Save Data Pointer (02); Restore Pointers (03); Table 180. Bit Position Table For Byte 7 Of Parallel Protocol Request - Hitachi HUS151473VL3800 - Ultrastar 73.4 GB Hard Drive Specifications

- 00h: 8 bit data bus (Narrow transfer agreement).
- 01h: 16 bit data bus (Wide transfer agreement).
• PCOMP_EN (Precompensation Enable) is used to negotiate if the pre-compensation is enabled
on all signals transmitted during DT DATA phases. The drive supports PCOMP_EN.
• RTI (Retain Training Information) is used to negotiate if the saving of paced data transfer training
information is made so that the retraining is not necessary on each connection. The drive support
RTI.
• RD_STRM (Read Streaming and Read Flow Control Enable) is used to negotiate if read stream-
ing and read flow control are enabled. The drive supports RD_STRM.
• WR_FLOW (Write Flow Control Enable) is used to negotiate if write flow control is enabled
during write streaming. The drive supports WR_FLOW.
• HOLD_MCS (Hold Margin Control Settings) is used to negotiate if any margin control settings
which has been set with the margin control subpage of the port control mode page is retained.
• QAS_REQ (Quick Arbitration and Selection Enable Request) is used to negotiate if QAS is
enabled. The drive supports QAS when IU_REQ is negotiated to be effective.
• DT_REQ (DT Clocking Enable Request) is used to negotiate if DT DATA phase is enabled. The
drive supports DT_REQ.
• IU_REQ (Information Unit Enable Request) is used to negotiate if information unit transfer is
enabled. The drive supports IU_REQ.
Table 180: Bit position table for Byte 7 of Parallel Protocol Request
7 6
QAS_REQ (Quick Arbitrate and Select) is not supported. The bit should be zero.
DT_REQ A bit of zero for DT_REQ (Double Transition Enable Request) indicates that DT DATA phases are to be disabled
when received from the originating SCSI device and that DT DATA phases are not supported when received from the respond-
ing SCSI device.
A DT_REQ bit of one indicates that DT DATA phases are to be enabled when received from the originating SCSI device and
that DT DATA phases are supported when received from the responding SCSI device.
IU_REQ (Information Unit Request) is not supported. The bit should be 0.

19.1.5 Save Data Pointer (02)

This message is sent from the drive to direct the Initiator to copy the active data pointer to the saved data pointer. The SAVE
DATA POINTER message is only sent if the Initiator has previously indicated the ability to accommodate disconnection and
reconnection via the IDENTIFY message.
The drive will send the SAVE DATA POINTER message to the Initiator prior to sending a DISCONNECT message to the Ini-
tiator if a data phase has occurred and another data phase is required to successfully complete the command.

19.1.6 Restore Pointers (03)

This message is sent from the drive to direct an Initiator to copy the most recently saved pointers to the corresponding com-
mand, data, and status pointers. Command and status pointers should be restored to the beginning of the present command and
status areas. The data pointer should be restored to the value at the beginning of the data area in the absence of a SAVE DATA
POINTER message or to the value at the point at which the last SAVE DATA POINTER message occurred. Refer to Section
5 4
Reserved
Hitachi Ultrastar 15K147 SCSI Hard Disk Drive Specification
Bit
3 2
QAS_REQ
219
1 0
DT_REQ IU_REQ