HP Dc5850 Technical Reference Guide: HP Compaq dc5850 Series Business Desktop - Page 41

Direct Memory Access - manual

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System Support System Board Connector PCI slot 1 (J20) PIRQ A Table 4-4. PCI Interrupt Distribution System Interrupts PIRQ B PIRQ C PIRQ D PIRQ E PIRQ F A B PIRQ G C PIRQ H D 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. 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 AMD SB700 South Bridge. Technical Reference Guide www.hp.com 4-7

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Technical Reference Guide
www.hp.com
4-7
System Support
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.
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 AMD SB700 South Bridge.
Table 4-4.
PCI Interrupt Distribution
System Interrupts
System Board
Connector
PIRQ
A
PIRQ
B
PIRQ
C
PIRQ
D
PIRQ
E
PIRQ
F
PIRQ
G
PIRQ
H
PCI slot 1 (J20)
A
B
C
D