IBM IC25N020ATDA04 - Travelstar 20 GB Hard Drive - Read DMA (C8 H;C9 H); Figure 93. Read DMA Command (C8 H;C9 H)

13.14 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 93. Read DMA command (C8h/C9h)
The Read DMA command reads one or more sectors of data from disk media, then transfers the data from
the device to the host.
The sectors are transferred 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)
Travelstar 48GH, 30GN & 15GN hard disk drive specifications
139