HP XU700 DMA Channel Controllers, Function, DMA controller, Default Values for, Interrupt Controllers, The following table summarizes how the DMA channels are allocated

5 HP BIOS

BIOS Addresses

	Default Values for	Function
	I/O Address Ports
03F8 - 03FF		COM1
04D0 - 04D1		Interrupt edge/level control
0778 - 077F		LPT1 ECP
0CF8 - 0CFF		PCI configuration space
C000	-	Power Management I/O space and ACPI Registers
C100	- C10F	SMBus I/O space

DMA Channel Controllers

Only “I/O-to-memory” and “memory-to-I/O” transfers are allowed. “I/O-to-I/O” and “memory-to-memory” transfers are disallowed by the hardware configuration.

The system controller supports seven DMA channels, each with a page register used to extend the addressing range of the channel to 16 MB.

The following table summarizes how the DMA channels are allocated.

	DMA controller
Channel	Function
DMA 0	Free
DMA 1	Free if not used for parallel port in Setup
DMA 2	Floppy disk drive controller
DMA 3	Free if not used for parallel port in Setup
DMA 4	Used to cascade DMA channels 0-3
DMA 5	Free
DMA 6	Free
DMA 7	Free

Interrupt Controllers

The system has an Interrupt controller which is equivalent in function to that of two 82C59 interrupt controllers. The following table shows how the interrupts are connected to the APIC controller. The Interrupt Requests (IRQ) are numbered sequentially, starting with the master controller, and followed by the slave (both of 82C59 type).

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