4–10 319865-008 Service Reference Guide, d300, dx6050
Serial and Parallel ATA Drive Guidelines and Features
4.6.1 Legacy Mode
The Legacy mode is used to access devices attached to the embedded IDE controllers. Each
channel requires two fixed I/O address ranges and an IRQ for each.
■ Primary Channel
❏ Command block: 1F0h - 1F7h
❏ Control block: 3F6h
❏ IRQ: 14
■ Secondary Channel
❏ Command block: 170h - 177h
❏ Control block: 376h
❏ IRQ: 15
4.6.2 Native Mode
The native mode is used to access devices attached to add-in cards and is not supported by many
legacy operating systems. Addresses are assigned by PCI Plug-n-Play BIOS and the IRQ is
shared with multiple controllers. Base Address Registers for the Command and Control Block
are found in the PCI Configuration Space.
■ Offset 10h—Primary Command base address
■ Offset 14h—Primary Control base address
■ Offset 18h—Secondary Command base address
■ Offset 1Ch—Secondary Control base address
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