Technical Reference Guide: HP Compaq 8100 Elite Series Business Desktop Computers

4-8 www.hp.com Technical Reference Guide

System Support

NOTES:

[1] 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, Windows

Vista, and Windows 7 operating systems. Systems running the Windows 95 or 98 operating

system will need to run in 8259 mode.

4.3.2 Direct 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 PCH I/O Controller Hub.

Table 4-5.

PCI Interrupt Distribution

System Interrupts

System Board

Connector

PIRQ

PCI slot 1 (J20) A B C D

PCI slot 2 (J21) [1] D A B C

PCI slot 3 (J22) [1] C D A B