The Small Computer System Interface (SCSI) is a parallel I/0 bus and protocol that permits the connection of a variety of peripherals including disk drives, tape drives, modems, printers, scanners, optical devices, test equipment, and medical devices to a host computer. The SCSI bus connects all parts of a computer system so that they can communicate with each other. It frees the host processor from the responsibility of I/O internal tasks. The SCSI protocol is a peer-to-peer relationship: one device does not have to be subordinated to another device in order to perform I/0 activities. A total of eight devices can be connected to the bus simultaneously. Only two of these devices can communicate on the bus at any given time.