I didn’t notice this one being mentioned:
http://www.smecc.org/The%20Architecture%20%20of%20the%20Burroughs%20B-5000.htm
The Architecture of the Burroughs B5000 - 20 Years Later and Still Ahead of the Times?
(article from 1982/1999)
Someone brought that up in Twitter when the CHERI architecture coming to ARM was being discussed (Department of Computer Science and Technology: Capability Hardware Enhanced RISC Instructions (CHERI))