Input/Output Base Address
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In x86 architecture, an input/output base address is a base address used for an I/O port.
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[edit] 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 |
This list is incomplete; you can help by expanding it.
Note: For many devices listed above the assignments are only defaults which can be changed via jumpers, DIP switches, or software.
[edit] See also
- IRQ - interrupt request
[edit] References
HelpPC Quick Reference Utility by David Jurgens
[edit] 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
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