In the x86 architecture, an input/output base address is a base address of an I/O port. In other words, this is the first address of a range of consecutive I/O port addresses that device uses.
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This table represents the common I/O address ranges for device assignments in IBM PC compatible computers. The base address is the first in each range. Each row of the table represents a device or chip within the computer system. For example, the address status port in the LPT device is 0x0001, adding the base address of LPT1 (0x0378) results in the address of the LPT1 status port being 0x0379.
When there are two or more identical devices in a computer system, each device would be mapped to a different base address (e.g. LPT1 and LPT2 for printers).
| I/O address range | Device |
|---|---|
| 00 – 1F | First DMA controller 8237 A-5 |
| 20 – 3F | First Programmable Interrupt Controller, 8259A, Master |
| 40 – 5F | Programmable Interval Timer (System Timer), 8254 |
| 60 – 6F | Keyboard, 8042 |
| 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 Programmable Interrupt Controller, 8259A, Slave |
| C0 – DF | Second DMA controller 8237 A-5 |
| F0 | Clear 80287 Busy |
| F1 | Reset 80287 |
| F8 – FF | Math coprocessor, 80287 |
| F0 – F5 | PCjr Disk Controller |
| F8 – FF | 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 |
| 2E2 – 2E3 | Data acquisition |
| 2F8 – 2FF | COM2 serial port |
| 300 – 31F | Prototype Card |
| 300 – 31F | Novell NE1000 compatible Ethernet network interfaces |
| 300 – 31F | AMD Am7990 Ethernet network interface, IRQ=5. |
| 320 – 323 | ST-506 and compatible hard disk drive interface |
| 330 – 331 | MPU-401 MIDI Processing Unit 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. Primary IDE controller (slave drive) (3F6–3F7h) |
| 3F8 – 3FF | COM1 serial port |
| CF8 – CFC | PCI configuration space |
Note: For many devices listed above the assignments can be changed via jumpers, DIP switches, or Plug-And-Play software.
HelpPC Quick Reference Utility by David Jurgens