HP Kayak XU700, Техническое справочное руководство, Страница: 74 / 124

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3 Interface Cards
SCSI Adapter Cards
Additional SCSI Card Features
The Adaptec® SCSI card provides double transition clocking, cyclical
redundancy check, and domain validation.
Feature Description
Double Transition
Clocking Changes the digital protocol to use both edges of
the SCSI request/acknowledge signal clock. It
allows designers to use Ultra2 cables. The signal
in an Ultra2 SCSI runs a 40 MHz, while data runs
at only 20 MHz or 80 MB/second on a 16-bit wide
bus.
Using both edges of the same signal at 40 MHz the
data rate can be increased to 40 MB/second or 160
MB/second on a 16-bit wide bus.
Cyclical Redundancy
Check Provides extra data protection for marginal cables
that are connected to external devices. The Ultra3
SCSI cyclical redundancy check detects all:
• Single error bits
• Double bit errors
• Odd number of errors
• Burst errors up to 32-bits long
Domain Validation Tests networks, cables, backplanes, terminators,
and hard disk drives to ensure that the
environment is operating at required specification.
If reliability is at risk the speed of transfer is
lowered.