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4 BIOS Overview
BIOS Addresses
BIOS Addresses
This section provides a summary of the main features of the HP system BIOS.
This is software that provides an interface between the computer hardware
and the operating system.
System Memory Map
Reserved memory used by accessory boards must be located in the area from
C8000h to EFFFFh.
HP I/O Port Map (I/O Addresses Used by the System
1
)
Peripheral devices, accessory devices and system controllers are accessed via
the system I/O space, which is not located in system memory space. The 64 KB
of addressable I/O space comprises 8-bit and 16-bit registers (called
I/O ports) located in the various system components. When installing an
accessory board, ensure that the I/O address space selected is in the free area
of the space reserved for accessory boards (100h to 3FFh).
0000 0000 - 0000 03FF Real-mode IDT
0000 0400 - 0000 04FF BIOS Data Area
0000 0500 - 0009 FC00 Used by OS
0009 FC00 - 0009 FFFF Extended BIOS Data Area
000A_0000 - 000B_FFFF Video RAM or
SMRAM (not visible unless in SMM)
000C 0000 - 000C 7FFF Video ROM
000C 8000 - 000F FFFF Adapter ROM, RAM, memory-mapped registers
000E 0000 - 000F FFFF System BIOS (Flash/Shadow)
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10 0000 - FF FFFF Memory (1 MB to 16 MB)
100 0000 - 1FF FFFF Memory (16 MB to 32 MB)
200 0000 -3FF FFFF Memory (32 MB to 64 MB)
400 0000 -1FFF FFFF Memory (64 MB to 512 MB)
FFFC0000 - FFFF FFFF 256 KB BIOS (Flash)
1.
This is for Physical memory. As soon as the PST has been
completed, the E0000-E8000 segment is released for UMBs.
1. If configured.
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