Corrupted BIOS Symptoms

How to recognise a corrupted or invalid PS1 BIOS file — and how to fix it.

The Definitive Check: File Size

A valid PS1 BIOS .bin file is exactly 524,288 bytes (512 KB). Any other size means the file is corrupted, was not fully extracted, or is the wrong file type entirely. This is the first thing to check before anything else.

On Windows: right-click the file → Properties → Size (not "Size on disk"). On macOS: Cmd+I → Size. On Linux: ls -la filename.bin.

Common Symptoms of a Corrupted BIOS

DuckStation reports "Invalid BIOS" or shows no checkmark

DuckStation validates BIOS files against known checksums when you point it at the BIOS directory. An invalid checksum means the file does not match any known PS1 BIOS version.

Cause: Corrupted download, incomplete extraction, or a file that is not actually a PS1 BIOS (e.g., a PS2 BIOS accidentally renamed).

Fix: Verify the file size is 524,288 bytes. If not, re-download. If the size is correct but DuckStation still rejects it, the file's contents are corrupted — re-download from a fresh source.

Emulator opens but games do not load (black screen)

The emulator started but cannot execute the game boot sequence. If the BIOS loads enough to start the emulator but is internally corrupted, it may fail partway through the hardware initialisation.

Fix: Replace the BIOS file with a fresh download. Also check that the game image itself is not corrupted — try a different game to isolate the issue.

No PlayStation logo / startup animation

DuckStation and ePSXe can optionally show the full PlayStation startup animation (the rising stone monoliths). If this is enabled but nothing appears, or the animation is garbled, the BIOS file may be partially corrupted.

Fix: Re-download the BIOS. If you are using "Fast Boot" mode, disable it temporarily to test whether the full startup animation plays correctly.

Audio issues — missing music or sound effects at startup

Very early Japanese BIOS versions (SCPH-1000, v1.0) have known limitations with CD audio. If you are using a v1.0 BIOS for a game that relies on it, you may encounter audio problems that are not related to corruption — they are a version limitation.

Fix: Switch to SCPH-3000 (NTSC-J v2.1) or SCPH-5500 (NTSC-J v3.0) for Japanese titles.

The file is still a .zip archive

One of the most common "corrupted BIOS" reports is actually an un-extracted archive. DuckStation and ePSXe cannot read ZIP files — they need the raw .bin file.

Fix: Right-click the downloaded file → Extract All (Windows) or double-click (macOS). Move the extracted .bin to your BIOS folder.

How to Verify Your BIOS File

  1. Check the file size: exactly 524,288 bytes. Any other size = corrupted.
  2. In DuckStation: Settings → BIOS. A valid file shows a checkmark and version string. An invalid file shows a warning icon or is not listed.
  3. If both size and checkmark are correct, the file is good. Any remaining issues are likely a region mismatch or game image problem, not the BIOS.