4 BIOS overview

BIOS addresses

Although the Setup program can be used to change some of the settings, the following address map is not completely BIOS dependent, but is determined partly by the operating system. Note that some of the I/O addresses are allocated dynamically.

 

I/O Address PortsFunction

 

 

 

0000

- 000F

DMA controller

 

 

0010-001F, 0022 -003F, 0044-005F,

Motherboard resources

0062-0063, 0065-006F, 0072-007F, 0084-0086,

 

04D0-04D1, 0080, 0088, 008C-008E, 0090-009F,

 

00A2-00BF, 00E0-00EF, 0400-047F, 0480-04BF,

 

04D0-04D1, 0800-0847F

 

 

 

 

0020

- 0021, 00A0-00A1

Programmable Interupt Controller

 

 

 

0040

- 0043

System Timer

 

 

0060, 0064

PC/AT Enhanced Keyboard

 

 

 

0061

 

System Speaker

 

 

 

0070

- 0071

RTC and CMOS data

 

 

 

0081

- 0083, 008F, 0087, 0089-008B,

DMA Controller

00C0-00DF

 

 

 

00F0 - 00FF

Numeric Data Processor

 

 

 

0170

- 0177

Ultra ATA Controller, Secondary ATA Controller

 

 

01F0 - 01F7

Ultra ATA Controller, Primary ATA Controller

 

 

 

0376

 

Ultra ATA Controller, Secondary ATA Controller

 

 

 

0378

- 037F, 0778 - 077F

LPT1 ECP

 

 

03F8 - 03FF

COM1

 

 

0CF8 - 0CFF

PCI bus

 

 

03B0-03BB, 03C0-03DF

Chipset Graphic Drivers

 

 

0540-054F

SMBus controller

 

 

B000-BFFF

PCI Bridge

 

 

BC00-BC7F

NIC

 

 

03F6, FFA0 - FFA7, FFA0-FFAF

Ultra ATA Controller, Primary ATA Controller

 

 

D400-D41F

USB Universal Host Controller

 

 

D800-D83F, DCFF

Audio

 

 

FFA0-FFA7

Primary ATA Controller

 

 

FFA0-FFAF

Ultra ATA Controller

 

 

FFA8-FFAF

Secondary ATA Controller

 

 

 

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