Programmatically speaking ... saying "the brain is a program" or "the universe is a program" raises some eyebrows. Likewise, replacing "brain" with "mind" or "program" with "computer".
The first objection might be that while there might be the possibility of a program on some supercomputer that simulates the brain, it will not be able to experience feelings like our brains actually do. Our brains, for one thing, are interacting with different kinds of chemicals, and a computer without these chemical molecules cannot experience things like how food tastes. A simulation running in a silicon-based computer will never experience anything like that.
I think this objection is correct. But counter unconventional conomputationalism to be the natural (or physical) alternative to what has been called computationalism (the idea that everything is some sort of abstract computation or simulation). There are not just silicon-based computers, but a variety of other natural (e.g. chemical-based) computers as well. (Now a program running on a silicon-based computer is a physical thing as well, just a different type of physical thing: electrons flowing through silicon gates.) This is the what is called "unconventional computing".
So in the view of uncomp (to shorten "unconventional computationalism") that there are no such things as "abstract" (in the sense of idealism or Platonism) computers or programs, only natural ones, and that silicon-based computers are not the only kinds of computers, then the brain could be viewed as follows: The brain is a neuron-based, chemical-based computer that can experience feelings that a silicon-based computer cannot by the nature of its physical substrate.
Uncomp sees nature as programs/computers. But as with programs on silicon-based computers, natural programs are compiled into a native code which are made of natural materials. ("Printouts" from 3D printers are becoming the realization of manufacturing versions of this, making even biological tissues that could replace organs in the human body.) There is even the far-out idea of black hole programs which can process an actual infinite number of steps in finite time, but that is just speculation.
On "program" vs. "computer": In terms of abstraction (in the concrete sense of this word in computer science, not in the idealistic sense of philosophy) layers, a program goes all the way down to pushing electrons through circuits. So taking the whole set of layers as a unit, one could refer to the while unit as (an integrated) program/computer. But talking about a "program/computer" is a little clumsy, so using "program" or "computer" should suffice without confusion as long as one refers to the upper layers as programs, the lower levels as "computer". Some hardware is microprogrammable, and some hardware is reconfiguarable.
So in the example of the robot that can experience taste like we can: In conventional computationalism, one might claim (dubiously, I think) that a silicon-based robot brain with the right programming might "experience" the same. But in uncomp, the actual chemicals involved in the human brain may have to be involved in the processing in the robot brain as well.
A simulation is not an assembly.
References:
Unconventional computing
Chemical computer
Blobotics
Malament-Hogarth spacetime
Abstraction layer
Programming the Universe
Reverse engineering
Molecular assembler
Unconventional Computation & Natural Computation 2014
