Input/Output Base Address
In x86 architecture, an input/output base address is a base address used for an I/O port.
Common I/O Base Address Device Assignments in IBM PC compatible computers
Base Address |
Device |
|---|---|
00 - 1f |
First DMA Controller 8237 A-5 |
20 - 3f |
First Interrupt Controller 8259A, Master |
40 - 5f |
8254-2 System Timer |
60 - 6f |
8042, Keyboard |
70 - 7f |
Real Time Clock, NMI mask |
80 - 9f |
DMA Page Register, 74LS612 |
87 |
DMA Channel 0 |
83 |
DMA Channel 1 |
81 |
DMA Channel 2 |
82 |
DMA Channel 3 |
8b |
DMA Channel 5 |
89 |
DMA Channel 6 |
8a |
DMA Channel 7 |
8f |
Refresh |
a0 - bf |
Second Interrupt Controller 8259A, Slave |
c0 - df |
Second DMA Controller 8237 A-5 |
f0 |
Clear 80287 Busy |
f1 |
Reset 80287 |
f8 - ff |
80287 Math coprocessor |
0f0 - 0f5 |
PCjr Disk Controller |
0f8 - 0ff |
Reserved for future microprocessor extensions |
100 - 10f |
POS Programmable Option Select (PS/2) |
110 - 1ef |
System I/O channel |
140 - 15f |
Secondary SCSI host adapter |
170 - 177 |
Secondary Parallel ATA Disk Controller |
1f0 - 1f7 |
Primary Parallel ATA Hard Disk Controller |
200 - 20f |
Game port |
210 - 217 |
Expansion Unit |
220 - 233 |
Sound Blaster and most other sound cards |
278 - 27f |
LPT2 parallel port |
280 - 29f |
LCD on Wyse 2108 PC SMC Elite default factory setting |
2b0 - 2df |
Alternate Enhanced Graphics Adapter (EGA) display control |
2e8 - 2ef |
COM4 serial port |
2e1 |
GPIB/IEEE-488 Adapter 0 |
2f8 - 2ff |
COM2 serial port |
2e2 - 2e3 |
Data acquisition |
300 - 31f |
Prototype Card |
300 - 31f |
Novell NE1000 compatible Ethernet network interfaces |
320 - 323 |
ST-506 and compatible hard disk drive interface |
330 - 331 |
MPU-401 UART on most sound cards |
340 - 35f |
Primary SCSI host adapter |
370 - 377 |
Secondary floppy disk drive controller |
378 - 37f |
LPT1 parallel port |
380 - 38c |
Secondary Binary Synchronous Data Link Control (SDLC) adapter |
388 - 389 |
AdLib Music Synthesizer Card |
3a0 - 3a9 |
Primary Binary Synchronous Data Link Control (SDLC) adapter |
3b0 - 3bb |
Monochrome Display Adapter (MDA) display control |
3bc - 3bf |
MDA LPT parallel port |
3c0 - 3cf |
Enhanced Graphics Adapter (EGA) display control |
3d0 - 3df |
Color Graphics Adapter (CGA) |
3e8 - 3ef |
COM3 serial port |
3f0 - 3f7 |
Primary floppy disk drive controller |
3f8 - 3ff |
COM1 serial port |
Note: For many devices listed above the assignments are only defaults which can be changed via jumpers, DIP switches, or software.
See also
- IRQ - interrupt request
References
HelpPC Reference Library by David Jurgens
External links
- Base address term definition from Webopedia
- Introduction to IRQs, DMAs and Base Addresses Copyright © 1999, Eugene Blanchard, Published in Issue 38 of Linux Gazette, March 1999
- The PC Guide
- Apogee FAQ at RinkWorks
- Programming the AdLib/Sound Blaster FM Music Chips
- I/O Ports and Controllers on IBM Compatibles and PS/2 at OS/2 Site Australia