Read Long Command (3Eh) - Maxtor Atlas 10K V Product Manual

5.24

READ LONG Command (3Eh)

The READ LONG command is used in conjunction with the WRITE LONG
command to allow the initiator to issue raw reads and writes of physical data blocks,
but address them as logical blocks with an assumed sector length of 512 bytes. These
two commands are used to verify the correction capability of the drive's ECC and to
create a known kind and location to verify the drive's recovery and bad sector
handling policies. The data format and field descriptions are shown in Table 5-140 and
Table 5-141 respectively.
Table 5-140
Bit
Byte
0
1
2 - 5
6
7 - 8
9
Table 5-141
Field
When the value in this field is 1, the drive corrects the data by the ECC before transferring it to
the initiator. When the value is 0, the drive does not perform ECC correction on the data.
Correct
NOTE: This bit, not the DCR bit of the Read Recovery page, governs the effect of error correction
for the READ LONG command.
RelAdr Relative addressing is not supported by the drive. This value must be 0.
Logical Block Ad-
Specifies the logical sector to read.
dress
Must be 578. This value reflects the number of bytes spanned by the ECC, including the ECC it-
self, rounded up to the next word (this is easiest understood in bits: 4096 data bits + 1 force error
Byte Transfer Length bit + 15 Logical Block Address bits + 16 cross check bits + 2 pad bits + 480 ECC bits + 6 pad bits
that are not written to media but are only needed for transfer = 4496 bits or 578 bytes). Any other
value in this field results in a CHECK CONDITION status and the appropriate sense data.
Table 5-142 shows the format of the data that is returned during the READ LONG
Command's data-in buffer transfer. The returned data always consists of 512 bytes of
data, followed by a two LBA bytes, two EDC bytes, and 60 ECC-related bytes.
Bit
Byte
0 - 511
512 - 513
514 - 515
516 - 577
5-102 Maxtor Atlas 10K V
READ LONG Command Descriptor Block-Data Format
7 6 5
READ LONG Command Descriptor Block-Field Descriptions
Table 5-142
READ LONG Command-Returned Data
7 6 5
Logical Block Address Bits + Force Error Bit
4 3
Operation Code (3Eh)
Reserved
Logical Block Address
Reserved
Byte Transfer Length (578)
Control
Description
4 3
Data (512 Bytes)
EDC (8 Bits)
60 ECC Bits + 8 Pad Bits
2 1 0
Correct RelAdr
2 1 0