Deskstar T7K500 Hard Disk Drive Specification
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12.46 Write DMA (CAh/CBh)
Table 155: Write DMA (CAh/CBh)
The Write DMA 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 Register16 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
Sector Count This indicates the number of continuous sectors to be transferred. If zero is specified, then
256 sectors will be transferred.
Sector Number This indicates the sector number of the first sector to be transferred. (L = 0)In LBA mode
this register contains the LBA bits 0–7. (L = 1)
Cylinder High/Low This indicates number of the first sector to be transferred. (L = 0) In LBA mode this reg-
ister contains the LBA bits 8–15 (Low) and bits 16–23 (High). (L= 1)
H This indicates the head number of the first sector to be transferred. (L = 0) In LBA mode
this register contains the LBA bits 24–27. (L = 1)
R This indicates the retry bit. This bit is ignored.
Input parameters from the device
Sector Count This indicates the number of requested sectors not transferred. The Sector Count will be
zero unless an unrecoverable error occurs.
Command Block Output Registers Command Block Input Registers
Register 7 6 5 4 3 2 1 0 Register 7 6 5 4 3 2 1 0
Data - - - - - - - - Data - - - - - - - -
Feature - - - - - - - - Error see below
Sector Count V V V V V V V V Sector Count V V V V V V V V
Sector Number V V V V V V V V Sector Number V V V V V V V V
Cylinder Low V V V V V V V V Cylinder Low V V V V V V V V
Cylinder High V V V V V V V V Cylinder High V V V V V V V V
Device/Head 1 L 1 D H H H H Device/Head - - - - H H H H
Command 1 1 0 0 1 0 1 R Status see below
Error Register Status Register
7654321 0 76543 21 0
CRC UNC 0 IDN 0 ABT T0N AMN BSY RDY DF DSC DRQ COR IDX ERR
V00V0V0 0 0V0V- 0- V
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