SCSI Description
￿￿￿￿4'#&The￿5READ-+2￿/#5SKIP-MASK￿%QOOCPFcommand￿￿'￿allowsJ￿the initiator to condition the function of the READ commands to allow only selected data to be transferred over the SCSI interface. A READ SKIP MASK command precedes a READ (10) command; the READ (10) command must be linked to the READ 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 5-149and Table 5-150respectively.
READ SKIP MASK Command-Data Format

 

 

 

 

 

 

 

 

 

0

 

 

Operation Code (E8h)

 

 

 

 

 

 

 

 

 

1

 

 

 

Reserved

 

 

 

 

 

 

 

 

 

 

 

2 -

(MSB)

 

Logical Block Address

 

 

 

 

 

(LSB)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6

 

 

 

Skip Mask Length

 

 

 

 

 

 

 

 

 

 

 

7 - 8

(MSB)

 

 

Transfer Length

 

 

 

 

 

 

(LSB)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

9

VU

 

 

Reserved

Flag

Link

 

 

 

 

 

 

 

 

 

$[VG$KV

 

￿

READ￿

SKIP￿MASK ￿Command-￿Field Descriptions￿

￿

￿

 

 

 

 

 

 

 

 

 

 

 

This field specifies the first logical block of the corresponding READ (10)

Logical Block(KGNFAddress￿

COMMAND. This allows a SEEK&GUETKRVKQPto begin immediately. The LBA of the fol-

 

Table

5lowing-149READ (10) command must the same as the LBA of the READ SKIP

 

 

 

MASK command.

 

 

 

 

 

 

 

 

 

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

Skip Mask Length

 

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.

 

 

 

 

 

 

 

 

 

This field must be equal to the transfer length in the linked READ (10) com-

Transfer Length

 

mand. The transfer length field must be equal to the number of “1” bits in

 

the skip mask. If a READ (10) is used with 0 as the transfer length, a trans-

Table5

-150fer length of 256 data blocks is implied.

 

 

Maxtor Atlas 10K III

5-119

Page 183
Image 183
Maxtor 10K III manual Operation Code E8h, Skip Mask Length, Reserved Flag Link