[ The PC Guide | Systems and Components Reference Guide | Motherboard and System Devices | System Resources | Input / Output (I/O) Addresses ]
I/O Address Summary Map
The table below shows the I/O addresses from 000 to 3FFh, along with the devices that typically use them. This table is slightly different than the ones that show default and optional use of IRQs and DMA channels. There are many different addresses of different sizes, so in order to keep the table a manageable size, it was made somewhat two-dimensional. Each row is 16 bytes and is divided into four columns; the first is for bytes 0 to 3, the second 4 to 7, the third 8 to B and the fourth C to F. So to find address 3BCh, you would look in the fourth column of row "3B0-3BFh".
Items in the table in bold print represent standard devices in a typical PC configuration. Items in regular print represent optional devices or optional locations for addresses of standard devices. Blank spaces are areas that are open. Multiple lines are used to show multiple items that go in the same address space. Where you see two or more items overlapping in the same address space, there is the potential for a resource conflict.
To see I/O address usage organized by device instead of address, see this device resource summary instead:
Addr. |
First Quad |
Second Quad |
Third Quad |
Fourth Quad |
000-00Fh |
DMA controller, channels 0 to 3 |
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010-01Fh |
(System use) |
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020-02Fh |
Interrupt controller #1 (020-021h) |
(System use) |
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030-03Fh |
(System use) |
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040-04Fh |
System timers |
(System use) |
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050-05Fh |
(System use) |
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060-06Fh |
Keyboard & PS/2 mouse (060h), Speaker (061h) |
Keyboard & PS/2 mouse (064h) |
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070-07Fh |
RTC/CMOS, NMI (070-071h) |
(System use) |
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080-08Fh |
DMA page register 0-2 (081-083h) |
DMA page register 3 (087h) |
DMA page registers 4-6 (089-08Bh) |
DMA page register 7 (08Fh) |
090-09Fh |
(System use) |
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0A0-0Afh |
Interrupt controller #2 (0A0-0A1h) |
(System use) |
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0B0-0BFh |
(System use) |
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0C0-0CFh |
DMA controller, channels 4-7 (0C0-0DFh, bytes 1-16) |
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0D0-0DFh |
DMA controller, channels 4-7 (0C0-0DFh, bytes 17-32) |
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0E0-0Efh |
(System use) |
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0F0-0FFh |
Floating point unit (FPU/NPU/Math coprocessor) |
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100-10Fh |
(System use) |
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110-11Fh |
(System use) |
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120-12Fh |
(System use) |
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130-13Fh |
SCSI host adapter, (130-14Fh, bytes 1 to 16) |
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140-14Fh |
SCSI host adapter, (130-14Fh, bytes 17 to 32) |
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SCSI host adapter, (140-15Fh, bytes 1 to 16) |
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150-15Fh |
SCSI host adapter, (140-15Fh, bytes 17 to 32) |
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160-16Fh |
Quaternary IDE controller, master drive |
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170-17Fh |
Secondary IDE controller, master drive |
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180-18Fh |
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190-19Fh |
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1A0-1AFh |
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1B0-1BFh |
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1C0-1CFh |
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1D0-1DFh |
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1E0-1EFh |
Tertiary IDE controller, master drive |
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1F0-1FFh |
Primary IDE controller, master drive |
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200-20Fh |
Joystick port |
(System use, 20C-20Dh) |
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210-21Fh |
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220-22Fh |
Sound card |
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SCSI host adapter, (220-23Fh, bytes 1 to 16) |
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230-23Fh |
SCSI host adapter, (220-23Fh, bytes 17 to 32) |
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240-24Fh |
Sound card |
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Non-NE2000 network card |
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NE2000 network card (240-25Fh, bytes 1 to 16) |
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250-25Fh |
NE2000 network card (240-25Fh, bytes 17 to 32) |
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260-26Fh |
Sound card |
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Non-NE2000 network card |
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NE2000 network card (260-27Fh, bytes 1 to 16) |
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270-27Fh |
(System use) |
Plug and Play system devices |
LPT2 (second parallel port) (color systems) |
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LPT3 (third parallel port) (monochrome systems) |
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NE2000 network card (260-27Fh, bytes 17 to 32) |
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280-28Fh |
Sound card |
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Non-NE2000 network card |
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NE2000 network card (280-29Fh, bytes 1 to 16) |
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290-29Fh |
NE2000 network card (280-29Fh, bytes 17 to 32) |
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2A0-2Afh vvv |
Non-NE2000 network card |
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NE2000 network card (2A0-2BFh, bytes 1 to 16) |
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2B0-2BFh |
NE2000 network card (2A0-2BFh, bytes 17 to 32) |
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2C0-2CFh |
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2D0-2DFh |
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2E0-2Efh |
COM4 (fourth serial port) |
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2F0-2FFh |
COM2 (second serial port) |
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300-30Fh |
Sound card (MIDI port) (300-301h) |
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Non-NE2000 network card |
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NE2000 network card (300-31Fh, bytes 1 to 16) |
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310-31Fh |
NE2000 network card (300-31Fh, bytes 17 to 32) |
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320-32Fh |
Non-NE2000 network card |
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NE2000 network card (320-33Fh, bytes 1 to 16) |
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Hard disk controller on old PC/XT |
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330-33Fh |
Sound card (MIDI port) (330-331h) |
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NE2000 network card (320-33Fh, bytes 17 to 32) |
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SCSI host adapter, (330-34Fh, bytes 1 to 16) |
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340-34Fh |
SCSI host adapter, (330-34Fh, bytes 17 to 32) |
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SCSI host adapter, (340-35Fh, bytes 1 to 16) |
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Non-NE2000 network card |
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NE2000 network card (340-35Fh, bytes 1 to 16) |
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350-35Fh |
SCSI host adapter, (340-35Fh, bytes 17 to 32) |
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NE2000 network card (340-35Fh, bytes 17 to 32) |
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360-36Fh |
Tape accelerator card (360h) |
Quaternary IDE controller (slave drive) (36E-36Fh) |
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Non-NE2000 network card |
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NE2000 network card (360-37Fh, bytes 1 to 16) |
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370-37Fh |
Tape accelerator card (370h) |
Secondary IDE controller (slave drive) (376-377h) |
LPT1 (first parallel port) (color systems) |
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LPT2 (second parallel port) (monochrome systems) |
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NE2000 network card (360-37Fh, bytes 17 to 32) |
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380-38Fh |
Sound card (FM synthesizer) |
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390-39Fh |
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3A0-3AFh |
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3B0-3BFh |
VGA/Monochrome Video |
LPT1 (first parallel port) (monochrome systems) |
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3C0-3CFh |
VGA/EGA Video |
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3D0-3DFh |
VGA/CGA Video |
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3E0-3EFh |
Tape accelerator card (3E0h) |
COM3 (third serial port) |
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Tertiary IDE controller (slave drive) (3EE-3EFh) |
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3F0-3FFh |
Floppy disk controller |
COM1 (first serial port) |
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Tape accelerator card (3F0h) |
Primary IDE controller (slave drive) (3F6-3F7h) |
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Next: Logical
Devices
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