@luckyluca - No worries on the code. I have some code that I am sure no one could follow and other code that's neat and well organized into functions. If it's something I plan to keep and reuse I try to organize and document. If not I really don't care how it looks! :) If you clean it up to the point you deem it worthy of sharing I would grateful and if not that's ok too.
To add to dankcushions description. The *.cfg files are auto-generated when you run a game. They contain things like the controls (inherited and/or explicit), number of coin mechanisms on the machine (are they individual coin slots or a single "communal" one), number of lives, dip switch settings, etc. They may contain/cover a huge gambit of settings and need to be stored somewhere. They can be modified through the menus but they aren't contained in the F2 operator "service mode".
Under the nvram folder you'll find *.nv files. It contains similar information like coins to start, lives to continue, high scores, etc., depending on the game.
I think the difference is nvram files were meant to be consistent across "boots" similar to how the actual arcade machines worked. Basically a service menu used by an arcade operator to set and store certain settings in NVRAM, i.e., if you played to long or scores were to high...BUMP...that difficultly up (you're using to much electricity and not bringin' enough quarters) or possibly down for a charity event or something. :)
Some of the games I tweak the configurations to what we knew/remember back in the day at the arcade or if you have a machine manual it's handy for setting the dips to the defaults. You can find some online.
If you're just testing games and not locked into any configuration structure or settings I would just go ahead and delete both sets of files when you're done if you prefer to keeps things tidy. You can also delete the hiscore files *.hi located in the "hi" subfolder.
