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Western Digital Hard Disk Drive OEM Specification
11.62 Write DMA Ext (35h)
Command Block Output Registers
Command Block Input Registers
Table 253 Write DMA Ext Command (35h)
The Write DMA Ext command transfers one or more sectors of data from the host to the device, and then the data is
written to the disk media.
The sectors of data are transferred through the Data Register 16 bits at a time.
The host initializes a slave-DMA channel prior to issuing the command. Data transfers are qualified by DMARQ and
are performed by the slave-DMA channel. The device issues only one interrupt per command to indicate that data
transfer has terminated and status is available.
If an uncorrectable error occurs, the write will be terminated at the failing sector
Output Parameters To The Device
The number of continuous sectors to be transferred low order, bits (7:0).
The number of continuous sectors to be transferred high order bits (15:8). If zero is
specified in the Sector Count register, then 65,536 sectors will be transferred.