MAME v152

[Harrison]

Which game is it exactly?

I just checked and Alien vs. Predator doesn't have any Parent roms and isn't a clone, so it should be a self contained rom set for the game in MAME and run by itself. There are also US and EU versions of the game, but both should work.

The reason for run errors is normally missing shared roms. The MAME development team have long been combining roms to reduce overall size. They look for arcade machines which all use/share the same roms. May arcade games were based on the same games, but with changed graphics/sound and these are classed as clones, or an arcade machine might share the same roms as others that deal with audio/music/control/graphics etc and just some of the roms for that specific game were different. Therefore MAME can have a Rom set where one game contains the parent rom set and there are loads of other arcade games that are classed as child sets and use some of the roms from the parent set. These will be shown in MAME as Clone games.

You also mentioned missing CHD. If it is a CHD based game then it would have originally been held on the arcade machine on a HDD or laserdisc, rather than just rom chips. MAME emulates these games by emulating the HDD or other media in a file called a CHD. The games ran with both roms and physical media, so you need both the MAME rom set for a game and it's CHD. CHDs can be huge (in the GBs).

[Ghost]

Hey Dave,

After I posted this message I went to check my games drive and discovered I had an older version of Mame in another map together with Aliens vs Predator and several other games.
When I tried this version the game did work.

Now here is the strange thing, this file is exactly the same file as the one I downloaded for the current version of Mame but that doesn't work. It is even unzipped like the one for the current Mame version.
Shouldn't it also just normally work?

The rom by the way is Aliens vs Predator Euro version, the one recommended on Emu Paradise to include all the parent files.

[Harrison]

MAME completely changed its rom structure some time ago, meaning that older ROM sets from earlier versions no longer worked at all. It is possible you have a ROM set from an earlier MAME version and this is why it refused to work.

[Ghost]

Is there some way to inform the MAME team or the people who reverse engineered the rom?
I am probably not the only one who ran into this problem and I am sure the MAME developer team wants to keep their program compatible with older roms.

[Demon Cleaner]

Rollback sets.

[Harrison]

No, the newer versions of MAME require completely redumped roms, so they are completely new versions of the original arcade rom chips. This is why older MAME rom files don't work with newer versions. It is by design and intended.