Memory-mapped I/O (MMIO) and port-mapped I/O (PMIO) are two complementary methods of performing enter/output (I/O) between the central processing unit (CPU) and peripheral gadgets in a pc (typically mediating entry by way of chipset). An alternative strategy is using devoted I/O processors, generally often known as channels on mainframe computer systems, which execute their own directions. The memory and registers of the I/O devices are mapped to (associated with) address values, so a memory address might discuss with both a portion of physical RAM or to Memory Wave Experience and registers of the I/O machine. Every I/O machine both screens the CPU's tackle bus and responds to any CPU access of an address assigned to that device, connecting the system bus to the desired gadget's hardware register, or makes use of a dedicated bus. To accommodate the I/O gadgets, some areas of the tackle bus utilized by the CPU should be reserved for I/O and should not be obtainable for normal physical memory