How to Install PS1 BIOS

Complete step-by-step installation guide for DuckStation, ePSXe, and RetroArch on PC, Mac, Linux, and Android.

Before You Begin

You need a PS1 BIOS .bin file (exactly 512 KB). Download one from the homepage if you haven't already. Extract the ZIP — the emulator needs the raw .bin file, not the compressed archive.

DuckStation (Windows, macOS, Linux)

  1. Open DuckStation and go to Settings → BIOS.
  2. Click the folder icon next to "BIOS Directory" and navigate to the folder where you saved your .bin file.
  3. Click OK. DuckStation will scan the folder and display detected BIOS files with their region (NTSC-U, NTSC-J, PAL) and version.
  4. A green checkmark next to a file confirms it is valid. You can have multiple BIOS files in the same folder — DuckStation auto-selects the best match per game.
  5. Start a game from File → Open Disc Image.

DuckStation Default BIOS Paths

  • Windows: Documents\DuckStation\bios
  • macOS: ~/Library/Application Support/DuckStation/bios
  • Linux: ~/.local/share/duckstation/bios

DuckStation (Android)

  1. Create a folder on your device's internal storage, e.g., Internal Storage/DuckStation/bios.
  2. Copy your .bin BIOS file into that folder using a file manager app.
  3. Open DuckStation → tap the three-dot menu → Settings → BIOS.
  4. Tap BIOS Directory and navigate to the folder you created.
  5. Tap OK — DuckStation will detect the file and display it in the BIOS list.

ePSXe (Windows)

  1. Locate your ePSXe installation folder (usually C:\Program Files\ePSXe or wherever you extracted it).
  2. Open the bios subfolder inside the ePSXe directory. If it doesn't exist, create it.
  3. Copy your .bin BIOS file into that folder.
  4. Launch ePSXe and go to Config → BIOS.
  5. Click Select, browse to your bios folder, and select the .bin file. Click OK.
  6. You're set — run a game via File → Run ISO.

ePSXe (Android)

  1. On first launch, ePSXe shows a setup wizard. Tap Next past the welcome screen.
  2. When prompted for a BIOS, tap Select BIOS File and navigate to where you saved the .bin file.
  3. Select the file and tap OK. ePSXe will confirm it with the BIOS version and region.
  4. Complete the remaining wizard steps (GPU, SPU plugins) and you're ready to play.

RetroArch — Beetle PSX HW Core

  1. In RetroArch, go to Online Updater → Core Downloader and install the PlayStation (Beetle PSX HW) core.
  2. Note your RetroArch system directory: Settings → Directory → System/BIOS.
  3. Copy your .bin BIOS file into that system directory. Beetle PSX HW looks for specific filenames — the most common are scph5501.bin (USA) and scph5500.bin (Japan).
  4. In RetroArch, load a PS1 game via Load Content and select the Beetle PSX HW core when prompted.
  5. The core will locate the BIOS automatically from the system directory.

Beetle PSX HW BIOS Filenames

Beetle PSX HW expects lowercase filenames matching the SCPH model number: scph1001.bin, scph5501.bin, scph5500.bin, scph5502.bin, etc. Rename your file to match if the core reports it as not found.

Verifying a Successful Install

In DuckStation: a valid BIOS shows a checkmark and displays the region (NTSC-U / NTSC-J / PAL) and version string (v2.0, v3.0, etc.) in the BIOS list.

In ePSXe: the BIOS path is shown in Config → BIOS without any error message.

In RetroArch: load a PS1 game — if the startup animation plays (the Sony PlayStation logo), the BIOS is installed correctly.

Troubleshooting

  • File not detected: Check the file is 524,288 bytes exactly. Any other size means it is corrupted or still zipped.
  • Wrong folder path: Use the Browse button inside Settings rather than typing a path manually.
  • Black screen after startup: Region mismatch. Use a BIOS matching your game's region.