BIOS Setup
PPC-1781
· 69 ·
Level
Function
DMA0 Unassigned
DMA1 Unassigned
DMA2 Unassigned
DMA3 Unassigned
DMA4
Used for DMAC cascade
DMA5 Unassigned
DMA6 Unassigned
DMA7 Unassigned
APIC
Advanced programmable interrupt controller. Most motherboards above P4
level support APIC and provide more than 16 interrupt sources, like IRQ16 -
IRQ23; while some others can have up to 28 interrupt sources, such as
motherboard supporting PCI-X. However, relevant OS are required to enable
that function.
IO Port Address
Only 16 IO address lines are designed for X86, from 0 ~ 0FFFFh; there is 64K
for the system I/O address space. In traditional ISA connector, only the
foregoing 1024 (0000 ~ 03FFh) are used while the ports above 0400h are used
by PCI and EISA connectors. Each peripheral will occupy portion of the space.
The table below shows the I/O connectors used in X86 platform.
Address
Device Description
000h – 001Fh
DMA controller #1
020h - 021h
Programmable Interrupt Controller
022h – 03Fh
Motherboard resource
040h - 043h
System Timer
044h – 05Fh
Motherboard resource
060h - 060h
PS/2 standard keyboard
