Some emulators need bios files to run: they are copies of the original console's internal chip (or system files, such as the Amiga Kickstarts). For legal reasons, Recalbox ships no bios (apart from a few free exceptions): you have to add them yourself, and the built-in bios checker tells you exactly which ones are missing, which ones are good and which ones are problematic.
All bios go into the /recalbox/share/bios/ folder, reachable over the network (\\RECALBOX\share\bios). Many bios belong in a specific subfolder (dc/, amiga/bios/, psx/…) with an exact file name, extension included: that is precisely what the checker shows for each bios in the FILE PATH field.
If you drop a bios directly at the root of
bios/with the right file name, the check moves it automatically into its expected subfolder.
START to open the MAIN MENU.BIOS CHECKING, then validate with the CHECK button.The window opens with all bios already scanned, sorted by system.
📷 Screenshot to come:
bios-checker.png
At the top, a message gives the global verdict: CONGRATULATIONS! ALL EMULATORS SHOULD WORK PROPERLY! — or the number of emulators that may not work properly until required bios are made available.
On the left, the list of systems and their bios. By default only your systems (the ones visible on your Recalbox) are listed; the X button switches between MY SYSTEMS and ALL SYSTEMS. A greyed-out bios is one that was not found on your drive.
On the right, the details of the selected bios:
| Field | Meaning |
|---|---|
SYSTEM |
the system this bios belongs to. |
CORE |
the emulator(s)/core(s) using this bios. |
FILE PATH |
the full path where to place the file, exact name included. |
MANDATORY |
YES: without this bios, the emulator won't work. NO: optional bios. |
MUST MATCH MD5 |
YES: the file's MD5 signature must match a known one. NO: an unrecognized file has good chances of working anyway. |
FILE FOUND ? |
is the file present at the right place? |
MATCHING MD5 ? |
does its signature match a known one? |
NOTE |
special remarks (bios only required for a given machine, free bios…). |
An explanation sentence sums up each case, for example: "Your bios file does match one of the known MD5. Everything will run fine!" or "This bios is required in order to run the emulator properly."
By selecting a system row, you get its figures: BIOS OK, BIOS UNSAFE, BIOS KO, plus BIOS NOT FOUND, MD5 OK and MD5 NOT OK.
At the bottom, the totals for your setup: x BIOS NOT FOUND - x NON-MATCHING BIOS FOUND - x GOOD BIOS FOUND!.
Each bios (and each system) gets a colored thumb:
Recalbox also warns you when launching a game: if a mandatory bios is missing for the chosen emulator, the message
At least one mandatory BIOS is missing for…offers to launch the game anyway.
| Button | Action |
|---|---|
| Up/Down | SELECT a bios or a system |
| Validate | MD5 LIST: show the MD5 signatures |
START |
RESCAN after adding files |
X |
switch MY SYSTEMS / ALL SYSTEMS |
| Back | CLOSE |
Validating on a bios opens the MD5 LIST screen showing Your bios' MD5 (green if recognized, red otherwise) and the Known MD5 List: a single bios can have several valid signatures (different revisions or regions). Validating on a system row shows all known signatures for all the system's bios.
📷 Screenshot to come:
bios-checker-md5.png
My bios is yellow with MATCHING MD5 ? at NO. Your file is not one of the referenced dumps. If MUST MATCH MD5 is NO, it has good chances of working anyway. Otherwise, look for a dump whose signature appears in the MD5 LIST.
An optional bios is missing, is it a problem? No: a MANDATORY: NO bios does not prevent the emulator from running. It is only used by some features or some games (the bios NOTE often says which).
Are my .zip bios (Neo Geo, Naomi…) checked? Yes: the signature is computed on the archive's content, not on the .zip file itself.
I added bios but nothing changes. Press START (RESCAN) in the checker to run the scan again.
Message BIOS DATABASE NOT FOUND OR DAMAGED!. The internal bios database is missing or damaged: restore or reinstall your Recalbox.
After each scan, Recalbox writes the file /recalbox/share/bios/missing_bios_report.txt: it lists, system by system, the missing (MISSING) or unrecognized (INCORRECT) bios, with their expected path, the affected cores, the notes and the valid MD5 signatures. Handy to hunt for files from your computer.
The WebManager also shows the state of your bios: Emulation section, bios tab. You get the System / BIOS / Current MD5 / Expected MD5s / Validity table, with the same color codes, per-status filters and one-click copy of MD5 signatures.