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T13/2132-D Revision 3 June 23, 2010
56 Working Draft Enhanced Disk Drive - 4 (EDD-4)
8.20.4.7 Offset 8 - DMA channel/Multiword DMA Type
If the BIOS has configured the system to perform multiword DMA data transfers in place of PIO transfers, this
field shall specify the DMA mode in the upper four bits, as per the definition in ATA/ATAPI-6 or later, and the DMA
Channel in the lower four bits. ATA channels that support PCI DMA bus mastering shall set the DMA channel to
zero. Note that the DMA Type field does not follow the format of the data returned by the device. The value of
the DMA mode shall not be limited to two.
8.20.4.8 Offset 9 - PIO type
If the BIOS has configured the system to perform PIO data transfers other than mode 0, this field shall specify the
PIO mode as per the definition in ATA-5 or later.
8.20.4.9 Offset 10-11 - BIOS selected hardware specific option flags
These bytes specify the current hardware options enabled by the BIOS, a bit for each of the options listed below.
8.20.4.9.1 Bit 0 - fast PIO
If the system is configured for a PIO mode greater than 0, this bit shall be set to one and byte 9 (PIO Type) shall
be used to configure the system. If this bit is cleared to zero, the PIO-Type field shall be ignored.
8.20.4.9.2 Bit 1 - fast DMA
If the system is configured for DMA, this bit shall be set to one and byte 8 (DMA Channel/DMA Type) should be
used to configure the system. If this bit and bit 11, clause 8.24.3.9.11, are cleared to zero, then the DMA
Channel/DMA Type field shall be ignored.
8.20.4.9.3 Bit 2 - ATA READ/WRITE MULTIPLE
If the system is configured for multi-sector transfers, this bit shall be set to one and byte 7 (sector count) specifies
the number of sectors used for each data transfer. If block PIO is disabled, ignore the block count field.
8.20.4.9.4 Bit 3 - CHS translation
If the device reports more than 1024 cylinders in the IDENTIFY DEVICE command data, this bit shall be set to
one. See 8.20.4.9.10 to determine the method of geometry translation.
8.20.4.9.5 Bit 4 - LBA translation
If the system is configured for LBA type addressing, this bit shall be set to one and the Extended INT 13h
interface (FN 41h through 48h) shall pass LBA values directly to the device. The conventional INT 13h interface
shall ignore this bit and shall use CHS. LBA-type addressing shall be available on devices with less than 1024
cylinders, and therefore bit 3 (CHS translation) shall be independent from bit 4 (LBA translation).
8.20.4.9.6 Bit 5 - removable media
If the device supports removable media, this bit shall be set to one and the extended INT 13h device locking and
ejecting subset shall also be supported.
8.20.4.9.7 Bit 6 - ATAPI device
If this ATA device implements the PACKET command feature set (ATAPI) as defined in ATA/ATAPI-5, this bit shall
be set to one.
8.20.4.9.8 Bit 7 - 32-bit transfer mode
If the BIOS has configured the host adapter to perform 32-bit wide data transfers, this bit shall be set to one.
8.20.4.9.9 Bit 8 - ATAPI device uses command packet interrupt
If bit 6 is cleared to zero, then this field shall be ignored and shall be zero. If bit 6 is set to one, this bit indicates
how the ATAPI devices signals it is ready to receive a packet command. When this bit is set to one, it indicates
that the ATAPI device returns an interrupt, and sets DRQ, when it is ready for a packet. When this bit is cleared
to zero, it indicates that the ATAPI device sets DRQ, without an interrupt, when it is ready for a packet.