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4.4 Maintenance, Diagnostic Commands
C141-C013 275
4.4.5 READ LONG (3E)
Bit
Byte
7 6 5 4 3 2 1 0
0 X'3E'
1 0 0 0 0 0 0
CORRCT
0
2 Logical Block Address (MSB)
3 Logical Block Address
4 Logical Block Address
5 Logical Block Address (LSB)
6 0 0 0 0 0 0 0 0
7 Transfer Byte Length (MSB)
8 Transfer Byte Length (LSB)
9 0 0 0 0 0 0 0 0
This command reads the logical data block data and its ECC byte, specified in the
"Logical block address" field in the CDB, from the disk media and transfers it to
the INIT. Normally, this command is used in combination with the WRITE
LONG command to perform checks of the ECC function. The operation object in
this command is 1 data block only.
Remark: The Pad Byte and Sync Mark patterns are not included in the transfer
data.
When "0" is specified in bit 1 of CDB byte 1, the "CORRCT (Corrected)" bit, the
HDD does not implement ECC correction processing of data read from the disk
media. When "1" is specified in the "CORRCT (Corrected)" bit, data errors that
can be corrected by ECC are transferred to the INIT after being corrected in the
HDD's data buffer.
When the "Transfer byte length" specifies zero, this command executes a seek
operation of the cylinder/track existing in the logical data block which is specified
in the "Logical block address" field in the CDB., then is terminated without data
being transferred to the INIT.
When a length (other than zero) which does not match the data format on the disk
media is specified in the "Transfer byte length" field in the CDB, this command is
terminated with a CHECK CONDITION status without executing a data transfer
to the INIT. At this time, the sense data indicate the following contents and the
INIT can determine the correct "Transfer byte length" from their contents.