What real platforms map hardware ports to memory addresses?

Question

I sometimes see statements that on some platforms the following C or C++ code:

int* ptr;
*ptr = 0;

can result in writing to a hardware input-ou

Answer 1

An NDIS driver on Windows is an example. This is called memory mapped I/O and the benefit of this is performance.

Answer 2

Motorola 68k series and PowerPC are the big ones.