According to Wikipedia, P′′ is a "primitive computer programming language created by Corrado Böhm in 1964 to describe a family of Turing machines." P′′ contains only four instructions has influenced languages such as Brainfuck.

While a modern interpreter would not be too difficult to write (I'm debating tackling it as a weekend project myself), are there any modern P′′ interpreters? What about references to the original source code/interpreter from the '60s?