Well, I started by reading through the UPM (the 8-section thing, with commands in I, system calls in II, etc). I also read a lot of Unix documentation which came as larger documents (e.g the Unix Intro, C Tutorial and spec, etc). I should point out that back then, this was a feasible task. Most man pages were really _a_ page, and often a short one. By the end of my time on the PWB1 system, there were about 300 commands in /bin (which includes sections II, VI and VIII), but a good chunk (I'd say probably 50 or more) were ones we'd written. So there were not that many to start with (section II was maybe 3/4" of paper), and you could read the UPM in a couple of hours. (I read through it more than once; you'd get more retained, mentally, on each pass.) There were no Unix people at all in the group at MIT which I joined, so I couldn't ask around; there were a bunch in another group on the floor below, although I didn't use them much - mostly it was RTFM. Mailing lists? Books? Fuhgeddaboutit! My next step in learning the kernel was to start reading the sources. (I didn't have access to Lyons.) I did an 'cref' of the entire system, and transferred the results to a large piece of paper, so I could see who was calling who in the kernel. That's all there was! I should point out that reading the sources to command 'x' taught you more than just how 'x' worked - you saw how people interacted with the kernel, what it could do, etc, etc. Noel