Shared memory mappings for devices

IBM used to do that in all its manuals as well, and it's an irritating style because acronyms are not abbreviations - they're words in their own right that are better known and have more meaning than the words from which they are derived. Sometimes the acquired meanings even contradict those words. The etymology of the acronym is still useful, of course, but the right way to do it is RAM (Random Access Memory), not Random Access Memory (RAM).

RAM is an interesting example, by the way, because words used illogically was another peeve Byte editors had and the magazine never used RAM to mean what most people meant by it: read/write memory. The term in Byte for that was "programmable memory." RAM would appear in Byte only in contrast with sequential access memory.