Communication with memory-mapped devices actually works pretty well in other languages. And surprisingly badly in C: when trying to directly use memory mapped

Communication with memory-mapped devices actually works pretty well in other languages. And surprisingly badly in C: when trying to directly use memory mapped space as backing store for C objects, compilers have freedoms about the memory accesses, which doesn't mix well with finicky mmio devices. (There are also platform differences which make this pretty nonportable). Reads and writes to memory mapped devices can be represented as eg function calls in other languages (and commonly in C too).