Micro computer manuals taught me how to write good documentation
Two of my many IT related treasures are a copy of the original ZX Spectrum and BBC Model B manuals, safely stored in the spare room. As the guy said in the article, manuals in those days were real documentation and they shaped the way I still write docs today. I write to my target audience, writing to the lowest common demoninator I know will need to read it and including everything you need to know without having to go away and learn tons. The Amstrad CPC manuals were real works of art, the originals in those binders and the wire-bound ones were just so clear and concise.
I must get myself Amstrad and Dragon32 manuals off ebay...