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Chapter 3 Hardware
LittleBoard 550 Reference Manual 23
Interrupt Channel Assignments
The channel interrupt assignments are shown in Table 3-1.
Table 3-1. Interrupt Channel Assignments
Device vs IRQ No. 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Timer
X
Keyboard
X
Secondary
Cascade
X
COM1
OD
COM2
DO
COM3
OO OD
COM4
OO DO
Floppy
X
Parallel
OD
RTC
X
IDE Primary
XO
IDE Secondary
OX
Math Coprocessor
X
PS/2 Mouse
X
PCI INTA
Automatically Assigned
PCI INTB
Automatically Assigned
PCI INTC
Automatically Assigned
PCI INTD
Automatically Assigned
Sound Blaster
DOOO
USB
Automatically Assigned
VGA
Automatically Assigned
Ethernet
Automatically Assigned
Legend: D = Default, O = Optional, X = Fixed
NOTE The IRQs for the Ethernet, Video, and Internal Local Bus (ISA) are
automatically assigned by the BIOS Plug and Play logic. Local IRQs
assigned during initialization can not be used by external devices.
Memory Map
The following table provides the common PC/AT memory allocations. Memory below 000500h is used
by the BIOS.