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8 System Resources
8.1 System Memory Map
Address Range (decimal)
Address Range (hex)
Size
Description
Start 128KB below 1MB
000E0000h-000FFFFFh
Low BIOS
Starts 20MB below 4GB
FEC00000h-FEC0040h
IO APIC
Start 19MB below 4GB
FED00000h-FED003FFh
HPET
Start 64 KB below 4GB
FFFF0000h-FFFFFFFFh
High BIOS
0K –1MB
1MB DOS
DRAM
8.2 I/O Map
Hex Range
Device
20h-21h, 24h-25h, 28h-29h, 2Ch-
2Dh, 30h-31h, 34h-5h, 38h-39h,
3Ch-3Dh
8259 Master
40h-43h, 50h-53h
8254s
60h, 64h
PS2 Control
61h, 63h, 65h, 67h
NMI Controller
70h-77h RTC
80h-83h Port
80h
92h Init
Register
A0h-A1h, A4h-A5h, A8h-A9h, ACh-
ADh, B0h-B1h,B4h-B5h, B8h-B9h,
BCh-BDh, 4D0h-4D1h
8259 Slave
2E8h-2FFh
COM2
3F8h-3FFh
COM1
B2h-B3h
Active Power Management
400h
PM Base address
500h
GPIO Base address
E000
SMBus base address for SB