I've finally built a second revision of the latest board, which fixes the issue with the CompactFlash card's DSACK generation.  See here for more details.  With the latest board, it can now load and boot the kernel from the CompactFlash card.  I fixed the mistaken footprints for the 74HC253 chips as well, and spaced the logic chips out more, to make it easier to assemble and bodge.  It was a dream to assembly, by comparison to the first revision.  I think it took me 4 to 6 hours in total, where the previous revision took 4 days of 6 - 8h each.

I honestly haven't touched it much after getting it working.  I've been distracted by another project.  But eventually I'll get around to modifying the kernel to allow virtual memory and isolated address spaces for processes, as well as work on the eventual multi-card computer version.