Geheugenmapped

Geheugenmapped, in English memory-mapped, is a method for interfacing with devices and memory where a device's registers and buffers are assigned specific addresses within the system’s main memory address space. This lets software access device functionality using standard load and store instructions, rather than specialized I/O instructions.

In a memory-mapped I/O system, hardware decodes part of the address space to route accesses to a device’s registers or its memory region. The same address space may include RAM, ROM and device memory. This approach contrasts with port-mapped I/O, where devices are accessed through separate I/O ports. Memory-mapped access can simplify software and enable large, contiguous buffers, but it also requires careful handling of caching, ordering and synchronization.

Applications are common in embedded systems and general-purpose computing. Peripherals such as graphics memory, network controllers and peripheral sensors can be mapped into the CPU’s address space. Operating systems often map device memory into user space via mechanisms like mmap. Architectures use PCIe memory regions (BARs) and other MMIO areas to expose device memory and registers to the CPU.

Key considerations include endianness, alignment, caching and memory coherency. Many systems designate device memory as non-cacheable or write-combining to preserve ordering and data freshness. Synchronization primitives such as memory barriers and cache coherence protocols are important, especially when DMA is involved. Geheugenmapped remains a fundamental technique across modern CPUs and embedded platforms.