Hi Ambrogino
CHDs_temp -> there are CHDs that are not verified that names are correct and fit to the latest MAME version. There could be CHDs that also have been removed/updated in the memantime. Another different is that in this folder the rar-parts are still 20MB big, in the final CHDs folder it size is 100MB slices. If you are looking for CHD check first the CHDs folder and if you don't find it check the CHDs_temp folder.
emma (???) -> collection for http://www.citylan.it/ . They are added to MAME from time to time .....
currentroms vs. mame-[version]-full (seem to contain the exact same set of ROMs?) -> yeah right, the currentfolder is a pointer to the *full folder. We use that "currentroms" in our update scripts (much easier to use all the time the same folder name ;-))
rollBack (in what situation would these files be necessary? -> the "currentroms" folder have all the roms for the latest offical MAME. It could be that you want to use an older MAME version, or a special build that needs an older set. In that case you must have the roms from the current-folder and the "rollback" folder. With a RomManager and a DAT you can "rebuild" it with this two folder to fit it for the needed older version of MAME.
update (will these ROMs and CHDs work in the latest version of MAME, or is it best to wait on these for the next MAME release?) -> this folder is used for the updates between the current official version and the next offical version of MAME. Keep in mind that in this folder are only "added" roms and not the complete roms. You must rebuild it yourself with a ROMmanager with the currentroms and the update folder to have a new "in-between" version (of course you must compile the exe yourself too). If you have no clue how to do it, wait for the next official release and wait until the "currentroms" folder is updated.
regards
Mucci
