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MODE SELECT 6.Command Specification
SONY AIT-3Ex drive SDX-800V series Ver.1.1 6-39
Table 6-36: MODE SELECT parameter list
Bit
Byte
7 6 5 4 3 2 1 0
0 Reserved
1 Reserved
2 Reserved Buffered Mode (001b) Speed (00h)
3 Block Descriptor Length (08h)
4 Density Code
5 (MSB) Number of Blocks (00 00 00h)
6
7 (LSB)
8 Reserved
9 (MSB) Block Length
10
11 (LSB)
Buffered Mode: Buffered Mode is the mechanism by which the drive implements Immediate Reporting on WRITE
commands.
If the field is ZERO, then the drive does not report a GOOD status on WRITE commands until the data blocks are
actually written to tape (not support).
If the Buffered Mode field is one, then the drive reports GOOD status on WRITE commands as soon as the data
block has been transferred to the buffer. This field should be set to ONE.
Speed: The drive only supports one speed, the default speed. Because of this, this field must be set to ZERO. Any
other value will cause a CHECK CONDITION status with an ILLEGAL REQUEST sense key is returned.
Block Descriptor Length: This specifies the length in bytes of all the block descriptors. Since the drive only allows
one block descriptor, this value must be eight. Any other value will cause a CHECK CONDITION status with an
ILLEGAL REQUEST sense key to be returned.
Note: The block descriptor specifies the media characteristics for the SDX drive. The block descriptor contains the
density code, number of blocks and block length fields.
Density Code: The supported values for the density code field are defined in the following table.
Note: 00h - Default: The use of the word “Default” is SCSI specific. It instructs the drive to use its default or only
density.
Table 6-37: Sequential-Access Density Codes
Code Value Code Value
00h
30h
31h
32h
38h
39h
3Ah
3Bh
7Fh
Default Format
AIT-1 Format
AIT-2 Format
AIT-3 Format
AIT-E Turbo Format
AIT-1 Turbo Format
AIT-2 Turbo Format
AIT-3Ex Format
No change from previous density
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.