This program is an interpreter for Post-Turing programs. It is a solution for the PhD qualification exam in Programming Languages at Stevens Institute of Technology as posed by Adriana Compagnoni in the Fall of 2007. This program is based on the code given in the appendix of the exam.
You can run the code in DrRacket. The following code taken from the exam shows how to use the interpreter:
(unparse (run (input-to-tape '(B 1 1 1)) (prog(parse-instrs copyx) 1)))