SCSI Primary Commands - 2.pdf

T10/1236-D Revision 20 18 July 2001A command queuing (CMDQUE) bit of one indicates that the device supports tagged tasks (command queuing) forthis logical unit (see SAM-2). A value of zero indicates the device server may support tagged tasks for this logicalunit (see the BQUE bit, above). Table 50 summarizes the relationship of the BQUE and CMDQUE bits.Table 50 — Relationship of BQUE and CMDQUE bitsBQUE CMDQUE Description0 0 No command queuing of any kind supported.0 1 Command queuing with all types of task tags supported.1 0 Basic task management model supported (see SAM-2)1 1 Illegal combination of BQUE and CMDQUE bits.ASCII data fields shall contain only graphic codes (i.e., code values 20h through 7Eh). Left-aligned fields shallplace any unused bytes at the end of the field (highest offset) and the unused bytes shall be filled with spacecharacters (20h). Right-aligned fields shall place any unused bytes at the start of the field (lowest offset) and theunused bytes shall be filled with space characters (20h).The VENDOR IDENTIFICATION field contains eight bytes of ASCII data identifying the vendor of the product. The datashall be left aligned within this field.NOTE 13 It is intended that this field provide a unique vendor identification of the manufacturer of the SCSI device.In the absence of a formal registration procedure, T10 maintains a list of vendor identification codes in use.Vendors are requested to voluntarily submit their identification codes to T10 to prevent duplication of codes (seeAnnex D).The PRODUCT IDENTIFICATION field contains sixteen bytes of ASCII data as defined by the vendor. The data shall beleft-aligned within this field.The PRODUCT REVISION LEVEL field contains four bytes of ASCII data as defined by the vendor. The data shall beleft-aligned within this field.The VERSION DESCRIPTOR fields provide for identifying up to eight standards to which the device claimsconformance. The value in each VERSION DESCRIPTOR field shall be selected from table 51. All version descriptorvalues not listed in table 51 are reserved. Technical Committee T10 of NCITS maintains an electronic copy of theinformation in table 51 on its world wide web site (http://www.t10.org/). In the event that the T10 world wide website is no longer active, access may be possible via the NCITS world wide web site (http://www.ncits.org), the ANSIworld wide web site (http://www.ansi.org), the IEC site (http://www.iec.ch/), the ISO site (http://www.iso.ch/), or theISO/IEC JTC 1 web site (http://www.jtc1.org/). It is recommended that the first version descriptor be used for theSCSI architecture standard, followed by the physical standard, followed by the physical/mapping protocol if any,followed by the appropriate SPC version, followed by the device type command set, followed by a secondarycommand set if any.Table 51 — Version descriptor values (part 1 of 5)VersionDescriptorStandardValueEPI ANSI NCITS TR-23:19990B3ChEPI (no version claimed)0B20hEPI T10/1134 revision 160B3BhFast-20 (no version claimed)0AC0hAnnex C contains the version descriptor value assignments in numeric order.86 dpANS SCSI Primary Commands - 2 (SPC-2)