I had to patch 2.0 series kernels to support my propriatery-interface 1X CD drive.  (LMSI CM 205).

 

I tried backtracking to a distro which had a prepatched 1.3 kernel for it.

 

I recall kde b3 (pre-1.0) on a 20Mb 486-80.

 

I recall the libc5/libc6 mess.  Trying to make Wordperfect 8.0 run on distros after the libraries it depended on had obsolescenced.  I recall when WP8 for linux could be bought in compusa, that 15 minute window, I got a rebate on it.