The second was sample libraries on floppy disk, where each disk would group together multiple recordings, each of a single pitch being played on the same instrument. These would typically be meticulous recordings of prohibitively expensive or difficult instruments such as grand pianos, violins, and flutes, ready to load and play on a humble keyboard.
In effect, these sample libraries were an evolution of the recording playback keyboards of the 1960s and 1970s such as the Mellotron and Orchestron, in that it was much cheaper for a studio to buy one than it was to routinely hire a choir of singers, or a string quartet. (As Mellotrons and Orchestrons have their own primitive charm, they were inevitably also sampled and sold on sample CD-ROMs.)
Both types of sample CD got more ambitious. Those that had evolved from DJ battle tools crammed together hundreds of breakbeats, trimmed and grouped together by tempo. Meanwhile, as newer samplers had more RAM, the sample CDs that had evolved from floppy disks featured increasingly comprehensive and expressive recreations of instruments, including samples of more pitches and velocities.
As home computers grew more powerful, hardware samplers gave way to software samplers, and mail order sample CDs gave way to instantly downloadable sample libraries on the Web.