Last updated: September 2026
DuckStation is the PS1 emulator I put on every device, and it has one hard rule: no BIOS, no game. The error is blunt about it. What the error does not tell you is that DuckStation does not care what the file is called, does not read subfolders, and accepts a PS2 dump in place of a PS1 one. Once you know those three things, the setup takes a minute.
This page is DuckStation-specific. The general PS1 file list, the RetroArch cores and the handheld firmwares are in my PS1 BIOS guide; this one covers how DuckStation itself finds, checks and picks a BIOS, and the file behind the most common search that lands here, the NTSC-U SCPH-5501.
The File Most People Want: SCPH-5501 (NTSC-U)
If you play North American games, this is the one:
| Conventional name | DuckStation’s label | Size | MD5 |
|---|---|---|---|
scph5501.bin | SCPH-5501, 5503, 7003 (v3.0 11-18-96 A) | 524,288 bytes | 490f666e1afb15b7362b406ed1cea246 |
The three model numbers share one image, so a dump from a 5501, 5503 or 7003 produces the same hash. DuckStation gives this file its highest priority for the NTSC-U slot, so when several US files sit in the folder it picks this one.
The filename is irrelevant to DuckStation. It scans the folder, hashes every file of the right size, and matches on the hash. scph5501.bin, ps-30a.bin, usa.bin and SCPH-5501.BIN are all the same file to it. The size is what it checks first: 524,288 bytes for a PS1 image, and anything else is skipped with an “incorrect size” note in the log.
Every PS1 BIOS DuckStation Knows
| File | Region | Console models | MD5 |
|---|---|---|---|
scph5500.bin | NTSC-J | SCPH-5500 (v3.0 09-09-96 J) | 8dd7d5296a650fac7319bce665a6a53c |
scph5501.bin | NTSC-U | SCPH-5501, 5503, 7003 (v3.0 11-18-96 A) | 490f666e1afb15b7362b406ed1cea246 |
scph5502.bin | PAL | SCPH-5502, 5552 (v3.0 01-06-97 E) | 32736f17079d0b2b7024407c39bd3050 |
scph1001.bin | NTSC-U | SCPH-1001, 5003, DTL-H1201, H3001 (v2.2 12-04-95 A) | 924e392ed05558ffdb115408c263dccf |
scph7001.bin | NTSC-U | SCPH-7001, 7501, 7503, 9001, 9003, 9903 (v4.1 12-16-97 A) | 1e68c231d0896b7eadcad1d7d8e76129 |
scph101.bin | NTSC-U | SCPH-101, the PSone (v4.5 05-25-00 A) | 6e3735ff4c7dc899ee98981385f6f3d0 |
DuckStation’s table has 24 PS1 entries; those are the ones a real-world dump produces. The v3.0 trio (5500, 5501, 5502) carries the best priority, the launch-console 1001 is ranked lower because of known bugs, and the late PAL revisions are ranked lower for their region checks. Every one of them supports DuckStation’s fast boot patch.
Files DuckStation loads but does not recognise
| File | MD5 | What happens |
|---|---|---|
psxonpsp660.bin (from PSP firmware 6.60) | c53ca5908936d412331790f4426c6c33 | Loads as an unknown BIOS with a warning. Not in DuckStation’s hash table. |
ps1_rom.bin (from PS3 firmware) | 81bbe60ba7a3d1cea1d48c14cbcc647b | Same. |
openbios.bin | none | Detected by its signature. Runs, fast boot unsupported. |
A file of the right size with an unknown hash still loads, and the log says it “may crash”. If a known BIOS is also in the folder, DuckStation always prefers the known one. The RetroArch cores are more relaxed about the PSP file; if you rely on it, that is the place to use it.
The PS2 shortcut
DuckStation reads a 4,194,304-byte PS2 BIOS image directly, because the PS2 firmware contains the PS1 boot ROM in its first 512 KB. If you already dumped a PS2 for PCSX2 or NetherSX2, drop the same .bin in DuckStation’s folder and you are done. DuckStation ranks PS2 images below real PS1 dumps because fast boot needs a dynamic patch on them, but they run the library.
Where the BIOS Folder Is
DuckStation scans one flat directory. Files inside a subfolder are not seen, so bios/psx/scph5501.bin is invisible.
| Platform | Default BIOS directory |
|---|---|
| Windows (installer) | %LOCALAPPDATA%\DuckStation\bios\ (older installs used Documents\DuckStation\bios\) |
| Windows (portable) | bios\ next to the executable, when portable.txt is present |
| Linux | ~/.local/share/duckstation/bios/ |
| Linux Flatpak, Steam Deck | ~/.var/app/org.duckstation.DuckStation/ under its data directory |
| macOS | ~/Library/Application Support/DuckStation/bios/ |
| Android | The folder you pick in Settings > BIOS; the app has no fixed path |
The version-proof way: Tools > Open Data Directory opens the right folder on desktop, and Settings > BIOS shows the BIOS Directory field, three region dropdowns (NTSC-J, NTSC-U/C, PAL), an Install BIOS button that copies a file in for you, and Refresh List. When a region dropdown resolves to a named file, that region is ready.
EmuDeck on Steam Deck puts the files flat in Emulation/bios/. Its docs are explicit: no PSX or PS1 subfolder. Batocera and Knulli use bios/ at the root of their data partition.
Region Auto-Select and Fast Boot
With Console Region on Auto, DuckStation reads the disc’s region and loads that region’s BIOS from the dropdowns. If only one region file exists and the disc is from another, it uses what it has and logs a region mismatch warning. Most games run fine that way; a few PAL titles with region checks do not, which is why the three-file set is worth having.
Fast Boot skips the Sony logo by patching the BIOS in memory. Every real PS1 dump in the table supports it. OpenBIOS does not, and DuckStation falls back to a full boot with a “cannot fast boot” message rather than failing. A handful of games depend on the boot sequence; disable fast boot per game in its properties if one misbehaves.
The Error, and What Causes It
The exact message is:
No BIOS image found for [region] region. DuckStation requires a PS1 or PS2 BIOS in order to run. For legal reasons, you must obtain a BIOS from an actual PS1/PS2 unit that you own (borrowing doesn’t count).
Four causes, in the order I check them:
- Wrong directory. The BIOS Directory field points somewhere else. Use Install BIOS or fix the path.
- Subfolder. The file is one level too deep. Move it up.
- Wrong size. Still zipped, truncated, or a
.binthat is actually a disc image. PS1 images are exactly 524,288 bytes. - Region set manually with no matching file. Console Region on NTSC-J with only a US BIOS. Set it to Auto.
A related one: DuckStation warns that a BIOS “is not a known good dump” but runs anyway. That is an unknown hash, usually a rarer revision or the PSP file. If games work, ignore it.
How to Get the File Legally
DuckStation’s own README says to dump it from your console “using Caetla or other means”. The routes:
- Caetla on a cheat cartridge. Caetla is firmware for the Xplorer, Action Replay and GameShark carts that turns them into a development interface. With it you can read the BIOS out over the parallel port. Old hardware, still works.
- FreePSXBoot. A memory card exploit for unmodified consoles. Write it to a card, boot, run a BIOS dumper, and the file comes back on the card. Covered in the PS1 BIOS guide.
- From a PS2 with biosdrain. A FreeMcBoot card, uLaunchELF and a USB stick produce the 4 MB PS2 image, which DuckStation reads directly. The full walkthrough is in the PS2 BIOS guide.
- From PS3 firmware. The PS3 update file contains a PS1 BIOS image, and a small tool extracts it. It loads as an unknown BIOS.
Any of the first three gives you a hash from the table above.
FAQ
What BIOS does DuckStation need?
Any real PS1 BIOS dump, or a PS2 BIOS dump. For US games the standard choice is the SCPH-5501 image, MD5 490f666e1afb15b7362b406ed1cea246.
Does the filename matter?
No. DuckStation matches on the file’s hash and size, not its name.
Where is the DuckStation BIOS folder on Windows?
%LOCALAPPDATA%\DuckStation\bios\ on current builds, Documents\DuckStation\bios\ on older ones. Tools > Open Data Directory takes you there either way.
Can I use psxonpsp660.bin in DuckStation?
It loads with an “unknown BIOS” warning. It is not in DuckStation’s table, so a real console dump is the safer choice.
Does DuckStation on Android need a BIOS?
Yes, the same file. Pick the folder under Settings > BIOS on first launch.
DuckStation | DuckStation on GitHub | Beetle PSX core docs
Last verified: September 2026