Read Dma (C8H/C9H); Figure 111. Read Dma Command (C8H/C9H) - IBM IC35L040AVVN07-0 - 40GB IDE Deskstar 120GXP 7200RPM UATA-100 07N9682 Specifications

11.13 Read DMA (C8h/C9h)

Command Block Output
Registers
Register
Data
Feature
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Command
Error Register
7 6 5
CRC UNC 0
V V 0

Figure 111. 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.
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
DMARQ and are performed by the slave-DMA channel. The device issues only one interrupt per com-
mand to indicate that data transfer has terminated and status is available.
If an uncorrectable error occurs, the read will be terminated at the failing sector.
Output parameters to the device
Sector Count
Sector Number
Cylinder High/Low
H
7 6 5 4 3 2 1 0
- - - - - - - -
- - - - - - - -
V V V V V V V V
V V V V V V V V
V V V V V V V V
V V V V V V V V
1 L 1 D H H H H
1 1 0 0 1 0 0 R
4 3 2 1
IDN 0 ABT T0N AMN
V 0 V 0
The number of continuous sectors to be transferred. If zero is specified,
256 sectors will be transferred.
The sector number of the first sector to be transferred. (L=0)
In LBA mode this register specifies the transfer of LBA address bits 0 - 7. (L=1)
The cylinder number of the first sector to be transferred. (L=0)
In LBA mode this register specifies the transfer of LBA address bits 8 - 15 (Low)
16 - 23 (High). (L=1)
The head number of the first sector to be transferred. (L=0)
In LBA mode this register specifies the transfer of LBA bits 24-27. (L=1)
Deskstar 120GXP hard disk drive specifications
Command Block Input
Register
Data
Error
Sector Count
Sector Number
Cylinder Low
Cylinder High
Device/Head
Status
Status Register
0 7 6 5
BSY RDY DF
V 0 V 0
128
Registers
7 6 5 4 3 2 1 0
- - - - - - - -
see below
V V V V V V V V
V V V V V V V V
V V V V V V V V
V V V V V V V V
- - - - H H H H
see below
4 3 2 1
DSC DRQ COR IDX ERR
V – 0 –
0
V