https://www.cs.brandeis.edu/~dkw/papers/ieee-hst-2013-paper....
The usable part of the work was a metadata co-processor that could enforce micro-policies:
http://nikos.vasilak.is/p/pump:hasp:2014.pdf
It was spun off as Dover’s CoreGuard which I don’t know much about:
https://www.dovermicrosystems.com/solutions/coreguard/
The original design did for your CPU what Jesus Christ does for your soul. Keeps it from burning up due to user failures or external attacks. The product can’t guarantee eternal life but others are researching that.
Back to the devices, there’s at least two families of coprocessors: typed, tagged designs like Burroughs B5000 and capability security like CHERI. SAFE was more like Burroughs or even System/38’s object-centered approach. If patents are a concern, one could always just redo B5000 model itself since it’s more secure than any mainstream architecture.