We show how to use recursive function theory to prove Turing universality of finite analog recurrent neural nets, with a piecewise linear sigmoid function as activation function. We emphasize the modular construction of nets within nets, a relevant issue from the software engineering point of view. Keywords. Neural computation, recursive function theory, modularity. 							
						
							
					 															
					João Pedro Guerreiro Neto, Hava T. Siegelma