ec1842 (not in MESS -- not sure if there are any dumps) is another interesting (aka horrible) beast -- it was apparently designed to run protected-mode OS for i286 (not sure if it was an original design or not).

But instead of i286 or its clone it uses a modified i8086 + external MMU + software emulator for opcodes that aren't implemented in the silicon.

The emulator --

Ongoing discussion --