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2 Motherboard Resources

2.1 Memory Map

Table 6. Memory Map

Address Range
(Decimal) Address Range (hex) Size Description
1024K-131072K 100000-8000000 127M Extended Memory
960K-1023K F0000-FFFFF 64K AMI System BIOS
952K-959K EE000-EFFFF 8K Main BIOS (available as UMB)
948K-951K ED000-EDFFF 4K ESCD (Plug and Play configuration area)
944K-947K EC000-ECFFF 4K OEM LOGO (available as UMB)
896K-943K E0000-EBFFF 47K AMI System BIOS
800-895K C8000-DFFFF 96K Available HI DOS memory (open to ISA and
PCI bus)
640K-799K A0000-C7FFF 160K On-board video memory and BIOS
639K 9FC00-9FFFF 1K Extended BIOS Data (moveable by QEMM†,
386MAX†)
512K-638K 80000-9FBFF 127K Extended conventional
0K-511K 00000-7FFFF 512K Conventional

2.2 I/O Map

Table 7. I/O Map

Address (hex) Size Description
0000 - 000F 16 bytes PIIX3 - DMA 1
0020 - 0021 2 bytes PIIX3 - Interrupt Controller 1
0040 - 0043 4 bytes PIIX3 - Timer 1
0060 1 byte Keyboard Controller Byte - Reset IRQ
0061 1 byte PIIX3 - NMI, speaker control
0064 1 byte Kbd Controller, CMD/STAT Byte
0070, bit 7 1 bit PIIX3 - Enable NMI
0070, bits 6:0 7 bits PIIX3 - Real Time Clock, Address
0071 1 byte PIIX3 - Real Time Clock, Data
continued ☛