The "Small Computer Systems Interface", a 1980s-era computer industry standard for connecting various devices (mostly disk drives) to computers for high-speed data transfer. In electronic music, the SCSI interface saw its heyday in the 1990s, when a number of samplers employed it as a means to connect hard disk drives for sample data storage. By about 1992, the advent of 16-bit samplers capable of sampling at 44.1 kHz or higher made it evident that floppy disk storage was not going to be adequate, and sampler manufacturers went looking for an alternative. At the time, the SCSI interface was widely used in the computer industry, and inexpensive hardware was available for sampler makers to integrate, so it became a de facto standard for samplers. Drives that were integrated included fixed-disk drives, magneto-optical drives (another popular technology in the 1990s), CD-ROM drives, and various forms of removable-cartridge drives (such as Syquest and Iomega Zip). A few samplers, e.g. the Akai S3000, also had the ability to use a SCSI interface to transfer sample data directly to/from a computer for sample editing, and this was much faster than dumping sample data over MIDI.
However, the SCSI interface was far from perfect. A proliferation of variants of the standard, all using different connectors and cables, meant that users had to match up the proper cables to their hardware and/or buy adapters. Each device on a SCSI bus had to be set to an individua device ID, which sometimes involved adding/removing jumpers on circuit boards, or using arcane bits of software to tell a device what its ID needed to be. The biggest headache was something called "termination". Each end of a bus needed to have a terminator. Some devices had terminators built in (which could usually be disabled by jumper if needed), but many required a "terminator plug" to be plugged onto one of the two SCSI ports at each end of the chain. Even then, it didn't always work the way it was supposed to; sometimes users found that a certain length cable would not work, but either a shorter one or a longer one would, or other equally bedeviling puzzles. Since cables were bulky and rather expensive, users sometimes had to go to some trouble and expense to produce a setup that worked.
The computer industry began to phase out the SCSI standard in the mid-2000s, in favor of newer methods that were less expensive and less troublesome, such as Serial ATA (SATA) and USB. Today, SCSI is only found on legacy equipment.