Parallel SCSI
（重定向自Differential SCSI）
Parallel SCSI (formally, SCSI Parallel Interface, or SPI) is one of the interface implementations in the SCSI family. In addition to being a data bus, SPI is a parallel electrical bus: There is one set of electrical connections stretching from one end of the SCSI bus to the other. A SCSI device attaches to the bus but does not interrupt it. Both ends of the bus must be terminated.