500300 Rev. U
Tape Drive Installation
1-7
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The bus must have at least two devices connected to it;
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The device addresses (SCSI ID) range from 0 through 7;
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A device's priority on the bus is determined by its address, with SCSI ID 7 being
the highest priority;
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Each device must have its own, unique SCSI ID;
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The physical location of a device on the bus has nothing to do with the priority
or addressing of that device;
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The total length of the cable, or series of cables, must not exceed six meters
(single-ended configuration) or 25 meters (differential configuration) as
measured from one end to the other.
In most systems, the host computer itself is one of the SCSI devices. This is usually
done using a host adapter, a board that resides within the host and that has one
SCSI connector to the outside world. Device ID 7 is normally reserved for the host
adapter to insure that the host has the highest priority among the other SCSI
devices. Disk drives containing system, application, and data files normally have the
next priority and are assigned a device ID of 5 or 6, while tape drives, printers, and
other low priority devices have correspondingly lower ID numbers.
