In memory-mapped I/O . . . . . . . .

the i/o devices and the memory share the same address space
the i/o devices have a separate address space
the memory and i/o devices have an associated address space
a part of the memory is specifically set aside for the i/o operation

The correct answer is: A. the i/o devices and the memory share the same address space.

In memory-mapped I/O, I/O devices are accessed through the same memory addresses as regular memory locations. This allows the CPU to access I/O devices directly, without the need for special I/O instructions.

Option B is incorrect because I/O devices do not have a separate address space. They share the same address space as regular memory locations.

Option C is incorrect because the memory and I/O devices do not have an associated address space. They share the same address space.

Option D is incorrect because a part of the memory is not specifically set aside for the I/O operation. The I/O devices share the same address space as regular memory locations.