SCS I Description
M axtor Atlas 10K III 5-177
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 5-2 24 and Tabl e 5-225 respectivel y .
WRITE SKIP MASK Command Descr iptor Block-Data Format
WRITE SKIP MASK Command- Field Description s
0 Operation Code (EAh)
1 Reserved
2 - 5 (MSB) Logic al Bl ock Address (LSB)
6 Skip Mask Length
7 - 8 (MSB) Transf er Length (LSB)
9 VU Reserved Flag Link
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 m ust the same as the LBA of th e W RITE SKIP
MASK command.
Skip Mask
Length This field indi cates the lengt h in bytes of the skip mask. The mask is up to
2048 bi ts, giv ing a data add ress c apabil ity of 1 MB in 512 -byte bl ock l ength.
The mask co nsists of a sequen ce of bits where a “1” bit is for the bl ocks of
data to be transferred, and a “0” for the blocks of data that are to be skipped.
The first “1” bi t of the mask corresponds to th e first LBA to be transferred.
Any unuse d bi ts at t he end of the last by te in t he mask must be set to 0. The
mask is transferred in the data-out buffer transfer of the skip mask command.
Transfer
Length bits in t he skip mask. If a WRITE (10) is used with 0 as the transfer
length, a transf er length of 256 data blocks is implie d.