The main reason for the existence of the Prologue 21 line was, of course, karaoke. When booted, most machines will load into a scrolling screen advertising songs available on the hard drive, horoscope from the last time connected to the server, and games available. To select a song, enter the associated number, between 1 and 5 digits, using the number pad on the front of the Prologue, then hit the button immediately to the right of 0 to enter.
Up to 10 more songs can be queued up after the one currently playing.
SEGA Prologue 21 