Should a music player's previous button go back sequentially or by history?

1. How did people listen to music in 1972?
2. Which was the first music player to record onto flat discs?

How did people listen to music in 1972?

In the 1970's cassette tapes were widely used to record and listen to music. They used magnetic tape, and the music played through from left to right. Once one side was done, you flipped it over for more songs on the other. Around the same time CDs (or Compact Disks) and CD players became widely available.

Which was the first music player to record onto flat discs?

Gramophone

In 1887, Berliner patented the first sound recording device that utilized grooved, flat disks, rather than cylinders.