ROMBuild is a ROM manipulation tool that is capable of creating
ROMs for the older arcade emus using MAME ones. An example of this
is by splitting ROMs in two or joining two together but ROMBuild
supports much more than this. It can can split, join, extract,
fill, patch, pad, interleave etc but to you the user that doesn't
really matter. The important thing is that MAME ROMs go in and ROMs
for another emulator come out. :)

When used in conjunction with the CMPro/ROMCenter dats that I have
produced you can generate ROM sets for practically any emulator
from MAME ROMs. In fact, the only ROMs you can't generate from MAME
sets are where MAME doesn't support the game.