Legacy Mode; Native Mode - HP Compaq dx6050 MT Reference Manual

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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