Quantum 10K II - Manual (Page 329)

Appendix B. SCSI Bus Signal Timing
B–8 Quantum Atlas 10K II Ultra 160/m SCSI Hard Disk Drives
Receive Negation Period - The minimum time required at a SCSI device receiving a REQ signal
for the signal to be negated while using synchronous data transfers.
Also, the minimum time required at a SCSI device receiving an ACK signal for the signal to be
asserted while using synchronous data transfers.
For SE fast-5 and fast-10 operation, the time period is measured at the 2.0 V level. For SE fast-20
operation the period is measured at the 1.9 V level.
Receive Setup Time - For ST data transfers the minimum time required at the receiving SCSI
device between the changing of DATA BUS and the assertion of the REQ signal or the ACK
signal while using synchronous data transfers.
For DT data transfers the minimum time required at the receiving SCSI device between the
changing of DATA BUS and the transition of the REQ signal or the ACK signal while using
synchronous data transfers.
Receive REQ (ACK) Period Tolerance - The minimum tolerance that a SCSI device shall allow to
be subtracted from the REQ (ACK) period.
REQ (ACK) Period - The REQ (ACK) period during synchronous data transfers is measured from
an assertion edge of the REQ (ACK) signal to the next assertion edge of the signal.
In DT DATA phases the nominal transfer period for data is half that of the REQ (ACK) period
during synchronous data transfers since data is qualified on both the assertion and negation
edges of the REQ (ACK) signal.
In ST DATA phases the nominal transfer period for data is equal to the REQ (ACK) period during
synchronous data transfers since data is only qualified the assertion edge of the REQ (ACK)
signal.
Reset Delay - The minimum time that the RST signal shall be continuously true before the SCSI
device shall initiate a reset.
Reset Hold Time - The minimum time that the RST signal is asserted. There is no maximum time.
Reset To Selection - The recommended maximum time from after a reset condition until a SCSI
target is able to respond with appropriate status and sense data to the TEST UNIT READY,
INQUIRY, and REQUEST SENSE commands (See SCSI Primary Commands-2 Standard).
Selection Abort Time - The maximum time that a SCSI device shall take from its most recent
detection of being selected or reselected until asserting the BSY signal in response. This time-
out is required to ensure that a target or initiator does not assert the BSY signal after a
SELECTION or RESELECTION phase has been aborted.