Fix a MAME CHD not found error with the correct folder layout
Keep the CHD unzipped in a folder MAME searches for the selected short name, normally a short-name folder inside one configured rompath. Read the missing-disk message, verify the CHD with the matching chdman, and check whether it is a delta that needs a parent CHD. A correct ROM ZIP does not prove the disk image is present.
Do this in order
- 01
Record the exact MAME version, selected system short name, configured rompath, and the full missing-disk message.
- 02
Confirm the ROM archive passes a targeted audit, then treat the CHD as a separate required object.
- 03
Place the CHD unzipped in the short-name folder inside a configured rompath and preserve its expected filename.
- 04
Run the matching `chdman info -i file.chd`, then `chdman verify -i file.chd` on a read-only copy.
- 05
If chdman or MAME reports a parent requirement, locate the authorized parent CHD and verify the relationship without flattening the delta.
- 06
Rerun the same MAME audit and launch; use the reported search locations before changing any unrelated setting.
Decision and diagnostic table
| Symptom | What it establishes | Next check |
|---|---|---|
| ROM audit passes; disk missing | ROM data and CHD lookup are separate | Short-name folder, filename, and rompath |
| chdman verify fails | CHD integrity or parent chain is wrong | Preserve original and return to authorized source |
| CHD exists inside ZIP/7z | Possible but officially discouraged layout | Move lawful CHD to a folder for random access |
MAME searches by machine identity
MAME searches configured rompaths using system, parent, BIOS, device, and software-list identities. The error text shows where it tried. Copy that evidence before inventing another directory tree.
CHD is already a random-access compressed format
Putting a CHD inside ZIP or 7z forces MAME to treat another archive layer around a file designed for random access. Official documentation recommends keeping CHDs in folders.
Integrity and rights are separate
`chdman verify` checks a read-only CHD’s integrity; the header also carries content digests and may identify a parent relationship. None of those facts establish permission to possess or redistribute the disk image.
CHDs commonly represent copyrighted hard disks, optical discs, or LaserDiscs. Use only your own lawful dump or an explicitly authorized release; this page provides no CHD, BIOS, ROM, or download source.