Appendix B. System Address Maps
Appendix B. System Address Maps
System Memory Map
Memory can be mapped differently if POST detects an error.
Table 50. System Memory Map (Fixed Address Ranges)
Address Range (Dec)
Address Range (Hex)
Size
Description
0–511 KB
00000–7FFFF
512 KB
Conventional
512 KB–638 KB
80000–9FBFF
127 KB
Extended conventional
639 KB
9FC00–9FFFF
1 KB
Extended BIOS data (moveable
by HIMEM, QEMM, 386MAX)
640 KB–767 KB
A0000–BFFF
128 KB
Video RAM
768 KB–799 KB
C0000–C7FFF
32 KB
Video ROM BIOS (shadowed)
800 KB–895 KB
C8000–DFFFF
96 KB
PCI/ISA space – available to ISA
adapter ROMs
896 KB–1 MB
E0000–EFFFF
F0000–FFFFF
128 KB
System POST only - available
after boot
ROM BIOS
1 MB–16 MB
100000–FFFFFF
15 MB
PCI/ISA space
16 MB–4095.872 MB
1000000–FFFDFFFF
4079.9 MB
PCI space (positive decode)
4095.872 MB–4096 (4 GB)
FFFE0000–FFFFFFFF
128 KB
System ROM BIOS (ISA bus)
Copyright IBM Corp. 1997
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