Section 5
SCSI Programming Guidelines
5.11.25
READ LONG COMMAND: OPCODE = E8(hex)
The READ LONG command (Table 5-45) requests that the
ProDrive
transfer data to the initiator. For each
sector read, the
ProDrive will transfer 512 data bytes followed
by
6 ECC bytes.
TABLE
5-45
READ
LONG Command
Bit 7
I
6
I
5
I
4
I
3
I
2
I
1
I
0
B~te
0
OPCODE=E8H
1
LUN=O
I (MSB)
LOOICAL
BLOCK ADDRESS
2-3 LOGICAL BLOCK ADDRESS
(LSB)
4 TRANSFER LENGTH
5
VU=O
I
RESERVED
=0
1
F
J
L
LOGICAL BLOCK ADDRESS - Specifies the logical block at which the READ LONG operation will
begin.
TRANSFER LENGTH - Specifies the number
of
logical blocks to be transferred. A transfer length
of
zero indicates that no logical blocks are to be transferred. Acceptable val,ues are
OO-FFH.
5.11.26
WRITE LONG COMMAND: OPCODE = EA(hex)
The WRITE command (Table 5-19) requests that the data transferred to the
ProDrive
be written in the area
specified by the logical block address. The data passed during the WRITE
LONG operation includes 512 data
bytes followed by 6 ECC bytes for each sector. The WRITE
LONG command is usually preceded by a READ
LONG command. The number and order
of
the bytes in the WRITE LONG command should be the same as
in
the READ LONG command.
TABLE
5-46
WRITE
LONG Command
Bit
7
I
6
I
5
I
4
I
3
I
2
J
1
I
Byte
0
OPCODE=
EAH
1
LUN=O
I
(MSB)
LOGICAL
BLOCK ADDRESS
2-3
LOGICAL BLOCK ADDRESS
4 TRANSFER LENGTH
5
VU=O
I
RESERVED
=0
I
F
I
LOGICAL BLOCK ADDRESS - Specifies the logical block at which the WRITE LONG
operation will begin.
«)
(LSB)
L
TRANSFER LENGTH - Specifies the number
of
contiguous logical blocks
of
data to be
transferred. A transfer length
of
zero indicates that logical blocks will be transferred. Acceptable
values are
OO-FFH.
SCSI
Programming Guidelines
5-69
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