Location of Port mapped I/O address space
问题 I know access to ports in I/O address spaces requires specific IN/OUT instructions and they are not part of Physical memory( RAM) but I have not understood Where is the I/O address space actually located (Physically)? (some sort of RAM in )I/O controller? Reserved side of physical memory? 回答1: On the early X86 processors (and also the 8080, Z80 etc) I/O address space was on the same data and address bus as the memory, but was accessed by activating a dedicated IO-request pin on the CPU So