Write Skip Mask Command Descriptor Block-Data Format; Write Skip Mask Command-Field Descriptions - Maxtor ATLAS 10K III Product Manual

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.
T a b l e 5 - 2 2 4 WRITE SKIP MASK Command Descriptor Block-Data Format
$ K V
 
$ [ V G
0
1
(MSB)
2 - 5
6
(MSB)
7 - 8
9 VU
T a b l e 5 - 2 2 5 WRITE SKIP MASK Command-Field Descriptions
( K G N F
Logical This field specifies the first logical block of the corresponding WRITE (10)
Block Ad- COMMAND. This allows a SEEK to begin immediately. The LBA of the fol-
dress lowing WRITE (10) command must the same as the LBA of the WRITE SKIP
Skip Mask This field indicates the length in bytes of the skip mask. The mask is up to
Length 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
T h i s f i e l d m u s t b e e q u a l t o t h e t r a n s f e r l e n g t h i n t h e l i n k e d W R I T E
Length
( 1 0 ) c o m m a n d . T h e t r a n s f e r l e n g t h f i e l d m u s t b e e q u a l t o t h e n u m b e r
bits in the skip mask. If a WRITE (10) is used with 0 as the transfer
o f " 1 "
 
Operation Code (EAh)
Reserved
Logical Block Address
Skip Mask Length
Transfer Length
Reserved
& G U E T K R V K Q P
MASK command.
length, a transfer length of 256 data blocks is implied.
SCSI Description
  
Flag
Maxtor Atlas 10K III

(LSB)
(LSB)
Link
5-177