Maxtor 10K V manual Inquiry Command 12h, 22INQUIRY Command Descriptor Block-Data Format, Evpd

5.9INQUIRY Command (12h)

The INQUIRY command allows the initiator to determine the kind of SCSI devices attached to its SCSI bus. It causes a device that is attached to a SCSI bus to return information about itself. The drive identifies itself as a Direct Access Storage Device that implements the applicable interfacing protocol. The drive does not need to access its storage medium to respond to the inquiry. The INQUIRY commands are described in Table 5-22 and Table 5-23.

The drive can provide two categories of data in response to an INQUIRY command: Standard Inquiry Data and Vital Product Data. Standard Inquiry Data contains basic data about the drive, and Vital Product Data comprises several pages of additional data. Each Vital Product Data page requires a separate INQUIRY command from the initiator.

An INQUIRY command is not affected by, nor does it clear, a Unit Attention condition.

Table 5-22INQUIRY Command Descriptor Block-Data Format

Bit	7	6	5		4		3	2	1	0
Byte
0					Operation		Code (12h)
1				Reserved					CmdDt	EVPD
2				Page Code or Operation Code
3						Reserved
4					Allocation Length
5						Control

Table 5-23INQUIRY Command Descriptor Block-Field Descriptions
Field	Description
CmdDt	Command Support Data. If CmdDt = 0 and EVPD (see below) = 0, the drive returns the
	Standard Inquiry Data. If CmdDt = 1 with EVPD = 0, the drive returns the Command Data
	specified by Page Code/Operation.
EVPD	Enable Vital Product Data. If EVPD = 0 and CmdDt (see above) = 0, the drive returns the
	Standard Inquiry Data. If EVPD = 1and CmdDt = 0, the drive returns the Vital Product
	Data Page specified by Page Code/Operation Code.
	Specifies the Vital Product Data Page or Command Support Data which is to be returned
Page Code or	by the drive when EVPD is set. Specifies the SCSI Operation Code for command support
	data to be returned by the drive when CmdDt is set. A CHECK CONDITION status is re-
Operation Code	turned if this field specifies an unsupported Page or Operation Code or if both EVPD and
	CmdDt are set. Table 5-27 lists the Page Codes for the Vital Product Pages supported by
	the drive. Table 5-37 lists the operation codes for the CmdDt information supported by the
	drive.
Allocation Length	Specifies the number of bytes of inquiry information the drive is allowed to return to the
	initiator during the command's data-in buffer transfer. Error status is not returned if the
	value in this field truncates the requested information.

Maxtor Atlas 10K V 5-19