The NeoGeo gameconsole has two processors:
* Motorola 68000 (16 bit)
* Zilog Z80 (8 bit)

The Z80 was mainly used as a kind of co-processor to control the audio.

GnGeo has the option to "overclock/underclock" these processors, for example if they do not synchronise good enough. Default is 0 (standard speed); values < 0 "will underclock"
I experimented a little with these options, but did not notice much difference.

But now that I made the config screen scrollable, I had room enough to add the buttons