IN/OUT access to addresses above 2^16?

How can I load/store data to the periphery which a开发者_开发百科ddress is bigger than 2¹⁶ with IN/OUT instructions.

When I use IN/OUT instruction, lets say OUT DX, AL, I know that the segment register of DX is not used so I can access only the first 2¹⁶ addresses (because DX is 16 bits wide).

One of my devices is on the address 18000h. How can I reach it? The memory/IO space overlaps (the M/IO pin is not used), so is it ok to say something like

MOV BX, 18000h
MOV [BX], AL

You can't with IN or OUT instruction!

The x86 processor supports an I/O address space that contains up to 65,536 8-bit I/O ports.

From Intel datasheet:

The processor permits applications to access I/O ports in either of two ways:

• Through a separate I/O address space
• Through memory-mapped I/O

Accessing I/O ports through the I/O address space is handled through a set of I/O instructions and a special I/O protection mechanism. Accessing I/O ports through memory-mapped I/O is handled with the processors general-purpose move and string instructions, with protection provided through segmentation or paging. I/O ports can be mapped so that they appear in the I/O address space or the physicalmemory address space (memory mapped I/O) or both.