Read Data (Mode 010B); Descriptor (Mode 011B) - IBM DDRS-39130 - Ultrastar 9.1 GB Hard Drive Specifications

7 6
BYTE 0
BYTE 1 (MSB)
BYTE 2
BYTE 3
Figure 98. R E A D B U F F E R Header
The buffer capacity specifies the total number of data bytes that are available in the file's data buffer. This
number is not reduced to reflect the allocation length nor is it reduced to reflect the actual number of bytes
written using the WRITE B U F F E R command.
Following the READ B U F F E R header, the file will transfer data from its data buffer.

7.18.2 Read Data (Mode 010b)

In this mode, the DATA IN phase contains buffer data.
Buffer ID field must be set to zero, indicating the data transfer buffer. If another value is specified, the
command is terminated with CHECK CONDITION status.
REQUEST and additional sense code to ILLEGAL FIELD IN CDB.
Buffer Offset specifies the offset of the memory space specified by the Buffer ID.
conform to the offset boundary requirements returned in the READ B U F F E R descriptor. If the value
exceeds the buffer specified, the command is terminated with CHECK CONDITION status. File shall set
sense key to ILLEGAL REQUEST and additional sense code to ILLEGAL FIELD IN CDB.
Allocation Length The file terminates the DATA IN phase when allocation length bytes of data have been
transferred or when the header and all available data have been transferred to the initiator, whichever is less.

7.18.3 Descriptor (Mode 011b)

In this mode, a maximum of four bytes of R E A D B U F F E R descriptor information are returned.
returns the descriptor information for the buffer specified by the Buffer ID.
Buffer ID field should normally be set to zero indicating the file data transfer buffer. If any other value is
specified the file returns all zeros in the R EAD B U F F E R descriptor.
Buffer Offset field is reserved.
Allocation Length must be set to four or greater. The file transfers the lesser of the allocation length or four
bytes of READ B U F F E R descriptor.
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O E M Spec. of DDRS-3xxxx
BIT
5 4 3 2
RSVD = 0
Buffer Capacity
The R E AD B U F F E R descriptor is defined in Figure 99 on
1 0
(LSB)
File shall set sense key to ILLEGAL
The initiator should
The file