Absolutely fantastic:) I've rather fallen into the trap of thinking of kernel code, including drivers, as being some sort of deep magic beyond human comprehension, but this makes it seem utterly straightforward; map a chunk of memory in the "hardware", map the memory in the OS, wire it up, use that to communicate. Is this how it works on newer OSs (*BSD, Linux, Illumos)? Are there equivalent tutorials for any modern FOSS *nix?