Of the following, which best characterizes computers that use memory-mapped I/O?

A

The computer provides special instructions for manipulating I/O ports

B

I/O ports are placed at addresses on the bus and are accessed just like other memory locations

C

To perform I/O operations, it is sufficient to place the data in an address register and call channel to perform the operation

D

I/O can be performed only when memory management hardwareis turned on