Defines an input/output bus for interconnecting comuters and peripheral devices. It defines extensions to the Small Computer System Interface (ISO 9316:1989), referred to herein as SCSI-1. It also provides more complete standardization of the previsoulsy defined command sets. It includes the necessary specification of the mechnancial, electrical, and functional characterestics of the interface to allow interoperability of conforming devices. This standard is referred herein as SCSI-2. The term, SCSI, is used wherever it is not necessary to distinguish between the two versions.