Maxtor ATLAS 10K III - Manual (Page 241)

SCSI Description
Maxtor Atlas 10K III 5-177
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The WRITE SKIP MASK command allows the initiator to condition the function of
the WRITE commands to allow only selected data to be transferred over the SCSI
interface. A WRITE SKIP MASK command precedes a WRITE (10) command; the
WRITE (10) command must be linked to the WRITE SKIP MASK command or the
skip mask is lost and a CHECK CONDITION status is returned. The data format and
field descriptions are shown in Table 5-224 and Table 5-225 respectively.
Table 5-224 WRITE SKIP MASK Command Descriptor Block-Data Format
Table 5-225 WRITE SKIP MASK Command-Field Descriptions
$KV
$[VG
       
0 Operation Code (EAh)
1 Reserved
2 - 5
(MSB)
Logical Block Address
(LSB)
6 Skip Mask Length
7 - 8
(MSB)
Transfer Length
(LSB)
9 VU Reserved Flag Link
(KGNF &GUETKRVKQP
Logical
Block Ad-
dress
This field specifies the first logical block of the corresponding WRITE (10)
COMMAND. This allows a SEEK to begin immediately. The LBA of the fol-
lowing WRITE (10) command must the same as the LBA of the WRITE SKIP
MASK command.
Skip Mask
Length
This field indicates the length in bytes of the skip mask. The mask is up to
2048 bits, giving a data address capability of 1 MB in 512-byte block length.
The mask consists of a sequence of bits where a “1” bit is for the blocks of
data to be transferred, and a “0” for the blocks of data that are to be skipped.
The first “1” bit of the mask corresponds to the first LBA to be transferred.
Any unused bits at the end of the last byte in the mask must be set to 0. The
mask is transferred in the data-out buffer transfer of the skip mask command.
Transfer
Length
This field must be equal to the transfer length in the linked WRITE
(10) command. The transfer length field must be equal to the number
of “1”
bits in the skip mask. If a WRITE (10) is used with 0 as the transfer
length, a transfer length of 256 data blocks is implied.