Read Dma (X 'C8' Or X 'C9') - Fujitsu MHW2120BK Maintenance Manual

Interface

(21) READ DMA (X 'C8' or X 'C9')

The READ DMA command reads data from sectors, starting from the sectors
specified in the Device/Head, Cylinder High, Cylinder Low, and Sector Number
fields and continuing for as many sectors as specified in the Sector Count field. A
value ranging from 1 to 256 can be specified for the number of sectors. In order to
specify 256, "00" must be set in the Sector Count field. For the protocol
concerning data transfers, see Section 5.4.4.
When the command is completed, either cylinder, head, and sector addresses
(CHS mode) or the logical block address (LBA mode) of the last sector is stored in
the Shadow Block Register.
If an error such as an uncorrectable disk read error is detected during execution of
the READ DMA command and continued operation not possible, the data transfer
stops after all data, including the data of the sector where the error was detected, is
transferred. The device notifies the host of the status by sending the RegDH FIS.
At this time, the number of remaining sectors including the sector where the error
was detected, and either cylinder, head, and sector addresses (CHS mode) or the
logical block address (LBA mode) of the sector where the error was detected are
stored in the Shadow Block Register.
The host system can select the DMA transfer mode by using the SET FEATURES
command, however, the transfer speed does not change.
•
Multiword DMA transfer mode 0 to 2
•
Ultra DMA transfer mode 0 to 5
•
Error reporting conditions
(1) A specified address exceeds the range where read operations are allowed
(ST = 51h, ER = 10h).
(2) The range where read operations are allowed will be exceeded by an address
during a read operation (ST = 51h, ER = 10h).
(3) An uncorrectable disk read error occurred (ST = 51h, ER = 40h).
(4) The sync byte indicating the beginning of a sector was not found
(ST = 51h, ER = 01h).
(5) A SATA communication error occurred (ST = 51h, ER = 0Ch).
(6) A Host Buffer CRC error occurred (ST = 51h, ER = 84h).
(7) An error other than the above errors occurred (ST = 51h, ER = 04h).
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