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4-18 System Board
Memory Map
The system memory map is shown in the following table.
System Memory Map
Memory Space Size Function
100000-18000000 383 MB Extended memory
FC000-FFFFF 16 KB Boot block
FA000-FBFFF 8 KB ESCD (Plug and Play Configuration and DMI)
F9000-F9FFF 4 KB Reserved for BIOS
F8000-F8FFF 4 KB OEM logo or Scan User Flash
E8000-E7FFF 64 KB POST BIOS
E0000-E7FFF 32 KB POST BIOS (currently available as UMB)
C8000-D7FFF 96 KB Available HI DOS memory (open to ISA and PCI bus)
A0000-C7FFF 160 KB Video memory and BIOS
9FC00-9FFFF 1 KB Extended BIOS data (movable by memory manager software)
80000-9FBFF 127 KB Extended conventional memory
00000-7FFFF 512 KB Conventional memory
I/O Addresses
The processor communicates with I/O devices by I/O mapping. The
hexadecimal (hex) addresses of I/O devices are listed in the following table.
Note
:
In Plug and Play systems, these addresses are
typical but may vary by configuration.
I/O Address Map
Address (Hex) I/O Device Name
0000-000F PIIX4 - DMA controller 1 (channel 0-3)
0020-0021 PIIX4 - interrupt controller 1
002E-002F Super I/O controller configuration registers
0040-0043 PIIX4 - counter/timer 1
0048-004B PIIX4 - counter/timer 2
0060 Keyboard controller byte - reset IRQ
0061 PIIX4 - NMI, speaker control
0064 Keyboard controller, command/status byte