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OEM MANUAL:K6602924
4.1.5 TRANSFER LENGTH
The Transfer Length specifies the amount of data to be transferred (normally in
logical blocks).
In some commands, the transfer length represents the number of requested bytes
as explained in their command descriptions.
In such cases, this field is referred to as the byte transfer length field.
Commands (6-byte commands) that allocates one byte to the transfer length field
can transfer a maximum of 256 blocks of data. Transfer lengths of 1 to 255
represent the number of blocks to be transferred and transfer length of 0
represents 256 blocks.
Commands (10-byte commands) that allocates two bytes to the transfer length
field can transfer a maximum of 65, 535 blocks of data. A transfer length of 0
indicates that no block is to be transferred.
Transfer lengths of 1 to 65, 535 represent the number of blocks to be transferred.
Commands (12-byte commands) that allocates four bytes to the transfer length
field can transfer a maximum of 4,294,967,295 blocks of data. A transfer length
of 0 indicates that no block is to be transferred.
Transfer lengths of 1 to 4,294,967,295 represent the number of blocks to be
transferred.
The transfer length of commands that transfer a parameter list to the controller is
called the parameter list length. The parameter list length is used to specify the
number of bytes to be transferred during the Data Out phase.
The transfer length of commands that return sense data to the host computer (e.g.,
REQUEST SENSE, INQUIRY, and MODE SENSE commands) is called the
Allocation Length. The allocation length is used to specify the number of bytes
that are allocated by the host computer for the data to be transferred.
The controller terminates the Data In phase when the number of bytes specified in
the Allocation Length field have been transferred or when all available sense data
have been transferred to the host computer, whichever is less.
4 SCSI COMMANDS
Revision: 1 / Date: 2003.03.06
Page: 66 / 273
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