Memory-mapped I/O (MMIO) and MemoryWave Guide port-mapped I/O (PMIO) are two complementary methods of performing enter/output (I/O) between the central processing unit (CPU) and peripheral units in a pc (often mediating access by way of chipset). An alternative method is using devoted I/O processors, commonly often called channels on mainframe computer systems, which execute their very own instructions. The memory and registers of the I/O units are mapped to (related to) tackle values, so a memory handle might seek advice from both a portion of physical RAM or to memory and registers of the I/O device. Every I/O system either screens the CPU's address bus and responds to any CPU access of an deal with assigned to that system, connecting the system bus to the desired machine's hardware register, or makes use of a devoted bus. To accommodate the I/O devices, some areas of the address bus used by the CPU should be reserved for I/O and must not be obtainable for regular bodily memory

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Pub: 23 Nov 2025 04:56 UTC

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