I was clued in on this by some buds in the Tandy TRS-80 community. It not only has loads of those manuals, but also books on Math and Science and Crackpottery! From Principia Mathematica and The Portrait in Photography to Mein Kampf and (dig it!) Adam Weishaupt: A Human Devil! Yes, campers, Mr Illuminati was both real and has had people writing bad stuff about him for the past 200+ years.
Check it out and report back with your finds. All available OCRed inaccurately, poorly edited, and in an assortment of formats.