Avago Technologies LSI53C320 - Manual (Page 65)

LSI53C320 Ultra320 SCSI Bus Expander Technical Manual B-1
Version 2.2 Copyright © 2003 by LSI Logic Corporation. All rights reserved.
Appendix B
Glossary
Block A block is the basic 512 byte size of storage that the storage media is
divided into. The Logical Block Address protocol uses sequential block
addresses to access the media.
Bus Expander Bus expander technology permits the extension of a bus by providing
some signal filtering and retiming to maintain signal skew budgets.
Device A single unit on the SCSI bus, identifiable by a SCSI address. It can be a
processor unit, a storage unit (such as a disk or tape controller or drive),
an output unit (such as a controller or printer), or a communications unit.
Differential A signaling alternative that employs differential drivers and receivers to
improve signal-to-noise ratios and increase maximum cable lengths.
Double
Transition
Clocking In Double Transition (DT) Clocking data is sampled on both the asserting
and deasserting edge of the REQ/ACK signal. DT clocking may only be
implemented on an LVD SCSI bus.
Host A processor, usually consisting of the central processing unit and main
memory. Typically, a host communicates with other devices, such as
peripherals and other hosts. On the SCSI bus, a host has a SCSI
address.
Initiator A SCSI device that requests another SCSI device (a target) to perform an
operation. Usually, a host acts as an initiator and a peripheral device acts
as a target.
Logical Unit The logical representation of a physical or virtual device, addressable
through a target. A physical device can have more than one logical unit.
LVD Low Voltage Differential. LVD is a robust design methodology that
improves power consumption, data integrity, cable lengths and support for
multiple devices, while providing a migration path for increased I/O
performance.