From the 2020 iteration of CCC, “What have we lost” is a presentation by TQ Hirsch, Calvin Bucley and Landon Rodgers. Covering, perhaps,
- Genera from Symbolics
- Interlisp-D
- BTRON (still in use - a legacy of Japan’s TRON)
- i from IBM (also still in use)
#rC3 - What have we lost? (50 mins plus 15mins Q&A)
via discussion at HN
also, semantically nearby and linked within but much mainstream, a legit online copy of a book, covering the rudiments of how to drive Unix, VMS, OS/400, VM/CMS, MVS:
- Fake Your Way Through Minis and Mainframes (456 pages)
by Bob DuCharme (originally published in 1994 as “The Operating System Handbook”)