Memory-Mapped Input and Output: A Device Register Is an Address
Memory-mapped input and output is the trick that makes hardware look like memory: the system reserves a block of addresses that do not belong to any memory chip, and wires them to a device instead. Storing a number at one of those addresses sets a register on the card, and loading from it reads one. This is why a driver can control hardware with ordinary load and store instructions, and why writing to the wrong address can command a device you never meant to touch.
Questions this Concept answers
- Why does memory mapping let a driver control hardware with ordinary load and store instructions?
Memory Mapped IO versus IO Mapped IO in Computer Architecture
Memory-mapped I/O and I/O-mapped I/O are two competing schemes for how a processor addresses peripheral devices: memory-mapped I/O assigns peripherals addresses within the same unified address space …