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D
Option Cards
Introduction
The Ultra Extender and Differential Converter Option
cards provide a single solution allowing the extension
of device connectivity and/or cable length of the SCSI
bus for the DEU subsystems.
When the Ultra Extender card is used, the circuitry
functions as a SCSI bus repeater for multiple single-
ended to single-ended cabling schemes while being
electrically isolated from each other. When the
Differential Converter card is used, the circuitry
functions as a SCSI bus converter for differential to
single-ended cabling schemes again while being
electrically isolated from each other. As SCSI command
and data passes from the source bus to the load bus,
signal filtering and re-timing are employed to maintain
the SCSI signal.
The cards feature TolerANT® technology, which
includes active negation on the SCSI drivers and input
signal filtering on the SCSI receivers. Active negation
causes the SCSI Request, Acknowledge, Data, and
Parity signals to be actively driven high rather than
passively pulled up by terminators. The receiver
technology improves data integrity in unreliable
cabling environments, where other devices would be
subject to data corruption. The TolerANT receivers
filter the SCSI bus signals to eliminate unwanted
transitions without long signal delays. This improved
driver and receiver helps eliminate double clocking of
data, the largest reliability issue with SCSI operations.
