SCSI Description

￿￿￿￿94+6'The ￿WRITE5-+2￿/#5SKIP-MASK￿%QOOCPFcommand￿￿'#Jallows￿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 5-224and Table 5-225respectively.

 

 

 

 

 

WRITE SKIP MASK Command Descriptor Block-Data Format

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

0

 

 

 

 

 

 

 

 

 

Operation

Code (EAh)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

1

 

 

 

 

 

 

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2 -

(MSB)

 

 

 

Logical Block Address

 

 

 

 

 

 

 

 

 

 

 

 

(LSB)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Skip Mask Length

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7 - 8

(MSB)

 

 

 

 

Transfer Length

 

 

 

 

 

 

 

 

 

 

 

 

 

(LSB)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VU

 

 

 

 

 

 

Reserved

 

Flag

Link

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

$[VG$KV

￿

 

WRITE￿

SKIP￿

MASK￿Command￿-Field Descriptions￿

￿

￿

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Logical(KGNF￿

 

 

This field specifies the first logical&GUETKRVKQPblock 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

 

 

 

 

 

 

 

 

 

 

 

MASK command.

 

 

 

 

 

 

 

 

Skip Mask

 

 

This field indicates the length in bytes of the skip mask. The mask is up to

 

TableLength5-224

 

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

 

 

ThisfieldmustbeequaltothetransferlengthinthelinkedWRITE

 

 

 

 

 

(10)commandbits in the.Thskiptransfermasklength. If a WRITEfield(10)mustis usedbeequalwith 0toasthenumbertransfer

 

Table

5-225

length, a

 

 

of 256 data blocks is implied.

 

 

 

 

 

 

 

 

 

 

 

 

 

of“1”

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Max or Atlas 10K III

5-177

Page 241
Image 241
Maxtor 10K III manual Write Skip Mask Command Descriptor Block-Data Format, TableLength5-224, 225, Operation