Tuesday, October 21, 2014

What is the difference Memory Mapped I/O and I/O mapped I/O?

In memory mapped I/O , the devices share the memory space with our RAM whereas in I/O mapped I/O the devices have separate address space than the memory.So, in I/O mapped I/O we can increase the address capacity of the system.
I/O mapped I/O uses special instructions to access the devices(IN, OUT).Since the external devices are not as fast as the processor so, I/O mapped I/O helps reduce the timing difference between the CPU and memory.The main advantage of memory mapped I/O is that it is easier to program it and it is suported by all the instructions and addressing mode(behave as if it is normal memory access).

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