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12 Maintaining and Troubleshooting the Gateway ALR 9200 Server
Drive Controllers and Connectors
The system board supports several controllers and connectors for the
control of the various drives that are or can be installed in the system.
SCSI Connectors
The system board includes two SCSI controllers. A narrow SCSI controller
(SYM53C810AE) is on the PCI-A bus, and a dual-channel wide LVD/SE
(Ultra2/Ultra) SCSI controller (SYM53C896) is on the PCI-B bus. The
narrow controller provides support for legacy 8-bit SCSI devices that may
be installed in the 5.25-inch drive bays. The wide controller drives one
SCSI backplane and provides support for external expansion.
Each controller has its own set of PCI configuration registers and SCSI I/O
registers. As a PCI 2.1 bus master, the wide controller supports burst data
transfers on PCI up to the maximum rate of 132 MB/sec using on-chip
buffers.
No logic, termination, or resistor loads are required to connect devices to
the SCSI controller other than termination in the device at the end of the
cable. The SCSI bus is terminated on the system board with active
terminators that can be disabled.
Wide SCSI A (LL) and Wide SCSI B Connectors (A)
Internally, each wide channel is identical, capable of operations using either
8- or 16-bit SCSI providing 10 MB/sec (Fast-10) or 20 MB/sec (Fast-20)
throughput, or 20 MB/sec (Ultra) or 40 MB/sec (Ultra-wide).
The wide controller contains a high-performance SCSI bus interface. It
supports SE mode with 8-bit (10 or 20 MB/sec) or 16-bit (20 or 40 MB/sec)
transfers and LVD mode with 8-bit (40 MB/sec) or 16-bit (80 MB/sec)
transfers.
Narrow SCSI Connector (II)
The narrow controller contains a high-performance SCSI core capable of
Fast 8-bit SCSI transfers in single-ended mode. It provides programmable
active negation, PCI zero wait-state bursts of faster than 110 MB/sec at 33
MHz, and SCSI transfer rates from 5 to 10 MB/sec.
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