Muistikartoitettuja

Muistikartoitettuja is a Finnish term that translates to "memory-mapped" in English. In the context of computer architecture and operating systems, it refers to a mechanism where a region of the computer's physical memory is directly associated with a hardware device or a specific area of memory. This direct mapping allows the CPU to access the hardware device's registers or memory as if it were just another location in RAM.

This technique is commonly used for input/output (I/O) operations. Instead of using dedicated I/O instructions, which can be slower and require special privileges, memory-mapped I/O allows devices to be controlled and accessed using the same load and store instructions used for regular memory access. This simplifies the instruction set and can improve performance.

Common examples of memory-mapped hardware include graphics cards, network interfaces, and peripheral control registers. When a program writes data to a memory address that is memory-mapped to a graphics card's frame buffer, that data appears on the display. Similarly, reading from a memory-mapped address associated with a network card might retrieve incoming data packets.

The operating system plays a crucial role in managing memory-mapped regions. It allocates specific address ranges to devices and ensures that these mappings are consistent and do not conflict with regular memory usage. This allows applications to interact with hardware in a standardized and efficient manner without needing to know the intricate details of the underlying hardware. The concept of memory mapping is fundamental to how modern operating systems and hardware interact.