Fujitsu MBA3073 SERIES Technical Manual page 23

(d) P1 (data group transfer enabled)
A signal that shall be continuously negated by the SCSI device driving the DB(15-0) signals and
shall be ignored by the SCSI device receiving the DB(15-0) signals during DT DATA phases.
(e) P1 (information unit and paced transfer enabled)
A signal that is sourced by SCSI device to indicate the data valid or data invalid state.
(f) P_CRCA (PARITY/CRC AVAILABLE) (SELECTION phase, ST DATA phase, COMMAND phase,
MESSAGE phase, or STATUS phase)
A signal sourced by the SCSI device driving the data bus during these phases. This signal is
associated with the DB(7-0) signals and is used to detect the presence of an odd number of bit
errors within the byte. The parity bit is driven such that the number of logical ones in the byte plus
the parity bit is odd.
The parity bits (P1 and P_CRCA) is optional for the system. The HDD handles the data bus
parity as follows:
•
The HDD has the data bus parity check function, and can enable or disable the parity check.
See Section 5.3.2 "SCSI Parity" of the Product Manual for setup details.
•
When valid data is sent to the data bus from the HDD, the parity data is always guaranteed
except for the ARBITRATION phase.
(g) P_CRCA (data group transfer enabled)
A signal sourced by a target during DT DATA phases to control whether a data group field is a
pad field, pCRC field, or data field. When asserted the data group field shall be pad or pCRC
fields that shall not be transferred to the ULP. When negated the data group field shall be a data
field that shall be transferred to the ULP.
Note:
ULP is "Upper Level Protocol".
(h) P_CRCA (information unit and paced transfer enabled)
During DT DATA phases when information unit transfers are enabled this signal is referred to as
P_CRCA and is sourced by the SCSI target port. Depending on the negotiated condition of read
streaming and write flow control the SCSI initiator port and SCSI target port usage for P_CRCA
is different. When information unit transfers are enabled the SCSI target port and SCSI initiator
port shall use the P_CRCA signal.
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