It's a neat photo, but I'm not the type to be satisfied with just looking at a historical document when I could be reading it. I did some digging , and I found this page on the NASA History website.You'll find a scanned to PDF copy of this manual, but you'll also find a bunch of other really shiny stuff.
BTW, some of the comments on Reddit are priceless.
You know what makes this really mindblowing? Not only did they have less computing power than a Commodore-64 did... but they managed to get PDFs to display.
Adobe's Reader wasn't so bloated back then.