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Parallel SCSI Interface Product Manual, Rev. A 123
Table 50: SPI L_Q information unit type
[2] Tag field is a 16-bit unsigned integer assigned by the application client and sent to the initiator in the Send
SCSI Command request. See Section
4.4.1, Task attribute message overview and codes.
[3] The Logical Unit Number field specifies the address of the logical unit of the I_T_L_Q nexus for the cur-
rent task. The structure of the Logical Unit Number field shall be as defined in the SCSI Architecture
Model-4 standard, Section 4.11. If the addressed logical unit does not exist, the task manager shall follow
the SCSI rules for selection of invalid logical units as defined in the SCSI Primary Commands - 4 (SPC-4)
standard. The eight bytes in this field provide 4 levels of addressing. Bytes 4-5 address the first level, etc.
to bytes 10-11, which address the fourth level. If LUN in SPI LQ information unit packet is X which is
greater than 0x3F (
>63), then the LUN in ID message sent back will be set to 0x3F (63). If LUN in SPI LQ
information unit packet is X which is not greater than 0x3F (
>63), then the LUN in ID message sent back
will be set to X.
[4] The Data Length field contains the length in bytes of the following information units. For SPI data stream
information units, the data length field contains the length in bytes of each SPI data stream information
unit that follows (i.e., the total number of bytes transferred would equal the data length times the number
of SPI data stream information units transferred). The data length shall not include any of the 4-byte
iuCRC nor any transmitted pad bytes (e.g., a data length of 509 with a iuCRC interval of zero or greater
Codes
Type Description
01h
Last
Command
Sent by a SCSI initiator port device to indicate a SPI command information unit shall follow
this SPI L_Q information unit. Indicates the initiator device shall not send any more SPI com-
mand information units during the current connection. The value of the Data Length field shall
be greater than or equal to 14h and less than or equal to 90h. The iuCRC Interval field shall be
set to zero and ignored by the target device. The Bidi Direction field shall be set to zero and
ignored by the receiving SCSI target device.
02h
Multiple
Command
Sent by a SCSI initiator port device to indicate a SPI command information unit shall follow
this SPI L_Q information unit. Indicates the initiator device has another SPI L_Q information
unit and SPI command information unit during the current connection. The value of the Data
Length
field shall be greater than or equal to 14h and less than or equal to 90h. The iuCRC
Interval field shall be set to zero and ignored by the SCSI target device. The IUCRC Interval
field shall be set to zero and ignored by the SCSI target device. The BIDI Direction field shall
be set to zero and ignored by the receiving target device.
04h
Data
Sent by a SCSI target port device to indicate a SPI data information unit shall follow this SPI
L_Q information unit. The Data Length field shall not be set to zero. For a bidirectional com-
mand, the direction of the SPI data information unit shall be indicated in the BIDI Direction
field of the SPI L_Q information unit as defined in Table
51.
05h
Data
stream
Sent by a SCSI target port device to indicate an unspecified number of SPI data stream infor-
mation units shall follow this SPI L_Q information unit. The Data Length field shall not be set to
zero. For a bidirectional command, the direction of the SPI data stream information units shall
be indicated in the BIDI Direction field of the SPI L_Q information unit as defined in Table
51.
08h
Status
Sent by a SCSI target port device to indicate a SPI status information unit may follow this SPI
L_Q information unit. A length of zero in the Data Length field shall indicate no SPI status
information unit shall follow the SPI L_Q information unit (see Section 6.2.5). The iuCRC Inter-
val field shall be set to zero and ignored by the SCSI target device. The BIDI Direction field
shall be set to zero and ignored by the receiving SCSI initiator device.
F0H -
FFh
vendor-specific.
All
others
Reserved.