This program is an interface to the original mp3 player, Diamond Rio 300. The RioExplorer offers an explorer type interface to the Diamond Rio, it is also compatible with memory cards. Features include random playlists from directories, random playlists from winamp playlist files, drag and drop add, playlist history, buffered changes, customizable UI. In addition to the UI, I have included the C++ source code for the ActiveX control that acts as the interface to the Diamond Rio.