https://blog.faceutil.com/2017/04/30/mame-dj-%eb%b3%b4%ec%9d%b4-dj-boy-%eb%8b%a4%ec%9a%b4-%eb%8b%a4%ec%9a%b4%eb%a1%9c%eb%93%9c-down-%e3%83%9d/