Highlight OPTION, then:
-Press A+START for Color Test
-Press C+START for Sound Test (with preliminary graphics)
-Press B+START for Jam Out mode (Ever played ToeJam & Earl?)
A, B, C, START: Play the many different DAC samples
Up, Down, Left, Right: Hold to change between sound banks
It's funny how it works quite similarly to TJ&E's. It might have been an old DAC testing program released for the devs to use and modify at will, or something.