Memory map
| Address Range (hex) | Amount | Function |
0 to 07FFFFh | 640 KB | DOS region, base system memory |
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|
|
0A0000h to 0BFFFFh | 128 KB | Video or SMM memory |
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|
|
0C0000h and 0DFFFFh | 128 KB | Expansion card BIOS and buffer |
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| area |
|
|
|
0E0000h to 0FFFFFh | 128 KB | System BIOS |
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|
|
0E0000h to 0EFFFFh | 2 MB | Extended system BIOS |
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|
|
FC000000h to FFFFFFFFh | 64 MB | PCI memory space |
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|
|
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).
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 | Description |
| Level |
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|
|
|
INTR | INT0 | Processor interrupt |
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|
|
NMI | N/A | NMI from PIC to processor |
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|
|
IRQ1 | INT1 | Keyboard interrupt |
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|
|
Cascade | INT2 | Interrupt signal from second 8259 |
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|
|
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 |
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| configure either) |
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|
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138System Specifications