We have a copy of 'CD-i Ready Steady Go' for years which is a CD-i Ready
disc: You can play it in any audio cd player to enjoy the music, but if
you play in a CD-i player, you'll see the accompanying graphics. If you
enjoy it on a CD-i player, you'll enjoy the CD-i program. This type was
mainly used for karaoke graphics or background of the music that you
are going to enjoy. This "CD-i Ready Steady Go" was one of the first
CD-i Ready discs, used for promotion of the format. We're not sure if
this actually was released as a regular disc.
The music was licensed by Polygram (owned by Philips at the time) and the CD-i Ready program was developed by Philips Freeland Studio (The same studio who make The 7th Guest and worked on Microcosm on CD-i). Andy AVAV Systems: "Promo Hybrid CD-DA & CDi Ready Disc 1991; Audio Tracks play in any CD Player; CD Interactive players have additional stills & info, selected via old style Radio Tuning Dial. Despite “Bronzing” PDO Blackburn Disc still plays (at the moment)"
[Credits & Source: Andy AVAV Systems]