Q: If these are based on original, pristine disks then why are many of them "fixed" (marked [f])?

A: Because this is the Jouyou ("everyday use") set. A completely pure preservation set is available here.

The fixed versions are superior for day-to-day usage.

The fixes are all analyzed by an expert to check that they function properly and nothing obvious was missed. This process can be time consuming.

Q: What about these [f,b] marked images?

A: The 'b' tag indicates that something is known (or strongly suspected) to be wrong with the image without having any adverse affects. You could think of it as meaning "best available" rather than "bad" since the latter suggests that the functionality might be impaired — if it's in our database then it should work fine.

Many fixed disks found "in the wild" work fine but don't meet our preservation standards and thus merit a 'b' tag, if they are included at all.

The thinking here is that it doesn't contribute any further pollution to hash something that's already widely available. So it's a temporary convenience until a better fixed image is found.

Q: Are the fixes guaranteed?

A: No, but they have all been checked pretty rigorously and we are confident in them. We have played through a number of games to completion during testing and we have yet to encounter any surprises when doing so.

There have been cases where we discovered that none of the images in circulation were fixed completely, so we seem to be more thorough in our analysis than those who came before us, at least.

Although it is unlikely, if you suspect a disk hashed in our database was improperly fixed, please contact us and we will investigate. (Although we do not and will not create any fixes ourselves.)

Q: Aren't there multiple ways to "fix" a disk?

A: Indeed. We only hash the best-available fixed image, based on analysis. In case of a tie, the image will be chosen arbitrarily. If there aren't any good quality fixed images for a particular disk, then hashes for that one will be omitted for now.

Q: What happens if a superior version of a fixed image is identified?

A: Since we only publish hashes for (at most) one non-pristine image per disk, if a better non-pristine image becomes available for analysis then the database will be updated and the hash will change. We aren't interested in cataloging all the junk out there.

Q: Why was the XML file updated but nothing changed?

A: It could be that one of the other files or sets was affected, as they are all derived from the same database. Another possibility is that there was a change to our database that was not visible in the end products, although it's rare for such spurious updates to actually get uploaded.

Q: Why is it so important to check the original disks?

A: Because images of unknown provenance are often modified, possibly in ways that can have subtle impacts. It is impossible to exhaustively evaluate modifications unless you can identify all such modifications, which is why pristine disk dumps are so valuable.

Another benefit is that we sometimes discover newer/better versions of a game that are not in circulation and would have been lost to history.

Q: What should I do for the disks that are not covered by your hash set?

A: In most cases, you can safely substitute a disk from any other source. There are no guarantees, but it will probably work fine. A few of the readily available disk images are corrupt or improperly fixed, however.

Q: Should I delete all these alternate images I have?

A: No, you should keep them around. Hashes for a few of them may eventually be added if they turn out to be legitimate variants or superior fixed versions.

Q: Why does this set only cover a fraction of what's available?

A: Because we have a limited number of real disks with which to check against. While it's possible to do some analysis solely using the dumps floating around in public, we don't do that because there are limits to what can be achieved without being able to examine disks in their original form. (This is first and foremost a preservation project, after all.)

Even when we do have the materials, some disks may not meet our criteria for having their hashes included. And in the case of the Jouyou set, we might not have gotten around to qualifying a fixed image yet, which has been a laborious process in a few cases.

Q: Need any help?

A: Absolutely! We cannot do this without you.

Contact information