Memory map – IBM CMX58886CX User Manual
Page 61
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