Negotiable Field Combinations; Message Restrictions - Seagate Ultra160 Product Manual

SCSI Interface Product Manual, Rev. B
2.12.9

Negotiable field combinations

Not all combinations of the negotiable fields are valid. Only the combinations defined in Table 19 shall be
allowed. All other combinations of the listed fields are reserved.
Table 19: Valid negotiable field combinations
Transfer Transfer
period REQ/ACK width
factor offset exponent
0Ah - FFh 00h 00h or 01h
0Ah - FFh 00h 00h or 01h
0Ah - FFh 01h - FFh 00h or 01h
09h - FFh 01h - FFh 01h
09h - FFh 01h - FFh 01h
0Ah - FFh 01h - FFh 00h or 01h
09h - FFh 01h - FFh 01h
08h 01h - FFh 01h
09h - FFh 01h - FFh 01h
08h 01h - FFh 01h
2.12.10

Message restrictions

PPR may be originated by SCSI initiator ports but shall not be originated by SCSI target ports. If bus expanders
are present, SCSI initiator ports should only use PPR when requesting values not attainable via WDTR and
SDTR (e.g., setting any protocol option bits to one). If a SCSI target port responds to PPR only with values that
are attainable via WDTR and SDTR (i.e., all protocol option bits set to zero), the SCSI initiator port should
repeat negotiation with a WDTR and SDTR negotiation sequence. This ensures that bus expanders that do not
support PPR are still able to handle data phases correctly.
Protocol options
0 0 0 0 0 0
0 0 0 0 0 1
0 0 0 0 0 0
0 0 0 0 0 0
0 0 0 0 0 1
0 0 0 0 0 1
0 0 0 0 0 0
or or
1 1
0 0 0 0 0 0
or or or or or
1 1 1 1 1
0 0 0 0 0 1
or or
1 1
0 0 0 0 0 1
or or or or or
1 1 1 1 1
Description
0 0 Use ST DATA IN and ST DATA OUT
phases to transfer data with asynchro-
nous transfers.
0 0 Use ST DATA IN and ST DATA OUT
phases to transfer data with asynchro-
nous transfers, and participate in QAS
arbitrations.
0 0 Use ST DATA IN and ST DATA OUT
phases to transfer data with synchronous
transfers.
1 0 Use DT DATA IN and DT DATA OUT
phases with data group transfers.
1 0 Use DT DATA IN and DT DATA OUT
phases with data group transfers, and par-
ticipate in QAS arbitrations.
0 0 Use ST DATA IN and DT DATA OUT
phases with data group transfers, and par-
ticipate in QAS arbitrations.
1 1 Use DT DATA IN and DT DATA OUT
phases with paced transfers and informa-
tion unit transfers.
1 1 Use DT DATA IN and DT DATA OUT
phases with synchronous transfers and
information unit transfers.
1 1 Use DT DATA IN and DT DATA OUT
phases with paced transfers and informa-
tion unit transfers, participate in QAS arbi-
trations, and issue QAS_REQUEST
messages to initiate QAS arbitrations.
1 1 Use DT DATA IN and DT DATA OUT
phases with information unit transfers,
participate in QAS arbitrations, and issue
QAS_REQUEST messages to initiate
QAS arbitrations.
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