 Traditionally, a computational system is intended as a mechanical artifact that takes input data, elaborates them algorithmically according to a set of instructions, and returns manipulated data as outputs. For instance, von Neumann (1945, p.1) states that “An automatic computing system is a (usually highly composite) device, which can carry out instructions to perform calculations of a considerable order of complexity”. Such an informal and well-accepted definition leaves some questions open, including whether computational systems have to be machines, whether they have to process data algorithmically and, consequently, whether computations have to be Turing complete.