The introduction of the sampler in the 1980s created one of the most significant technological and creative shifts in the history of music. The original hardware samplers are the digital equivalent of an analog tape recorder. Rather than recording the audio signal onto a magnetic tape, sounds were recorded digitally into Random Access Memory. Most samplers can only reproduce an acceptable instrument three, four, or five notes from the original root note so if a replica of an instrument is required; it must be sampled at every few intervals. While Sample Playback Software has become the primary format for those who need to reproduce real instruments, for everything else, dance music artists will often look towards the older hardware samplers. During the reign of hardware samplers, sample content was delivered on a compact disk that could be installed into a hardware sampler. Many of the standard sample contents available consist of loops or single hits.