Travelstar 5K100 Hard Disk Drive Specification
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13.13 Read DMA (C8h/C9h)
Table 83: Read DMA command (C8h/C9h)
The Read DMA command reads one or more sectors of data from disk media and then transfers the data from the
device to the host. It transfers the sectors through the Data Register 16 bits at a time.
The host initializes a slave-DMA channel prior to issuing the command. The data transfers are qualified by the
DMARQ and are performed by the slave-DMA channel. The device issues only one interrupt per command to indi-
cate that the data transfer has terminated and that status is available.
If an uncorrectable error occurs, the read 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,
256 sectors will be transferred.
LBA Low This indicates the sector number of the first sector to be transferred. (L = 0).
In LBA mode, this register specifies that LBA address bits 0–7 are to be transferred
(L = 1)
LBA High/Mid This indicates the cylinder number of the first sector to be transferred. (L = 0).
In LBA mode this register specifies LBA address bits 8–15 (Mid) and 16–23 (High) to be
transferred. (L = 1)
H This indicates the head number of the first sector to be transferred. (L = 0).
In LBA mode this register specifies the LBA bits 24–27 to be transferred. (L = 1)
R This indicates the retry bit, but this bit is ignored.
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
LBA Low V V V V V V V V LBA Low V V V V V V V V
LBA Mid V V V V V V V V LBA Mid V V V V V V V V
LBA High V V V V V V V V LBA High V V V V V V V V
Device 1 L 1 D H H H H Device - - - - - H H H H
Command 1 1 0 0 1 0 0 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
00000V0 0 0V0V- 0- V
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