrain.elffile from the project’s releases page and put it on the stick. - Plug the stick into the PS2 and start your homebrew launcher (for example uLaunchELF from the FreeMcBoot menu).
- Run biosdrain. In uLaunchELF, open
mass:/(the USB stick) and launchbiosdrain.elf. - Wait for it to finish. It reads the BIOS chips and writes the files to the USB stick. The screen tells you when it’s done.
- Copy the files to your phone using a computer or a USB-C/OTG adapter. Put them in a folder such as
Internal storage/PS2/bios.
Add the BIOS to ARMSX2 or NetherSX2
- Open the emulator. On first start it asks for the BIOS; otherwise go to Settings → BIOS.
- Tap Import BIOS (or choose the BIOS folder) and select the
.binfile. - Pick the BIOS from the list. Any region plays games from every region in an emulator.
Now add your games and play. Our ARMSX2 setup guide walks through the rest, and our list of the best PS2 games for Android gives you ideas.
Common problems
- “BIOS not found”: the file isn’t in the folder the emulator is looking at, or it’s still inside a zip. Extract it and import the
.binfile. - “Invalid BIOS” or the emulator rejects it: the file is incomplete. A full PS2 BIOS is about 4 MB. Dump it again.
- The PS2 doesn’t see the USB stick: format it as FAT32 with an MBR partition table, or try a smaller, older stick.
FAQ
Is it legal to download a PS2 BIOS?
No. The PS2 BIOS is copyrighted by Sony, so downloading it is not legal. Dumping the BIOS from a PS2 you own for your own use is the legal way.
Which PS2 BIOS is best for ARMSX2?
Any working BIOS dumped from a PS2 works. The region does not matter much in an emulator: one BIOS can play games from every region.
Can I play PS2 games on Android without a BIOS?
No. ARMSX2, NetherSX2 and other PS2 emulators need a BIOS file to start games.
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