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16 mode sense (6) command (1ah) – Quantum 10K II User Manual

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SCSI Description

Quantum Atlas 10K II Ultra160/m SCSI Hard Disk Drives

5–103

5.16

MODE SENSE (6) Command (1Ah)

The MODE SENSE (6) command allows the initiator to read the drive's sector
descriptor and mode pages. The MODE SENSE Command Descriptor Sector is
shown in Figure 5–42 and the data fields are described in Table 5–45. The Mode
Parameter Header is shown in Figure 5–43 and the data fields are described in Table
5-46.

Bit

Byte

7

6

5

4

3

2

1

0

0

Operation Code (1Ah)

1

Logical Unit Number

Reserve

d

DBD

Reserved

2

PC

Page Code

3

Reserved

4

Allocation Length

5

Control

Figure 5–42 MODE SENSE (6) Command Descriptor Block — Data Format

Table 5–45 MODE SENSE Command — Field Descriptions

Data Field

Description

DBD

Disable Block Descriptor. When the value is 0, the drive returns its Block
Descriptor followed by the requested page(s). When the value is 1, the
drive returns only the requested pages.

PC

Page Control. Determines which type of page values are returned. These
values are:
00b Current
01b Changeable
10b Default
11b Saved

Page Code

The Page Code field determines the pages to be returned to the initiator
in the command's data-in buffer transfer. Refer to Tables 5-26 and 5-47
for a complete list of the Mode Pages (changeable and read-only). A
Page Code of 3Fh causes all supported pages to be returned.