I re-found Red Hat 9 - "Shrike" the other day. The Red Hat site had some seriously detailed manuals that go with that. Clear, large, good.
Red Hat 9, I would call, the first of the modern Linux distributions. I know that Debian was in good shape about that time... but... overall the market-share wasn't so hot for Deb at that time.
Now, I am an ubuntu fanatic...!
But, if you feel like ubuntu is masking too much of the nuts and bolts, yet, still...