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BDM-610000050 Rev A Chapter 4: Using the cpuModule 53
Memory Map
The ISA portion of the cpuModule addresses memory using 24 address lines. This allows a maximum of 2
24
locations, or 16 MB of memory.
Table 36 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 36 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