HP C2246 Technical Reference Manual page 92

Read Long
The READ LONG command requests the Target to transfer a specific block of data to the
Initiator. The data transferred
will
include all header, data, and ECC (Error Correction
Code) bytes.
Read Long Command Descriptor Block (CDB)
Bit
Byte
1
I
6
I
5
I
4
I
3
I
2
I
1
I
0
00 Opcode= 3EH
01 Logical Unit Number
I
Reserved
I
CORRCT
I
RelAdr=O
02-05 (MSB=02) Logical Block Address (LSB=05)
06 Reserved
07-08
(MSB=07)
Byte Transfer Length
(LSB=08)
09
Control Byte
CORRCT {Corrected). A CORRCT bit of one (1) instructs the Target to correct the data
by ECC before transferring it to the Initiator. A CORRCT bit of zero (0) causes the logical
block to be read and transferred without any error detection or correction.
Logical Block Address. This field specifies the starting address for the Read Long operation.
The operation will continue for the length specified by the Byte Transfer Length field.
Byte Transfer Length. This field should specify exactly the number of bytes available for
transfer. A value of zero in this :field indicates that no data bytes will be transferred. This
condition is not considered an error.
If the number of bytes specified matches exactly the available data length, the most recent
data written in the specified logical block will be transferred. If a requested transfer length
value does not match exactly the available data length, the Target will truncate to the total
transfer length available.
A-36 SCSI Command Descriptions
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I
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