Hi,
The default ROMS behavior should be changed. On the application startup, a folder ~/Library/Application Support/PCem should be created and the default roms,configs,nvr, etc. should be copied from $executable_path/../Resources/SKEL to that folder, so that the user can customize them without actually modifying the /Applications/PCem.app binary. If that initial provisioning is done, PCem shouldn't complain about ROMS at startup anymore. The expected path of ~/PCem or /usr/share/pcem is not documented in the error dialog box nor in stderr, nor is it created automatically.
Thanks,
R.