Instruction manual

Configuration Page 3-3
Eagle 450 Installation and Technical Manual, Rev. 00
SCSI CONFIGURATION
The Eagle 450 offers two SCSI busses: Wide and narrow. The Wide SCSI bus offers higher performance
when used with Wide SCSI-2 or Ultra SCSI drives. Using the proper adapters, you can attach both Wide
and narrow devices—disk drives, tape drives, and SCSI diskette drives—to either the Wide or narrow
bus. However, using narrow devices on the Wide bus may affect the performance of Wide drives on the
bus.
You can use only one of the two SCSI busses. You cannot attach cables to both connectors and use
both busses at once.
The number of devices you can attach to the SCSI bus can be limited by three factors: the legal number
of SCSI IDs, cabling limitations—total length and device spacing—and the number of drive bays
available in the chassis. After a discussion of the type of SCSI devices you can use, the following
sections describe configuration rules for the Wide and narrow busses, including mixing device types and
termination issues.
Never
plug a SCSI device into the SCSI cable, or remove one from the cable, while system power
is on. Doing so could seriously damage the device and/or the CPU board. The Eagle 450 uses
tolerant active negation on the SCSI bus, which makes the bus more sensitive in these situations
than on previous Alpha Micro computers.
SCSI Device Types
You can attach any supported SCSI device to either the Wide or narrow SCSI bus, using the appropriate
adapter if necessary, as described below. Supported devices include:
•
Narrow, Wide and UltraSCSI disk drives
•
¼” streaming tape drives with capacities up to 26GB
•
4mm DAT (Digital Audio Tape) drives
•
The AM-446 RAID subsystem for the safety of redundant data storage
•
The AM-642 StoP (SCSI to Pertec) converter to use ½” magnetic tape as a SCSI device
•
CD-ROM drives
•
3.5” SCSI diskette drives. The Eagle 450 is the first AMOS system to support SCSI diskette
drives, removing the need for a separate diskette controller.
Alpha Micro offers a wide array of both narrow and Wide SCSI disk drives and tape drives. For current
product offerings and prices, please see the latest AMOS Hardware Price List.
Wide SCSI Configuration Rules
The Wide SCSI bus allows up to 15 SCSI IDs, so the limiting factors are the number of device bays in
the chassis and, especially, cabling considerations.
Because of the higher performance of the Wide bus,
it is critical to follow the cabling specification strictly, or performance and reliability will suffer.