that imitate more well-known rides) are equipped with simple integrated circuits that continually playback one melody or repeat a set of melodies in sequence. These have evolved in the sense that the earliest musically-enabled rides played back only a single monophonic melody repetitively. In contrast, later ones played multiple polyphonic melodies whilst sometimes including short sound or speech samples. Later rides could also use a tape deck, while more recent rides may have a solid-state audio playback device akin to flash-based MP3 players. Usually, the music chosen is generic children's songs, while on licensed rides, the theme song for the licensed character would be used. However, in rare cases, some rides play traditional pop music, and for private rides, the owner may request a song that has personal relevance to be programmed into the ride. Many modern rides are programmed to play multiple melodies, with the music changing each time the ride is used, the logic being to prolong the interest of the child on the ride. However, some modern rides, in particular licensed character ones, are usually programmed to play a single melody or song, which is usually the theme song of the character's television show or film. There are also some exceptions where there are licensed rides playing totally unrelated pieces of music or non-licensed rides that play only one particular tune, for example, a song about cars on a car-themed ride, the Thomas theme tune on a Thomas the Tank Engine ride, the Postman Pat theme tune on a Postman Pat ride and the Fireman Sam theme tune on a Fireman Sam ride. Certain rides exist that do not emphasize music but play a running narration or tell a story instead. They usually have generic instrumental music running softly in the background while the story is being told. Modern rides Newer, more advanced rides do not usually start as soon as coins are inserted; instead they prompt the rider, parent or guardian to press a start button, so as to allow the rider to seat him/herself comfortably before starting the ride. Often, these rides will also play a message before movement begins and may also play an ending message once the ride ends, to let the rider know that it is safe to disembark. Other safety precautions commonly found in more advanced rides include: allowing use of the start button to pause the ride, so the rider