I wish more people knew about the Burroughs Large Systems[0] machines. I haven't written any code for them, but I got turned-on to them by a financial Customer who ran a ClearPath Series A MCP system (and later one of the NT-based Clearpath machines with the SCAMP processor on a card) back in the late 90s, and later by a fellow contractor who did ALGOL programming for Unisys in the mid-70s and early 80s. It seems like an architecture with an uncompromising attitude toward security, and an utterly parallel universe to what the rest of the industry is (except for, perhaps, the IBM AS/400, at least in the sense of being uncompromising on design ideals).

[0] https://en.wikipedia.org/wiki/Burroughs_Large_Systems

Yes, IBM i and z/OS, are the other survivors.