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138
System Specifications
Memory map
Interrupts
The following table suggests a logical interrupt mapping of interrupt sources.
It reflects a typical configuration, but you can change these interrupts. Use
the information to determine how to program each interrupt. The actual
interrupt map is defined using configuration registers in the I/O controller.
I/O Redirection Registers in the I/O APIC are provided for each interrupt
signal. The signals define hardware interrupt signal characteristics for APIC
messages sent to local APIC(s).
Address Range (hex)
Amount
Function
0 to 07FFFFh
640 KB
DOS region, base system memory
0A0000h to 0BFFFFh
128 KB
Video or SMM memory
0C0000h and 0DFFFFh
128 KB
Expansion card BIOS and buffer
area
0E0000h to 0FFFFFh
128 KB
System BIOS
0E0000h to 0EFFFFh
2 MB
Extended system BIOS
FC000000h to FFFFFFFFh
64 MB
PCI memory space
Important
If you disable either IDE controller to free the interrupt for
that controller, you must physically unplug the IDE cable
from the system board. Simply disabling the drive by
configuring the SSU option does not make the interrupt
available.
Interrupt
I/O APIC
Level
Description
INTR
INT0
Processor interrupt
NMI
N/A
NMI from PIC to processor
IRQ1
INT1
Keyboard interrupt
Cascade
INT2
Interrupt signal from second 8259
IRQ3
INT3
Serial port A or B interrupt from SIO device (you can
configure either)
IRQ4
INT4
Serial port A or B interrupt from SIO device (you can
configure either)
8508366.book Page 138 Tuesday, October 23, 2001 11:29 AM
Summary of Contents for 7400
Page 6: ...vi 8508366 book Page vi Tuesday October 23 2001 11 29 AM ...
Page 22: ...14 System Features 8508366 book Page 14 Tuesday October 23 2001 11 29 AM ...
Page 98: ...90 Using the BIOS Setup Utility 8508366 book Page 90 Tuesday October 23 2001 11 29 AM ...
Page 110: ...102 Managing Your System 8508366 book Page 102 Tuesday October 23 2001 11 29 AM ...
Page 132: ...124 Troubleshooting 8508366 book Page 124 Tuesday October 23 2001 11 29 AM ...
Page 148: ...140 System Specifications 8508366 book Page 140 Tuesday October 23 2001 11 29 AM ...
Page 156: ...148 Index 8508366 book Page 148 Tuesday October 23 2001 11 29 AM ...