There's been quite a few of these systems over time. Especially sold commercially.

IBM System/38, evolved into AS/400 and IBM i, is one of architectures described in this book:

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

Far as language-based security, the first mainframe for businesses used a high-level language combined with a CPU that dynamically checked the programs. Still sold by Unisys but I doubt hardware checks still exist.

http://www.smecc.org/The%20Architecture%20%20of%20the%20Burr...

The Flex Machine implemented capabilities and trusted procedures in the microcode:

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

ASOS supported a mix of methods where each app was Ada for its safety features but a MLS kernel modeled in Gypsy separated various security levels:

https://pdfs.semanticscholar.org/42a4/e6f812538c18461277c58a...

SAFE explored tagging at CPU level which got commercialized as CoreGuard or Inherently Secure Processor:

http://www.crash-safe.org/papers.html

https://www.draper.com/explore-solutions/inherently-secure-p...

In embedded, there's Java processors that run bytecode natively with some support for separation. They blur the line between VM's and native apps:

http://ajile.com/index.php?option=com_content&view=article&i...

He's probably talking about AS/400, and it's hardware/software codesigned VM. For some reason people call those mainframes.

AS/400 though does use hardware heavily in it's isolation model, going so far as to have a custom PowerPC variant currently that adds tagged memory.

Both AS/400 and System/370 have a so called language environments.

And yes I call them mainframes, because it is as I always heard people referring to them during my Summer job back in the day, so the name stuck with me even it isn't correct.

Language environment in IBM parlance is closer to "ABI" than "VM", or "sandbox" in the rest of the world. It's a common set of idioms to allow two languages (generally ASM and a higher level language like C) to call eachother and interoperate.