Choose the correct MAME BIOS region without replacing random files
Run `-listbios` for the exact system and MAME build, keep the default unless you have a documented reason to change it, and pass only a listed short BIOS name through `-bios`. Re-audit after the change; a different BIOS selection cannot repair missing or incorrect firmware bytes.
Do this in order
- 01
Record the exact MAME/core version, system short name, current language/region symptom, and audit output.
- 02
Run `mame -listbios shortname` and save the available short BIOS names and descriptions.
- 03
Start with the documented `default`; if a different region is required, select one listed name with `-bios` or the frontend equivalent.
- 04
Run `mame shortname -verifyroms` again and resolve every named missing or incorrect BIOS file from your authorized source.
- 05
Cold-start the machine and verify language, region, controls, and NVRAM behavior without changing unrelated settings.
- 06
Store the chosen BIOS name with the exact build and roll back if an update changes the list or audit.
Decision and diagnostic table
| Symptom | Likely issue | Decisive evidence |
|---|---|---|
| Wrong language or market | Different valid BIOS selected | `-listbios` plus current `-bios` value |
| Unknown BIOS name | Name belongs to another release or system | Exact build’s BIOS list |
| Missing/incorrect BIOS file | Content dependency failure | Targeted `-verifyroms` output |
| BIOS changes but game still fails | ROM, CHD, driver, or configuration layer | Audit and first runtime error after default reset |
BIOS choice and BIOS integrity are separate
MAME’s `-listbios` verb reports the options available to the exact system, and `-bios` selects one of those names. Selection decides which valid firmware path to use; it does not manufacture files or correct a checksum.
Keep the default when you do not need a specific region or firmware revision. A frontend label can lag behind the bundled core, so the core-generated list is the authoritative menu.
Region changes can affect persistent machine data
Firmware choices can influence language, market settings, and initialization behavior. Preserve NVRAM before changing BIOS selection and use a cold start so an old machine state does not hide the result.
Do not reuse a save state created with a different BIOS as the first test. Prove the default boot path, then restore only compatible progress data.
Write down a reproducible BIOS decision
A useful record contains MAME/core revision, system short name, selected BIOS short name, audit date, and the source of the authorized firmware data. This makes an update failure reversible.
If an upgrade removes or renames an option, inspect the new build’s list and release history. Do not solve a name mismatch by downloading a BIOS pack.
Firmware can be copyrighted even when technically required. Obtain BIOS data only from hardware and sources you are authorized to use; a listed hash is not download permission.