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12.66 Write DMA Ext (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
Table 255 Write DMA Ext Command (35h)
Command Input
Field
Description
FEATURE
Reserved
COUNT
The number of logical sectors to be transferred. A value of 0000h
indicates that 65,536 logical sectors are to be transferred
LBA
LBA of first logical sector to be transferred
DEVICE
Bit Description
7:5 Obsolete
4 Transport Dependent
3:0 Reserved
Command
7:0 35h
Output Parameters To The Device
Sector Count Current
The number of continuous sectors to be transferred low order, bits (7:0).
Sector Count Previous
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.
Sector Number Current
LBA (7:0).
Sector Number Previous
LBA (31:24).
Cylinder Low Current
LBA (15:8).
Cylinder Low Previous
LBA (39:32).
Cylinder High Current
LBA (23:16).
Cylinder High Previous
LBA (47:40).
Input Parameters From The Device
Sector Number (HOB=0)
LBA (7:0) of the address of the first unrecoverable error.
Sector Number (HOB=1)
LBA (31:24) of the address of the first unrecoverable error.
Cylinder Low (HOB=0)
LBA (15:8) of the address of the first unrecoverable error.
Cylinder Low (HOB=1)
LBA (39:32) of the address of the first unrecoverable error.
Cylinder High (HOB=0)
LBA (23:16) of the address of the first unrecoverable error.
Cylinder High (HOB=1)
LBA (47:40) of the address of the first unrecoverable error.
Normal Outputs
See Normal Outputs in Section 12.8 Flush Cache Ext (EAh)
Error Outputs
See Error Outputs in Section 12.65 Write DMA FUA Ext (3Dh)
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Hard Disk Drive Specification