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6.26
SEARCH DATA EQUAL (31 H )
BIT
BYTE
07
06
05
04
03
02
01
00
------1------1------1------1------1------1------1------
00
0
0
1
1
0
0
0
1
01
Logical Unit Number
1
Invertl
Reserved
(0 )
02
(MSB)
Logical Block Address
03
Logical Block Address
04
Logical Block Address
05
Logical Block Address
(LSB)
06
Reserved (0)
07
Number of Blocks
08
Number of Blocks
09
Reserved
(0 )
1
Flag
1
Link
Figure 6-42.
SEARCH DATA EQUAL Command
This powerful extended address command provides for a search and
compare on equal of any data on the disk.
A starting block
address and number of blocks to search are specified and a search
argument
is
passed
from
the Host
which
includes
a
byte
displacement (not supported) and the data to compare.
This command allows the host to perform a high speed data verify.
Unlike the VERIFY Command which only checks for ECC errors,
the
search data equal will compare a chosen data pattern against data
contained in selected blocks "on the fly."
This feature provides
an excellent method of verifying disk integrity after format by
searching not equal for a "6C" or other unique fill character.
The Invert bit (Byte 01, Bit 04) inverts the sense of t.he search
comparison operation.
With Invert on,
a SEARCH DATA EQUAL com-
mand would succeed on data not equal.
The link bit see to zero indicates that no command is linked to
the SEARCH DATA EQUAL command.
lfthe 'search is satisfied, the
command is terminated with CONDITION MET status.
A REQEST SENSE
command following a successful SEARCH DATA EQUAL can be issued to
determine the Logical Block Address at the matching record.
500504-00
6-56
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