Seagate Ultra 160, Ultra 320 SPI LQ information unit type, Codes Type Description, F0H, FFh All

Table 50:		SPI L_Q information unit type
Codes	Type		Description
			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-
01h		Last	mand information units during the current connection. The value of the Data Length field shall
		Command	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.
			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
02h		Multiple	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
		Command
			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.
			Sent by a SCSI target port device to indicate a SPI data information unit shall follow this SPI
04h		Data	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.
			Sent by a SCSI target port device to indicate an unspecified number of SPI data stream infor-
05h		Data	mation units shall follow this SPI L_Q information unit. The Data Length field shall not be set to
		stream	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.
			Sent by a SCSI target port device to indicate a SPI status information unit may follow this SPI
08h			L_Q information unit. A length of zero in the Data Length field shall indicate no SPI status
		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 -			vendor-specific.
FFh
All			Reserved.
others

[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

Parallel SCSI Interface Product Manual, Rev. A 123