Chapter 3 BIOS Setup
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104-1649CLD2NA Series
System Resources Managed by BIOS under X86 Platform
We define three kinds of system resources here: I/O port address, IRQ interrupt
number and DMA number.
DMA
Level
Function
DMA0 DRAM
Refresh
DMA1
Unassigned
DMA2
Unassigned
DMA3
Unassigned (sometimes used for hard disk)
DMA4
Used for DMAC cascade
DMA5
Unassigned
DMA6
Unassigned
DMA7
Unassigned
APIC
Advanced programmable interrupt controller. Most of motherboards above P4 level
support APIC and provide more than 16 interrupt sources such as IRQ16 - IRQ23
while some others support up to 28 interrupt sources such as which supports PCI-X.
However, the related OS is required in order to enable that function and only the OS
above Windows 2000 could support that function currently.
IO Port Address
There is 64K for the system I/O address space. Each external device will occupy
portion of the space. The table below shows parts of the distribution of the I/O
address. As the address of PCI device (e.g. PCI network card) is configured by
software, it is not listed in this table.