I meant that in an engineering sense, not a theoretical one, and deliberately moved from "computer program" to "code." If I have Lisp code that I want to run, and all I can run it in is C, it's not going to work. To get it to work, it's often easier to write a Lisp interpreter in C and use the old code than rewrite the code myself. And that's two languages intended to be used by humans and operate on silicon substrates with binary logic.
And so, can you write a 'human interpreter' on silicon with binary logic? Theoretically, sure. Practically, there might not be enough silicon to faithfully emulate it in anything close to realtime. But even if you manage it, you've just moved the platform into the realm of software- you haven't divorced the code and the platform.
My informed but ultimately presumably inaccurate guess is: if I buy about a million or so high end GPUs, and a few hundred petabytes of hard drives, I am somewhere in the ballpark of a human brain.
Given Moores law, that number is going to diminish. Given more knowledge about neurology valuable reductions in simulation complexity will be possible; you probably won't need a chromodynamics simulation to accurately replicate personality, the thermal noise in our brainware is far too great to depend on that kind of accuracy.
But yes, a human interpreter is ultimately possible because human minds are neuron actvity and neuron activity is physics and physics are as far as we know, turing computable.
Here is a 2-hour slide presentation I made for college students and teens:
You Are A Brain
It's an introduction to realist thinking, a tour of all the good stuff people don't realize until they include a node for their brain's map in their brain's map. All the concepts come from Eliezer's posts on Overcoming Bias.
I presented this to my old youth group while staffing one of their events. In addition to the slide show, I had a browser with various optical illusions open in tabs, and I brought in a bunch of lemons and miracle fruit tablets. They had a good time and stayed engaged.
I hope the slides will be of use to others trying to promote the public understanding of rationality.
Note: When you view the presentation, make sure you can see the speaker notes. They capture the gist of what I was saying while I was showing each slide.
Added 6 years later: I finally made a video of myself presenting this, except this time it was an adult audience. See this discussion post.