Avago Technologies LSI53C120 - Manual (Page 53)

LSI53C120 Ultra SCSI Bus Expander B-1
Appendix B
Glossary
ACK/ Acknowledge – Driven by an initiator, ACK/ indicates an acknowledgment
for 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 which 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.
Autoconfigura-
tion Ports Three 8-bit ports (Address, Write_Data, and Read_Data) used by
software to access the configuration space on each Plug and Play card.
The configuration space is implemented as a set of 8-bit registers. These
registers are used by the Plug and Play software to issue commands,
check status, access the resource data information, and configure the
Plug and Play hardware.
Block A block is the basic 512 byte region of storage into which the storage
media is divided. 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 both the initiator and the target device.