Avago Technologies LSI53C140 - Manual (Page 69)

LSI53C140 Ultra2 SCSI Bus Expander C-1
Ver. 2.1 Copyright © 1998–2001 by LSI Logic Corporation. All rights reserved.
Appendix C
Glossary
ACK/ Acknowledge – Driven by an initiator, ACK/ indicates an acknowledgment
or a SCSI data transfer. In the target mode, ACK/ is received as a
response to the REQ/ Signal.
ANSI American National Standards Institute.
Arbitration The process of selecting one respondent from a collection of several
candidates that request service concurrently.
Asserted A signal is asserted when it is in the state that is indicated by the name of
the signal. Opposite of negated or deasserted.
Assertion The act of driving a signal to the true state.
Asynchronous
Transmission Transmission in which each byte of the information is synchronized
individually through the use of Request (REQ/) and Acknowledge (ACK/)
signals.
ATN/ Attention – Driven by an initiator, indicates an attention condition. In the
target role, ATN/ is received and is responded to by entering the Message
Out Phase.
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.
BSY/ Busy – Indicates that the SCSI Bus is being used. BSY/ can be driven by
the initiator or the target device.
Bus A collection of unbroken signal lines that interconnect computer modules.
The connections are made by taps on the lines.
Bus Expander Bus expander technology permits the extension of a bus by providing
some signal filtering and retiming to maintain signal skew budgets.