SCSI Description
5-20 Maxtor Atlas 10K III
The INQUIRY command allows the initiator to det ermine the ki nd of SCSI devi ces
at ta che d to its S C SI bus . I t cause s a d e v ic e that i s attached to a SCSI bus to re tur n
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 INQU IRY 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.
INQU IRY Comm a nd Descriptor Block-Data Format
INQUIRY Com ma nd De scriptor Block-Field Descriptions
0 Ope ration C o de (12h )
1 Reserved CmdDt EVPD
2 Page Code or Operation Code
3 Reserved
4 Allocation Length
5 Control
CmdDt Command Support Data. If CmdDt = 0 and EVPD (see below) = 0, the drive
retur ns the Standar d Inquiry Data. If CmdDt = 1 with EVPD = 0, the drive
returns the Command Data specified by Page Code/O peration.
EVPD Enable Vital Product Data. If EVPD = 0 and CmdDt (see above) = 0, the drive
retur ns the Standar d Inquiry Data. If EVPD = 1and CmdDt = 0, the drive re-
turns the Vital Product Data Page specified by Page Code/Operation Code.
Page C o de o r
Operati on Code
Specif ies t he Vit al Pr oduct Dat a Page or Command Support Data whi ch is t o
be returned by the drive when EVPD is set. Specifies the SCSI Operation Code
for command s uppor t data to be re turned by the dri ve w hen CmdDt i s set. A
CHECK CONDITION status is returned if this field specifi es an unsupport ed
Page or Operation Code or if both EVP D and Cm dDt ar e set. Table 5-27 li sts
the Page Codes for the Vita l Product Page s supported by the drive. Table 5-
41 lis ts the operation codes fo r the CmdDt in formati on supported by the
drive.
Allocation Length
Specif ies the numb er of bytes of i nquiry information the drive is al lowed to
return to the initiator during the command's data-in buffer transfer. Error sta-
tus is n o t re tu r n ed if the valu e in th is fie l d tr u n ca t es th e re que ste d in fo r m a -
tion.