Quantum 10K II - Manual (Page 113)

SCSI Description
5–46 Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives
INQUIRY Command (12h) (continued)
Table 5–17A Negotiated Rate Information Page — Field Descriptions
Field Definition
Transfer Period Factor Applicable values of this field are provided in Appendix C.
REQ / ACK Offset This is the negotiated value of Req / Ack offset between the initiator and
the target. For Single Transition (ST) data transfers, the REQ/ACK Offset is
the maximum number of REQ assertions allowed to be outstanding
before a corresponding ACK assertion is received at the target: Data
transfer size may be 1 or 2 bytes. For Double Transition (DT) data
transfers, the REQ/ACK Offset is the maximum number of REQ assertions
allowed to be outstanding before a corresponding ACK assertion is
received at the target: Data transfer size is 2 bytes.
AIP Asynchronous Information Protection. If = 1, drive supports AIP. If = 0,
device does not support AIP.
AIPD Asynchronous Information Protection Generation Disabled. If = 1, AIP
generation is disabled. If = 0, AIP generation is enabled.
AIPCE Asynchronous Information Protection Checking Enabled. If = 1, AIP
protection is enabled. If = 0, AIP protection is disabled.
TWE Transfer Width Exponent. The transfer width is 2 n bytes. If set to 0, 1 byte
is selected; if set to 1, 2 bytes are selected.
PARL Parallel Protocol. When = 1, this field indicates the negotiation occurred
with a Parallel Protocol message format. When = 0, this field indicates
the negotiation occurred with a Synchronous Data Request message
format.
FAIR Fairness. When set = 1, the Fairness algorithm is enabled. When set = 0,
the algorithm is disabled.
SYNC Synchronous Mode. When set = 1, the data transfer bus is operating in
synchronous mode. When set = 0, the data transfer bus is operating in
asynchronous mode.
QAS
(Note that the value of this
field must be 0 if the value in
PARL is 0) Quick Arbritrate Support Enable. When = 0, indicates that QAS is to be
disabled when received from initiator and that QAS is disabled when
received from target. When = 1, indicates that QAS is to be enabled
when received from initiator and that QAS is enabled when received from
target. See Appendix C.
DT
(Note that the value of this
field must be 0 if the value in
PARL is 0) Double Transition Enable. When = 0, indicates that DT DATA is to be
disabled when received from initiator and that DT DATA phases are
disabled when received from target. When = 1, indicates that DT DATA
phases are to be enabled when received from initiator and that DT DATA
phases are enabled when received from target. See Appendix C.
IU
(Note that the value of this
field must be 0 if the value in
PARL is 0) Information Units Enable. When = 0, indicates that information unit
transfers shall not be used when received from the initiator and that
information unit transfers are disabled when received from the target.
When = 1, indicates that information unit transfers shall be used when
received from the initiator and that information unit transfers are enabled
when received from the target. See Appendix C.