Both he and I realized that there's lots of answers to modern problems in those old papers, as history repeats a lot in IT. The field has a problem of passing wisdom down to next generations or just generalizing solutions. The constraints and OS/hardware competitiveness also made lots of inherently interesting solutions to problems that you're unlikely to see re-appear outside of embedded or special-purpose. Fun stuff to read.

If interested, Timeline of Operating Systems is a good start. Just pick summary of anything major (minus DOS's) and dig into references if it interests you.

https://en.wikipedia.org/wiki/Timeline_of_operating_systems

The capability systems were also forward-thinking with much modern work on OOP, isolation, etc slowly reinventing its methods. Easy extension plus strong security/reliability were their thing.

https://homes.cs.washington.edu/~levy/capabook/index.html

Here's a paper vezzy-fnord shared with a lot of nice examples with features that defined future work and some still ahead of modern systems:

http://brinch-hansen.net/papers/2001b.pdf

Lots of old stuff that still beats modern, mainstream stuff on key metrics. Hopefully, you'll dig into some of it and enjoy the "arcane" stuff yourself. It's arcane, but sometimes awesome too. :)