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MODE SELSECT
Code Value
00h
30h
31h
38h
39h
3ah
7Fh
Number of Blocks: A MODE SENSE field which will be returned as ZERO, indicating that all of the remaining
logical blocks on the media will have the medium characteristics specified by the block descriptor, or until a
subsequent MODE SELECT command changes those parameters. This field must be set to ZERO on a MODE
SELECT otherwise a CHECK CONDITION status will be returned with an ILLEGAL REQUEST sense key.
Block length: The Block Length field specifies the length in bytes of each logical block transferred over the SCSI
bus. A block length of ZERO indicates that the length is variable. Any other value indicates the number of bytes per
block that the drive must handshake over the bus. This establishes block length such that the transfer length for
read, write and verify type commands will be a block count not a byte count.
Note: It is value of this field together with the Fixed Bit Field in the READ, or WRITE commands that determines
whether the drive is in Fixed or Variable block mode.
Mode
Fixed Block
Variable Block
The default fixed block size is 512 bytes however, the drive will accept a variable command (fixed bit of ZERO)
without reporting an error.
Note: Minimum block-size is 2. If a non ZERO block-size is 1, CHECK CONDITION status will be return, and Sense
Key will be ILLEGAL REQUEST.
Following the Block Descriptor are the MODE SELECT pages. They are the method by which the device parameters
are set. Each page has a two byte header which identifies the page code and indicates the number of bytes in that
page.
Bit
7
Byte
0
PS
1
PS: when the Page Savable bit is set, this indicates that the page contains saved parameters. This bit will never be
set as there is no non-volatile RAM on the drive into which parameter data may be saved.
The page codes that are supported are:
SONY AIT-2 Turbo drive SDX-550V series Ver.1.0
Table 6-31: Sequential-Access Density Codes
Code Value
Default Format
AIT-1 Format
AIT-2 Format
AIT-E Turbo Format
AIT-1 Turbo Format
AIT-2 Turbo Format
No change from previous density
Fixed Bit in Read, Write & Verify
1
0
Table 6-32: MODE SELECT Page Header
6
5
Reserved
Additional Page Length
4
3
2
Page Code
6.Command Specification
Block Length in
Mode Select/Sense
Block Size
0
1
0
6-39
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