James, all computer simulations are programmed by a set of instructions that are translated into a machine language native to the computer on which the instructions are executed.
The difference between a compiled set of instructions and an interpreted set is slight; both are what is called Turing-complete. Both are efficient. Instructions that use compilers take a comparatively longer time to write and a comparatively shorter time to execute; interpretative instructions take a comparatively shorter time to write and a comparatively longer time to execute. It all comes out in the wash; some methods are better adapted to specific tasks than others.
I suggest that to simulate a continuous function such as Joy's, with two randomly fluctuating (dichotomous) variables, the interpretative method reduces the chance that the random function (called ThrowDie in Chantal Roth's simulation) can be corrupted in the compilation of code. Though I can't speak as an expert -- perhaps one will show up.
No computer actually computes a continuous function -- computer code is digital. A differential equation, e.g., is converted to a difference equation before being executed in a program. The function can be made arbitrarily smooth.
(cf., the iteration of an n-sided-gon into the approximation of a circle. Or imagine that the randomly thrown straight lines of uniform length -- by which one can calculate curvature to arbitrary accuracy, by a Monte Carlo algorithm on a grid -- are not bound by grid lines, and nevertheless generates a beautiful regular curve, such as the sine wave of Joy's model, in a coordinate free manner. Are we looking at the wave function of the universe? If such a wave lives in the space of all possible correlated points of a parallelized 3-sphere, we need postulate neither wave function collapse nor nonlocality, to get the same strong quantum correlations as predicted by quantum theory.)
Tom