13.13 Read DMA (C8h/C9h)
see belowStatus1 1 0 0 1 0 0 RCommand
- - - - H H H HDevice/Head1 L 1 D H H H HDevice/Head
V V V V V V V VCylinder HighV V V V V V V VCylinder High
V V V V V V V VCylinder LowV V V V V V V VCylinder Low
V V V V V V V VSector NumberV V V V V V V VSector Number
V V V V V V V VSector CountV V V V V V V VSector Count
see belowError- - - - - - - -Feature
- - - - - - - -Data- - - - - - - -Data
7 6 5 4 3 2 1 0Register7 6 5 4 3 2 1 0Register
Command Block Input RegistersCommand Block Output Registers
V-0-V0V0V0V0V0VV
ERRIDXCORDRQDSCDFRDYBSYAMNT0NABT0IDN0UNCCRC
0123456701234567
Status RegisterError Register
Figure 98. 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 indicate 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, 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 specifies that LBA address bits 0–7 are to be
transferred. (L = 1)
Cylinder High/Low 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 (Low) 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.
Travelstar 60GH & 40GN hard disk drive specifications
135
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