Past Masters, Volumes One & Two
The arrival of the era of compact discs affected how collectors of Beatles music would want to possess and archive the songs they recorded over their eight-year history. Apple (with EMI's Parlophone in the UK and their Capitol affiliate in the US) produced and released a two-CD set called Past Masters ion March 7, 1988. It was originally part of a CD package of all the studio albums, the US LP of Magical Mystery Tour, and the Past Masters collection. This digital version of the catalogue was called The Beatles Box Set, and became available in three formats: CD, LP and cassette. Later, the Past Masters compilation became available separately.
The concept of Past Masters was to compile the recordings that never were released in studio albums. Most of them are songs that came out on 45 rpm singles (a- and b-sides). If the song appeared on a studio album in a different version from the single, it was included in the collection. Added were the two German versions of Beatles songs (Sie Lieb Dich and Komm, Gib Mir Deine Hand), the Across the Universe recording for the World Wildlife Fund, and Bad Boy, which had only been released in the US.