I don’t remember when the last time I worked with a computer that even had a manual as such. I think it was my TI-99/4A, but it could have been the Tandy 1000HX.

Edit: wrongola! Turns out, the last machine I worked with that had a real manual was either a MicroVAX, or a PDP-11, both of which I used in college. Writing ASM for the PDP-11 was great! I just wish I was better at program then, lol. :)