June 23, 2010 |
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| Table 25 — Device parameter table extension | |
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| Offset | Type |
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| Word | BIOS selected hardware specific option flags |
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| Bit | Description |
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| 15:14 | Reserved |
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| 13 |
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| 12 | HPA Active |
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| 11 | Ultra DMA accessing enabled |
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| 10:9 | Translation type |
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| 8 | ATAPI device uses command packet interrupt |
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| 7 |
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| 6 | ATAPI device |
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| 5 | Removable media |
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| 4 | LBA translation enabled |
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| 3 | CHS translation enabled |
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| 2 | ATA READ/WRITE MULTIPLE accessing enabled |
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| 1 | DMA accessing enabled |
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| 0 | PIO accessing enabled |
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| Word | Reserved |
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| 14 | Byte | 30h, version level of this table. |
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| 15 | Byte | Checksum, 2's complement of the 8 bit unsigned sum of bytes |
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8.20.4.1 Offset 0-1 - I/O port base
This word is the
8.20.4.2 Offset 2-3 - control port base
This word is the
8.20.4.3 Offset 4 - head prefix
The upper four bits of this byte shall be logically ORed with the head number, or upper four bits of the LBA, each time the disk is addressed. It contains the ATA DEV bit and the LBA addressing bits that are preset, and makes these functions transparent to any software using this extension. The LBA addressing bit is set for each disk access and shall not be used to determine the LBA capability of the system. See the LBA translation enabled bit described in clause 8.24.3.9.5 for system LBA capability.
8.20.4.4Offset 5 - BIOS use only BIOS use only.
8.20.4.5Offset 6 - IRQ number
Each ATA channel requires an assigned Interrupt number. This byte identifies which IRQ is used by this device's channel.
8.20.4.6 Offset 7 - READ/WRITE MULTIPLE command block count
If the device was configured to use the READ/WRITE MULTIPLE command, then this field shall contain the block size of the transfer, in sectors, used by the BIOS.
Working Draft Enhanced Disk Drive - 4 | 55 |
