from bochs: http://bochs.sourceforge.net/techspec/PORTS.LST

0x0000-0x001F	The first legacy DMA controller, often used for transfers to floppies.
0x0020-0x0021	The first Programmable Interrupt Controller
0x0022-0x0023	Access to the Model-Specific Registers of Cyrix processors.
0x0040-0x0047	The PIT (Programmable Interval Timer)
0x0060-0x0064	The "8042" PS/2 Controller or its predecessors, dealing with keyboards and mice.
0x0070-0x0071	The CMOS and RTC registers
0x0080-0x008F	The DMA (Page registers)
0x0092	        The location of the fast A20 gate register
0x00A0-0x00A1	The second PIC
0x00C0-0x00DF	The second DMA controller, often used for soundblasters
0x00E9	        Home of the Port E9 Hack. Used on some emulators to directly send text to the hosts' console.
0x0170-0x0177	The secondary ATA harddisk controller.
0x01F0-0x01F7	The primary ATA harddisk controller.
0x0278-0x027A	Parallel port
0x02F8-0x02FF	Second serial port
0x03B0-0x03DF	The range used for the IBM VGA, its direct predecessors, as well as any modern video card in legacy mode.
0x03F0-0x03F7	Floppy disk controller
0x03F8-0x03FF	First serial port
