Read Buffer Command - Sony CDU-541 Interface Manual

CDU-541 CD-ROM DRIVE SCSI INTERFACE MANUAL
If the logical block address plus the transfer length requested exceeds that
reported by the READ CAPACITY data a CHECK CONDITION status will be returned.
The sense key is set to ILLEGAL REQUEST and the additional sense code is set
to LOGICAL BLOCK ADDRESS NOT VALID.
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5 .
2
.16.
READ BUFFER
Command
==============================================================================
Bit:
7
6
5
4
3
2
1
o
Byte :
=============================================================================-
o
I
Operation Code (3Ch)
-----1-----------------------------------------------------------------------
1
I
Logical Unit Number
I
Reserved
I
Mode
-----1-----------------------------------------------------------------------
2
1
Reserved
-----1-----------------------------------------------------------------------,
3 I
(MSB)
I
-----1--- ---I
4 1
Buffer Offset
I
-----1--- ___
I
5
I
(LSB)
-----1-----------------------------------------------------------------------
6 1
(MSB)
-----+---
, ,
7
Transfer Length
-----1---
8
I
(LSB)
-----1-----------------------------------------------------------------------
9 I
Control Byte
==============================================================================
The READ BUFFER command is used in conjunction with the WRITE BUFFER command
as a diagnostic function for testing controller memory and the bus integrity.
This command will not alter the medium.
The function of this command and the meaning of fields within the command
descriptor block depend on the contents of the mode field. A mode field value
of zero indicates that the buffer offset is zero. A mode field value of one
indicates that the buffer offset is valid and the data will be placed in the
buffer with that offset.
The buffer offset is the byte offset within the buffer where the data will
be retrieved. If the controller is unable to accept the specified buffer
offset, it will return CHECK CONDITION status and it will set the sense key to
ILLEGAL REQUEST.
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