Fujitsu MBA3073 SERIES Technical Manual page 92

When the INIT detects an assertion of the P_CRCA signal and the REQ signal is negated (i.e., no
pad field required),
1) INIT transfers data bytes for all outstanding REQs received prior to the REQ that had the
P_CRCA signal asserted. INIT drives the DB(15-0) signals to their desired pCRC values.
2) INIT delays at least one transmit setup time, asserts the ACK signal and holds the DB(15-
0) signals valid for a minimum of one transmit hold time and the ACK signal asserted for
a minimum of a transmit assertion period.
3) INIT drives the DB(15-0) signals to their desired pCRC values and delays at least one
transmit setup time.
4) INIT negates the ACK signal and holds the DB(15-0) signals valid for a minimum of one
transmit hold time and the ACK signal negated for a minimum of a transmit assertion
period.
After either of the above sequence is complete the TARG has ended a data group.
As a result of a data group always being an even number of transfers, the REQ and ACK
signals are negated both before and after the transmission of the data group. The TARG
fetches the value of the DB(15-0) signals within one receive hold time of the transition of
the ACK signal.
The INIT uses the pad bytes, if any, in the generation of the transmitted pCRC. The TARG
then uses those pad bytes, if any, for checking against the computed pCRC for the current
data group. Upon receipt of the last byte of the pCRC field, the received pCRC and
computed pCRC is compared.
If received pCRC and computed pCRC do not match (i.e., a pCRC error is detected), or if an
improperly formatted data group is transferred, then the associated data group is
considered invalid.
If the TARG does not retry transferring the information transfer or it exhausts its retry limit
the TARG goes into a STATUS phase and send a CHECK CONDITION status with a
sense key set to ABORTED COMMAND and an additional sense code set to SCSI
PARITY ERROR for the task associated with the pCRC error.
12 C141-C015