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Memory map – IBM BDM-610000049 User Manual

Page 69

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BDM-610000049

Rev G

Chapter 4: Using the cpuModule

59

Memory Map

Table 41 shows how memory in the first megabyte is allocated in the system.

Memory beyond the first megabyte can be accessed in real mode by using EMS or a similar memory manager.
See your OS or programming language references for information on memory managers.

Table 41

First Megabyte Memory Map

Address (hex)

Description

C0000–FFFFFh ROM

256 KB BIOS in Flash EPROM, shadowed into DRAM during runtime.

C0000–EFFFFh

Run time user memory space. Usually, memory between C0000h and CFFFFh
is used for the BIOS of add-on VGA video cards.

A0000–BFFFFh

Normally used for video RAM as follows:

EGA/VGA
Monochrome
CGA

0A0000–0AFFFFh
0B0000–0B7FFFh
0B8000–0BFFFFh

00502–9FFFFh

DOS reserved memory area

00400–00501h

BIOS data area

00000–003FFh

Interrupt vector area