readme-2021.md, status-2021.md — the front page and status of the old YACC1-2020 git repo (2021-03/07).
pcb-readme-2021.md — how the old PCB/Production vs Working folders were meant (replaced by the per-card layout here).
NOTES Jan 2:17 orig.rtf — January 2017 build notes (gen-1 → 2020 transition ideas).
general-notes/ — 2020 design notes (NOTES-Update from old project.rtf, dev notes.rtf).
The 142 MB yacc1.pptx presentation (and the 90 MB PDF of it in the gen-1 backup) are NOT in the tree: see
migration/large-files-manifest.tsv for their location and checksums.