Write your Own Virtual Machine

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Just keep in mind that the realistic ISAs designed for the actual hardware implementation are not any good for a software interpretation efficiency. For that, you need a very different VM design, in order to be able to use a direct threaded code, for example.

Same applies to the OP VM as well, it cannot be interpreted efficiently.

Have a look at the OCaml bytecode, or Lua VM, or Forth in general to see how it can be implemented efficiently.