# Yearn BIOS setup: check required files for each platform
Language: en
Canonical: [Yearn BIOS setup: check required files for each platform]()
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Published: 2026-10-23T00:00:00+08:00
Modified: 2026-10-23T10:34:09+08:00
Author: Bison
Understand the different roles of ROM and BIOS, check required PS1 files and NDS status, retain source information and investigate missing-file messages after import.
English translation of the [Chinese original](), translated on 2026-10-23. The article body uses automated translation; app descriptions, historical reading notes and video subtitles receive separate editorial checks. Original publication dates, attribution, code and version notes are retained.
When Yearn reports a missing BIOS, first identify the platform. BIOS is a system file required by the emulation environment; a ROM contains the game you want to run. They cannot replace each other. This article covers status inspection, importing your own files, and checking results, without providing download sources for copyrighted files.
## Read which platform the notice concerns first
Record which game shows the notice, which platform the library displays, and whether the error explicitly mentions BIOS. If a GBA sample is wrongly identified as PS1, check the imported file's real type before seeking a PS1 BIOS. Misidentified platforms and genuinely missing system files require different investigations.
Yearn's settings provide BIOS management. Inspect status by platform, especially the PS1/NDS distinction: the current interface describes a built-in open-source replacement for NDS, while PS1 provides a workflow for importing user-supplied system files. One platform requiring extra files does not mean every platform needs the same additions.
## Prepare your own BIOS copy
Use system files you are entitled to use from a clear source, keeping an import copy separately from the original. Check filename and size first to ensure it is not a webpage, archive, or renamed empty file. Keep BIOS files separate from game ROMs rather than in one indistinguishable directory to avoid selecting the wrong item.
Common names in PS1 management include scph5500.bin, scph5501.bin, and scph5502.bin. These identify particular system files. Renaming an arbitrary bin to one of these names does not supply the same contents. If your material lacks version and source information, verify it with the lawful source instead of repeatedly renaming files until a notice disappears.
## Choose import in Settings
Open BIOS management and choose Import BIOS File to bring up the system picker. Select the prepared copy, wait for completion, and inspect the list. Handle one file at a time so size mismatches, reading failures, and other notices can be linked to the correct material.
After import, check the displayed name, platform, and status. If it still shows missing, verify the selected file, whether a cloud placeholder has downloaded, and whether an extra extension was added—for example, a file that looks like bin but is actually bin.txt. Do not delete the entire BIOS directory after a failure; retain other working files.
## Check the result with one game
Once the status is correct, return to the game that produced the message and try again. Record separately whether the BIOS notice disappears and whether the game reaches its title screen. Recognizing a system file does not prove every game image is complete or guarantee support for all regions and special formats.
If the notice disappears but the screen remains black, investigate ROM completeness and disc tracks instead of continuing to replace BIOS files. Keep verified settings unchanged and compare a lawful sample with a clear file structure. This avoids changing BIOS, image, and display settings together and losing track of which change mattered.
## Understand the built-in NDS status
If the NDS section describes a built-in open-source BIOS, try the current default configuration first. It means the app includes replacement files for that path, not that every NDS game, touchscreen method, and save has been individually verified. Check results for the specific content.
If the built-in status is abnormal or reports missing files, record the app and OS versions and reopen settings to confirm. Do not copy similarly named files from another console's directory or clear all app data to repair one notice. For bundled-resource problems, clear error records are more useful for feedback than blind overwriting.
## Keep a brief configuration record
Keep a table of platform, imported filename, source description, import date, and test game. Record only your own material, and do not post real personal file paths or device identifiers publicly. On a new device, the table reminds you which files need preparing again rather than assuming save synchronization also synchronized BIOS files.
Before a major device cleanup, retain lawful-source BIOS copies in your own backup location. Keep each file with its source description and record the app version in which it worked. During restoration, verify the file and compare with the same game to reduce reorganization time.
## Frequently asked questions
**Why does game loading still fail after BIOS import?** BIOS is only one layer. A PS1 image may lack companion files, or the game file may be damaged or unsupported by the current core. Use the new error text to determine whether BIOS checking has already passed.
**Will installing files for every region guarantee compatibility?** No. File quality, game edition, region, and emulation implementation can all affect results. More files do not replace verification.
**Can I rename a ROM to a BIOS filename?** No. Extensions and names identify files but cannot change their internal contents. This exercise is complete when the platform status has a clear result and you can distinguish subsequent runtime issues from missing-BIOS issues.
## Recheck the actual filename
Inspect the full name in system file information, not just the truncated list title. Record trailing spaces, duplicate extensions, and download-added numbers. Keep the original and correct verified names only in the import copy. Return to the BIOS list afterward, inspect status again, and retry the same game.
## Related tutorials and sources
Continue reading [Startup error troubleshooting]() and [PS1 companion files]().
Information checked: October 23, 2026.[Yearn App Store description]() and [Apple release lookup]()lists public version 1.0.2, requiring iOS / iPadOS 17 or later. The interface may change between versions. Check operation and saving for each game using the steps provided.