The "trick" of single-operation ISAs is that in order to achieve Turing completeness, they have to pick an instruction that effectively "encodes" multiple diffe

The "trick" of single-operation ISAs is that in order to achieve Turing completeness, they have to pick an instruction that effectively "encodes" multiple different instructions. So if you actually wanted to make and optimize one enough to be a "real" computer, you'd effectively end up with a conventional RISC architecture, where the only difference would be this weird way to encode instructions sprinkled on top of it. Once you're there, it's just Turing machines all the way up: build a compiler, build an interpreter, run nodejs, whatever. Processors are so fast these days you could probably live with the inefficiency, assuming sufficiently smart compilers are available for the architecture. It's just... not that different. Computers are weird like that.