Section 5
SCSI Programming Guidelines
TABLE
5·17
REASSIGN
BLOCKS Defect
List
Defect List Header·
~l
RESERVED
=0
2-3
(MSB)
DEFECT LIST LENGTH
(LSB)
Defect Descriptor(s):
0-4 I (MSB)
DEFECT LOGICAL
BLOCK
ADDRESS
(LSB)
I
The defect descriptor specifies a four-byte defect logical block address that contains the defect. The defect
addresses must be in ascending order. All
of
the 512-byte sectors associated with a logical block
(I,
2,
or
4
sectors) will be reassigned.
If
the drive has insufficient capacity to reassign all
of
the defective logical blocks, the command will
tenninate with a CHECK
CONDITION status and the sense key will be set to MEDIUM ERROR. The
logical block address
of
the first logical block not reassigned will be returned
in
the information bytes
of
the
sense data.
5.11.6
READ COMMAND: OPCODE = 08{hex)
The READ command (Table 5-18) requests that the target transfer data to the initiator.
5.11.6.1
Command Structure
TABLE
5·18
READ
Command
Bit 7
I
6
I
5
I
4
I
3
I
2
I
I
I
0
Byte
0
OPCODE=08H
1
LUN=O
I
(MSB)
LOGICAL BLOCK ADDRESS
2-3 LOGICAL BLOCK ADDRESS
(LSB)
4
TRANSFER LENGTH
5
VU=O
I
RESERVED
=0
I
F
I
L
LOGICAL BLOCK ADDRESS (Byte
1,
Bits 4-0; Bytes 2-3) - Specifies the logical
block at which the READ operation will begin.
TRANSFER LENGTH (Byte 4) - Specifies the number
of
contiguous logical blocks
of
data to
be transferred. A transfer length
of
zero indicates that 256 blocks shall be transferred. Acceptable
values are
OO-FFH'
5-36
SCSI
Programming
Guidelines
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