Often, data stored in memory must be protected from naturally occurring and malicious errors. Methods for constructing codes that are robust with respect to errors injected into the data as well as into the address (in which the data are to be stored) are described. Several ways of extending data-protecting codes to address-and-data protecting codes are presented, and a generalization of the concepts behind CPCs – low cost codes for which no error injected into the data is ever completely masked – is given. A fundamental difference between attacks on the address and data and attacks that only target the data is detailed, and the consequences of this fundamental difference are briefly considered.