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TAPE UNIT SCSI COMMANDS M2488 PRODUCT GUIDE
4-18 CG00000-011503 REV. A April 1997
4-3.6 INQUIRY command 12h
The INQUIRY command provides a means for an initiator to request information regarding parame-
ters of the target and any attached peripheral devices.
4-3.6.1 INQUIRY CDB Description
The INQUIRY CDB is a six-byte command. The bytes are shown below and described in
Table 4-15. Common fields are described in paragraph 4-3.1 on page 4-4.
BITS
BYTES 7 6 5 4 3 2 1 0
0
0 0 0 1 0 0 1 0
1
LUN Reserved EVPD
2
Page Code
3
Reserved
4
Allocation Length
5
Reserved Flag Link
Note: Changeable fields in the CDB are shaded.
Table 4-15. INQUIRY Field Description
BYTE BIT VALUE DESCRIPTION
0 0-7 12h Operation code.
1 0 1
0
An Enable Vital Product Data (EVPD) bit of one specifies that the target returns
the optional Vital Product Data (VPD) specified by the Page Code field. See sec-
tion 5-3 for the description of the MTU VPD pages or section 6-4 for the
description of the MC VPD pages supported by the INQUIRY command.The
EVPD bit and its relationship to the Page Code field is shown in Table 4-16.
An EVPD bit of 0 indicates transfer of normal INQUIRY data.
2 0-7 The Page Code codes are described in Table 4-17.
4 0-7 The Allocation Length field specifies the maximum number of bytes that the initi-
ator has allocated for returned INQUIRY data. An allocation length of zero indi-
cates no INQUIRY data is to be transferred. This condition is not considered as an
error.
The target terminates the DATA IN phase when allocation length bytes are trans-
ferred or when all available INQUIRY data is transferred to the initiator, which-
ever is less. The user should specify an allocation length of at least 68h (104)
when normal Inquiry data (EVPD=0) is requested.