How does a new bootleg ROM get added to MAME's list?

[jez9999]

So I've found a bootleg ROM for the arcade SF2: The World Warrior that replaces sf2jh.zip. It's a boss hack of the original Japanese version and seems to be somewhat widespread with a bunch of YouTube videos showing gameplay from it. When I replace sf2jh.zip with it and run it from the commandline (the UI prevents me because of invalid checksums, of course), it runs fine. So, how does a new bootleg get added to MAME's official list? Seems to me that this version should be in the list.

[Tafoid]

So I've found a bootleg ROM for the arcade SF2: The World Warrior that replaces sf2jh.zip. It's a boss hack of the original Japanese version and seems to be somewhat widespread with a bunch of YouTube videos showing gameplay from it. When I replace sf2jh.zip with it and run it from the commandline (the UI prevents me because of invalid checksums, of course), it runs fine. So, how does a new bootleg get added to MAME's official list? Seems to me that this version should be in the list.

Generally, you'd want to see it added to HBMAME (Homebrew MAME) which basically holds anything MAME cannot confirm was an actual bootleg in the day or one of the 1000's of hacked roms for various effects. Provenance means everything for addition to MAME. If you own the original boardset this romset was played on in the arcade, it may be something we can add to main MAME project. Otherwise, https://hbmame.1emulation.com/ is the home for that emulator.

[jez9999]

Shouldn't MAME's UI provide some mechanism to add these "unrecognized" hacks, then? Perhaps this one is a hack that was done more recently, but I'd like to play it from the MAME UI and I can't because it obviously says that the game has invalid checksums.

[mhoes]

Shouldn't MAME's UI provide some mechanism

Nope. The current behaviour is intentional.

to add these "unrecognized" hacks, then?

If you start this game regularly, you can create a '.cmd' file containing the commandline startup command, and doubleclick that to start it.

Perhaps this one is a hack that was done more recently

Which is why it would belong in HBMAME, and not MAME.

but I'd like to play it from the MAME UI and I can't because it obviously says that the game has invalid checksums.

Again, for fully intentional reasons.

[jez9999]

Erm, what intentional reasons, out of interest? Either you have a UI that allows you to conveniently run the ROMs you want (which are supported by MAME, ie. if I throw it at MAME it will work, whether the UI thinks it has an invalid checksum or not) or you might as well tell people to set up .cmd files for all their ROMs.

[mhoes]

Erm, what intentional reasons, out of interest? Either you have a UI that allows you to conveniently run the ROMs you want (which are supported by MAME, ie. if I throw it at MAME it will work, whether the UI thinks it has an invalid checksum or not) or you might as well tell people to set up .cmd files for all their ROMs.

(DISCLAIMER: people more knowledgeable on the subject than me please correct me if I'm wrong here, but) :

MAME doesn't work by just "throwing random ROMs at it, and magically expect them to work". That's just not how emulation works.

Personally, I can think of multiple reasons why there might be checksums at all (but there might be more) :

- Your storage (HDD/SSD/etc) has defects on it, resulting in a corrupt ROM, which MAME will not be able to detect without checksums.
- How is MAME magically supposed to differentiate between "your random ROMs" that will work, and "other random ROM's" which will not ? Checksums allow for determining if any given ROM is known to be supported by MAME, or not.
- Differentiate between 'old romsets of a particular system that are now known to be bad dumps', and 'good redumps that are known to be correct' ?

As far as I can tell, the only reason the commandline allows you to bypass checksums at all, is so that developers that are working on adding/improving support for previously unsupported hardware and associated ROMs can have a way to bypass a check that will obviously fail as the support for them has not been added yet. Regular users should be protected from running unknown/unsupported ROMs, at the very least in order to prevent them from submitting bug reports for things that are known to not be supported.

[jez9999]

It would be trivial to add an option to MAME's UI for "add custom ROM for X" where it was made clear that the files expected were the same as a certain ROM but the checksums weren't being checked. The user would be "protected" because unless they explicitly added this custom ROM it wouldn't appear.

[mhoes]

It would be trivial to add an option to MAME's UI for "add custom ROM for X" where it was made clear that the files expected were the same as a certain ROM but the checksums weren't being checked. The user would be "protected" because unless they explicitly added this custom ROM it wouldn't appear.

Real world experience has shown that the average human mind just doesn't seem to work that way. If people would have your suggested modified MAME UI option, they would quickly proceed to forget about it, and/or assume that once they have it set up, that it would mean that the unknown ROM's are fully 'supported' in MAME (which would not necessarily be the case). Leading them to submit bug reports on the bugtracker wasting everyone's time with things that are known to not be supported/working. If you think that this will not happen, think again, as something similar already does: When a system/game is partially present in MAME but not fully supported yet because the emulation is known to be incomplete, you get a big red warning box stating that this is so when you start the emulation. And even though there is this big red warning box telling people that the machine simply does not work, they still show up on the bugtracker submitting bugs for systems that the developers are fully aware of are not working. I can only assume the same thing would happen if your suggested UI modification was added.