In the memory mapped I/O interfacing , peripherals are connected/interfaced over the address bus. If there are 32 address lines , then theoretically we can interface 2 power 32 devices to the CPU. This interfacing also includes MEMR and MEMW (Memory Read and Memory write signals).
In the Port Mapped I/O interfacing , peripherals are again connected to the same address lines . Just the instructions for reading and writing would be different like inportb and outportb and the control signals would be IOR and IOW (IO READ and IO WRITE) . But the number of devices which can be interfaced will probably be less i.e. 2 power 16 .
Why is this difference between Memory Mapped I/O and Port Mapped I/O.