HP 8000 tower manual Direct Memory Access, PCI Interrupt Distribution

System Support

Table 4-5.

PCI Interrupt Distribution

					System Interrupts
System Board		PIRQ	PIRQ	PIRQ	PIRQ	PIRQ	PIRQ	PIRQ	PIRQ
Connector		A	B	C	D	E	F	G	H
PCI slot 1	(J20) [1]					A	B	C	D
PCI slot 2	(J21) [1]					D	A	B	C
PCI slot 3	(J22) [2]					C	D	A	B

NOTES:

[1]SFF and CMT only

[2]CMT only

The PCI interrupts can be configured by PCI Configuration Registers 60h..63h to share the standard ISA interrupts (IRQn).

✎The APIC mode is supported by Windows NT, Windows 2000, and Windows XP, and Windows Vista operating systems. Systems running the Windows 95 or 98 operating system will need to run in 8259 mode.

4.3.2Direct Memory Access

Direct Memory Access (DMA) is a method by which a device accesses system memory without involving the microprocessor. Although the DMA method has been traditionally used to transfer blocks of data to or from an ISA I/O device, PCI devices may also use DMA operation as well. The DMA method reduces the amount of CPU interactions with memory, freeing the CPU for other processing tasks. For detailed information regarding DMA operation, refer to the data manual for the Intel 82801 ICH10 I/O Controller Hub.

4-8 www.hp.com Technical Reference Guide