| ATA COMMAND BLOCK AND SET DESCRIPTION |
Read Sector — 20h, 21h
The Read Sector command allows the host to read sectors 1 to 256 as specified in the Sector Count register. If the sector count is set to 0h, all 256 sectors of data are made available. When the command code is issued and the first sector of data has been transferred to the buffer, the DRQ bit is set. The Read Sector command is terminated by writing the cylinder, head, and sector number of the last sector read in the task file. On error, the read operation is aborted in the errant sector.
Table 43: Read Sector — 20h, 21h
Register | D7 | D6 | D5 | D4 |
| D3 | D2 | D1 | D0 |
Feature |
|
|
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| X |
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| |
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|
|
| ||
Sector Count |
|
|
| Sector Count |
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| ||
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|
|
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| ||||
Sector Number |
|
| Sector Number |
|
| ||||
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|
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| ||||
Cylinder Low |
|
| Cylinder Low |
|
| ||||
|
|
|
|
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| ||||
Cylinder High |
|
| Cylinder High |
|
| ||||
|
|
|
|
|
|
| |||
Drive Head | 1 | LBA | 1 | Drive |
| Head Number | |||
|
|
|
|
|
|
|
|
| |
Command |
|
|
| 20h or 21h |
|
|
| ||
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All unauthorized use and/or reproduction is prohibited.
PAGE 42 | JUNE 17, 2008 | DOCUMENT: |