I have learned that there is a new ROM set for every new MAME version. The current version is 0.179. Someone told me I need version 0.139 for my emulator. So I downloaded the DAT file for 0.139 from here:
http://www.progettosnaps.net/dats/
But in the archive for 0.139 there is not just one DAT file, there are:
MAME 139.dat
MAME 139u1.dat
MAME 139u2.dat
MAME 139u3.dat
MAME 139u4.dat
So please, what does "u1" (and so on) mean? Are those further updates within 0.139? Why aren't they just 0.140 (and 0.141 etc.) then?
And when someone speaks about 0.139, which version does he mean? The real "MAME 139.dat" or is the latest version meant ("MAME 139u4.dat")?
Lots of question, thanks guys!