Legacy ISA I/O Address Assignments

The following table lists I/O addresses used by legacy ISA devices and therefore considered fixed.

Legacy ISA System I/O

I/O AddressDefault system function
0000 � 000FSlave DMA
0010 � 0018System
0001FSystem
0020 � 0021Master 8259
0040 � 0043, 0048 � 004BPIT #1, PIT #2
0050 � 0052System
0060Keyboard / mouse controller
0061System control port B
0064Keyboard / mouse status
0070 � 0071NMI Enable / real-time clock
0081 � 008BDMA page registers
0090 � 0091System
0092System control port A
0093 � 009FSystem
00A0 � 00A1Slave interrupt controller
00C0 � 00DEMaster DMA controller
00F0 � 00F1Coprocessor busy clear/reset
0170 � 0177Secondary IDE controller
01F0 � 01F7Primary IDE controller
0201Joystick interface
0220 � 022FSound Blaster
0278 � 027ALPT 2 (XT parallel port 3)
02E8 � 02EFAlternate COM (4)
02F8 � 02FFCOM 2
0330 � 0331MPU-401
0376IDE Controller
0378 � 037ALPT 1 (XT parallel port 2)
0388 � 038BFM synthesis
03B0 � 03BBMDA, EGA / VGA
03BC � 03BELPT 3 (XT parallel port 1)
03C0 � 03DFEGA / VGA
03E0 � 03E7PCIC PCMCIA controllers
03E8 � 03EFAlternate COM (3)
03F0 � 03F7FDC
03F8 � 03FFCOM 1
0534 � 0537Windows Sound System-compatible
0CF8 � 0CFBPCI ports