Adaptec USBXchange User Guide - Page 22

User's Guide: USBXchange • 22 Understanding SCSI SCSI (pronounced "scuzzy") stands for Small Computer System Interface. SCSI is an industry standard computer interface for connecting up to seven SCSI devices (such as hard disk drives, CD-ROM drives, and scanners) to a common SCSI bus. A SCSI bus is an electrical pathway consisting of a SCSI adapter (such as the USBXchange adapter) installed in a computer and one or more SCSI devices. When more than one SCSI device is connected to your computer, it is referred to as a SCSI chain. SCSI cables are used to connect the devices to the SCSI card. For the SCSI bus to function properly, SCSI IDs must be assigned to the SCSI devices and the SCSI adapter, and the SCSI bus must be properly terminated. The LED display located on top of your USBXchange will flash to indicate activity in the SCSI bus. SCSI IDs Each device attached to the USBXchange, as well as the adapter itself, must be assigned a unique SCSI ID number from 0 to 7. A SCSI ID uniquely identifies each SCSI device on the SCSI bus and determines priority when two or more devices are trying to use the SCSI bus at the same time. o The USBXchange is preset to SCSI ID 7, which gives it the highest priority on the SCSI bus. o In Windows 98 and Windows 2000 you can use the Device Manager to view the SCSI ID and other information about each installed SCSI device. o If you installed Adaptec EZ-SCSI® software (sold separately), you can use the SCSIExplorer™ utility to view the SCSI ID and other information about each installed SCSI device. o On a Macintosh, you can use the SCSIProbe software to view information about each installed SCSI device. Terminating the SCSI Bus To ensure reliable communication on the SCSI bus, terminators must be installed (or enabled) on the devices at the physical ends of the SCSI bus. The terminators on all devices between the physical ends must be removed (or disabled). SCSI termination is required whether you have one or many SCSI devices connected. Termination on the USBXchange is permanently enabled, since it is always at one end of the SCSI bus.