Input/Output Base Address

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Base address is also called I/O port, I/O address, I/O port address and base port.

[edit] Common I/O Base Address Device Assignments in IBM PC compatible computers

Base Address	Device
0f - 1f	First DMA Controller 8237 A-5
20 - 3f	First Interrupt Controller 8259A, Master
40 - 5f	8254-2
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
170-177	Secondary ATA Hard Disk Controller
1f0 - 1f7	Primary ATA Hard Disk Controller
200 - 20f	Game Controller/Joystick
210 - 217	Expansion Unit
278 - 27f	LPT2 Parallel port
280 - 29F	LCD on Wyse 2108 PC SMC Elite default factory setting
2e8 - 2ef	COM4
2e1	GPIB Adapter 0
2f8 - 2ff	COM2
2e2 - 2e3	Data acquisition
300 - 31f	Prototype Card
300 - 31f	3Com EtherLink default factory setting
320 - 32f	XT Hard disk interface
378 - 37f	LPT1 Parallel port
380 - 38c	SLDC/Secondary Bi-sync interface
3a0 - 3a9	Primary Bi-sync interface
3b0 - 3bb	Monochrome display
3c0 - 3cf	EGA display control
3d0 - 3df	Color/Graphics Display (CGA)
3e8 - 3ef	COM3
3f0 - 3f7	Floppy disk controller
3f8 - 3ff	COM1

[edit] See also

• IRQ - interrupt request

[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