Abstract. This paper deals with simulation and reversibility in the context of Cellular Automata (ca). We recall the de nitions of ca and of the Block (bca) and Partitioned (pca) subclasses. We note that pca simulate ca. A simulation of reversible ca (r-ca) with reversible pca is built contradicting the intuition of known undecidability results. We build a 1-r-ca which is intrinsic universal, i.e., able to simulate any 1-r-ca.