Every IBM AS/400 (and its predecessors S/36, S/38) came with all the manuals which took up more than one book shelf (IIRC back in the day this made IBM the largest publisher in the world). In high school I had this minimal wage office job where my responsibilities were not entirely clear, but I spent a lot of time reading those manuals, especially the "Structured Query Language/400" and RPG IV, and eventually negotiated a programming job because I was able to completely automate the tasks I was given.

Thinking back, I think those "systems" (as IBM referred to them) were pretty cool. You could upgrade any part of it, including the central processing units without taking it down, which is pretty remarkable even today. As I recall a "reboot" was referred to as IPL (Initial Program Load) and you only did those when IBM said it was necessary - those things never crashed.