Block Descriptor; Page Descriptor - IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive Specifications

When used with the M O D E SENSE command, a Write Protect (WP) bit of zero indicates that the
medium is write enabled.
Block Descriptor Length specifies the length in bytes of the block descriptors.
When used with the M O D E SELECT command, zero or eight are supported by the file.
When used with the M O D E SENSE command, the file returns eight to indicate that only a single block
descriptor is available.

7.9.2.2 Block Descriptor

BYTE 0
BYTE 1
BYTE 2
BYTE 3
BYTE 4
BYTE 5
BYTE 6
BYTE 7
Figure 71. M O D E Parameter Block Descriptor
The Block descriptor provides formatting information about the Number of Blocks (user addressable) to
format at the specified Block Length.
Number of Blocks
When used with the M O D E SELECT command, the Number of Blocks field must be;
Zero to indicate not to change available blocks
0 x F F F F F F to indicate all available blocks
The exact number of blocks in the data area of the file, which can be obtained with the M O D E
SENSE
The number of blocks less than exact one, in order to CLIP the number of blocks
Any other value is invalid, and causes the command to fail with CHECK CONDITION status.
When used with the M O D E SENSE command, the field contain exact number of blocks.
Block Length
When used with the M O D E SELECT command, the Block length field must contain 512 or zero, or
the file will terminate the command with CHECK CONDITION status.
When used with the M O D E SENSE command, the field will return always contain 512 .

7.9.2.3 Page Descriptor

Number of Blocks (MSB)
(LSB)
Density code = 0
Block Length
SCSI C O M M A N D SET
91